Anti-Müllerian Hormone in the Domestic Dog during the Anestrus to Oestrous Transition

Correlation of Anti-Müllerian hormone serum concentration measured in proestrus and estrus with the litter size as a fertility marker in bitches

The use of the anti-Müllerian hormone (AMH) serum concentration as a fertility marker has been shown in cows, sheep and mares and has been indicated in one study in female dogs. The aim of this study was to investigate the connection between the AMH serum concentration, taken at two defined time points during the bitch`s heat, and the litter size to investigate whether AMH can be used as a practical measurement for the individual breeding bitch to predict litter size. The study was carried out on 27 healthy female dogs presented for pre-breeding examination, considering all previously known influencing factors on AMH in the bitch such as age, body weight and estrous cycle phase at the time the sample was taken. Due to the AMH increase in early proestrus and its drop around ovulation, AMH was measured in blood samples taken within the first three days of heat (AMH1) and near ovulation (AMH2) with AMH1 being significantly higher than AMH 2 (p < 0.001). There was a highly significant negative correlation of body weight and AMH at both sampling times (p < 0.001). There were no significant results when the dogs were paired and grouped according to high or low AMH concentrations, but a significant effect of AMH serum concentration on litter size was found in the multifactorial analysis when the dogs were matched according to their body weight (AMH1: p = 0.022; AMH2: p = 0.030). In conclusion, a significant effect of the AMH concentration and the litter size among female dogs with matching body weight could be found, but a much larger sample collection is needed to evaluate reference intervals for AMH for bitches of different weight to predict the fertility of an individual bitch in the future.

Physiological Anti-Müllerian Hormone Concentrations in Male and Female Dogs and Cats before and around Puberty

In recent years several studies established the diagnostic value of anti-Müllerian hormone (AMH) in companion animals. However, less is known about physiological AMH concentrations in young individuals highlighting the necessity to apply the diagnostic findings to this group. The aim of this study was to determine the AMH values of healthy male and female dogs between the age of 8 and 48 weeks, tomcats under 8 weeks and up to 48 weeks of age and queens between 2 to 12 weeks of age. In total, 96 blood samples were collected. Anti-Müllerian hormone was measured in all samples and testosterone was measured in the oldest age group of the males in both species. The hormones were analyzed using a human based chemiluminescence immune assay. Overall, AMH concentrations were higher in males than in females (p < 0.001). According to the AMH concentration there was no difference in males, but queens had significant higher AMH concentrations than bitches (p < 0.001). AMH remained high in males up to week 24 and decreased significantly thereafter (tomcats: p = 0.015; male dogs: p = 0.013), which correlated with an increase in testosterone levels for male dogs only. In bitches, AMH remained below the detection limit until the week 16 and slightly increased subsequently. In queens, AMH was detectable from the beginning with a significant increase in the older age group (p = 0.003). Half of the cats in the older age group even approached the chemiluminescence immune assay's upper limit. The results show that female cats secrete AMH much earlier than female dogs in which AMH secretion begins just shortly before the start of the puberty. In the male animals, the decrease in AMH concentration around puberty was similar in dogs and cats, but a correlation with the increase of testosterone was only observed in dogs. Further research is required to determine the origin of the high AMH concentrations in female kittens and the lack of correlation between testosterone and AMH concentrations in male kittens.

Determination of anti-Müllerian hormone levels in blood and urine in fertile cats

In recent years, blood anti-Müllerian hormone (AMH) levels have been investigated in female animals to diagnose many conditions, such as the presence of ovarian tissue, follicle reserve, and granulosa cell tumors. Since blood collection is an invasive method, diagnosis with a non-invasive method is important in terms of practicality and animal welfare. This study aimed to investigate the presence of AMH in cat urine and determine whether a correlation exists between blood and urine AMH levels. In addition, it was aimed at revealing whether there was a change in blood and urine AMH levels according to ovarian follicle distribution. Twenty-seven healthy, fertile female cats in the follicular phase were included. Following blood and urine sample collection, a routine ovariohysterectomy was performed. Histological analysis of the removed ovarian tissue was used to determine ovarian follicle types. While both AMH and estrogen levels were determined in blood samples, only AMH levels were investigated in urine samples. Blood AMH levels averaged 10.61 ± 0.75 ng/mL (range: 5-16 ng/mL), while urine AMH levels averaged 5.67 ± 0.91 ng/mL (range: 0.2-13 ng/mL). While urinary AMH level was <1 ng/mL in 7 cats, urinary AMH was >1 ng/mL in all remaining cats. While the study demonstrated AMH excretion in urine, no correlation was found between blood and urine AMH values. However, a significant positive correlation was observed between blood AMH levels and serum estrogen levels (P < 0.001). These findings suggest that urinary AMH may be a product of proteolytic degradation, potentially leading to inaccurate estimations of ovarian activity based solely on urine AMH levels.

