Litter size at birth in purebred dogs--a retrospective study of 224 breeds

Maternal and fetal factors for determining the cesarean section type (scheduled/emergency) in bitches

One hundred and forty bitches and their offspring (689 puppies) were involved in this study. The influence of different maternal features such as age, breed (brachycephalic/non-brachycephalic), previous births (primiparous/multiparous), health status (complete/incomplete) and litter size over the type of cesarean sections (scheduled/emergency), the neonatal survival, and the incidence of congenital malformations were also examined. Scheduled cesareans were predominant (104/140), of which 90 % were brachycephalic breeds and females were mostly between 2 and 4 years old (54.8 %), multiparous (88.4 %) and with a correct health status (67.3 %). Emergency cesarean sections mainly involved non-brachycephalic breeds (80 %) and were carried out mostly in females under 4 years of age (72.2 %), primiparous (77.7 %), with incomplete health status and a large litter size (47.2 %). Perinatal mortality was notably higher in emergency C-sections (3.25 % and 13.3 %, scheduled and emergency C-sections, respectively); the highest incidence of neonatal mortality was recorded in young females (<2, 2-4 years old), primiparous and with incomplete health status. Congenital anomalies were observed in 4.50 % (31/689) of the puppies, with anasarca (38.71 %) and cleft palate (29.03 %) being the most frequently observed malformations. A higher incidence of congenital malformations was detected in puppies from dams with incomplete sanitary health and from inbreeding cross. Overall, the study provides valuable insights into the complex interplay between maternal characteristics and cesarean outcomes. Appropriate genetic selection, good sanitary health conditions, and the age of the reproducers, are pivotal factors in planning for gestation and improving the survival of neonates.

Evaluation of embryo-foetal biometry and its correlation with parturition date in Toy Poodle bitches

Estimating the parturition date in dogs is challenging due to their reproductive peculiarities that. Ultrasonographic examination serves as a tool for studying embryo/foetal biometry and estimating the time of parturition by measuring foetal and extra-foetal structures. However, due to reproductive differences among various dog breeds, such estimates may have a non-significant pattern, representing inaccuracies in the estimated date of birth. This study aimed to monitor pregnant Toy Poodle bitches and establish relationships between ultrasonographically measured foetal and extra-foetal dimensions and the remaining time until parturition. Eighteen pregnant Toy Poodle bitches were subjected to weekly ultrasonographic evaluations and measurements of the inner chorionic cavity diameter, craniocaudal length (CCL), biparietal diameter (BPD), diameter of the deep portion of diencephalo-telencephalic vesicle (DPTV), abdominal diameter, thorax diameter (TXD), placental thickness and the renal diameter (REND). These parameters were retrospectively correlated with the date of parturition and linear regressions were established between gestational measurements and days before parturition (DBP). All analyses were conducted using the Statistical Package for Social Sciences (IBM® SPSS®) program at a 5% significance level. The foetal measurements that showed a high correlation (r) and reliability (R2) with DBP were BPD [(DBP = [15.538 × BPD] - 39.756), r = .97 and R2 = .93], TXD [(DBP = [8.933 × TXD] - 32.487), r = .94 and R2 = .89], DPTV [(DBP = [34.580 × DPTV] - 39.403), r = .93 and R2 = .86] and REND [(DBP = [13.735 × REND] - 28.937), r = .91 and R2 = .82]. This statistically validates the application of these specific formulas to estimate the parturition date in Toy Poodle bitches.

Scientific and technical assistance on welfare aspects related to housing and health of cats and dogs in commercial breeding establishments

This Scientific Report addresses a mandate from the European Commission according to Article 31 of Regulation (EC) No 178/2002 on the welfare of cats and dogs in commercial breeding establishments kept for sport, hunting and companion purposes. The aim was to scrutinise recent recommendations made by the EU Platform on Animal Welfare Voluntary Initiative on measures to assist the preparation of policy options for the legal framework of commercial breeding of cats and dogs. Specifically, the main question addressed was if there is scientific evidence to support the measures for protection of cats and dogs in commercial breeding related to housing, health considerations and painful procedures. Three judgements were carried out based on scientific literature reviews and, where possible a review of national regulations. The first judgement addressed housing and included: type of accommodation, outdoor access, exercise, social behaviour, housing temperature and light requirements. The second judgement addressed health and included: age at first and last breeding, and breeding frequency. Judgement 3 addressed painful procedures (mutilations or convenience surgeries) and included: ear cropping, tail docking and vocal cord resections in dogs and declawing in cats. For each of these judgements, considerations were provided indicating where scientific literature is available to support recommendations on providing or avoiding specific housing, health or painful surgical interventions. Areas where evidence is lacking are indicated.

Association between Birth Weight and Mortality over the Two First Months after Birth in Feline Species: Definition of Breed-Specific Thresholds

In many species, low birth weight is identified as a major determinant for neonatal survival. The objectives of the present study were (i) to assess, in a large feline purebred population, the impact of birth weight on 0-2 months mortality in kittens, and (ii) if such mortality occurs, to define cut-off values for birth weight to identify at-risk kittens. Data from 5596 kittens from 15 breeds and provided by 194 French breeders were analysed. A logistic mixed model was used to identify low birth weight, being a male, and being born in a large litter as significant risk factors for kitten mortality during the first two months after birth. Classification and regression tree analysis was used to define the thresholds, first at the species level and, when possible, at the breed level. Two thresholds were defined to group kittens into three categories: low, moderate, or high risk of 0-2 months mortality (normal, low, and very low birth weight, respectively). In our population, 19.7% of the kittens were classified as low birth weight and 1.9% as very low birth weight. Critical thresholds may differ between breeds with similar birth weight distributions and equivalent mortality rates (e.g., Russian Blue/Nebelung vs. Egyptian Mau). These critical birth weight thresholds, established in 15 breeds, could be used to identify kittens requiring more intensive nursing to improve survival.

[Real-time analysis of parturition in bitches of a medium-sized breed]

OBJECTIVE

Observation of the birth processes in healthy bitches under controlled conditions. The primary aim was to gain more insight into the natural birth process. Additional goal was to determine under which circumstances caregivers seek veterinary assistance.

MATERIAL AND METHODS

Data regarding length of gestation, the course of the parturition process, litter size, as well as neonatal characteristics were collected from 345 Boxer bitches. A real-time evaluation supplied the data concerning the birth process itself. Statistical analysis included single- and multi-factor variance analyses, as well as correlation, regression, and rank correlation analyses.

RESULTS

Mother dogs with fewer fetuses were gravid for a significantly longer period than those with a high number (p=0.0012). The proportion of live neonates decreased significantly from the 5th litter onwards (p=0.0072). Female neonates exhibited a lower birth weight than male neonates (p<0.0001). Diurnal influences on the onset of stage II were not found. Birth processes could be divided into 3 groups based on the recorded progression: group 1 - eutocia (54.6%), group II - eutocia with prophylactic measures by the caregiver (20.5%), and group III - dystocia (24.9%). Bitches of group 1 were slightly younger than those of groups 2 and 3. In groups 2 and 3, the proportion of older primiparae (≥4 years) was significantly higher than in group 1 (p<0.05). The total duration of labor differed significantly between groups 1 and 2 (p<0.0001). Significant differences were seen between the groups in labor activity. In group 3, the proportion of bitches with a type I (=primary) weakness in labor was strikingly high (45.2%). In 83.8% of the births (groups 1 and 2), one or more pauses in labor (>60 min) occurred during the expulsive phase. This was correlated with litter size (p=0.0025), but not with age or birth number. The rate of stillbirth was positively correlated with duration of the birth process. Reasons for veterinary intervention primarily pertained to conditions of type II and III labor weakness (inadequate contractions of the uterus during parturition). The average time span between identification of a birth disorder and presentation of the bitch to a practice/clinic was 4.8±3.3 hours.

CONCLUSION AND CLINICAL RELEVANCE

In pre-partum-counselling, special attention should be paid to conditions of hyperfetia (>20% above the mean) as well as uniparous and biparous gravidity and these dams should be classified as risk patients with regard to the course of parturition. In the case of birth complications, rapid veterinary intervention is warranted in order to minimize the development of maternal inanition and fetal vitality depression.

Bayesian analysis of genetic and environmental effects on litter traits in a red fox (Vulpes vulpes) herd under long-term selection

The economic efficiency of fur animal farms is considerably influenced by reproductive performance. The objectives of this study are to determine the effects of individual and maternal inbreeding, birth year, and dam and sire age on litter size at birth (LSB) and at weaning (LSW) and on preweaning mortality (PWM) in a red fox herd under long-term selection, and to determine the heritability of these traits. In total, 37,973 pedigreed individuals were used to calculate the inbreeding coefficients, based on records of 14,527 litters of 3856 dams born from the year 1958 to 2015. Two data sets (all data and data for the Polish variety) were analyzed. The highest heritability was estimated for PWM (0.292, 0.306) and the lowest for LSW (0.114, 0.115). In contrast to paternal and maternal inbreeding, litter inbreeding was found to exert a significant influence. The absence of significant effects of most varieties may suggest relatively large genetic similarity in the world red fox population. This corresponds with the similarity of the results obtained for the total herd and for the Polish variety. Favorable genetic trends were observed for the studied traits, indicating that the selection applied had been a relatively effective approach to improving these traits.

