The effects of surgical and chemical castration on intermale aggression, sexual behaviour and play behaviour in the male ferret (Mustela putorius furo)

The Use of Gonadotropin Releasing Hormone to Manage Intraspecific Agonism in a Coalition of Male Lions (Panthera leo)

While housing nonbreeding all-male social groups of African lion (panthera leo) is a necessary part of managing this polygynous species ex situ, resulting intraspecific agonistic behavior can negatively impact animal welfare and guest experience, undermining two primary objectives of modern zoological gardens. Improvest is a gonadotropin releasing factor analog-diphtheria toxoid conjugate marketed for temporary immunological castration which has proven successful in reducing aggression in other zoo-housed species. To the authors' knowledge, the use of this technique has not been described in male African lions; reticence to use GnRH agonists may stem from concern about phenotypic effects (mane loss) and zoo visitor perception. We describe the use of Improvest in conjunction with other management changes to manage agonism in a coalition of African lions (3.0) housed at the Oakland Zoo. Daily agonism scores were calculated via animal care staff records, fecal testosterone levels were measured, and monthly photos were taken to monitor phenotypic changes. While agonism scores varied seasonally in three pretreatment years, a significant (p < 0.05) reduction in the frequency of agonistic behavior began within 2 months of initial treatment. Two lions showed testosterone suppression within 2 months of receiving the first vaccine, while the third showed suppression beginning in the period 4 months after the first vaccine. Mane loss occurred in all three lions, and time to mane regrowth varied between individuals. Improvest, combined with other management strategies, decreased overall fecal testosterone and intraspecific agonism in these lions, and may be an effective tool in other male coalitions.

Anti-Müllerian Hormone Concentrations for Determining Resumption of Sertoli Cell Function following Removal of a 4.7 mg Deslorelin Implant in Tomcats

Background: Deslorelin implant use in cats is a medical alternative to surgical sterilization, and due to its prolonged efficacy, its use has shown growing interest in the veterinary community. In the case of breeding facilities, its removal is often requested for the early restoration of testicular function. As anti-Müllerian hormones (AMH) in males is dependent of testosterone secretion, its assay may determine the restoration of testicular steroid secretion. An average of 3 weeks has been already described for tomcats' testicular function resumption after implant removal, but information about AMH concentrations in deslorelin-treated tomcats is lacking. Methods: Fourteen tomcats were treated for temporary suppression of fertility with a 4.7 mg deslorelin implant, which was surgically removed after 3, 6 or 9 months (n = 6, 4 and 4 tomcats, respectively). A general clinical and reproductive check with a gonadorelin stimulation test for testosterone determination was performed before deslorelin implant administration. After implant removal, tomcats' testicles were ultrasonographically checked for volume determination every 1-2 weeks with observation of the glans penis (presence or absence of spikes) and blood collection to assay both testosterone and AMH concentrations. Results: AMH concentrations increased significantly during the deslorelin treatment from 20.95 ± 4.97 ng/mL to 82.41 ± 14.59 ng/mL (p < 0.05). Following implant removal, AMH concentrations progressively decreased to pre-treatment levels, with a value of 28.42 ± 7.98 ng/mL on the third week post-removal where testosterone secretion was again detected. Conclusions: Even if a big variability of AMH concentrations exists between male individuals, resumption of tomcats' testicular function following a deslorelin treatment can be determined by AMH assay.

Endocrine Diagnostics for Exotic Animals

Endocrine disease in exotic species is less common than in small animals. Nevertheless, the diagnostic principles used in small animals can be adapted to evaluate endocrine disease in many of the exotic species although species-specific aspects need to be considered. This article covers important diseases such as thyroid dysfunction in reptiles and birds, hyperthyroidism in guinea pigs, and hyperadrenocorticism in ferrets. Glucose metabolism in neoplasms affecting normal physiology, such as insulinoma in ferrets and gastric neuroendocrine carcinoma in bearded dragons, is discussed. Calcium abnormalities, including metabolic bone disease in reptiles and hypocalcemia in birds, are also covered.