Half-life of serum anti-Müllerian hormone and changes after gonadectomy in adult female and male dogs with normal and abnormal gonads

Anti-Müllerian hormone (AMH) is a biomarker for the presence of gonadal tissue. Changes in serum AMH after gonadectomy are not well established, and its serum half-life is unknown in dogs. We measured serum AMH with a validated electro-chemiluminescent immunoassay in adult female (n = 12) and male (n = 7) dogs with normal gonads, as well as in dogs with gonadal pathology (ovarian remnant syndrome, ORS n = 3, testicular tumor [Leydig cell, Sertoli cell, seminoma] n = 3, unilateral abdominal cryptorchid n = 4) on the day of gonadectomy (D0), and on D3, D7, D14 (females and males), and D21, D28 (males only). Males had higher AMH concentrations than females independent of gonadal status (P < 0.001). Dogs with ORS had lower initial AMH (0.45 ± 0.43 ng/ml) than bitches with normal gonads (1.16 ± 0.44 ng/ml; P = 0.027). Cryptorchid dogs had higher initial concentrations (80.57 ± 52.81 ng/ml) than males with normal gonads (7.92 ± 2.45 ng/ml; P = 0.004), and those with testicular tumors (18.63 ± 5.04 ng/ml) were intermediate (P ≥ 0.250). AMH decreased over time (P ≤ 0.012) and was 0.01-0.04 ng/ml by D14 in females and 0.02-0.12 ng/ml by D28 in males. Serum half-life in the whole study population was 2.85 ± 0.51 days and did not differ between groups. In conclusion, serum AMH can differentiate between intact and gonadectomized status of adult dogs by 14 days after ovario(hyster)ectomy in females and by 28 days after surgical castration in males.

Serum anti-Müllerian hormone around the time of ovulation simulated by exogenous hormones in clouded leopards (Neofelis nebulosa)

Anti-Müllerian hormone (AMH) is produced by granulosa cells of the antral follicles. It serves as a promising biomarker for ovarian reserve and responsiveness to ovarian stimulation in humans and domestic animals. This study aimed to validate the AMH Gen II enzyme-linked immunosorbent assay (ELISA) and correlate ovarian structures with serum AMH concentrations after stimulation treatment in clouded leopards (Neofelis nebulosa). Serum samples were collected from 12 women (age 6.21 ± 3.56 years), and serum AMH concentrations were analysed using AMH Gen II ELISA. The animals were divided into two groups based on ovarian structures [preovulatory follicles (>2 mm) and/or corpora hemorrhagica] along with the presence of uterine tonicity visualized laparoscopically around the time of ovulation. Animals that exhibited these reproductive features were identified as the responder group (n = 9, aged 7.59 ± 2.96 years), whereas those lacking the corresponding features were assigned to the nonresponder group (n = 3, aged 2.06 ± 0.53 years). The intra-assay coefficient of variation (CV) and interassay CV was 3.56% and 7.75%, respectively. The linearity of AMH dilution was confirmed (r2  = .998), and the percentage of recovery ranged from 93% to 115%. The results demonstrated that overall serum AMH concentrations around the time of ovulation were negatively correlated with age (rs  = -.692, p = .013). However, serum AMH concentrations were not correlated with the average number of ovarian structures (rs  = -.535, p = .074). Thus, AMH Gen II ELISA was validated in clouded leopards. Around the time of ovulation, serum AMH decreased with advancing age and ovarian responsiveness cannot be evaluated using serum AMH.