Prevalence of cesarean sections in swiss Bernese Mountain Dogs (2001-2020) and identification of risk factors

BACKGROUND

Dystocia is an important limiting factor in animal breeding due to its cost, stress for the mother and risk of death for the neonates. Assessment of incidence and characteristics of dystocia and the inherent risk of Cesarean section are of major importance. The aim of the present study was to evaluate the reproductive performance of Bernese Mountain Dogs in Switzerland, with a particular focus on the prevalence of Cesarean sections due to dystocia, and identification of possible risk factors.

RESULTS

The investigated population included 401 bitches, 207 sires, and 1127 litters. Litter size was significantly influenced by age and parity of the dam. Incidence of Cesarean section was 30.4%, with 2.0% of procedures being elective. History of previous Cesarean section, age of the dam, and a small litter size significantly influenced the risk for Cesarean section. The stillbirth rate was 12.0%, and the number of stillborn pups was significantly higher for litters delivered by Cesarean sections after birth of the first pup. The inbreeding coefficient had a low to non-significant impact on all reproductive parameters (e.g., litter size, number of stillborn pups).

CONCLUSION

The sample of Bernese Mountain Dogs of our study had an increased prevalence of Cesarean sections compared to the literature, and advanced age of the dam, litter size and prior Cesarean sections in the dam's reproductive history was identified as significantly influencing factors. In order to improve pups' survival rate, elective Cesarean section may be indicated in bitches that have had a previous Cesarean-section/s, are of advanced age, and/or have a small litter.

Involvement of Oxytocin and Progesterone Receptor Expression in the Etiology of Canine Uterine Inertia

An altered oxytocin and progesterone receptor (OXTR and PGR, respectively) expression was postulated in canine uterine inertia (UI), which is the lack of functional myometrial contractions. OXTR and PGR expressions were compared in uterine tissue obtained during C-section due to primary UI (PUI; n = 12) and obstructive dystocia (OD, n = 8). In PUI, the influence of litter size was studied (small/normal/large litter: PUI-S/N/L: n = 5/4/3). Staining intensity in immunohistochemistry was scored for the longitudinal and circular myometrial layer and summarized per dog (IP-Myoscore). Mean P4 did not differ significantly between PUI (n = 9) and OD (n = 7). OXTR and PGR expressions (ratios) were significantly higher in PUI (OXTR: p = 0.0019; PGR: p = 0.0339), also for OXTR in PUI-N versus OD (p = 0.0034). A trend for a higher PGR IP-Myoscore was identified (PUI-N vs. OD, p = 0.0626) as well as an influence of litter size (lowest PGR-Myoscore in PUI-L, p = 0.0391). In conclusion, PUI was not related to higher P4, but potentially increased PGR availability compared to OD. It remains to be clarified whether OXTR is upregulated in PUI due to a counterregulatory mechanism to overcome myometrial quiescence or downregulated in OD due to physiological slow OXTR desensitization associated with an advanced duration of labor. Identified OXTR differences between myometrial layers indicate the need for further research.

Factors affecting reproductive performance in the Swedish Bernese mountain dog

Background

Good reproductive performance is fundamental for the development of a breed. Previous studies have indicated that the Bernese mountain dog has a relatively high prevalence of reproductive problems such as a high prevalence of dystocia and a low mean litter size. When reproduction is impaired, selection for other traits, including improved health, will become more difficult. The aim of this study was therefore to evaluate reproductive data and factors affecting these in the Bernese mountain dog. Data collected by the Swedish Sennenhund Club during the years 2010–2020 were evaluated by statistical analyses.

Results

Information from 1287 reported matings were included with a total of 614 bitches and 399 sires. For five reported matings that did not result in a litter, there was no information about the male identity. The reported matings resulted in 798 litters (62% whelping rate) from 502 bitches and 314 males. Paternal and maternal age had a significant effect on whelping rate with a negative effect of increasing age (P < 0.01). Median litter size at birth (LSB) was 6.00 (range 0–14) and was significantly affected by both paternal (P = 0.021) and maternal age (P < 0.001). Parity affected litter size at birth with a lower litter size in 4 year old bitches giving birth to their first litter compared to bitches giving birth to their second to fourth litters. Stillbirth occurred in 51.6% of the litters with a total of 15.4% puppies being stillborn. Total puppy mortality, including stillbirth, was 19.1%. The only factor affecting stillbirth was LSB while both LSB and season affected the risk of having post-natal puppy loss in the litter. The total prevalence of caesarean sections (CS) was 33.0%. The risk of CS decreased significantly with increasing parity and increased with increasing age. The risk of CS was significantly higher for litters with 1–2 puppies compared with litters with 3–9 puppies. The coefficient of inbreeding (F) calculated on 5 generations had no effect on any of the outcomes.

Conclusions

Parity and maternal age had opposite effects on reproductive outcomes with a positive effect of parity on increasing litter size and decreasing CS rate. The proportion of unsuccessful matings was high with a negative effect of increasing age of both males and females.

Birth weight distribution in Golden and Labrador retriever dogs: A similar morphotype with a different trend. Preliminary data

Birth weight (bW) is considered an indicator of neonatal maturity and a predictor of neonatal mortality. According to its importance, many efforts have been made so far to identify physiological body weight ranges at birth. Due to the high heterogeneity among breeds, optimal bW is difficult to define in dogs. The aim of this study was to carefully analyze the shape and pattern of the bW distribution in dogs. Furthermore, the role of breed on bW determination was specifically investigated in relation to maternal (age, weight, height, diet, season, litter size) and neonatal (sex, malformations, assistance at birth) aspects. For these purposes two canine breeds with very similar phenotypic characteristics, Golden and Labrador retrievers, were selected. An accurate statistical model to explore bW distribution and compare it between Goldens and Labradors was developed. At birth most of the Golden and Labrador pups (estimated 95th percentile) weighed up to 630 g and 500 g, respectively. The estimated 5th percentile of bW distributions was 295 g in Golden and 290 g in Labrador pups. These lowest values could be indicative cut-offs of underweight pups. The probability of neonatal mortality within 1 week of life decreased with increasing bW (P = 0.031) and was higher in Golden than Labrador pups even though this difference was not significant. In conclusion, our results suggest that genetics have a relevant influence on the determination of birth weight which is confirmed to be closely associated with neonatal mortality.

Refining the APGAR Score Cutoff Values and Viability Classes According to Breed Body Size in Newborn Dogs

The Apgar score (AS) represents a key tool for neonate assessment, but the possible breed effect on AS in newborn puppies has never been investigated. Therefore, data from 234 dog litters born by caesarean section, grouped according to breed body size (BBS) (small, medium, large), were evaluated. Live-birth puppies were assessed through AS within 5 min of delivery, and classified in viability classes: 0−3 severely distressed, 4−6 moderately distressed, 7−10 not distressed. Statistical analysis evaluated possible differences of AS and viability class according to BBS, and between BBS and puppies’ mortality. Results showed no differences in the distribution of mortalities among BBSs. However, an effect of BBS on the AS was found, with small-sized puppies being the most represented in the severely distressed class, but having the best survival chance compared to large-sized newborns. Through receiver-operating-characteristics analysis, the AS new cutoff values for survival and for death <24 h and 24 h−7 days of age were identified, and the viability classes were redefined, with a narrower class of moderately distressed puppy specific for each BBS. In conclusion, the refining of the AS in dog species is imperative, with cutoff values and viability classifications that must be adapted to the BBS.

Dead or Alive? A Review of Perinatal Factors That Determine Canine Neonatal Viability

Simple Summary

The article summarizes the current knowledge on factors related to pregnancy, parturition, and newborns that affect the health status of a puppy and determine its chances for survival and development. The detailed information is provided in terms of breed predispositions, objectives of pregnancy monitoring, potential sources of complications, and veterinary advances in care and treatment of perinatal conditions. Successful pregnancy outcomes still pose challenges in veterinary neonatology; thus, publications presenting the current state of knowledge in this field are in demand.

Abstract

The perinatal period has a critical impact on viability of the newborns. The variety of factors that can potentially affect the health of a litter during pregnancy, birth, and the first weeks of life requires proper attention from both the breeder and the veterinarian. The health status of puppies can be influenced by various maternal factors, including breed characteristics, anatomy, quality of nutrition, delivery assistance, neonatal care, and environmental or infectious agents encountered during pregnancy. Regular examinations and pregnancy monitoring are key tools for early detection of signals that can indicate disorders even before clinical signs occur. Early detection significantly increases the chances of puppies’ survival and proper development. The purpose of the review was to summarize and discuss the complex interactions between all elements that, throughout pregnancy and the first days of life, have a tangible impact on the subsequent fate of the offspring. Many of these components continue to pose challenges in veterinary neonatology; thus, publications presenting the current state of knowledge in this field are in demand.