Double-Blind, Placebo-Controlled Trial of Cyproterone Acetate to Prevent Flare-Up Effect on Dogs Implanted With Deslorelin

Deslorelin slow-released implants are registered in Europe for the reversible suppression of fertility in male dogs. After administration, a time-limited increase in sex hormones concentration and related behavioral problems may be observed. The aim of this work was to assess whether cyproterone acetate, a synthetic progestogen, can prevent this flare-up effect. Eighteen privately-owned entire male dogs were enrolled in this double-blind, placebo-controlled, randomized clinical trial. All subjects received a 4.7 mg deslorelin implant by SC route and 1-3 capsules containing either cyproterone acetate 2 mg/kg (N = 9) or a placebo (N = 9), by oral route BID for 14 days, depending on the dog's weight. The dogs were followed for 28 days. An increase in the blood testosterone concentration was observed in respectively 9/9 and 7/9 dogs of the control and cyproterone groups (p = 0.47). However, a worsening of the sex hormone related problems (i.e., urinary marking, mounting, aggressiveness toward other dogs and/or escape) was only observed in the placebo group, in 56 or 66% of the dogs as measured by respectively the veterinarian and the owners. Our study suggests that cyproterone acetate is effective and safe to supress the deslorelin induced behavioral flare-up effect, but not the rise in testosterone.

Effects of Lupron and surgical castration on fecal androgen metabolite concentrations and intermale aggression in capybaras (Hydrochoerus hydrochaeris)

To curb agonistic interactions in a bachelor group of three male capybaras (Hydrochoerus hydrochaeris), a single dose of leuprolide acetate (Lupron®) was used in an attempt to chemically sterilize the males. Concurrently, fecal androgen metabolite (FAM) concentrations were quantified via enzyme immunoassay to monitor changes in testosterone production after injection of the gonadotropin-releasing hormone agonist. When Lupron proved ineffective in suppressing intraspecific aggression, surgical castration was performed on two males, with continued noninvasive endocrine monitoring. In all three capybaras, FAM concentrations increased initially as a result of the luteinizing hormone surge, but then decreased significantly following chemical sterilization. Surgical castration resulted in further, persistent declines in FAM concentrations in two males, while the third, intact male demonstrated a rise in FAM to pre-Lupron concentrations at 8.5 and 9.5-month postadministration. Despite successful suppression of sperm and testosterone production, intermale aggression continued, ultimately necessitating separation of the animals and transfer to other holding institutions. Under this set of conditions, a single Lupron dose was inadequate for suppressing intraspecific aggression in a group of three males with a pre-established history of aggression.

[GnRH agonist implants in small animal practice - what do we know 13 years following EU registration?]

The availability of GnRH agonist implants offers the possibility of a reversible, temporary downregulation of endocrine and germinative testicular function in male dogs and hobs. This review provides an overview of the registered indication, the induction of temporary infertility in healthy, intact, sexually mature male dogs (4.7 and 9.4 mg deslorelin) and hobs (9.4 mg deslorelin) as well as various off-label indications. Off-label use requires strict indications, informed consent from the owner and a lack of licensed medication (safe and optimum effect). Off-label indications in the male dog include sexual-hormone dependant (disturbing) behavior, benign prostatic hyperplasia, small adenomas of the hepatoid glands and alopecia X. Successful use of deslorelin implants for estrus suppression in jils, but also for the treatment of hyperadrenocorticism in ferrets in general have been described. Similarly, hormonal castration can be induced in tomcats and queens. The variable time to onset of effect and its duration (extremely variable in some animals) represent a challenge for breeders. No (sufficient) contraceptive activity was identified in male rabbits and male guinea pigs; however, treatment did successfully suppress the estrus cycle in female individuals of these species, as well as reproductive activity in male and female rats. Regarding the use in birds and reptiles, significant species-specific differences exist with regard to efficacy, time until onset of effect and duration of downregulation. In birds, the implant is efficient to fully suppress egg laying in chicken, Japanese quail and psittacids. In doves, egg laying is only significantly reduced. Successful treatment of reproduction-associated (unwanted) behaviour patterns (feather picking, aggression) has also been described. In some male birds, namely zebrafinch and Japanese quail, the deslorelin implant is suitable to reduce testosterone levels. Successful treatment of hormone-dependent tumours (Sertoli-cell tumorus) in budgerigars has been described as well as the modulation of specific behavior in turkeys and an efficacy in facilitating their keeping (i. e. reduction of aggression). In reptiles, only the successful use of deslorelin in iguana has been demonstrated to date.