Effect of a GnRH Antagonist on Anti-Müllerian Hormone and Follicular Population in Anestrous Bitches

The objective of this study was to describe the effect of the third-generation GnRH antagonist, acyline, on ovarian follicular population and serum anti-Müllerian hormone (AMH) concentrations in female dogs. Four late anestrous bitches were administered 330 μg/kg SC acyline every 10 days for 60 days and followed up for 45 days. Blood samples were drawn on days -1, 15, 30, 45, 60, 75, 90 and 105 for AMH determination. Then, the females were ovariectomized and the excised ovaries were gross and histologically evaluated. The total ovarian follicles were counted. None of the female dogs presented estrus during treatment. Only one bitch presented an ovulatory estrus 20 days after treatment. The total number of ovarian follicles in these bitches was 96,200.10 ± 26,125.12, with 84.13%, 11.36%, 7.8% and 0.01% corresponding to primordial, primary, secondary and antral structures, respectively. Pretreatment AMH concentrations were 0.62 ± 0.17 ng/mL. This hormone varied throughout the study period (p < 0.01), diminishing to nadir values during treatment to then rapidly recover after its effect (0.2 ± 0.05 vs. 0.67 ± 0.22 ng/mL; p < 0.01). Acyline rapidly and reversibly prevented the initiation of cycling without affecting follicle count but diminishing serum AMH concentrations.

Vincristine-associated total antioxidant and oxidant status of ovaries and in vitro nuclear oocyte maturation in dogs with canine transmissible venereal tumor

The aim of this study is to evaluate the effects of scheduled vincristine sulfate therapy on canine oocyte quality and nuclear oocyte maturation, associated with total antioxidant and oxidant status of ovaries and Anti-Müllerian Hormone (AMH) concentrations in dogs with Canine Transmissible Venereal Tumor (CTVT). Six bitches suffering from CTVT and six healthy bitches were included in the study. Hemogram was carried out weekly. AMH measurements and ovariohysterectomy operations were performed after the termination of vincristine sulfate therapies. Tissue samples from ovaries were utilized for Malondialdehyde (MDA), reduced Glutathione (GSH), Superoxide Dismutase (SOD), Total Anti-oxidative Status (TAS), Total Oxidative Status (TOS) measurements, and Oxidative Stress Index (OSI) was calculated. Collected oocytes were evaluated for meiotic competence, after In Vitro Maturation (IVM) and parthenogenetic activation. No difference between the two groups was observed in hematologic parameters (P > 0.05). Meiotic stages of Germinal Vesicle Break Down (GVBD), Metaphase I (MI), and Metaphase II (MII) were significantly different between groups (P < 0.05). The number of oocytes reaching MII and meiotic resumption was lower in the CTVT group. Furthermore, AMH concentrations, oxidant parameters (OSI, TOS, and MDA), and antioxidant parameters (GSH, SOD, and TAS) were also statistically different between groups (P < 0.05). The results of this study show that vincristine sulfate application in the treatment of CTVT could alter oxidant/antioxidant status in ovaries. Apart from these, oocyte quality and IVM rates seem to decline related to gonadotoxicity. Moreover, AMH could be an important marker in the evaluation of oocyte qualities in bitches, as it is in women.

Serum Anti-Müllerian Hormone Levels and Estrous Monitoring of GnRH Agonist Deslorelin-Induced Estrus in Bitches: A Pilot Study

This study was performed to monitor estrous patterns and, more importantly, changes in anti-Müllerian hormone (AMH) concentrations during the peri-ovulatory period in deslorelin-induced estrous bitches. Healthy anestrous bitches (n = 4) were used. Estrus and ovulation were monitored after deslorelin implantation. Blood samples were collected for analysis of progesterone, estradiol-17ß and AMH concentrations before implantation (day 0) and on days 6, 8, 10, 12, 14, 16, 18, 20 and 22 after implantation. Six days following treatment, all bitches showed estrus signs. Ovulation took place between days 12 and 15. Circulating AMH concentrations varied among bitches from 0.12 to 3.08 ng/mL. However, no significant differences in AMH levels (mean ± SD) were observed between day 0 and days following post-implantation (p > 0.05). There were no significant correlations between AMH and estradiol or AMH and progesterone (p > 0.05). Ultrasonographically, the number of clearly identifiable ovarian follicles was higher before ovulation and the area of ovaries increased after ovulation (p < 0.05). Except for AMH, changes in vaginal cytology, estradiol-17ß and progesterone levels observed in our study were similar to naturally occurring estrus. Large intra- and inter-individual variation in AMH were observed suggesting that AMH is currently not suitable as a canine fertility marker to monitor ovarian response to deslorelin treatment for estrus induction.

