Desexing Dogs: A Review of the Current Literature

Is castration leading to biological aging in dogs? Assessment of lipid peroxidation, inflammation, telomere length, mitochondrial DNA copy number, and expression of telomerase and age-related genes

BACKGROUND

Biological aging is a complex process influenced by various factors, including reproductive status and castration. This study aimed to evaluate the impact of castration on biological aging in dogs.

METHOD

Fifteen male crossbred dogs were randomly divided into a sham-operation control group (n = 5) and a castrated group (n = 10). Blood samples were collected at weeks 0, 4, 8, 12, 16, and 18 post-surgery. Malondialdehyde (MDA as indicator of Lipid peroxidation), C-reactive protein (as an indicator of inflammation), telomere length, mitochondrial DNA (mtDNA) copy number, and the expression of age-related (P16, P21, TBX2) and telomerase-related (TERT) genes were assessed in blood samples.

RESULTS

Plasma MDA levels were higher in the control group at weeks 16 and 18, while CRP levels were higher only at week 18. Telomere length and mtDNA copy number were lower in the control group at week 18. Gene expression analysis showed that P16 was lower in the control group at weeks 8 and 12, P21 and TERT were lower at weeks 16 and 18, and TBX2 was lower at weeks 16 and 18. The TBX2/P16 ratio was lower in the control group at weeks 16 and 18 but higher at week 12, while the TBX2/P21 ratio did not differ between groups.

CONCLUSION

Castration appears to have a protective effect against biological aging in dogs, as evidenced by lower lipid peroxidation, inflammation, and age-related changes in telomere length, mtDNA copy number, and gene expression.

Effect of neutering timing in relation to puberty on health in the female dog-a scoping review

BACKGROUND

Effects of neutering on bitch health have been reported, and are suggested to relate to bitch age at the time of neutering for some diseases. However, variation between published studies in terms of study populations and methodologies makes comparison and consolidation of the evidence difficult.

OBJECTIVE

A scoping review was designed to systematically search the available literature to identify and chart the evidence on the effect of neutering timing in relation to puberty on five health outcomes: atopy, developmental orthopaedic disease (DOD), neoplasia, obesity and urogenital disease.

DESIGN

A protocol was registered, and literature searches were conducted in CAB Abstracts, Medline and Web of Science. Studies were reviewed against inclusion criteria. Data on study and population characteristics and health outcomes were charted for the final included studies.

RESULTS

A total of 1,145 publications were reviewed across all five searches; 33 were retained for inclusion and charting. Only six of the 33 studies categorised the timing of surgical neutering as prepubertal or post-pubertal; one investigating mammary neoplasia and the other five, urogenital disease, commonly urinary incontinence. No studies were identified that examined the impacts of neutering bitches before or after puberty on atopy, DOD or obesity. One study considered bitches that were pre or post-pubertal at the time of the first treatment with deslorelin acetate for oestrus suppression and 26 examined the effects on health related to age, rather than pubertal status, at neutering.

CONCLUSION

This scoping review suggests that robust evidence to support veterinarians, those working with dogs and dog owners when discussing the timing of neutering relative to puberty does not yet exist. The impact of neutering before or after puberty on atopy, DOD, neoplasia, obesity and urogenital disease in female domesticated dogs remains unclear.

Investigation of the Relationship between Plasma Nesfatin-1 Levels and Neutering in Dogs

Neutering of dogs, whether male or female, provides various benefits such as contraception, population control, and the prevention of reproductive disorders and undesirable sexual behaviors. However, it is also associated with an increased risk of obesity, which may be directly linked to post-neutering hormonal changes. Our study aims to determine the effects of neutering on plasma levels of nesfatin-1, serotonin, dopamine, TSH, and T4-hormones implicated in obesity and metabolic regulation. Fourteen dogs (seven males and seven females), aged between 1 and 3 years, were included in this study. Male dogs underwent orchiectomy and females underwent ovariohysterectomy. Blood samples were collected before surgery and on days 7 and 14 post-operatively to measure the plasma levels of these hormones using ELISA. The results showed a significant decrease in nesfatin-1, serotonin, and T4 levels, along with a significant increase in TSH levels in both male and female dogs post-neutering. While these hormonal changes are likely part of the body's adaptive response to neutering, they may represent a potential mechanism that contributes to the long-term tendency toward obesity in neutered dogs.

Canine on the Couch: The New Canary in the Coal Mine for Environmental Health Research

Human health is intimately connected and tied to the health of our environment and ecosystem, with only a very small fraction of the risk for chronic diseases explained by genetics alone. Companion animals are prone to disease types that are shared with people, including cancers and endocrine disorders, reinforcing the thought that environmental factors contribute to the risks for chronic diseases. These factors include air and water pollution and the built environment. As such, there is increasing interest in pursuing research with companion animals, and specifically dogs, as sentinel species to inform comparative health assessments and identify risk factors for disease. Of the canine diseases for which environmental exposure research has been published, cancers have received the most attention. This review summarizes two main aspects of this comparative approach: (1) cancers that occur in dogs and which are similar to humans and (2) research investigating environmental exposures and health outcomes in dogs. The goal of this review is to highlight the diverse conditions in which pet dogs may provide unique perspectives and advantages to examine relationships between environmental exposures and health outcomes, with an emphasis on chemical pollution and cancer. Furthermore, this review seeks to raise awareness and stimulate discussion around the best practices for the use of companion animals as environmental health sentinels.

Male animal sterilization: history, current practices, and potential methods for replacing castration

Sterilization and castration have been synonyms for thousands of years. Making an animal sterile meant to render them incapable of producing offspring. Castration or the physical removal of the testes was discovered to be the most simple but reliable method for managing reproduction and sexual behavior in the male. Today, there continues to be global utilization of castration in domestic animals. More than six hundred million pigs are castrated every year, and surgical removal of testes in dogs and cats is a routine practice in veterinary medicine. However, modern biological research has extended the meaning of sterilization to include methods that spare testis removal and involve a variety of options, from chemical castration and immunocastration to various methods of vasectomy. This review begins with the history of sterilization, showing a direct link between its practice in man and animals. Then, it traces the evolution of concepts for inducing sterility, where research has overlapped with basic studies of reproductive hormones and the discovery of testicular toxicants, some of which serve as sterilizing agents in rodent pests. Finally, the most recent efforts to use the immune system and gene editing to block hormonal stimulation of testis function are discussed. As we respond to the crisis of animal overpopulation and strive for better animal welfare, these novel methods provide optimism for replacing surgical castration in some species.