Factors influencing ease of whelping and its relationship with maternal behaviour and puppy perinatal mortality in commercially bred dogs

For dog breeders, parturition is a critical stage in the reproductive cycle of the dam. Evidence in other mammals suggests that a difficult labour can influence maternal behaviour and offspring viability during the first hours postpartum. However, the effect of whelping difficulty on the onset of maternal behaviour has not yet been investigated in domestic dogs. Here we developed an ease of whelping (EoW) index in dams maintained within a Commercial dog Breeding Establishment (CBE) environment and investigated the relationship between intrinsic and extrinsic factors (breed group according to size/weight, litter size, parity, whelping season and origin of the dam), EoW, early maternal behaviour and puppy perinatal mortality. The behaviour of 30 dams was observed throughout the whelping process, starting 24 h before delivery of the first puppy until birth of the last puppy. Parturition duration, birth interval, and behaviours indicative of distress, restlessness, and general activity were scored and included in a Principal Component Analysis to construct the EoW index. Subsequently, mother-pup interactions and puppy perinatal mortality were recorded during the first 24 and 72 h postpartum respectively. Results showed that EoW was significantly affected by whelping season, litter size and origin of the dam (whether she was born and raised within the CBE or brought in). Furthermore, mothers that experienced more difficult parturitions (higher EoW score) spent more time lying in contact with their puppies during the first 24 h postpartum. Time in contact with puppies was also significantly affected by breed group. Nursing duration was significantly affected by breed group and origin of the dam. Additionally, medium-size breed (10-20 kg) puppies were significantly less likely to experience perinatal mortality than large breeds (> 20 kg). These findings are particularly relevant for the welfare of breeding dams maintained in large-scale CBEs where the staff-to-dog ratio might be insufficient to adequately manage multiple simultaneous parturitions.

Progesterone Concentrations during Canine Pregnancy

Simple Summary

For breeders and bitches alike, pregnancy is a challenging period. Insufficient serum progesterone concentrations have frequently been suggested to be responsible for pregnancy loss or early parturition, without any scientific evidence to support those claims. In this study, a large number of bitches was followed throughout pregnancy, and serum progesterone concentrations were determined to deduce which concentrations could be considered normal. Three blood samples were collected, one each during early, mid and late pregnancy. The results indicated that progesterone concentrations can be lower than previously described as adequate in the veterinary literature, with the bitch still exhibiting no signs of pregnancy distress and giving birth to healthy puppies at the expected time.

Abstract

Pregnancy and lactation are amongst the most challenging times of a bitch’s life. Most studies focusing on the endocrinological aspect of pregnancy consider only a small number of animals. The aim of this study was to evaluate progesterone (P4) concentrations in a large number of bitches during early, mid and late pregnancy. In total, 126 bitches of various breeds were recruited following a thorough clinical and gynecological examination during estrus. Blood samples were collected three times (T1–T3) during pregnancy or from non-pregnant dogs in diestrus, and P4 was measured via chemiluminescence. At T1 (11–19 days post-ovulation (dpo)), serum P4 concentrations were 30.23 ± 6.65 ng/mL and 28.45 ± 6.26 ng/mL, at T2 (23–32 dpo) they were 22.73 ± 6.27 ng/mL and 22.59 ± 5.77 ng/mL and at T3 (52–60 dpo) they were 6.68 ± 2.18 ng/mL and 3.17 ± 2.26 ng/mL, in pregnant (n = 98) and non-pregnant (n = 23) dogs respectively. The P4 concentrations differed significantly between pregnant and non-pregnant animals at the last examination (p ≤ 0.001). In the context of hypoluteoidism, the gathered data yielded interesting results. Overall, 28 out of 98 pregnant bitches showed a greater decline (>15 ng/mL) in P4 concentrations from early to mid-pregnancy, and 56 bitches showed P4 concentrations lower than deemed adequate (>20 ng/mL at T1 and T2, >5 ng/mL at T3) according to existing recommendations. Despite not being supplemented with P4, none of those animals suffered from abortion or preterm delivery. Considering that supplementation of P4 can entail considerable risks for the bitch and the puppies, more research on P4 concentration patterns, diagnosis of hypoluteoidism and treatment indications and options is indicated.

Molecular basis for the evolved instability of a human G-protein coupled receptor

Membrane proteins are prone to misfolding and degradation. This is particularly true for mammalian forms of the gonadotropin-releasing hormone receptor (GnRHR). Although they function at the plasma membrane, mammalian GnRHRs accumulate within the secretory pathway. Their apparent instability is believed to have evolved through selection for attenuated GnRHR activity. Nevertheless, the molecular basis of this adaptation remains unclear. We show that adaptation coincides with a C-terminal truncation that compromises the translocon-mediated membrane integration of its seventh transmembrane domain (TM7). We also identify a series of polar residues in mammalian GnRHRs that compromise the membrane integration of TM2 and TM6. Reverting a lipid-exposed polar residue in TM6 to an ancestral hydrophobic residue restores expression with no impact on function. Evolutionary trends suggest variations in the polarity of this residue track with reproductive phenotypes. Our findings suggest that the marginal energetics of cotranslational folding can be exploited to tune membrane protein fitness.

Integral membrane proteins are prone to misfolding, especially mammalian gonadotropin-releasing hormone receptors (GnRHRs). Chamness et al. show that the evolved instability of mammalian GnRHRs stems from adaptive modifications that disrupt translocon-mediated membrane integration, suggesting that membrane protein misfolding can be exploited to tune fitness.

Investigations on the potential role of prostaglandin E2 in canine uterine inertia

Prostaglandin (PG) E2 plays a crucial role in the endocrine network of canine parturition and we hypothesized that PGE2, 15-hydroxyprostaglandin dehydrogenase (HPGD) and PG-transporter (PGT) might be involved in the development of primary uterine inertia (PUI). We investigated PTGE synthase (PTGES), PTGE receptors 2/4 (PTGER2/4), HPGD and PGT expression on the mRNA- and protein-level in interplacental (IP) and uteroplacental (UP) tissues of bitches presented with dystocia undergoing emergency caesarean section. Groups were formed retrospectively based on strict criteria: PUI (n = 12; small/normal/large litter - PUI-S/N/L: n = 5/4/3), and obstructive dystocia (OD, n = 8). Respective mRNA expressions (ratio) between PUI and OD in IP and UP, between PUI dogs with different litter sizes, between PUI-N and OD in IP, and overall between IP and UP were compared. PTGES, PTGER2, PTGER4, HPGD and PGT mRNA expressions did not differ significantly between PUI and OD in IP or UP. PUI-N PTGES mRNA expression was higher than PUI-S/L (P = 0.0203/P = 0.0186) and OD (P = 0.0314). Higher PTGES (P = 0.0112) and a tendency for higher PTGER2 (P = 0.059) mRNA-expressions were detected in UP versus IP. Other than hypothesized, we did not find a difference in PGE2 production and signaling between PUI and OD, indicating that altered uterine PTGES, PTGER2, PTGER4, HPGD and PGT expression was likely not causative for PUI. However, higher PTGES expression in PUI-N compared to OD might point to a possible role of PGE2 during the course of parturition. Higher PTGES expression in PUI-N compared to PUI-S/L indicates an influence of litter size, the underlying cause and biological relevance of which remain to be clarified.

The influence of lunar cycle at the time of conception on sex offspring distribution in dogs

The effect of seasonal variation and lunar cycles on reproductive parameters in dogs is unknown. Lunar cycles have important effects on several biological events. Controversy exists about the influence of lunar cycles on offspring sex ratio. This study examined the sex offspring distribution of 973 puppies (48% females and 52% males) from 150 bitches in Italy between 2015 and 2020. A two-way ANOVA followed by post-hoc t-test (Bonferroni correction) was used to analyze the influence of season and lunar phase on offspring sex ratio at conception. Sex offspring distribution was not affected by season, whereas lunar phase had a significant effect (p< .05). During the new moon, the proportion of male puppies born was significantly lower than during the full moon phase (p < .05). We conclude that season had no effect on sex offspring distribution. The new moon phase at conception appeared to be related to a lower male sex ratio at birth. Further studies assessing additional factors will help provide a better understanding of the lunar cycle differences observed in the sex ratio distribution of dogs.

Canine Placenta Histological Findings and Microvascular Density: The Histological Basis of a Negative Neonatal Outcome?

Simple Summary

Accurate examination of the placenta, mainly by gross inspection rather than by histology, is common in clinical practice in some species, for example, in horses, but not carried out routinely in dogs. Placenta alterations in the mare can indicate malfunction, and data exist that intrauterine fetal nutrition influences both perinatal health, but also performances in adult life. Often placenta lesions are not easily appreciable on macroscopical examination, and histology is the best way to assess damage associated with sick newborns. The results of this paper underline the association between placenta injuries and outcome conditions in puppies and confirm, also in dogs, histological placenta investigation as a useful adjunctive tool in the evaluation of the newborn’s health and prognosis.

Abstract

Placenta is essential for the development of the fetus, and its impaired function can lead to a negative outcome (i.e., neonatal mortality). In dogs, investigations on placenta histology and neonatal outcome in healthy bitches are lacking, and a contribution is provided in this study to emphasize the use of placenta histology in practice. Fifty-one placentas from 11 litters were collected during cesarean section, classified according to the litter size (large (L) or small (S)) and the outcome, this latter as healthy (Group 1) or dead within 7 days (Group 2). The placenta/puppy weight ratio (PPR) was calculated, and specimens were formalin-fixed and paraffin-wax embedded, and on the resulting histological slides, capillary density (CD) was quantified. Among necrosis, calcification, and intravascular leucocytes, only the presence of multifocal-confluent necrosis (significantly more frequent in Group 2) was associated with a higher risk of death within 7 days (odds ratio = 30.7). Mixed logistic regression ruled out the effect on death both of a bitch and cesarean type (programmed vs. emergency). PPR and CD values were associated with litter size; large litters had lower PPR (p < 0.01) and higher CD (p < 0.05) than small litters. The relationship between PPR and CD was negative and significant (p < 0.01). Necrosis was a frequent finding in canine placentas, but only when multifocal-confluent was it associated with a poor outcome. The litter size influenced PPR (lower in L) and CD (higher in L), and this is likely due to the plasticity of placenta adaptation.