Reproduction in South American wild canids—A review

Canids occupy the top of the food chain and are fundamental in sustaining a wild animal/environmental balance. South America, the most biodiverse continent, has 11 species of canids inhabiting diverse biomes, with or without overlapping territories. Although several species are threatened, little is known about their reproductive biology. Remarkably, basic knowledge regarding ejaculate characteristics, sexual behavior, female reproductive cycles, pregnancy and management, and parturition are scarce or absent. These gaps complicate or preclude development of conservation programs. This review compiles the current knowledge of the reproductive biology of South American canids and discusses implications of this scenario.

Anti-Müllerian hormone concentrations in queens throughout the estrous cycle

Studies in cats and dogs have proven the usefulness of anti-Müllerian hormone (AMH) as a diagnostic tool to determine the castration status or to diagnose ovarian remnant syndrome. Yet the secretion pattern of AMH over the estrous cycle in queens has not been investigated so far. Seven healthy sexually intact female cats were examined daily for signs of estrous behavior over a trial period of 4 months. Five queens showed regular estrous behavior, 1 queen was mated in her first heat and 1 queen never showed any signs of heat. To distinguish between inter-estrus and metestrus progesterone levels were determined. Serum samples for AMH and progesterone measurement were collected from the regular cycling queens in late anestrus, at several times during heat, inter-estrus and metestrus, from the mated queen during her first heat and during pregnancy, and in the acycling queen at various times during the trial period. The measured AMH values in anestrus were significantly (P < 0.05) higher than in heat (P < 0.001), metestrus (P = 0.12) and inter-estrus (P = 0.449). In anestrus the median AMH levels were 10.26 ng/ml (range 4.96 to 22.90 ng/ml), in heat 5.97 ng/ml (range 3.32- 22.96 ng/ml), in inter-estrus 10.47 (range 3.35-22.96 ng/ml) and in metestrus 6.38 ng/ml (range 4.50-10.75 ng/ml. The pregnant cat showed median AMH concentrations of 6.47 ng/ml (range 5.60-9.80 ng/ml) during her pregnancy. The acycling queen had solely low AMH values with a median concentration of 0.39 ng/ml. In conclusion there were high variations of the AMH levels among and within the individual cats and between heat cycles in the single cat. Remarkable high AMH concentrations were measured in the younger queens of the study in their first estrous cycles and also in anestrus, when less ovarian activity is expected. Further studies are necessary to emphasize the reasons for these high AMH concentrations especially in young queens.

Assessment of anti-Müllerian hormone in mares' transitional period and in relation to fertility in elderly mares

Anti-Müllerian Hormone (AMH) has been linked to reproductive tract abnormalities in mares and stallions. This study aimed at evaluating AMH as a biomarker for two reproductive conditions in mares. In the first part of this study, plasma AMH was evaluated as an early indicator of the onset of cyclicity in mares in the transitional period from the anovulatory phase during winter anoestrus to the cyclic phase during the breeding season. Ten mares between 8 and 17 years old were included in the experiment which lasted from mid-February until the end of April. Ovarian activity was monitored with ultrasonography three times per week, the detection of a corpus haemorrhagicum/luteum was documented and antral follicle counts (AFC) were recorded. Blood samples were collected weekly by jugular venipuncture during the whole study period to compare AMH concentrations before and after the first ovulation of the year. The second objective was to evaluate if plasma AMH concentrations in middle-aged mares are linked to fertility and could serve as a prognostic marker in that age group. A total of 41 privately-owned clinically sound mares aged between 12 and 21 years of various breeds were inseminated with fresh or frozen semen. Mares were scanned between day 14 and 20 and the "early pregnancy rate" included only positive pregnancy examinations after the first observed cycle in the season of each mare. Potential associations between the early pregnancy rate in the first cycle and the explanatory factors AMH concentrations, age, status of the mare, stud, development of post-breeding endometritis, number of inseminations and semen type were analysed using logistic regression models. In the first part of the study, correlation between AMH and AFC for the whole study period (P = 0.0002, ρ = 0.55) as well as prior to (P = 0.008, ρ = 0.58) and after the first ovulation (P = 0.0007, ρ = 0.69) were observed. However, AMH concentrations before and after the first ovulation of the year were not statistically different. The second part of the study revealed no association between early pregnancy rate and AMH concentrations or any of the other mentioned factors. In conclusion, this study showed no evidence of a difference between AMH concentrations before and after the first ovulation of the year thus not supporting the use of AMH as a biomarker to predict the onset of cyclicity in mares. We could furthermore not show a relationship between plasma AMH concentrations and early pregnancy rates in this cohort of animals.