Success in the Natural Detection Task is influenced by only a few factors generally believed to affect dogs' olfactory performance

Research into dogs' olfactory ability is growing rapidly. However, generalising based on scientific results is challenging, because research has been typically conducted on a few specially trained subjects of a few breeds tested in different environmental conditions. We investigated the effects of temperature and humidity (outdoors), age, test location, sex, neutering status, and repeated testing (outdoors and indoors) on the olfactory performance of untrained family dogs (N = 411) of various breeds. We employed the Natural Detection Task with three difficulty levels, from which we derived two performance metrics: Top Level and Success Score. Temperature (0-25 °C) and humidity (18-90%) did not affect olfactory performance. Young adult dogs surpassed other age groups in reaching the Top Level. Sex and neutering status showed no discernible influence on Top Level and Success Score. Dogs performed better in both metrics when tested indoors compared to outdoors. In the test-retest procedure no significant learning effect was observed. We confirmed on untrained companion dogs that olfactory performance declines with age and rejected some factors that have been previously hypothesised to significantly affect dogs' olfactory success. The influence of the testing environment was notable, emphasising the need to consider various factors in understanding dogs' olfactory capabilities.

Spay/neuter laws as a debated approach to stabilizing the populations of dogs and cats: An overview of the European legal framework and remarks

To reduce the (over) population of unwanted companion non human animals, namely dogs and cats. They are used to lower negative impacts on human societies and on the animals themselves, and opting for the neutering status is usually considered a demonstration of "responsible ownership." In Western countries, however, such provisions are not uniform and must increasingly be balanced with the recognition of animals as sentient beings with interests under the law. Furthermore, there is no consensus on whether routine neutering benefits both human and nonhuman parties, and the veterinary profession progressively claims the need for case-by-case management. Such premises make deciding how to manage companion animals' reproductive lives legally challenging. The current work examines the European legal framework for companion animal protection and animal legal status after providing a brief overview of the global problem of overpopulation. Subsequently, the author discusses the main legal approaches to controlling companion animal reproduction, in European countries. Remarks about the legally binding option and on alternative approaches are provided, while highlighting the persistent need for appropriate and coherent European legislation.

Longevity of companion dog breeds: those at risk from early death

The companion dog is one of the most phenotypically diverse species. Variability between breeds extends not only to morphology and aspects of behaviour, but also to longevity. Despite this fact, little research has been devoted to assessing variation in life expectancy between breeds or evaluating the potential for phylogenetic characterisation of longevity. Using a dataset of 584,734 unique dogs located within the UK, including 284,734 deceased, we present variation in longevity estimates within the following: parental lineage (purebred = 1 breed, crossbred ≥ 2 breeds), breed (n = 155), body size (large, medium, small), sex (male, female) and cephalic index (brachycephalic, mesocephalic, dolichocephalic). Survival estimates were then partitioned amongst phylogenetic clades: providing evidence that canine evolutionary history (via domestication and associated artificial selection) is associated with breed lifespan. This information provides evidence to inform discussions regarding pedigree health, whilst helping current/prospective owners, breeders, policy makers, funding bodies and welfare organisations improve decision making regarding canine welfare.

The effect of neuter status on longevity in the Rottweiler dog

Surgical sterilization or neutering of dogs is a commonly performed procedure in veterinary practices in many countries. In recent decades, concerns have been raised regarding possible side effects of neutering, including increased risk of certain neoplastic, musculoskeletal and endocrinological conditions. Considering that age serves as a significant confounding factor for some of these conditions, evaluating longevity statistics could provide valuable insights into the impact of neutering. The aim of this study was to compare longevity between neutered and sexually intact male and female Rottweilers, using electronic patient records collected by the VetCompass Australia database. Male and female Rottweilers neutered before 1 year of age (n = 207) demonstrated an expected lifespan 1.5 years and 1 year shorter, respectively, than their intact counterparts (n = 3085; p < 0.05). Broadening this analysis to include animals neutered before the age of 4.5 years (n = 357) produced similar results.

The Pathological and Ultrasonographic Evaluation of the Chemical Castration in Dogs using Calcium Chloride Injection

Many researchers have been curious about the chemical sterilization method, which may be a choice of castration. The 20% calcium chloride ethanolic solution can prevent animals from some tumors and control the side effects of surgical castration. This experiment divided 12 male mixed-breed dogs into sham and chemical groups (n=6). Normal saline and 20% calcium chloride (20 ml/testis) were injected in the sham and chemical group's testis, respectively. Ultrasonography and related scoring were operated at 0-, 7-, 14-, and 2-days post-injection to evaluate echogenicity and measure the left testes' dimensions. Blood samples were taken on days 0, 7, 14, and 21 of the experiment evaluating the superoxide dismutase (SOD), glutathione peroxidase (GPx), and testosterone levels. The semen in the left epididymis of the chemical group was aspirated on day 21 post-injection for counting the sperm numbers. The testes of all dogs were surgically removed at 21 days post-injection, and the left one was put in formaldehyde for tissue processing. The intertubular edema, necrosis of the seminiferous tubules, neutrophil infiltration, and calcification was scored. The average dimensions of the chemical groups' left testes significantly decreased 7, 14, and 21 days after injection. The echogenicity of the testes decreased in the chemical group. A significant echogenicity difference was observed between the first day and the 7th and 14th day in ultrasonography. Calcium chloride injection failed to reduce the mean testosterone levels on all experimental days compared to day zero. Otherwise, the sperm number in the left testes of the chemical group decreased on day 21 post-injection. The degree of intertubular edema with neutrophil infiltration and severe tubular necrosis in the chemical group was significantly higher than in the sham group on the experimental days, including 7, 14, and 21. The mild calcification in the chemical group is likely the reason for higher echogenicity on day 21. The scrotum was swelled and ulcerated in the chemical group. Ultrasound is effective in demonstrating the castration ability of calcium chloride in the chemical method. Due to the inflammatory clinical effects, the chemical method is recommended in dogs only when surgical methods are unavailable.

The assessment of haematologic and serum chemistry parameters in canine pyometra: a systematic review and meta-analysis

OBJECTIVES

Pyometra is common in non-spayed adult female dogs requiring early diagnosis and treatment to increase the survival rate. The diagnosis of pyometra is mainly based on clinical examination and anamnesis. Radiography, ultrasonography and laboratory analyses are recommended to support a diagnosis. The aim of this study was to assess blood parameters associated with pyometra by performing a systematic review and meta-analysis.

MATERIALS AND METHODS

The review was conducted in accordance with PRISMA guidelines. A search of three databases (PubMed, Google Scholar and CAB abstracts) was performed in July 2022. Studies providing information about laboratory parameters for both the pyometra group and healthy control group dogs were eligible for inclusion. Data extraction included the first author's name, publication year, country, number of participants in both groups, mean values of selected studies, standard deviation values, and blood parameters. The risk of bias for each study was evaluated, and a random-effects meta-analysis was performed.