Copy number variation underlies complex phenotypes in domestic dog breeds and other canids

Extreme phenotypic diversity, a history of artificial selection, and socioeconomic value make domestic dog breeds a compelling subject for genomic research. Copy number variation (CNV) is known to account for a significant part of inter-individual genomic diversity in other systems. However, a comprehensive genome-wide study of structural variation as it relates to breed-specific phenotypes is lacking. We have generated whole genome CNV maps for more than 300 canids. Our data set extends the canine structural variation landscape to more than 100 dog breeds, including novel variants that cannot be assessed using microarray technologies. We have taken advantage of this data set to perform the first CNV-based genome-wide association study (GWAS) in canids. We identify 96 loci that display copy number differences across breeds, which are statistically associated with a previously compiled set of breed-specific morphometrics and disease susceptibilities. Among these, we highlight the discovery of a long-range interaction involving a CNV near MED13L and TBX3, which could influence breed standard height. Integration of the CNVs with chromatin interactions, long noncoding RNA expression, and single nucleotide variation highlights a subset of specific loci and genes with potential functional relevance and the prospect to explain trait variation between dog breeds.

Implications of the RhoA/Rho associated kinase pathway and leptin in primary uterine inertia in the dog

The underlying functional and molecular changes in canine primary uterine inertia (PUI) are still not clarified. Leptin (Lep) and obesity negatively affect uterine contractility in women, partly mediated by the RhoA/Rho associated kinase pathway, affecting myometrial calcium sensitization. We hypothesized that increased uterine Lep/Lep receptor (LepR) or decreased RhoA/Rho associated kinase expression contributes to PUI in dogs, independent of obesity. Dogs presented for dystocia were grouped into PUI (n = 11) or obstructive dystocia (OD, still showing strong labor contractions; n = 7). Interplacental full-thickness uterine biopsies were collected during Cesarean section for relative gene expression (RGE) of RhoA, its effector kinases (ROCK1, ROCK2), Lep and LepR by qPCR. Protein and/or mRNA expression and localization was evaluated by immunohistochemistry and in situ hybridization. RGE was compared between groups by one-way ANOVA using body weight as covariate with statistical significance at P < 0.05. Uterine ROCK1 and ROCK2 gene expression was significantly higher in PUI than OD, while RhoA and Lep did not differ. LepR RGE was below the detection limit in five PUI and all OD dogs. Litter size had no influence. Lep, LepR, RhoA, ROCK1, ROCK2 protein and/or mRNA were localized in the myometrium and endometrium. Uterine protein expression appeared similar between groups. LepR mRNA signals appeared stronger in PUI than OD. In conclusion, lasting, strong labor contractions in OD likely resulted in downregulation of uterine ROCK1 and ROCK2, contrasting the higher expression in PUI dogs with insufficient contractions. The Lep-LepR system may affect uterine contractility in non-obese PUI dogs in a paracrine-autocrine manner.

Influence of ADAPTIL® during the Weaning Period: A Double-Blinded Randomised Clinical Trial

Simple Summary

The process of weaning can potentially affect the development of dogs due to frustration of both the dam and the puppies and, consequently, affect their interactions. Comprehending the dam and puppies’ interactions during the weaning process could provide information to help overcome the challenges of this period. In addition, the use of ADAPTIL^®, a dog-appeasing pheromone, could potentially reduce the stress and decrease the frustration associated with weaning. To better understand the dam and puppies’ interactions around the weaning time and the effect of ADAPTIL^®, 25 bitch/litter dyads were evaluated under the influence of ADAPTIL^® (n = 14) or a placebo (n = 11). Video recording allowed the evaluation of the dam and puppies’ behaviours at weeks three/four, weeks five/six and weeks seven/eight). Contact of the dam and the puppies were inversely affected when compared to puppy-to-puppy interactions. Over time, the dam spent less time with the puppies, and the puppies played more often with their littermates. Under ADAPTIL^®, the puppies seemed to cope better with frustration, and the bitches were more relaxed in the presence of the puppies. The perception of the breeders measured by visual analogue scales indicated a beneficial outcome of the use of the pheromone in the dam/puppies relationship during the weaning period.

Abstract

ADAPTIL^®, a dog-appeasing pheromone, was shown to modify the dam–puppies’ interactions during the neonatal period but could also influence the weaning period. Fourteen bitch/litter dyads continuously exposed to ADAPTIL^® from the third/fourth weeks until the seventh/eighth weeks postpartum were compared to 11 dyads exposed to a placebo. Maternal and puppy behaviours were video-recorded, and at three time points (weeks three/four, weeks five/six and weeks seven/eight) after parturition. The well-being of the puppies and the overall relationship with the bitch were assessed using visual analogue scales (VAS) completed by the caregivers. All mothering behaviours, such as time of contact, licking and the amount of time dedicated to nursing puppies, decreased gradually from weeks three/four to weeks seven/eight. A switch in nursing position was observed over time: the use of the standing position increased compared to the lying position. The treatment had an effect on the nursing position: bitches in the ADAPTIL^® group nursed more often in a lying (p = 0.007) or sitting position (p = 0.037), whereas for the placebo group, they favoured the standing position (p = 0.011). Once the puppies became more demanding for suckling, the bitches started showing rejection signs or aggressive growling, with a peak at weeks seven/eight. The pheromone seemed to reduce the intensity of avoidance in bitches exposed to ADAPTIL^® at all time points. The score of all events combined as a sign of frustration showed a difference over the full period (p = 0.003), with the placebo group having a significantly higher score. From the caregiver perspective (through the VAS), under ADAPTIL^®, the bitches were calmer when puppies tried to suckle (p = 0.001), more tolerant towards pups (p = 0.025), showed a greater motherly attitude (p = 0.016), the puppies cried less when left alone (p < 0.001) and interactions amongst pups were more harmonious (p = 0.055). Under ADAPTIL^®, the bitches were less annoyed by the puppies, who seemed to cope better with frustration. The breeders perceived a benefit of the pheromone during the weaning period.

Polyphony of domestic dog whines and vocal cues to body size

In domestic dogs Canis familiaris, vocal traits have been investigated for barks and growls, and the relationship between individual body size and vocal traits investigated for growls, with less corresponding information for whines. In this study, we examined the frequency and temporal traits of whines of 20 adult companion dogs (9 males, 11 females), ranging in body mass from 3.5 to 70.0 kg and belonging to 16 breeds. Dog whines (26–71 per individual, 824 in total) were recorded in conditioned begging contexts modeled by dog owners. Whines had 3 independent fundamental frequencies: the low, the high and the ultra-high that occurred singly as monophonic calls or simultaneously as 2-voice biphonic or 3-voice polyphonic calls. From the smallest to largest dog, the upper frequency limit varied from 0.24 to 2.13 kHz for the low fundamental frequency, from 2.95 to 10.46 kHz for the high fundamental frequency and from 9.99 to 23.26 kHz for the ultra-high fundamental frequency. Within individuals, the low fundamental frequency was lower in monophonic than in biphonic whines, whereas the high fundamental frequency did not differ between those whine types. All frequency variables of the low, high, and ultra-high fundamental frequencies correlated negatively with dog body mass. For duration, no correlation with body mass was found. We discuss potential production mechanisms and sound sources for each fundamental frequency; point to the acoustic similarity between high-frequency dog whines and rodent ultrasonic calls and hypothesize that ultra-high fundamental frequencies function to allow private, “tete-a-tete” communication between members of social groups.

Apgar score or birthweight in Chihuahua dogs born by elective Caesarean section: which is the best predictor of the survival at 24 h after birth?

Background

In the dog, the correct management of parturition and the prompt neonatal evaluation and assistance can reduce the perinatal mortality rates that are particularly high in toy breeds. Newborn evaluation and factors addressing prognosis are pivotal to guarantee the correct neonatal assistance. Assessment of the Apgar score with viability classification and birthweight are recognized as predictors for neonatal survival in dogs, but breed-specific data are needed for a more feasible application in the dog species, in which wide differences among breeds are known. The present study aimed therefore to: (a) assess the role of Apgar score and birthweight as predictors for the survival of Chihuahua newborn puppies in the first 24 h of life; (b) to assess a cut-off of the Apgar score and birthweight values that can predict the survival of Chihuahua newborn puppies in the first 24 h after birth; (c) to assess the possible effect played by maternal parity, newborn gender and litter-size on Apgar score in Chihuahua newborn puppies, in order to provide breed-specific data for a better neonatal assistance.

Results

Data obtained from 176 normal developed Chihuahua puppies born by elective Caesarean section, showed that 62%, 28% and 10% of puppies were classified in the Apgar score classes 7–10, 4–6 and 0–3, respectively, with survival at 24 h after birth of 97%, 96%, 39%, in the three Apgar classes of viability, respectively. Apgar score was a better predictor for survival at 24 h after birth than birthweight (AUC 0.93, P < 0.0001; AUC 0.69, P < 0.01, respectively). Litter-size of 7 puppies/litter plays a negative effect on Apgar score. Apgar score is a better predictor of survival at 24 h than birthweight, and the best cut-off of Apgar score for survival at 24 h after birth is 4, with 96% sensitivity and 77% specificity.