Anti-Müllerian Hormone and OPU-ICSI Outcome in the Mare

Anti-Müllerian hormone (AMH) reflects the population of growing follicles and has been related to mammalian fertility. In the horse, clinical application of ovum pick-up and intracytoplasmic sperm injection (OPU-ICSI) is increasing, but results depend largely on the individuality of the mare. The aim of this study was to assess AMH as a predictor for the OPU-ICSI outcome in horses. Therefore, 103 mares with a total follicle count above 10 were included in a commercial OPU-ICSI session and serum AMH was determined using ELISA. Overall, the AMH level was significantly correlated with the number of aspirated follicles and the number of recovered oocytes (p < 0.001). Mares with a high AMH level (≥2.5 µg/L) yielded significantly greater numbers of follicles (22.9 ± 1.2), oocytes (13.5 ± 0.8), and blastocysts (2.1 ± 0.4) per OPU-ICSI session compared to mares with medium (1.5-2.5 µg/L) or low AMH levels (<1.5 µg/L), but no significant differences in blastocyst rates were observed. Yet, AMH levels were variable and 58% of the mares with low AMH also produced an embryo. In conclusion, measurement of serum AMH can be used to identify mares with higher chances of producing multiple in vitro embryos, but not as an independent predictor of successful OPU-ICSI in horses.

Evaluation of combined assessments of serum anti-Müllerian hormone and progesterone concentrations for the diagnosis of ovarian remnant syndrome in dogs

OBJECTIVE

To determine the usefulness of combined assessments of serum anti-Müllerian hormone (AMH) and progesterone (P4) concentrations for diagnosis of ovarian remnant syndrome (ORS) in dogs.

DESIGN

Prospective case series.

ANIMALS

602 bitches that had previously undergone ovariohysterectomy or ovariectomy without hysterectomy and that were being evaluated for ORS.

PROCEDURES

Serum AMH and P4 concentrations were measured in a single serum sample obtained from each of the 602 dogs; results were classified as positive, negative, or inconclusive. Following AMH testing, submitting veterinarians were offered reimbursement for shipping and histologic evaluation of any tissue removed during treatment of dogs for which serum samples had been assessed.

RESULTS

Tissue samples were provided from 53 of 55 dogs that underwent surgical abdominal exploration. Of 48 dogs with histologically confirmed ORS, 25 were positive for both AMH and P4 and 23 were positive for AMH or P4 or test results were inconclusive. No dogs with histologically confirmed ORS were negative for both AMH and P4. Tissue samples that included no ovarian tissue were obtained from 5 dogs that were positive for both AMH and P4. In 2 dogs that were negative for both AMH and P4, no ovarian remnant was identified and no tissue was removed at the time of exploratory surgery.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that combined determination of AMH and P4 concentrations in a single serum sample can be an effective diagnostic test for spayed dogs suspected to have ORS. Histologic analysis of excised tissues to assess the completeness of surgical treatment in dogs with ORS is warranted.

Intraovarian regulation of folliculogenesis in the dog: A review

Dog reproductive cycle is unique among other mammals in that females experience long and variable periods of ovarian inactivity. Neuroendocrine controls of the reproductive cycle have been thoroughly studied in the dog. However, there is little information regarding endocrine, paracrine and autocrine controls of dog ovarian folliculogenesis. Advancements in the understanding of mechanisms regulating dog ovarian follicle development will be helpful in the establishment of an approach to control cyclicity in this species. Furthermore, such information will likely be useful for the establishment of an in vitro follicle culture system to preserve fertility of genetically valuable disease models or endangered canids. This review highlights current knowledge on dog folliculogenesis with emphasis on endocrine, paracrine and autocrine controls of follicular development.