RESULTS

We included 44 studies which investigated 12 blood parameters. High heterogeneity was detected in all parameters in these meta-analyses. The following blood parameters were increased in dogs with pyometra: white blood cell (mean=27.75×109  L-1 , mean difference (MD)=17.16, 95% confidence interval (CI) 14.85 to 19.47), monocytes (mean=2.06×1012 /L, MD=1.37, 95% CI 0.99 to 1.74), blood urea nitrogen (mean=41.42 mg/dL MD=18.06, 95% CI 12.26 to 23.85), alkaline phosphatase (mean=212.78 IU/L, MD=137.51, 95% CI 81.81 to 88.62), and aspartate aminotransferase (mean=48.31 IU/L, MD=16.96, 95% CI 10.61 to 23.30). The following parameters were reduced: red blood cell (mean=5.42 1012 /L, MD=-1.37, 95% CI -1.68 to -1.05), haemoglobin (mean=121.20 g/L, MD=-30.57, 95% CI -39.70 to 21.45), albumin (mean=23.71 g/L, MD = -8.16, 95% CI -11.46 to -4.86). Lymphocyte, creatinine, urea, and alanine transaminase parameters were increased in some studies and decreased in others.

CLINICAL SIGNIFICANCE

In canine pyometra, some blood parameters are consistently increased, some consistently decreased, and some increased or decreased depending on the study.

A role for GnRH in olfaction and cognition: Implications for veterinary medicine

Pulsatile secretion of gonadotropin-releasing hormone (GnRH) is essential for the activation and maintenance of the function of the hypothalamic-pituitary-gonadal (HPG) axis, which controls the onset of puberty and fertility. Two provocative recent studies suggest that, in addition to control reproduction, the neurons in the brain that produce GnRH are also involved in the control postnatal brain maturation, odour discrimination and adult cognition. Long-acting GnRH antagonists and agonists are commonly used to control fertility and behaviour in veterinary medicine, primarily in males. This review puts into perspective the potential risks of these androgen deprivation therapies and immunization on olfactory and cognitive performances and well-aging in domestic animals, including pets. We will also discuss the results reporting beneficial effects of pharmacological interventions restoring physiological GnRH levels on olfactory and cognitive alterations in preclinical models of Alzheimer's disease, which shares many pathophysiological and behavioural hallmarks with canine cognitive dysfunction. These novel findings raise the intriguing possibility that pulsatile GnRH therapy holds therapeutic potential for the management of this behavioural syndrome affecting older dogs.

The Impact of Pediatric Neutering in Dogs and Cats-A Retrospective Study

Surgical sterilization is a common procedure in veterinary practice; yet, the age at which to perform said procedure is still a controversial topic since the common practice of performing this surgery at the "conventional" age of 6 months is not supported by concrete scientific data. Therefore, it leaves space for veterinary professionals to opt for pediatric neutering, especially in the context of shelter medicine, since it allows the adoption of younger animals and is an important tool used to combat the overpopulation of stray animals by preventing their reproduction, even though some of the studies regarding the long-term effects of this approach seem to have contradictory results. Consequently, the present study aims to evaluate the impact of pediatric neutering on the occurrence of obesity, behavioral changes and urinary and joint diseases by posing an inquiry by means of telephone questionnaire to 105 owners of cats and dogs neutered and adopted from Coimbra Municipal Animal Shelter. The analysis of the gathered data did not show any statistically significant relationship between age of neutering and the presence of any of the aforementioned conditions in the animals under study.

Inflammaging in domestic dogs: basal level concentrations of IL-6, IL-1β, and TNF-α in serum of healthy dogs of different body sizes and ages

Inflammaging, a "hallmark of aging," refers to a chronic, progressive increase in the proinflammatory status of mammals as they age, and this phenotype has been associated with many age-related diseases, including cardiovascular disease, arthritis and cancer. Though, inflammaging research is common in humans, there is a lack of data for this process for the domestic dog. Here, serum concentrations of IL-6, IL-1β and TNF-α in healthy dogs of different body sizes and ages were measured to determine whether inflammaging may play a mechanistic role in aging rates in dogs, similar to those found in humans. Using a four-way ANOVA, a significant decrease in IL-6 concentrations in young dogs with the rest of the age categories showing increased IL-6 concentrations was found, similar to humans. However, only young dogs have decreased IL-6 concentrations, with adult dogs having similar IL-6 concentrations to senior and geriatric dogs, implying differences in aging rates between humans and dogs. And, there was a marginally significant interaction between sex*spayed or neutered status and IL-1β concentrations with intact females having the lowest IL-1β concentrations compared with intact males, and spayed and neutered dogs. The presence of estrogen in intact females may, overall, decrease inflammatory pathways. This implies that age at spaying or neutering may be an important aspect to consider for inflammaging pathways in dogs. Furthermore, sterilized dogs often die of immune-related diseases, which could be linked to the increases in IL-1β in sterilized dogs found in this study.

How size and genetic diversity shape lifespan across breeds of purebred dogs

While the lifespan advantage of small body size and mixed breed status has been documented repeatedly, evidence for an effect of genetic diversity across dog breeds is equivocal. We hypothesized that this might be due to a strong right-censoring bias in available breed-specific lifespan estimates where early-dying dogs from birth cohorts that have not died off completely at the time of data collection are sampled disproportionately, especially in breeds with rapidly growing populations. We took advantage of data on owner reported lifespan and cause of death from a large public database to quantify the effect of size and genetic diversity (heterozygosity) on mortality patterns across 118 breeds based on more than 40,000 dogs. After documenting and removing the right-censoring bias from the breed-specific lifespan estimates by including only completed birth cohorts in our analyses, we show that small size and genetic diversity are both linked to a significant increase in mean lifespan across breeds. To better understand the proximate mechanisms underlying these patterns, we then investigated two major mortality causes in dogs - the cumulative pathophysiologies of old age and cancer. Old age lifespan, as well as the percentage of old age mortality, decreased with increasing body size and increased with increasing genetic diversity. The lifespan of dogs dying of cancer followed the same patterns, but while large size significantly increased proportional cancer mortality, we could not detect a significant signal for lowered cancer mortality with increasing diversity. Our findings suggest that outcross programs will be beneficial for breed health and longevity. They also emphasize the need for high-quality mortality data for veterinary epidemiology as well as for developing the dog as a translational model for human geroscience.