Conclusions

The different proportion of “normal viable” and “less viable” neonates in comparison to other studies highlights that Chihuahua puppies born by elective Caesarean section should be carefully evaluated at birth to provide correct assistance.

A model of puppy growth during the first three weeks

Neonatal mortality in puppies is highly variable, with large scale surveys still reporting average values around 10% –15%. Weight measurement is the simplest way to monitor the development of the puppies, and a weight loss during the first 48 hr has been recognized as one of the factors that puts puppies at a higher risk of neonatal mortality. However, little is known about what constitutes optimum growth up to 3 weeks. In this study, a mathematical formula with the form P = P₀ exp (0.13084 x ‐ 0.001616 x²), where P is weight on Day x and P₀ is weight on Day 0, obtained by multiple linear regression, is presented and validated with data from 345 puppies belonging to 60 litters of 19 different breeds, from toy to giant size, showing that it appropriately describes maximum puppy growth rate during the neonatal period for all breeds. This formula is in agreement with previous studies and generic recommendations that can be found in the literature on puppy growth from birth to 21 days regarding relative daily weight gain. It can be easily introduced in a spreadsheet or used to build growth charts that can help the breeder or the veterinarian in monitoring and evaluating puppy growth during the neonatal period. Although deviations from the maximum growth rate can now be quantified, there is still a need to determine the limits beyond which supplementary feeding is advised/required.

Uterine expression of smooth muscle alpha- and gamma-actin and smooth muscle myosin in bitches diagnosed with uterine inertia and obstructive dystocia

Primary uterine inertia (PUI) is the most common type of dystocia in dogs. We hypothesized that PUI develops because of lower than normal expression of the basic contractile elements in the uterus, i.e., smooth muscle (SM) α- and γ-actin and SM-myosin, and that the expression of these proteins is influenced by the number of fetuses present in utero. Full-thickness inter-placental uterine biopsies were collected during Cesarean sections from dogs with PUI (n = 11), and from bitches with obstructive dystocia (OD) still presenting strong labor contractions (designated as the control group, n = 7). Relative gene expression was determined by semi-quantitative real-time (TaqMan) PCR, and protein localization by immunohistochemistry. Gene expression between PUI and OD bitches, and between PUI bitches carrying small, large, or average number of fetuses according to their breed, were compared. Uterine SM-γ-actin and SM-myosin mRNA levels were significantly higher in PUI than in OD dogs, while SM-α-actin did not differ. PUI bitches carrying large litters had lower uterine SM-γ-actin gene expression than those with small litters (P = 0.008). Immunostaining for SM-actin isoforms and SM-myosin was present in the myometrium, and localization pattern and staining intensity appeared similar in the PUI and OD groups. All proteins stained in blood vessels, and SM-γ-actin was also present in endometrial luminal and glandular epithelium. In conclusion, higher uterine SM-γ-actin and SM-myosin gene expression in PUI bitches, compared with OD dogs, might be an indication of abnormal progression with labor. Whether this is the cause of PUI due to an intrinsic error of the myometrium not becoming committed to labor, or the consequence of inadequate endocrine or mechanical stimuli, is not clear. Litter size was previously shown to be one of the risk factors for the development of uterine inertia in dogs, and our findings suggest possible differing uterine pathophysiology of PUI with respect to litter size.

Body size, inbreeding, and lifespan in domestic dogs

Inbreeding poses a real or potential threat to nearly every species of conservation concern. Inbreeding leads to loss of diversity at the individual level, which can cause inbreeding depression, and at the population level, which can hinder ability to respond to a changing environment. In closed populations such as endangered species and ex situ breeding programs, some degree of inbreeding is inevitable. It is therefore vital to understand how different patterns of breeding and inbreeding can affect fitness in real animals. Domestic dogs provide an excellent model, showing dramatic variation in degree of inbreeding and in lifespan, an important aspect of fitness that is known to be impacted by inbreeding in other species. There is a strong negative correlation between body size and lifespan in dogs, but it is unknown whether the higher rate of aging in large dogs is due to body size per se or some other factor associated with large size. We used dense genome-wide SNP array data to calculate average inbreeding for over 100 dog breeds based on autozygous segment length and found that large breeds tend to have higher coefficients of inbreeding than small breeds. We then used data from the Veterinary medical Database and other published sources to estimate life expectancies for pure and mixed breed dogs. When controlling for size, variation in inbreeding was not associated with life expectancy across breeds. When comparing mixed versus purebred dogs, however, mixed breed dogs lived about 1.2 years longer on average than size-matched purebred dogs. Furthermore, individual pedigree coefficients of inbreeding and lifespans for over 9000 golden retrievers showed that inbreeding does negatively impact lifespan at the individual level. Registration data from the American Kennel Club suggest that the molecular inbreeding patterns observed in purebred dogs result from specific breeding practices and/or founder effects and not the current population size. Our results suggest that recent inbreeding, as reflected in variation within a breed, is more likely to affect fitness than historic inbreeding, as reflected in variation among breeds. Our results also indicate that occasional outcrosses, as in mixed breed dogs, can have a substantial positive effect on fitness.

Bodyweight at Birth and Growth Rate during the Neonatal Period in Three Canine Breeds

Simple Summary

The 349 recognized canine breeds differ greatly in bodyweight and, therefore, in birthweight and neonatal growth. The weight and growth of puppies are easily measurable, and are possible early indicators of problems. Low birthweight has been linked to neonatal mortality based on results obtained by grouping breeds according to their adult bodyweight. Breed-specific ranges of birthweight and growth would allow for the identification of puppies at risk. Our aim was to evaluate the birthweight and early growth of healthy puppies of three breeds in a breed-specific manner. Birthweight, expressed as percentage of mothers’ bodyweight, showed that puppies of a large breed are born smaller than puppies of a small breed. Puppies of a large breed gain weight slower than puppies of a small breed. Sex has no impact on birthweight, whereas litter size influences birthweight and weight gain. Based on our procedure, we considered 29 of 213 puppies to be of a low birthweight, whereas 160 of 213 might have been considered of a low birthweight if using the classical criteria (based on breed groups). This shows the importance of breed-specific evaluations of birthweight. Further research is needed on the importance of breed-specific evaluations for early growth.

Abstract

Weight at birth (bBW) and early weight gain have been linked to the risk of neonatal mortality. Pups are described to be of low bBW if weighing less than one standard deviation (SD) below the mean. Most studies classified breeds according to their expected adult bodyweight. Our aim was to evaluate the breed specificity of these parameters. We assessed the bBW of 213 puppies of Bernese Mountain Dog (BMD), Tibetan Terrier (TT), and Lhasa Apso (LA) breeds, as well as the neonatal growth rate of 133 puppies of BMD and TT. BMD puppies were born relatively smaller than puppies of TT and LA (p ≤ 0.0001) and gained less weight than TT puppies during the first 14 days (p ≤ 0.05). Litter size had a significant impact on bBW and daily gain until the onset of the third week for BMD (p < 0.0001 and p = 0.0005, respectively) and TT (p = 0.0003 and p = 0.0064, respectively). When using bBW means and SD specifically assessed according to breed, 29 out of the 213 neonates of our study were judged as being of low bBW, whereas, when using the classical criteria (based on breed groups), the number of low bBW pups was 160 of 213. These results suggest that evaluations of bBW and neonatal growth should be performed in a breed-specific manner.

Uterine and umbilical resistance index and fetal heart rate in pregnant bitches of different body weight

The aim of this study was to compare uterine and umbilical artery blood flow and fetal heart rate (FHR) in small, medium and large body weight (BW) dogs during the second half of pregnancy. Purebred pregnant bitches were assigned to one of the following groups according to their BW: small (S; ≤10 kg), medium (M; 11-25 kg) and large (L; >25-45 kg). Uterine and umbilical Doppler and M-mode ultrasonography was conducted every 10 days from Day 30-60 (Day 0 = first day of gestation). From Day 40, uterine and umbilical artery resistance index (RI) progressively and differentially decreased in the three groups (P < 0.01) being less in L than S bitches (P < 0.01). Litter size but not maternal BW (P > 0.1) affected uterine RI on Days 40 (r = 0.39; P < 0.01) and 50 (r = 0.41; P < 0.01). Conversely, on Day 60, maternal BW (r = 0.61; P < 0.01) had an effect on uterine RI while litter size did not (P > 0.1). Fetal heart rate increased from Day 30-50 and decreased to the time of parturition (P < 0.01) without differences among groups at any time point (P > 0.1). Uterine and umbilical blood flow differentially increased throughout mid- and late-pregnancy in breeds with large and small BW. These differences were affected by litter size on Days 40 and 50, and by maternal BW on Day 60. Conversely, during this same period, FHR did not vary among BW groups. Physiological variations should be considered when gestational ultrasonic examination is interpreted in different BW bitches.