O uso do cloridrato de piridoxina para induzir estro em cadelas

RESUMO Os agonistas dopaminérgicos são utilizados para induzir estro em cadelas, pois atuam na síntese e liberação de prolactina. Objetivou-se avaliar o efeito da piridoxina como indutor de estro em cadelas por agir na neurotransmissão dopaminérgica. Foram selecionadas 40 cadelas em anestro, divididas em quatro grupos experimentais, tratadas com 10mg/kg/dia (G1) e 50mg/kg/dia (G2) de cloridrato de piridoxina, 5µg/kg/dia (G3) de cabergolina e grupo controle/placebo (G4) por até 20 dias. Foram realizadas citologias vaginais a cada 24h para acompanhamento do ciclo estral e análises hormonais (FSH, LH e PRL) no dia zero e 120h do início do tratamento. As cadelas do G3 (100%) manifestaram proestro após 12 dias de tratamento aproximadamente, tempo inferior aos demais grupos (P<0,05). Apenas uma cadela do G1 e uma do G2 ficaram gestantes contra oito fêmeas do G3 e nenhuma do G4 (P<0,05). As concentrações plasmáticas de prolactina foram reduzidas nas fêmeas do G2 e G3 (P<0,05). As demais avaliações hormonais não sofreram influência do tratamento (P>0,05). O cloridrato de piridoxina foi ineficiente para induzir estro em cadelas, mas foi capaz de suprimir a prolactina, de forma semelhante à cabergolina, quando utilizado na dose de 50mg/kg/dia.

Anti-Müllerian hormone in dogs and cats reproduction

The anti-Müllerian hormone (AMH) is a glycoprotein secreted by Sertoli cells in males and granulosa cells in females. It has first been determined in blood serum of dogs and cats by Place et al. in 2011 with the use of a human-based ELISA test. Meanwhile, different immunoassays have been validated for AMH determination in animals and a variety of studies have demonstrated the clinical significance of AMH. This review summarizes the current knowledge about AMH in dogs and cats and describes future opportunities for its diagnostic use.

Anti-Müllerian hormone inhibits luteinizing hormone-induced androstenedione synthesis in porcine theca cells

AMH (Anti-Müllerian Hormone) is involved in the regulation of follicle growth initiation and inhibits FSH-induced aromatase expression and estrogen production in granulosa cells. However, the function of AMH in steroidogenesis by theca cells remains unclear. The aim of this study is to investigate the role of AMH as a regulator of the basal and stimulated steroid production by pig granulosa cells (pGCs) and theca cells (pTCs). PGCs and pTCs were incubated with hormones AMH, LH (luteinizing hormone), FSH (follicle stimulating hormone), individually or in combination. The expression of CYP19A1, HSD3B1, CYP11A1, LHCGR, and CYP17A1 mRNA were evaluated by quantitative reverse transcriptase PCR. In pGCs, 10 ng/mL AMH significantly decreased the FSH-stimulated effect on FSHR and CYP19A1 expression and estradiol production. In pTCs, LH treatment significantly increased the expression of HSD3B1, CYP11A1, LHCGR, and androstenedione or progesterone production (P < 0.05). Additionally, 10 ng/mL AMH also significantly decreased the LH-stimulated effects on the expression of HSD3B1, CYP11A1, CYP17A1, LHCGR and androstenedione production. Transfection with siAMHR2-I abolished the suppressive effects of AMH on LH-induced HSD3B1 expression and androstenedione production. Taken together, these results demonstrate that AMH is involved in FSH induced estradiol production in pGCs and LH induced androstenedione production in pTCs by regulating the steroidogenesis pathway.

Immunohistochemical and qPCR determination of the expression and serum level of anti-Müllerian hormone in pre-pubertal, intact and ovarian remnant syndrome detected bitches