Laparoscopic Salpingectomy and Vasectomy to Inhibit Fertility in Free-Ranging Nutrias (Myocastor coypus)

The nutria (Myocastor coypus), an invasive alien species, is widely spread in Europe. Pursuant to regulation (EU) no. 1143/2014, the nutria is subject to management programs to reduce its spread. Surgical fertility control is considered an acceptable method, particularly in urban circumstances, avoiding euthanasia. To maintain the hormonal patterns and the social and behavioral dynamics, surgical infertilization preserving the gonads (i.e., salpingectomy and vasectomy) is recommended. Mini-invasive surgery is an eligible choice when dealing with wildlife, allowing reduced captivation time. For these reasons, 77 free-ranging nutrias, captured in urban nuclei in Italy, underwent infertilization under general anesthesia; laparoscopic salpingectomy and vasectomy were performed on 32 animals and traditional surgery on the remainder, leaving the gonads in place. A three-port technique was used, with two paramedian trocars (5 mm) for the instruments and a median one for the telescope. Ablation was obtained through Onemytis® plasma device, allowing a rapid surgical time with no need to place visceral sutures; the skin was surgically closed. After recovery, the animals were released, and no overt complications were noted. No modification of the behavioral patterns was noted, and the population decreased during the following months.

Pet Ownership in Aotearoa New Zealand: A National Survey of Cat and Dog Owner Practices

This study used an online survey distributed between January and March 2019 to adults residing in Aotearoa New Zealand (NZ) to investigate cat and dog owner practices. Of the 2385 respondents, 885 (37%) owned both cat/s and dog/s, while 652 (28%) and 609 (26%) owned cat/s only or dog/s only, respectively. Nine percent of respondents (n = 212) did not own a cat or dog when the survey was administered. Gaps were identified in the practices of NZ pet owners with regard to regular grooming, immunizations, and deworming treatments. It was also found that many pets, especially cats, were allowed to wander freely both inside and outside the house. Collectively, these gaps in practice raise parasitology and infection concerns which may impact negatively on animal welfare and may increase the prevalence of zoonotic diseases. This study also revealed the need to improve desexing practices, particularly in dogs. Respondents in the survey expressed the wish to have pets regardless of the financial strain they may impose, indicating that future research should focus on reducing the financial burden of pet ownership along with promoting positive pet ownership practices. Our findings suggest the need for better education resources about pet ownership which are easily accessible and target diverse populations. The findings of this study will aid in developing appropriate educational resources to promote animal welfare and increase pet-related knowledge among the NZ populace.

Effects of castration and sterilization on baseline and response levels of cortisol-A case study in male guinea pigs

An uncontrolled reproduction of animals in human hands should be avoided. To meet this goal, animals are widely castrated, i.e., the gonads are completely removed. Since the gonads are the most important source of sex hormones, this is a serious intervention in the entire endocrine system of an organism. Sterilization is a much less invasive procedure. Thus, it could have advantages over castration. Therefore, the overall aim of this study was to analyze the effect of castration vs. sterilization on the release of glucocorticoids, i.e., an important indicator for welfare. Taking domestic guinea pigs as a model system, we studied baseline and response cortisol values (cortisol is the main glucocorticoid in guinea pigs) in castrated, sterilized, sham-operated and intact males and baseline values in their cohoused females. Whereas baseline values of males did not differ between the groups, castrated males showed significantly higher cortisol response levels than intact, sham-operated and sterilized males. Females housed with castrated, sterilized, sham-operated or intact males did not differ in their cortisol concentrations, neither shortly after being placed with the respective male or after being co-housed for several weeks. Overall, the results support the hypothesis that castrated males exhibited a higher cortisol responsiveness during acute challenge which could point to a generalized impaired welfare of castrated males in comparison to intact, sham-operated and sterilized males. Our results provide first evidence for a potential negative impact of castration on the animals' welfare, while at the same time pointing toward sterilization representing a less invasive, promising alternative. Therefore, the results may stimulate future research on this topic to further detect potential welfare-related side effects of castration.

Histomorphometry and μCT scan analysis of osteoporosis in spayed female dogs

Background

Both humans and small animals suffer from similar metabolic and structural diseases that impact the musculoskeletal system; however, instead of studying animal disease in its own right, animals are more often used as models for research into various human ailments, such as osteoporosis. There are few studies indicating that animals may suffer from osteoporosis, which raises the question of why small animals, which we believe to be equally susceptible, receive so little attention. With this research, we hope to draw the attention of researchers to the fact that the examination of animals for this disease is just as important as the examination of humans; human osteoporosis research receives a great deal of attention, while animals and their health are neglected.

Aims

We aimed to analyze the bone volume fraction (BV/TV) and thickness of first (L1) and second (L2) lumbar vertebrae samples from five cadavers using histomorphometric analysis. In addition, we aimed to investigate one cadaver using microcomputed tomography (μCT) imaging.

Methods

The L1 and L2 vertebrae from five dog carcasses were used to evaluate the BV/TV and the trabecular thicknesses. We used precise sampling criteria, and also developed a methodological approach to the study of the vertebrae. Using semi-automated methods, we performed histomorphometric analysis and μCT data analysis.

Results

We used five dog cadavers in this research. During the histomorphometry study, we observed that the lowest L1 BV/TV ratio was 7.88% and the highest was 23.08%. The L2 vertebrae BV/TV ranged from 11.58% to 23.7%. The L1 and L2 lumbar trabeculae thicknesses were also measured. L1's smallest trabecula was 17.34 microns and its largest was 31.88. The L2 vertebrae trabecula thickness was 18.76-30.75 microns. BV/TV and trabecular thickness were positively correlated (and vice versa). The two-tailed p value was less than 0.00001. This difference is statistically significant. After μCT analysis, we discovered regions in the vertebral body with low porosity; these cavities are usually filled with connective tissue. The bone tissue in these areas is more vulnerable, meaning fracture risk has increased.

Conclusions

Animals should not just be considered as models for osteoporosis in humans, but also as potential patients. A single test, such as histomorphometry, may not be sufficient; more advanced technology, such as μCT, is required, since it reveals the pores that make the vertebral column more brittle and susceptible to fracture.

Level of Estrogen in Females-The Different Impacts at Different Life Stages

Historically, a high level of estrogen in women is regarded as the signature for a longer lifespan than men. Estrogen is known to be responsible for the development and regulation of the female reproductive system and secondary sex characteristics. Ovariectomy brings on numerous complications such as early menopause, heart disease, and osteoporosis. Thus, ovariectomy impacts the long-term health and lifespan of women. However, the level of estrogen at different life stages should be managed differently. Life quality can be measured in many ways, but mainly it relates to how an individual is doing in terms of being healthy, comfortable, and able to participate in or enjoy life experiences. First of all, ovariectomy not only reduces the level of estrogen but also destroys the reproductive metabolism and potentially other metabolism functions; it may also reduce the lifespan because of the overall impact, not necessary due to the low level of estrogen. Secondly, according to the principal law of the lifespan (PLOSP), the impacts of ovariectomy at different life stages will be different. The objective of this article is to provide readers with a new view of the research on estrogen. Based on the PLOSP, we recapture the estrogen levels at different life stages and explore potential alternative approaches to the manipulation of the levels of estrogen based on the biological features of the difference life stages. Thus, a low level of estrogen in the early life stage may make a woman live longer than a woman with a normal level of estrogen. However, a low estrogen level does not equal ovariectomy. Here, we explain the different impacts of the estrogen levels during different life stages; the effects on the lifespan of the manipulation of estrogen levels at different life stages; and the differences among the estrogen levels, ovariectomy effects, life stages, and lifespan. The personalized manipulation of estrogen levels and relevant growth factors according to the characterization of the life stages may be able to extend the heathy lifespan of women.