Fertility outcome after medically treated pyometra in dogs

Cystic endometrial hyperplasia-pyometra complex (CEH/P) is a challenge in canine reproduction. Present study aimed to assess fertility after medical treatment. One-hundred-seventy-four bitches affected by CEH/P received aglepristone on days 1, 2, 8, then every 7 days until blood progesterone < 1.2 ng/mL; cloprostenol was administered on days 3 to 5. Records were grouped according to bodyweight (BW): small (< 10 kg, n = 33), medium (10 ≥ BW < 25 kg, n = 44), large (25 ≥ BW < 40 kg, n = 52), and giant bitches (BW ≥ 40 kg, n = 45). Age; success rate; aglepristone treatments number; relapse, pregnancy rates; diagnosis-relapse, -first, -last litter intervals; litters number after treatment, and LS were analyzed by ANOVA. Overall age was 5.14 ± 1.75 years, without difference among groups. Treatment was 100% successful, without difference in treatments number (4.75 ± 1.18), relapse (15/174, 8.62%) and pregnancy (129/140 litters, 92.14%) rates, intervals diagnosis-relapse (409.63 ± 254.9 days) or -last litter (418.62 ± 129.03 days). The interval diagnosis-first litter was significantly shorter (163.52 ± 51.47 days) and longer (225.17 ± 90.97 days) in small and giant bitches, respectively. Overall, 1.47 ± 0.65 litters were born after treatment. Expected LS was achieved in each group, as shown by ΔLS (actual-expected LS by breed, overall -0.40 ± 1.62) without differences among groups. Concluding, CEH/P affects younger dogs than previously described. Relapses were rarer than previously reported. Medical treatment with aglepristone+cloprostenol is effective and safe, preserving subsequent fertility, as demonstrated by negligible changes in LS.

Factors influencing English Bulldog bitch fertility after surgical uterine deposition of fresh semen

The aim of this study was to evaluate the effect of body weight, oxytocin deposition in the uterus at artificial insemination (AI), vaginal cytology, serum progesterone (P₄) concentration at AI, semen volume and total sperm cells per AI on whelping rate and litter size of English Bulldogs bitches following intrauterine surgical semen deposition. Seventy-eight English Bulldog bitches were artificially inseminated via semen infusion (number of sperm cells inseminated 300-2500 × 10⁶) at the uterine body with fresh semen without extender and under general anesthesia. Whelping rate was greater (P < 0.05) in bitches with >23 kg than bitches with <23 kg (83.9 vs 63.8%). Whelping rate was greater (P < 0.01) in bitches with >75% vaginal cornified epithelium at AI (85.1%) than animals with <75% cornified epithelium (51.6%). Whelping rates were influenced (P < 0.01) by the semen volume at AI (54.3% vs 86.1% for bitches receiving <4 mL or >4 mL of semen). Litter size was larger (P < 0.05) in bitches >23 kg than lighter animals (3.72 ± 1.79 and 2.30 ± 1.46 pups per litter, respectively). Litter size was not influenced by sperm concentration, semen volume, vaginal cytology, serum P₄ concentration and infusion of oxytocin in the uterus at AI (P > 0.1). The results of this study indicate that increasing body weight of English Bulldog bitches is related to higher whelping rates and larger litter size. Also, >75% of superficial cornified vaginal cells (squamous) at AI and >4 mL semen volume maximize whelping rates in this breed of dogs.

Time course of serum cobalamin, folate, and total iron binding capacity concentrations in pregnant bitches and association with hematological variables and survival

Background

Hypocobalaminemia, hypofolatemia and iron deficiency are associated with pregnancy‐related anemia (PRA) and neonatal survival (NS) in women. Similar associations have not been investigated in pregnant bitches.

Objectives

To investigate time course and associations of serum cobalamin, folate and iron status indicators with hematological variables and NS in pregnant bitches.

Animals

Forty‐eight pregnant bitches.

Methods

A prospective cohort study. Pregnancy was confirmed by abdominal ultrasonography twice during mid‐ and late pregnancy, concurrently with blood sampling. Associations among pregnancy stage, NS and laboratory variables were assessed by generalized estimating equations.

Results

Compared with midpregnancy, serum cobalamin (adjusted mean [95% confidence interval, CI]) decreased at late pregnancy (430 pg/mL [394‐466] versus 330 pg/mL [303‐357], respectively; P < .001), whereas serum folate did not. Every increment of 1 in parity number or litter size corresponded to 28.6 pg/mL (95% CI, 5.6‐51.6; P = .02) and 20.3 pg/mL (95% CI, 10.9‐29.7; P < .001) decrease in serum cobalamin concentration. Compared with midpregnancy, serum iron (P < .001) and transferrin saturation (P = .01) increased at late pregnancy. The decrease in red blood cell count (P < .001) at late pregnancy was significantly, albeit weakly, correlated with decreasing serum folate concentration (r = 0.33; P = .02). None of the measures was associated with NS.

Conclusions and Clinical Significance

Pregnancy‐related anemia was common at late pregnancy. Unlike in women, in pregnant bitches, serum iron and transferrin saturation were increased at late pregnancy. Future studies are warranted to investigate the clinical ramifications of hypocobalaminemia in pregnant bitches and the utility of prophylactic folate administration in mitigating PRA.

Inbreeding depression causes reduced fecundity in Golden Retrievers

Inbreeding depression has been demonstrated to impact vital rates, productivity, and performance in human populations, wild and endangered species, and in recent years, the domestic species. In all cases, standardized, high-quality phenotype data on all individuals are invaluable for longitudinal analyses such as those required to evaluate vital rates of a study cohort. Further, many investigators agree upon the preference for and utility of genomic measures of inbreeding in lieu of pedigree-based estimates of inbreeding. We evaluated the association of measures of reproductive fitness in 93 Golden Retrievers enrolled in the Golden Retriever Lifetime Study with a genomic measurement of inbreeding, F_ROH. We demonstrate a statistically significant negative correlation between fecundity and F_ROH. This work sets the stage for larger scale analyses to investigate genomic regions associated with fecundity and other measures of fitness.

Genome-wide association analysis uncovers variants for reproductive variation across dog breeds and links to domestication

BACKGROUND AND OBJECTIVES

The diversity of eutherian reproductive strategies has led to variation in many traits, such as number of offspring, age of reproductive maturity and gestation length. While reproductive trait variation has been extensively investigated and is well established in mammals, the genetic loci contributing to this variation remain largely unknown. The domestic dog, Canis lupus familiaris is a powerful model for studies of the genetics of inherited disease due to its unique history of domestication. To gain insight into the genetic basis of reproductive traits across domestic dog breeds, we collected phenotypic data for four traits, cesarean section rate, litter size, stillbirth rate and gestation length, from primary literature and breeders' handbooks.

METHODOLOGY

By matching our phenotypic data to genomic data from the Cornell Veterinary Biobank, we performed genome-wide association analyses for these four reproductive traits, using body mass and kinship among breeds as covariates.

RESULTS

We identified 12 genome-wide significant associations between these traits and genetic loci, including variants near CACNA2D3 with gestation length, MSRB3 and MSANTD1 with litter size, SMOC2 with cesarean section rate and UFM1 with stillbirth rate. A few of these loci, such as CACNA2D3 and MSRB3, have been previously implicated in human reproductive pathologies, whereas others have been associated with domestication-related traits, including brachycephaly (SMOC2) and coat curl (KRT71).

CONCLUSIONS AND IMPLICATIONS

We hypothesize that the artificial selection that gave rise to dog breeds also influenced the observed variation in their reproductive traits. Overall, our work establishes the domestic dog as a system for studying the genetics of reproductive biology and disease.

LAY SUMMARY

The genetic contributors to variation in mammalian reproductive traits remain largely unknown. We took advantage of the domestic dog, a powerful model system, to test for associations between genome-wide variants and four reproductive traits (cesarean section rate, litter size, stillbirth rate and gestation length) that vary extensively across breeds. We identified associations at a dozen loci, including ones previously associated with domestication-related traits, suggesting that selection on dog breeds also influenced their reproductive traits.

The Australian dingo: untamed or feral?

BACKGROUND

The Australian dingo continues to cause debate amongst Aboriginal people, pastoralists, scientists and the government in Australia. A lingering controversy is whether the dingo has been tamed and has now reverted to its ancestral wild state or whether its ancestors were domesticated and it now resides on the continent as a feral dog. The goal of this article is to place the discussion onto a theoretical framework, highlight what is currently known about dingo origins and taxonomy and then make a series of experimentally testable organismal, cellular and biochemical predictions that we propose can focus future research.

DISCUSSION

We consider a canid that has been unconsciously selected as a tamed animal and the endpoint of methodical or what we now call artificial selection as a domesticated animal. We consider wild animals that were formerly tamed as untamed and those wild animals that were formerly domesticated as feralized. Untamed canids are predicted to be marked by a signature of unconscious selection whereas feral animals are hypothesized to be marked by signatures of both unconscious and artificial selection. First, we review the movement of dingo ancestors into Australia. We then discuss how differences between taming and domestication may influence the organismal traits of skull morphometrics, brain and size, seasonal breeding, and sociability. Finally, we consider cellular and molecular level traits including hypotheses concerning the phylogenetic position of dingoes, metabolic genes that appear to be under positive selection and the potential for micronutrient compensation by the gut microbiome.

CONCLUSIONS

Western Australian Government policy is currently being revised to allow the widespread killing of the Australian dingo. These policies are based on an incomplete understanding of the evolutionary history of the canid and assume the dingo is feralized. However, accumulated evidence does not definitively show that the dingo was ever domesticated and additional focused research is required. We suggest that incorporating ancient DNA data into the debate concerning dingo origins will be pivotal to understanding the evolutionary history of the canid. Further, we advocate that future morphological, behavioural and genetic studies should focus on including genetically pure Alpine and Desert dingoes and not dingo-dog hybrids. Finally, we propose that future studies critically examine genes under selection in the dingo and employ the genome from a wild canid for comparison.