The aim of this study was to determine the serum concentrations, ovarian presence and expression of anti-Müllerian hormone (AMH) in pre-pubertal, bitches with signs of ovarian remnant syndrome (ORS) and intact bitches. In addition, we aimed to verify the suitability of serum AMH concentrations for diagnostic purposes in sterilized bitches and/or in suspected cases of ORS in the field of veterinary medicine. For this purpose, 36 healthy female dogs divided into six groups: proestrus, oestrus, dioestrus, anoestrus, pre-pubertal and ORS. Serum AMH concentrations were determined by electrochemiluminescence immunoassay, and ovarian presence and distribution of AMH was confirmed by immunohistochemical and qPCR techniques. According to the results of qPCR, while the expression values of AMH were at the highest concentrations in the proestrus and oestrus, there was a statistically significant decrease in these values at the later stages of the cycle (p < 0.05). According to hormone analysis, the serum AMH values of the ORS group had decreased significantly compared with the proestrus and oestrus (p < 0.05). Although serum AMH levels of ORS group were increased compared with anestrus and pre-pubertal groups, this increase was statistically non-significant (p > 0.05). Immunohistochemically, AMH expression was first observed in the granulosa cells of primordial follicles in folliculogenesis. Expression values were the highest in the proestrous and oestrus groups, but values from bitches in later stages of the cycle were statistically significant decrease in comparison with these groups (p < 0.05). As a result, AMH concentration and expression were found to be higher in proestrus and oestrus than in other periods (p < 0.05). In addition, the measurable level of AMH concentration in bitches with ORS is an indication that it can be used in the diagnosis of ORS.

Changes in anti-Müllerian hormone concentrations in bitches throughout the oestrous cycle

Studies in female dogs proved the measurement of anti-Müllerian hormone (AMH) as a diagnostic tool to distinguish ovarioectomized from intact females or to diagnose ovarian remnant syndrome. Furthermore, its usability to diagnose a granulosa cell tumour and predict litter size was also investigated in female dogs. Although serum AMH was previously shown to increase during the transition from anoestrus to pro-oestrus in dogs, changes in AMH concentration over the entire oestrous cycle have not yet been determined. The aim of this study was to investigate the secretion pattern of AMH throughout the oestrous cycle in non-pregnant bitches. As a preliminary step, we tested our assay by measuring AMH concentrations in serum samples of 19 intact bitches (10 in anoestrus, 3 in pro-oestrus, 3 in oestrus, 3 in metoestrus) and 19 spayed females of different age and breed. For the main study, 20 healthy female dogs were examined (10 Beagles, and 10 Labrador crossbreeds, body weight 10-28 kg, age 1-6 years) during a normal oestrous cycle. Serum samples were collected in late anoestrus, at several times during pro-oestrus and oestrus, as well as 28 days and 4.5 months after ovulation. Blood collection was combined with a gynaecological examination including progesterone measurement. Serum concentration of AMH was determined using a chemiluminescence immunoassay validated for dog serum. In the preliminary test, intact bitches in various stages of the oestrous cycle had significantly higher serum AMH levels (0.19-1.45 ng/ml) than spayed females (0.01-0.06 ng/ml, P < 0.001). In cycling Beagle and Labrador crossbreed bitches participating in our main study, AMH concentrations were between 0.09 and 2.65 ng/ml with higher AMH concentrations in Beagles but overall high inter-individual and intra-individual variation. The highest AMH values were reached in the last three weeks before the onset of heat until six days before ovulation, and the lowest AMH concentrations were recorded during preovulatory oestrus in 6, metoestrus in 7 or anoestrus in 7 dogs. Serum AMH concentrations increased significantly from late anoestrus up to six days before ovulation and decreased significantly over the last three days before ovulation. A further significant decrease occurred from the last days of oestrus to metoestrus and mid anoestrus. This study shows that the used AMH assay can clearly distinguish between intact and spayed females and that the serum AMH pattern over the oestrous cycle is similar in all bitches, but with high variation among the breeds and among and within bitches. These changes in the AMH concentration are a challenge in timing serum sample collection and interpreting AMH values in bitches. Further studies are necessary to emphasize the factors influencing the AMH concentration.

Presence of anti-Müllerian hormone (AMH) during follicular development in the porcine ovary

BACKGROUND

Anti-Müllerian hormone (AMH) is expressed by granulosa cells of developing follicles and plays an inhibiting role in the cyclic process of follicular recruitment by determining follicle-stimulating hormone threshold levels. Knowledge of AMH expression in the porcine ovary is important to understand the reproductive efficiency in female pigs.

RESEARCH AIM

In the present study we investigated the expression of AMH during follicular development in prepubertal and adult female pigs by immunohistochemistry, laser capture micro-dissection and RT-qPCR.