Reasons for and Behavioral Consequences of Male Dog Castration—A Questionnaire Study in Poland

Simple Summary

In many Western countries, castration is the most popular surgical desexing procedure in dogs. Castration may deliver health and behavioral benefits, and it is recommended by veterinary and shelter communities. The aim of the present study was to identify the reasons for male dog castration and to determine the owners’ perceptions about changes in dog behavior before and after castration. An online survey was posted on social networking sites dedicated to dogs. The answers showed that the main reason for castration was undesirable behavior, including hyperactivity, roaming, mounting, aggression, marking and others. Castration reduced aggressive behaviors towards dogs and other animals. This surgery increased the number of dogs that were fearful of unfamiliar dogs/humans, as well as dogs with sound phobias, while decreased the prevalence of hiding behavior. Castration greatly decreased incidences of roaming, mounting and urine marking as well as the dog’s overall activity. Thus, it can be concluded that while castration can resolve many undesirable behaviors in male dogs, the arguments for and against neutering should always be considered on an individual basis.

Abstract

In many Western countries, castration is the most popular surgical desexing procedure in dogs. The aim of the study was to identify the reasons for male dog castration and to determine the owners’ perceptions about changes in dog behavior before and after castration. An online survey was posted on social networking sites dedicated to dogs. A total of 386 respondents participated in the survey. The main reason (39%) for castration was undesirable behavior, including hyperactivity (8%), roaming (8%), mounting (7%), aggression (5%), marking (5%) and others (5%). This surgery did not change the prevalence of aggressive behaviors towards people, but it reduced aggressive behaviors towards dogs and other animals. Castration did not reduce the presentation of anxious behavior in fearful dogs. Castration increased the number of dogs that were fearful of unfamiliar dogs/humans, as well as dogs with sound phobias, while decreased the prevalence of hiding behavior. This procedure greatly decreased incidences of roaming, mounting and urine marking as well as the dog’s overall activity. Thus, it can be concluded that while castration can resolve many undesirable behaviors in male dogs, the arguments for and against neutering should always be considered on an individual basis.

Systematic review of dog bite prevention strategies

BACKGROUND

The prevention of dog bites is an increasingly important public health topic, as the incidence of serious injury continues to rise.

OBJECTIVES

To evaluate the effectiveness of interventions to prevent dog bites and aggression.

METHODS

Online databases were searched (PubMed, Cochrane Library, Embase and Google Scholar), using the search terms: dog/s, canine, canis, kuri, bite/s, bitten, aggression, attack, death, fatal, mortality, injury/ies, prevention, intervention, for studies between 1960 and 2021. All study designs were considered. Outcomes of interest were the incidence of dog bites or dog aggression. Non-English studies, and those without full-text access were excluded.

RESULTS

Forty-three studies met the review criteria, including 15 observational and 27 interventional studies. Fifteen studies investigating dog-control legislation, including leash laws, stray dog control and infringements indicated this can reduce dog bite rates. Breed-specific legislation had less of an effect. Six studies investigating sterilisation, showed while this may reduce dog bites through a reduction in the dog population, the effect on dog aggression was unclear. An alcohol reduction programme showed a significant reduction in dog bite rates in one study. Seven studies assessing educational approaches found that intensive adult-directed education may be effective, with one study showing child-directed education was not effective. Eight studies on dog training (two police-dog related), and six evaluating dog medication or diet were generally low quality and inconclusive.

CONCLUSIONS

Multiple strategies including effective engagement with indigenous communities and organisations will be required to reduce dog-bites and other incidents involving dog aggression. This review provides some evidence that legislated dog control strategies reduce dog bite rates. Available evidence suggests greater restrictions should be made for all dogs, rather than based on breed alone. Due to a burden of child injury, protection of children should be a focus of legislation and further investigations. Prevention strategies in children require redirection away from a focus on child-directed education and future research should investigate the effectiveness of engineering barriers and reporting strategies.

The activity patterns of nonworking and working sled dogs

There are limited studies investigating the combined effects of biological, environmental, and human factors on the activity of the domestic dog. Sled dogs offer a unique opportunity to examine these factors due to their close relationship with handlers and exposure to the outdoors. Here, we used accelerometers to measure the activity of 52 sled dogs over 30 days from two locations in Canada. The two locations differ in the working demands of dogs, therefore we used linear mixed effects models to assess how different factors impact daytime and nighttime activity of working versus nonworking dogs. During the daytime, we found that males were more active than females among nonworking dogs and younger dogs were more active than older dogs among working dogs. Alaskan huskies had higher activity levels than non-Alaskan husky breeds in working sled dogs during the day. Nonworking dogs were slightly more active during colder weather, but temperature had no effect on working dogs’ activity. The strongest predictor of daytime activity in working dogs was work schedule. These results indicate that the influence of biological factors on activity varied depending on dogs’ physical demands and human activity was the most powerful driver of activity in working dogs.

Life tables of annual life expectancy and mortality for companion dogs in the United Kingdom

A life table is a tabulated expression of life expectancy and mortality-related information at specified ages in a given population. This study utilised VetCompass data to develop life tables for the UK companion dog population and broken down by sex, Kennel Club breed group, and common breeds. Among 30,563 dogs that died between 1st January 2016 and 31st July 2020, life expectancy at age 0 was 11.23 [95% confidence interval (CI): 11.19-11.27] years. Female dogs (11.41 years; 95% CI: 11.35-11.47) had a greater life expectancy than males (11.07 years; 95% CI: 11.01-11.13) at age 0. Life tables varied widely between breeds. Jack Russell Terrier (12.72 years; 95% CI: 12.53-12.90) and French Bulldog (4.53 years; 95% CI: 4.14-5.01) had the longest and shortest life expectancy at age 0, respectively. Life tables generated by the current study allow a deeper understanding of the varied life trajectory across many types of dogs and offer novel insights and applications to improve canine health and welfare. The current study helps promote further understanding of life expectancy, which will benefit pet owners and the veterinary profession, along with many other sectors.

Age of sexual maturity and factors associated with neutering dogs in the UK and the Republic of Ireland

BACKGROUND

Surgical neutering of dogs is common, however the average age that dogs reach sexual maturity, are neutered, and dog owners' attitudes to neutering in the UK and the Republic of Ireland have not been explored in a longitudinal study.