A Solution for the Shortage of Detection Dogs: A Detector Dog Center of Excellence and a Cooperative Breeding Program

Currently, demand for US-bred and born detector dogs exceeds available supply, while reliance on foreign-bred sources introduces many unnecessary and unwanted risks. With proper management of a domestic supply line, U.S. breeders can improve both health and behavior by applying scientific principles to breeding and raising of detector dogs. A cooperative national detector dog breeding and development program will mitigate the current shortage of domestic-bred dogs that meet the health and behavior standards required by government, military, and law enforcement agencies. To coordinate such a cooperative, we propose a Detector Dog Center of Excellence (DDCoE) led by representatives of academic canine science programs guided by an advisory board of stakeholders. As a non-governmental organization, the DDCoE will oversee selective breeding of dogs owned by breeders, purchase the resulting puppies, and its members will supervise puppy raising until dogs are of a suitable age to be purchased by government agencies or other working dog organizations. The DDCoE will serve as an approved vendor to facilitate the procurement process. Breeding decisions will be based on proven quantitative genetic methods implemented by a specialized database. A national working dog semen bank will ensure conservation of diverse genetic material and enhance selection response by providing numerous potential sires. As a data collection and genetic evaluation center, the DDCoE will lead research to define quantitative traits involved in odor detection, to understand how these traits develop, and methods to optimize training of dogs endowed with enhanced odor detection ability.

Colour Flow Mapping examination: An useful screening test for the early diagnosis of ductus venosus patency in canine newborns

Ductus venosus (DV) closure plays a key role in hepatic circulation adaptation to postnatal metabolic function, and DV patency might develop a congenital portosystemic shunt (CPSS). The noninvasive Color Flow Mapping (CFM) examination, a validated method to diagnose CPSS in adult dogs, is routinely performed to assess DV closure after birth in humans. This study aimed to describe the feasibility of the ultrasonographic evaluation of the DV after birth and to determine its closure time in healthy Great Dane neonates. Patency of DV in serial Color Flow Mapping (CFM) examinations and bodyweight (BW) were recorded on Days 0-3-6-9 in 24 neonates that were classified as having patent (PDV) or closed ductusvenosus (CDV) basing on CFM signal presence/absence. Since the 3rd day, DV diameter was recorded. Data were analysed by ANOVA (p < 0.05). All dogs resulted healthy 1 year later. The number of PDV and CDV puppies at birth was not different on Day 3 (24 and 0 vs. 22 and 2, PDV and CDV, respectively), whereas it resulted different on Days 6 (24 and 0 vs. 14 and 10) and 9 (24 and 0 vs. 0 and 24); on Day 3, it was different compared to Days 6 and 9; on Day 6, it was different from Day 9. Reduction of DV diameter resulted positively related to neonatal BW growth. The CFM evaluation of DV closure after birth in Great Dane puppies represents a feasible technique. Present results suggest the time of functional closure in normal neonates within 9 days after birth. Thus, CFM examination, as an early screening test for DV patency evaluation, performed 10 days after birth, may identify suspicious dogs at risk that would require further investigations. Further studies are needed to deepen the role of a delayed closure in low bodyweight and preterm puppies.

Seasonality in oestrus and litter size in an assistance dog breeding colony in the United Kingdom

Evidence of seasonality in oestrus in bitches within specialist breeding programmes, such as those for assistance dogs, may support colony management through tailoring the distribution of resources required for breeding throughout the year. However, at present there are conflicting data regarding seasonality in oestrus (and litter size) in domestic dogs. The primary objective of this study was to investigate seasonal variations in oestrus and litter size in a large assistance dog breeding colony in the UK in order to optimise colony management. The authors analysed the annual distribution of 3624 observations of oestrus collected from 568 brood bitches from January 2005 to June 2014. The authors also evaluated the relationship between month and litter size for 1609 litters observed during the same period. There was no evidence of regular seasonal variations in oestrus or litter size by meteorological season or month. The lack of seasonality in oestrus may be a function of dogs in the UK, particularly valuable breeding bitches, being exposed to fairly constant environmental conditions throughout the year as a consequence of artificial light and heating during the winter months. The authors’ findings suggest that special consideration of the annual distribution of oestrus and litter size is unnecessary for the management of assistance dog breeding colonies similar to those in the UK.

Factors affecting the reproductive performance of bitches: A prospective cohort study involving 1203 inseminations with fresh and frozen semen

The aim of this prospective cohort study was to utilize multivariable statistical methods to identify factors that significantly affected whelping rate, litter size and gestation length in a large population of bitches of many different breeds, presented for routine breeding management. In addition, we aimed to determine the incidence of dystocia and the proportion of bitches undergoing a caesarean section procedure. A total of 1146 individual bitches representing 84 different breeds contributed 1203 inseminations over the 9 year (2007-2015) study period. Bitches were inseminated with either frozen-thawed (n = 645), fresh (n = 543) or chilled (n = 15) semen from 1371 different males. The mean (SD) whelping rate was 74± 4% and the mean litter size was 5.8 ± 3.1 pups per litter for all bitches in the study. The whelping rate was significantly lower in bitches inseminated with frozen-thawed semen compared with bitches inseminated with fresh semen (71% vs 80% respectively; P < 0.001). Semen that was classified as having poor motility (<30% progressive) resulted in a significantly lower whelping rate (37%) than semen classified as good (30-65% progressive; whelping rate = 67%) or excellent (>65% progressive; whelping rate = 79%). There was a linear decline in whelping rate with advancing age. Greyhounds and Labradors demonstrated a significantly higher whelping rate (88% and 94% respectively) compared with all other breeds (71.3%, P < 0.001). Bitches inseminated with frozen-thawed semen had significantly smaller litter sizes than bitches inseminated with fresh semen (5.4 ± 3.1 vs 6.2 ± 3.0 pups per litter respectively; P = 0.02). Smaller breeds had significantly smaller litters (4.4 ± 2.1 pups) than medium (5.2 ± 2.9 pups), large (5.9 ± 2.9 pups) or giant (6.7 ± 3.8 pups) breeds. For each advancing year of age, litter size decreased by 0.13 pups per litter. The mean (SD) gestation length from LH0 was 65 ± 1.9 d. Greyhounds had a significantly longer pregnancy duration (68.0 ± 1.5 d) than other breeds. For each additional year of bitch age, gestation length increased by 0.11 days (P < 0.01), and for each additional pup per litter, gestation length was reduced by 0.08 days (P < 0.05). Of the 890 bitches for which whelping outcomes were recorded; 409 (46%) whelped normally without assistance, 249 (28%) had an elective C-section, 205 (23%) underwent an emergency C-section and 27 (3%) were medically managed or required veterinary assistance for dystocia. Brachycephalic breeds were 11.3 (95CI = 9.3-17.9; P < 0.001) times more likely to have a C-section compared to all other breeds. Bitches with litter sizes of one or two pups had a C-section rate of 83%, whereas bitches with litter sizes of three or more pups had a C-section rate of 43% (P < 0.001). This study provides important clinical information to optimise whelping rates, litter size and the prediction of whelping in certain breeds for clinicians working in canine reproduction.

A National Census of Birth Weight in Purebred Dogs in Italy

Simple Summary

Birth weight is a key factor for neonatal mortality and morbidity in most mammalian species. The great morphological variability in size, body weight and breed, as well as in skeletal and cranial conformation makes it challenging to define birth weight standards in dogs. A total of 3293 purebred pups were surveyed to study which maternal aspects can determine birth weight considering head and body shape, size, body weight and breed in bitches, as well as litter size and sex in pups. In our sample, multivariate analysis outcomes suggested that birth weight and litter size were directly proportional to maternal size. The maternal body shape influenced both birth weight and litter size, whereas the maternal head shape had impact only on birth weight. Sex differences in birth weight were found. Birth weight and litter size also varied among breeds. The results of the present study could have practical implications allowing one to identify pups in need of admission to intensive nursing care, as occurs in humans. A deeper knowledge of the factors that significantly influence birth weight could positively affect the canine breeding management helping to prevent and reduce neonatal mortality.

Abstract

Despite increasing professionalism in dog breeding, the physiological range of birth weight in this species remains unclear. Low birth weight can predispose to neonatal mortality and growth deficiencies in humans. To date, the influence of the morphotype on birth weight has never been studied in dogs. For this purpose, an Italian census of birth weight was collected from 3293 purebred pups based on maternal morphotype, size, body weight and breed, as well as on litter size and sex of pups. Multivariate analysis outcomes showed that birth weight (p < 0.001) and litter size (p < 0.05) increased with maternal size and body weight. Birth weight was also influenced by the maternal head and body shape, with brachycephalic and brachymorph dogs showing the heaviest and the lightest pups, respectively (p < 0.001). Birth weight decreased with litter size (p < 0.001), and male pups were heavier than females (p < 0.001). These results suggest that canine morphotype, not only maternal size and body weight, can affect birth weight and litter size with possible practical implications in neonatal assistance.