RESULTS AND CONCLUSION

Although in many aspects the immunohistochemical localization of AMH in the porcine ovary does not differ from other species, there are also some striking differences. As in most species, AMH appears for the first time during porcine follicular development in the fusiform granulosa cells of recruited primordial follicles and continues to be present in granulosa cells up to the antral stage. By the time follicles reach the pre-ovulatory stage, AMH staining intensity increases significantly, and both protein and gene expression is not restricted to granulosa cells; theca cells now also express AMH. AMH continues to be expressed after ovulation in the luteal cells of the corpus luteum, a phenomenon unique to the porcine ovary. The physiological function of AMH in the corpus luteum is at present not clear. One can speculate that it may contribute to the regulation of the cyclic recruitment of small antral follicles. By avoiding premature exhaustion of the ovarian follicular reserve, AMH may contribute to optimization of reproductive performance in female pigs.

Identifying ovarian tissue in the bitch using anti-Müllerian hormone (AMH) or luteinizing hormone (LH)

Reliable methods for determining whether or not a bitch has ovarian tissue present are needed for cases with unknown neutering status. Vaginal cytology consistent with heat is indicative of functional ovarian tissue. Other methods are required when the bitch is not presented in suspected heat. Progesterone can be analyzed during 2 months after suspected heat. During other stages, assays for the analyses of anti-Müllerian hormone (AMH) and luteinizing hormone (LH) have been used. The AMH assay is expected to give detectable concentrations (positive) in bitches with ovarian tissue, and the LH assay should give negative results in intact bitches, except during the pre-ovulatory LH peak. The aim of the present study was to study the diagnostic efficiency for detecting ovarian tissue in bitches using an AMH assay developed for human samples, and a semi-quantitative rapid immune migration (RIM™) LH assay developed for use in dogs. An AMH concentration of ≥0.1 μg/L, and an LH concentration of ≤1 μg/L, was set as the cut-off for presence of ovarian tissue. Client or staff owned bitches were included (N = 125). There were 73 intact bitches that were classified as being in heat (N = 25); in luteal phase (N = 12); or in anestrus (N = 36), and 52 spayed bitches that showed no clinical signs of estrogen influence. In total 64 of the 73 intact bitches (88%) were correctly identified using AMH, and 70/73 (96%) intact bitches were correctly identified using the LH assay. Excluding bitches in heat, the corresponding figures were 42/48 (88%) for AMH and 48/48 (100%) for LH. Of the 52 spayed bitches, 51 (98%) were correctly identified using the AMH assay and 49 (94%) were correctly identified using the LH assay. In this population, the predictive value of a positive AMH for intact bitches was 98%, and of a negative AMH for spayed bitches was 85%. Excluding bitches in heat, the predictive value of a negative LH test for intact bitches was 94%, and the predictive value of a positive LH test for identifying spayed bitches was 100%. It was concluded that analyses of AMH and LH are useful for detecting ovarian tissue in bitches, but that low concentrations of AMH may be obtained in intact bitches, classifying them as spayed. For LH, bitches in suspected estrus should not be tested to avoid the pre-ovulatory LH-surge, that otherwise may cause intact bitches being incorrectly identified as spayed.

Age-associated and deslorelin-induced declines in serum anti-Müllerian hormone concentrations in female cheetahs, Acinonyx jubatus

Anti-Müllerian hormone (AMH) is widely used in human medicine to non-invasively estimate the size of the ovarian follicle reserve and to predict the ovarian response to gonadotropin stimulation in the context of assisted reproductive technologies (e.g., IVF). These applications of AMH testing have recently expanded to non-human mammals, with production animals, such as cows, goats and sheep being the primary focus of AMH research. However, few investigations have involved exotic species, and in particular carnivores. In this study, we measured AMH concentrations (0.078-3.078ng/mL) in archived serum samples that had been collected from 36 adult female cheetahs across their reproductive lifespan (2-15years of age). Similar to other mammals, AMH concentration in cheetahs declined with age, and its variability among females of the same age was considerable. The rates at which AMH declined over time in individual cheetahs were also highly variable. Five cheetahs had been contracepted with the long-acting GnRH agonist deslorelin for 6-18months prior to sample collection, and their AMH concentrations were relatively low compared to untreated females. In this first study of AMH in an exotic carnivore, the findings demonstrate that the age-associated decline in AMH is highly variable and that deslorelin appears to suppress AMH concentration in serum. Owing to the increased use of assisted reproductive technologies in ex situ populations of threatened and endangered species, such as cheetahs, the present study's findings will need to be taken into consideration if AMH is to be used successfully to optimize breeding management decisions in exotic species.