METHODS

Owner-reported data on the timing of the first oestrus, timing of neutering and the reasons given for neutering dogs by 12 and 15 months of age were summarised. Factors associated with neutering at 15 months and factors associated with intention to neuter were quantified using multivariable logistic regression.

RESULTS

At 15 months of age, 90.0% (n = 207/230) of unneutered females had had their first oestrus. By 7, 9, 12 and 15 months of age, 22.1% (n = 131/593), 32.2% (197/593), 45.4% (n = 269/593) and 59.9% (n = 352/593) of dogs were neutered, respectively. Breed purity, dog's source, owners' intentions to neuter and the number of dogs in the household were associated with neuter status at age 15 months. Dog's sex, Kennel Club registration, dog's source, dogs intended to be working dogs and previous dog ownership were associated with intentions to neuter. Preventing puppies was the most common reason for neutering.

CONCLUSION

Understanding factors that shape owners' intentions to neuter can inform owner-vet discussions regarding whether to neuter a dog and the optimal age for doing so.

Ovariectomy reduces the risk of tumour development and influences the histologic continuum in canine mammary tumours

Influence of neutering on canine mammary tumorigenesis has been a source of vivid discussion over the last decades. The purpose of this retrospective study was to describe the association between neuter status, tumour size and degree of malignancy in a large population of 625 female dogs with altogether 1459 removed mammary tumours (MTs). MT-bearing dogs were predominantly intact (80.3%) and intact dogs were overrepresented in the tumour population compared to the control group of >19 000 females (p < .0001). Multiple MT occurred in 340 patients (54.4%) and were significantly more common in intact dogs (57.8% vs. 40.7% spayed). Neutered dogs were not only significantly more likely to have a malignant MT (p < .0001) but were significantly more often affected by more aggressive tumour subtypes (p < .0001). Positive correlation between increasing tumour size and increasingly malignant phenotype was slightly stronger in spayed (r_s  = .217; p = .021) compared to intact (r_s  = .179; p = .0003) patients. After ovariectomy, progression from benign to malignant occurs in smaller size tumours, as MT ≥2 cm in diameter were malignant in 86.9% of the spayed patients, compared to 62.0% in intact patients (p = .0002). Intact bitches have a higher risk for MTs and tumour multiplicity. MTs in neutered females are more often malignant and belong to more aggressive subtypes compared to MTs in intact dogs. In neutered bitches, histologic progression from benign to malignant and further along the cancer progression continuum occurs at smaller tumour sizes.

Animal reservoirs of SARS-CoV-2: calculable COVID-19 risk for older adults from animal to human transmission

The current COVID-19 pandemic, caused by the highly contagious respiratory pathogen SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), has already claimed close to three million lives. SARS-CoV-2 is a zoonotic disease: it emerged from a bat reservoir and it can infect a number of agricultural and companion animal species. SARS-CoV-2 can cause respiratory and intestinal infections, and potentially systemic multi-organ disease, in both humans and animals. The risk for severe illness and death with COVID-19 significantly increases with age, with older adults at highest risk. To combat the pandemic and protect the most susceptible group of older adults, understanding the human-animal interface and its relevance to disease transmission is vitally important. Currently high infection numbers are being sustained via human-to-human transmission of SARS-CoV-2. Yet, identifying potential animal reservoirs and potential vectors of the disease will contribute to stronger risk assessment strategies. In this review, the current information about SARS-CoV-2 infection in animals and the potential spread of SARS-CoV-2 to humans through contact with domestic animals (including dogs, cats, ferrets, hamsters), agricultural animals (e.g., farmed minks), laboratory animals, wild animals (e.g., deer mice), and zoo animals (felines, non-human primates) are discussed with a special focus on reducing mortality in older adults.

Prevalence of Reproductive Disorders including Mammary Tumors and Associated Mortality in Female Dogs

Female dogs, especially intact or neutered lately, are at increased risk for reproductive disorders including mammary tumors (MTs). This retrospective study evaluated the prevalence of reproductive pathology and associated mortality in a cohort of female dogs presented at a single veterinary clinic. The medical records of female dogs born in 2000–2003 were reviewed. The study included 599 cases, of which 293 were followed up until death. Causes of death were analyzed according to the spaying status. Among the 599 female dogs, 306 were intact (51%), 50 (8%) had been spayed before 2 years of age (ES, early spaying), and 243 (41%) after 2 years (LS, late spaying). During their lifetime, 79 dogs (13.2%) developed pyometra, and 160 (26.7%) a mammary tumor. Among the 293 dogs with complete follow-up, 103 (35.1%) had at least one MT during their lifetime, of which 53 (51.5%) died of their mammary cancer. Spayed (ES + LS) female dogs had a 4-fold decreased risk of dying from mammary cancer (OR = 0.23, 95% CI 0.11–0.47, p < 0.0001) compared to intact females. In this low-sterilization rate population, MTs developed in 35.1% of female dogs over their lifetime and was the cause of death in half of them.

Restoration of Reproductive Hormone Concentrations in a Male Neutered Dog Improves Health: A Case Study

This case study reports on the use of hormone therapy to treat a dog with a range of physical and behavioral signs that began after gonadectomy. A male mixed breed dog neutered at 7 months of age presented at 1 year with health issues impacting quality of life. Reduced mobility, limping, rapid weight gain, and fear of unfamiliar people were treated over the next 3 years with trials of pain medication, joint supplements, thyroxine, antidepressant, and significant diet restrictions. Frequent carprofen administration and daily joint supplements reduced limping, but mobility was still poor. Weight stabilized on a strict diet but fear and anxiety responses to strangers continued to worsen. Hormone restoration therapy was initiated when the dog was almost 4 years of age. Weekly subcutaneous administration of testosterone cypionate (0.5 mg/kg) significantly reduced pain and increased muscle mass, thereby improving mobility. However, supraphysiologic concentrations of luteinizing hormone were not reduced with testosterone therapy so a gonadotropin-releasing hormone agonist was implanted. After hormone restoration, appetite was reduced, and anxiety and fear behaviors became manageable. The testosterone and gonadotropin-releasing hormone agonist treatment was easily administered, had no known side effects, and the owners were pleased with the outcome.

The Effect of Castration on Peripheral Autonomic Neurons Supplying Mammalian Male Genitourinary System

This review paper deals with the influence of androgens (testosterone) on pelvic autonomic pathways in male mammals. The vast majority of the relevant information has been gained in experiments involving castration (testosterone deprivation) performed in male rats, and recently, in male pigs. In both species, testosterone significantly affects the biology of the pathway components, including the pelvic neurons. However, there are great differences between rats and pigs in this respect. The most significant alteration is that testosterone deprivation accomplished a few days after birth results some months later in the excessive loss (approximately 90%) of pelvic and urinary bladder trigone intramural neurons in the male pig, while no changes in the number of pelvic neurons are observed in male rats (rats do not have the intramural ganglia). In the castrated pigs, much greater numbers of pelvic neurons than in the non-castrated animals express CGRP, GAL, VIP (peptides known to have neuroprotective properties), and caspase 3, suggesting that neurons die due to apoptosis triggered by androgen deprivation. In contrast, only some morpho-electrophysiological changes affecting neurons following castration are found in male rats. Certain clinicopathological consequences of testosterone deprivation for the functioning of urogenital organs are also discussed.