Factors influencing litter size and puppy losses in the Entlebucher Mountain dog

A good reproductive performance is a central element of animal breeding. The breeders of Entlebucher Mountain dogs observed a decrease of the mean litter size and an increase of the number of unsuccessful matings in the past years. The aim of the present study was to identify factors with an influence on fertility in this breed. In total, 915 litters from 202 sires and 348 dams from 1986 to 2013 entered the analyses. The total puppy losses (7.4%) reduced the mean litter size at birth of 5.49 ± 2.13 to a mean litter size at registration of 5.08 ± 2.05. There was no deviation from the expected equal sex distribution for puppies at birth and at registration, as well as for puppy losses consisting of stillborn puppies and puppies which died or had to be euthanized before registration. The mean annual litter inbreeding coefficient increased from 0.37 in 1986 to 0.40 in 2013 and was correlated with the year of birth of the litter (Kendall's tau b = 0.46). The age of the dam and parental inbreeding were identified as significant predictors with a negative effect on litter size at birth. For the litter size at registration the age and inbreeding of the dam had a significant negative effect and a 1% increase of dam inbreeding is expected to decrease the litter size at birth and registration by 0.1 and 0.09 puppies, respectively. The occurrence of total puppy losses decreased during the years and was more frequent in larger litters. In addition, in litters of older parents the occurrence of puppy losses was more frequent than in litters from younger parents. The final generalized linear mixed-effects models for litter size at birth, litter size at registration and for total puppy losses explained 36%, 33% and 22% of the total variance, respectively. The impact of inbreeding and parental age on fertility of the Entlebucher Mountain dog was small and the influence of the dam was much bigger than the one of the sire. Other factors must be responsible for the variability of litter sizes not explained by the models. Without changes of breeding circumstances, a further increase of inbreeding must be expected. Therefore, a close monitoring and minimizing of inbreeding must be followed up by the breeding community.

Reproductive performance and pre-weaning mortality: Preliminary analysis of 27,221 purebred female dogs and 204,537 puppies in France

The objective of this study was to describe efficiency of reproduction of purebred dogs in field breeding conditions, from mating to weaning in France. Data were collected between 2010 and 2014 in 5,667 French breeding kennels via a reproduction management software (Breeding Management System, Royal Canin, Aimargues, France). Effect of breed size (Mini: adult body weight <10 kg; Medium: 10-25 kg; Maxi: 25-40 kg; Giant: >40 kg), age of dam and male on pregnancy rate, abortion rate and litter size were evaluated by multivariable models. Data on 45,913 heats (all with mating), from 27,221 bitches from 248 breeds, were analysed. At mating, mean age (±SD) was 3.1 ± 1.8 years for bitches and 3.3 ± 2.0 for males. Males originated from the same kennel as the females in 88.5% of the matings. Based on breeder's evaluation of the pregnancy status, pregnancy rate (number of pregnant females based on breeders declaration/number of heats) was 87.8% and abortion rate was 6.8%. Finally, 81.9% of the mated females gave birth to a litter. On 37,946 litters (204,537 puppies), mean litter size was 5.4 ± 2.8 puppies (range 1-24), which was influenced by breed size and dam age (p < .0001). Stillbirth rate was 7.4% and puppy mortality rate (stillbirth + mortality until 2 months of age) was 13.4%. Prolificacy and puppy mortality rates were affected by breed size and within a breed size, by breed. Despite probable approximations (as data originate from breeders declaration), this large-scale analysis provides reference values on reproductive performance in dogs.

Cortisol fetal fluid concentrations in term pregnancy of small-sized purebred dogs and its preliminary relation to first 24 hours survival of newborns

Along the perinatal period, in mammals, cortisol (C) plays a pivotal role in the final intrauterine fetal maturation and in the early neonatal adaptation. Because of the scarce knowledge about canine perinatology, the present study was aimed to assess the C concentrations in amniotic and allantoic fluids collected, without invasiveness, from small-sized, purebred newborn puppies born by elective cesarean section, at term of pregnancy. Possible correlations between fetal fluid C concentrations and maternal parity, litter size, birth weight, Apgar score, were evaluated. In addition, the possible effect of fetal fluid C concentrations on newborn survival at 24 hours of age, and the effect of the litter or the newborn gender on fetal fluid C concentrations were also assessed. The results, obtained from 50 born alive, normal-weight puppies, without gross physical malformation, showed that C concentration was higher in allantoic than in amniotic fluid (P < 0.01), even if a strong positive correlation between the two fluids C concentration was found (P < 0.0001; R = 0.83). Neither amniotic nor allantoic C concentrations were correlated to maternal parity, litter size, birth weight, and Apgar score. Interestingly, higher amniotic (P < 0.05), but not allantoic, C concentrations were found in puppies not surviving at 24 hours after birth. Therefore, it could be suggested that this parameter may be useful for the recognition, at birth, of puppies needing special surveillance during the first day of age. A significant (P < 0.001) effect of the litter in both amniotic and allantoic C concentrations was found. In conclusion, the present results showed that in small-sized purebred puppies, born at term by elective cesarean section, the exact fetal, maternal, or placental source contributing to fetal fluid C concentrations remains to be clarified. From a clinical perspective, however, the evaluation of amniotic C concentration at birth seems useful for the detection of puppies that need special surveillance during the first 24 hours of age, and should be coupled to the early newborn evaluation by Apgar score. However, the small total number of newborns, and especially of the dead puppies enrolled in the present study, suggests that further, more-focused investigations on a large number of subjects are needed before the method could be considered for application in the clinical practices.

Changes in serum progesterone concentrations in Bernese mountain dogs and Cavalier King Charles Spaniels during pregnancy

Progesterone (P4) concentrations during canine pregnancy follow a specific pattern. Although the general pattern is similar, it is likely that breed-specific differences exist. Detailed knowledge about the physiological range of P4 concentrations may be helpful in cases of suspected hypoluteoidism. The aim of this study was to investigate P4 changes during pregnancy in a small and a large breed, to obtain reference values for specific intervals during pregnancy and to test for breed- or body weight-specific differences. We studied P4 concentrations in pregnancies from healthy Bernese mountain dogs (BMDs, n = 6) and Cavalier King Charles Spaniels (CKCSs, n = 6) with a normal reproductive history. Blood samples for P4 were taken to determine the day of ovulation and after confirmation of pregnancy in regular intervals from Days 23 to 29 to Days 60 to 64. Bernese mountain dogs delivered 6.2 ± 2.6 puppies (range: 3-9) 63.4 ± 1.5 (range: 61-65) days after ovulation (excluding data from one BMD with elective c-section) and CKCS delivered 3.3 ± 1.9 puppies (range: 1-5) 63.5 ± 1.1 (range: 62-65) days after ovulation. In general, the P4 concentrations of individual dogs continuously decreased from the first to the last sampling during pregnancy. Respective mean concentrations were Days 23 to 29: 19.2 ± 4.3/22.2 ± 3.9 ng/mL (BMD/CKCS), Days 30 to 34: 15.6 ± 2.3/17.7 ± 5.8 ng/mL, Days 35 to 39: 12.5 ± 2.8/14.1 ± 3.4 ng/mL, Days 40 to 44: 8.9 ± 1.4/11.8 ± 3.7 ng/mL, Days 45 to 49: 7.7 ± 1.6/8.9 ± 1.9 ng/mL, Days 50 to 54: 6.0 ± 1.3/8.7 ± 7.1 ng/mL, Days 55 to 59: 4.7 ± 1.2/5.3 ± 2.8 ng/mL, and Days 60 to 64: 3.69 ± 1.86/2.62 ± 0.42 ng/mL. ANOVA indicated significant differences over time within each breed when considered individually (P < 0.0001 each), but not between breeds although mean P4 was slightly lower in BMD until Days 55 to 59. The present data clearly confirm the previously described P4 pattern during canine pregnancy with highest P4 concentrations obtained in the first interval (Days 23-29) and a subsequent decrease of P4. The lack of a significant rapid prepartal P4 drop might be related to methodological issues (time of last collection in regards to parturition). Other than expected, we failed to proof significant differences in P4 between CKCS and BMD. Further studies are required to confirm the results on a larger population of both breeds, but also other large-sized breeds to test for the hypothesis if BMD might have lower P4 concentrations and smaller litter size compared to other large breeds with larger litter size.

The role of birth weight on litter size and mortality within 24h of life in purebred dogs: What aspects are involved?

In humans, scientific evidence emphasizes the role of birth weight on neonatal welfare, morbidity and mortality. In canine species, defining normal ranges of birth weight is a harder issue due to a great morphological variability in size, body weight and breed. The aim of this study was to correlate birth weight with litter size and mortality within 24h of life in 789 pups from 140 litters of purebred dogs and to investigate the aspects that might affect these factors. Birth weight was influenced by maternal size, weight and age (P<0.001). The lightest pups were from toy sized or weighing up to 10 kg bitches. Conversely, bitches aged 2-8 years whelped heavier pups than younger and older mothers. Birth weight was also related both to litter size, with heavier pups in smaller rather than in larger litters from medium sized bitches, and breed (P<0.05). Unexpectedly, birth weight did not differ between live born and stillborn pups. However, birth weight was lower in pups dying within 24h of life (P<0.05). High mortality of pups was related both to short pregnancies (P<0.05), also showing lighter litters (P<0.001), and to dystocic parturitions (P<0.001). Litter size was associated with parity, type and number of mating, and length of pregnancy (P<0.001). Low birth weight appears to predispose to early neonatal mortality suggesting a predominant role of the breed rather than size and weight in determining birth weight in pups.