Metabolomic Changes Are Predictive of Aging in Laying Hens

Aging in vertebrates is an extremely complex process that is still poorly understood. One confining factor to studying vertebrate aging is the lack of appropriate models. The laying hen is a good model to study vertebrate aging, as it can be maintained under standard housing conditions, its breeds are genetically well defined and it exhibits significant aging phenotypes at around 18 months of age. Furthermore, laying hens are maintained in a challenging realistic environment and possess a fully functional immune system. Here we used, for the first time, metabolomic profiling of laying hens' blood for identifying biomarkers of aging. Random forest classifier was used to quantify the quality of the markers and found that the markers can predict the correct age group of individuals with 90% accuracy. Animals under time-restricted feeding, a condition known to increase health span, appeared younger under the markers, indicating that the aging biomarkers can also predict the effectiveness of environmental treatments. Additionally, we found that noise, defined as the ratio between the standard deviation and the mean, is an exceptionally robust and universal biomarker of aging, as metabolomic noise increases significantly with age in laying hens, humans, and mice. Our study suggests the laying hen as a useful model to study aging in vertebrates and establishes metabolomic noise as a novel, universal biomarker of aging.

An Investigation into the Impact of Pre-Adolescent Training on Canine Behavior

Simple Summary

Current thinking about puppy training is that it should be performed as early in a dog’s life as possible to prevent the later development of behavior problems. However, no study has been performed to see if early puppy training (before 3 months of age) does present clear advantages over training at a later age, in terms of the subsequent development of adult behavior problems. This retrospective study examined the age at which adult dogs were trained as puppies and whether there were advantages of training puppies before 4 months of age or between 5 and 6 months of age. We found no difference in the age of puppy training and the subsequent development of behavior problems. Aggression, compulsive behavior, destructive behavior, and excessive barking were all reduced in dogs that had attended puppy training before 6 months of age compared to a control group of dogs that had not attended puppy training classes. Ancillary findings about the entire study population were that dogs acquired as pups at 12 weeks of age or less had reduced odds of exhibiting fear or anxiety and engaging in destructive behavior. In addition, male dogs were found to have reduced odds of developing aggressive behavior, compulsive behavior, and mounting/humping and increased odds of rolling in repulsive materials. Neutered dogs of either sex were found to have increased odds of developing fear and anxiety, increased odds of escaping/running away, exhibiting coprophagia, and rolling in repulsive materials. The odds of problematic jumping decreased with age.

Abstract

An online survey about puppy training was sent to members of the Center for Canine Behavior Studies and posted on our social media platforms. Six hundred forty-one (641) qualifying owners provided information on 1023 dogs. About half (48%) of the dogs involved in the study attended puppy training and the balance (52%) did not. The goal of the study was to find out whether puppy training at various ages (1–3 months, 4 months, 5–6 months) helped prevent behavior problems later in life (≥1 year). Attending training at 6 months of age or younger resulted in 0.71 the odds of developing aggressive behavior (95% CI: 0.53–0.97; p = 0.030), 0.64 the odds of having a compulsive behavior (95% CI: 0.45–0.92; p = 0.015), 0.60 the odds of exhibiting destructive behavior (95% CI: 0.37–0.96; p = 0.035), 0.68 the odds of excessive barking (95% CI: 0.47–0.99; p = 0.043), and 1.56 the odds of house soiling (95% CI: 1.08–2.27; p = 0.019). Ancillary findings about the entire study population were that dogs acquired at 12 weeks of age or younger were found to have 0.65 the odds of fear/anxiety (95% CI: 0.46–0.92; p = 0.016) and 0.50 the odds of exhibiting destructive behavior (95% CI: 0.31–0.79; p = 0.003). In addition, male dogs were found to have 0.68 the odds of developing aggressive behavior (95% CI: 0.53–0.88; p = 0.003), 0.66 the odds of developing compulsive behavior (95% CI: 0.49–0.88; p = 0.006), 0.37 the odds of mounting/humping (95% CI: 0.26–0.52; p < 0.001), and 1.53 the odds of rolling in repulsive materials (95% CI: 1.18–1.97; p = 0.001). Neutered dogs of either sex were found to have 3.10 the odds of fear/anxiety (95% CI: 2.05–4.72; p < 0.001), 1.97 the odds of escaping/running away (95% CI: 1.12–3.69; p = 0.025), 2.01 the odds of exhibiting coprophagia (95% CI 1.30–3.19; p = 0.002), and 1.72 the odds of rolling in repulsive materials (95% CI: 1.12–2.66; p = 0.014). The odds of problematic jumping deceased by 0.84 for each 1-year increase in age (95% CI: 0.80–0.88; p < 0.001).

Influence of Gonadectomy on Canine Behavior

Due to the lack of unequivocal scientific evidence, gonadectomy's effects on dogs' behavior are still debated. Since veterinarians differ in their opinion, there may be considerable diversity in the advice received by owners. This study aimed to evaluate the effects of gonadectomy on dog behavior across time. Ninety-six dog owners (48 control dogs and 48 experimental dogs) were interviewed twice (T0 and T1, nine months later) to obtain information about their dog's behavior. No change was found in the eating behavior or weight of dogs of both groups. Compared to T0, at T1, experimental dogs were reported to show less mounting behavior, pull on the leash, and roaming behaviors. Marking behavior did not vary across time for both groups of dogs. A tendency to reduce owner-directed aggression was observed at T1 for experimental male dogs, while no change was observed for male controls. The literature reports conflicting information about the effect of gonadectomy on behavior, suggesting that further studies about this topic should be undertaken.

A Mapping Study of Veterinary Literature on Perceptions and Attitudes of Female Canine Spaying

This is a mapping study conducted to evaluate the characteristics of where content that engages in perspectives or attitudes on female dog spaying is published. Three databases, CAB Direct, PubMed, and Scopus, were systematically searched. There were 84 out of 642 papers identified and screened for relevance on attitudes or perceptions on female canine spaying. These 84 articles were then examined for recurring authors, institutional representation, and publisher information. Additionally, information regarding the population being addressed, veterinarian or client, was noted with most literature addressing the veterinary perspective. Many important articles were published in a wide array of journals from many countries, which suggests the importance of not only browsing journals but also searching for relevant literature in databases like CAB Abstracts and MEDLINE.

A qualitative exploration of South African men's perceived effects of Androgen Deprivation Therapy (ADT) as a treatment for advanced prostate cancer

OBJECTIVE

We undertake qualitative research with men treated in a Pretoria, South Africa Oncology clinic to address men's self-reported experiences on androgen deprivation therapy (ADT).

METHODS

Analyses rely upon 22 men's responses to open-ended questions during interviews. These men were 63-78 years of age, and almost all married (three widowed), had children and were no longer engaged in paid work.

RESULTS

In addressing questions about the anticipated and experienced positive and broader side effects of ADT, men referred to its treatment for prostate cancer, with several generally specifying health or life. Patients also referred to a variety of more specific effects such as pain, nausea, difficulties urinating, gaining weight, low energy and sleep disruptions that appeared to reflect a mixture of influences of prostate cancer, ADT and oncological treatment. In addressing a question about the effects of ADT on romantic/sex life, 16 of 19 married men referred to deleterious impacts on their sex lives. With respect to perceived family, work or broader social life impacts, some men noted others' worries and social support.

CONCLUSION

Findings are situated within discussions of existing research on ADT largely from North American or European samples, and broader views of testosterone and male social behavior.

Active and social life is associated with lower non-social fearfulness in pet dogs

Behavioural problems are leading welfare issues in domestic dogs. In particular, anxiety-related behavioural problems, such as fearfulness and noise sensitivity are highly prevalent conditions that cause distress to fearful dogs. To better understand the environmental factors associated with non-social fear, including noise sensitivity, fear of novel situations, and fear of surfaces and heights, a large online survey including data on 13,700 Finnish pet dogs was performed by the dog owners. After fulfilling inclusion criteria, this data consisted of 9,613 dogs with fear of fireworks, 9,513 dogs with fear of thunder, 6,945 dogs with fear of novel situations, and 2,932 dogs with fear of surfaces and heights. Logistic regression analyses revealed that dogs with frequent non-social fear had experienced less socialisation during puppyhood, were more often neutered, had inexperienced owners, lived without conspecifics, participated less frequently in activities or training, and lived in more urban environments. In addition, we identified several breed differences, and a tendency of more common non-social fear in small dog breeds, which suggests a genetic background. Non-social fearfulness has a negative effect on well-being of the dogs. Our findings suggest that the socialisation and the living environment and the value of other dogs' company and owner interaction via activities and training may improve the well-being of the dogs.

Self-reports of Dutch dog owners on received professional advice, their opinions on castration and behavioural reasons for castrating male dogs

Male dogs are often castrated based on the thought that it facilitates well-behavedness. However, the causal evidence for this from prospective studies lacks and the existing associative studies present mixed results depending on the studied behaviours. We aimed to gain insight into possible factors driving an owner's decision to castrate their male dog, through a quantitative survey based on a convenience sample. We determined the advice owners received from three types of dog professionals (veterinarian practitioners, behavioural trainers, behavioural therapists) and the owners' assessments of castration's behavioural effects. Data on 491 Dutch owners of castrated and intact male dogs were analysed with Chi-square tests. Results indicate that owners of both castrated and intact dogs received castration advice most often from veterinarian practitioners, with pro-castration at higher frequencies for owners of castrated dogs (Chi-square, P<0.001). Overall, most owners disagreed with or were neutral about statements on castration positively affecting male dog behaviour at a population level. Nevertheless, 58% (N = 145) of the owners of castrated dogs (N = 249) reported that correcting unwanted behaviour was a reason to castrate their own male dog. Unwanted behaviour involved aggression in 50% (N = 70) of the owner-dog dyads. Castrated dog's aggression changes were reported on most as 'no change'. The second most common answer indicated an aggression decrease in dogs castrated to correct unwanted behaviour and an increase in dogs castrated for other reasons (Chi-square, P<0.001). The increase in aggression in a subset of castrated dogs is concerning, as aggression can pose risks to the dog's welfare. We acknowledge the limitations of our study which identifies associations rather than provides causal evidence. Still, we recommend professionals' awareness of possible negative behavioural changes following castration, like increased aggression. Future research on behavioural consequences of castrating dogs needs to build a more solid knowledge base for balanced advice regarding castration.

Lifespan of companion dogs seen in three independent primary care veterinary clinics in the United States

Background

The privately owned companion dog is an emerging model in comparative medicine, notably because it shares the human environment including its risk factors, is affected by many analogous age-related diseases, receives comparable medical care, and has excellent veterinary medical data available.

Past studies of dog lifespan have used academic, corporate or insurance data. While independent primary care data exist for the UK, none have as of yet been published for the US. This study analyzed data from three independent primary care US veterinary hospitals and identified factors that influence lifespan and mortality in a cohort of n = 20,970 privately owned dogs using Kaplan-Meier survival estimators and Cox Proportional Hazards modelling, including body size as a covariate.

Results

As previously reported, body size was negatively correlated with lifespan. Gonadectomy was associated with a longer lifespan, with the effect being stronger in females than in males. This lifespan advantage was conserved in gonadectomized female dogs that lived to at least ages 5 and 8 years. We did not find significant differences in lifespan between purebred and mixed breed dogs; however, breeds with larger effective population sizes and/or lower inbreeding coefficients had median survival times 3–6 months longer than breeds with smaller effective population sizes or higher inbreeding coefficients, indicating that these measures of genetic diversity may be affecting breed lifespans. We also found that dog breeds belonging to the “Mountain” ancestral group had median survival times that were 3.5–4.6 years shorter than other purebred dog groups, which remained significant even when correcting for body size.

Conclusions

Our findings show that it is possible to obtain and analyze data from independent veterinary clinics in the US, an approach that could be useful for studies of comparative epidemiology under the One Health and One Welfare paradigms. We also show that the lifespan effects of gonadectomy are not identical between the sexes and should be investigated separately by sex in future analyses. More research is needed to further clarify the influence of age at gonadectomy, as well as the factors leading to the observed differences in lifespan in the “Mountain” ancestral group and in dog breeds of varying inbreeding coefficients and effective population sizes.

A short life on the farm: aging and longevity in agricultural, large-bodied mammals

As average human lifespans increase across the globe, companion animals, specifically dogs and cats, are also living longer with more age-related morbidities. However, a similar trend is not seen in mammalian livestock species. Cows, pigs, goats, and sheep, as well as more niche mammalian species raised across the world, have been primarily raised for their economic benefit to humans and are culled from the population once their production declines. To this end, we lack clear knowledge about the age-related morbidities and causes of death that afflict livestock animals due to natural aging, as well as detailed age-specific survival rates. Here, we review the current state of the field of agricultural mammal aging, as well as provide specific questions and directions that may provide novel resources for veterinarians and aging biologists. By raising awareness of the overall quality of life and ongoing health of individual livestock animals, we can potentially increase production into older life stages, leading to decreased costs to farmers and improved welfare for the animals themselves.