Ferret Behavior Medicine

Domestic ferrets (Mustela putorius furo) are common zoologic companion animals and display specific body language and vocalizations. Social interactions, play behavior, and resting periods are important keystone in domestic ferret behavior. Specific housing and environmental enrichment are recommended to preserve the expression of normal behavior and physiology in ferrets. Presence of abnormal behaviors, including aggression, urination and defecation outside the litter box, stereotypies, and absence of play behavior, should be carefully monitored by veterinarians and ferret owners to assess ferret wellness. Specific considerations, such as deafness, poor vision, and hybridation with other mustelids, may play a role in ferret behavior.

Sex bias and omission in neuroscience research is influenced by research model and journal, but not reported NIH funding

Neuroscience research has historically demonstrated sex bias that favors male over female research subjects, as well as sex omission, which is the lack of reporting sex. Here we analyzed the status of sex bias and omission in neuroscience research published across six different journals in 2017. Regarding sex omission, 16% of articles did not report sex. Regarding sex bias, 52% of neuroscience articles reported using both males and females, albeit only 15% of articles using both males and females reported assessing sex as an experimental variable. Overrepresentation of the sole use of males compared to females persisted (26% versus 5%, respectively). Sex bias and omission differed across research models, but not by reported NIH funding status. Sex omission differed across journals. These findings represent the latest information regarding the complex status of sex in neuroscience research and illustrate the continued need for thoughtful and informed action to enhance scientific discovery.

Revisiting a Previously Validated Temperament Test in Shelter Dogs, Including an Examination of the Use of Fake Model Dogs to Assess Conspecific Sociability

Simple Summary

Globally, many unwanted dogs enter rescue shelters. Shelter staff often avail of behavioural tests as an early screening tool to identify areas of concern to minimise the welfare risk associated with long-term kennelling and failed adoptions. A number of requirements need to be verified in order for a test to become a useful assessment tool, including how reliable and accurate the measurements are. For these tools to be widely used, they need to be feasible and reproducible. We refined a previously validated temperament test for shelter dogs’ assessment, developed in Italy, and applied it to two populations of shelter dogs in the UK. The test measured dog behaviour in the kennel, sociability towards people and other dogs, docility to leash, playfulness, cognitive skills, and reactivity. The test proved easy to replicate, with key outcomes that are consistent with existing research on this topic. Furthermore, an additional experiment provided support for the use of fake dogs instead of real ones to assess sociability to dogs. However, we also highlight the importance of interpreting these data with caution, and advocate the use of behavioural tests as a partial screening tool to be used in conjunction with more extensive behavioural and welfare monitoring.

Abstract

This study assessed the feasibility and reproducibility of a previously validated temperament test (TT) for shelter dogs. The test was developed to measure dog behaviour in the kennel, and traits of sociability towards people and other dogs, docility to leash, playfulness, cognitive skills, and reactivity. We introduced the use of differently sized fake dogs to check their appropriateness in correctly assessing sociability to dogs to broaden its applicability (as the original study used real stimulus dogs). We hypothesised that dogs’ responses may be modulated by the body size of the stimulus dog presented. The reduction analysis of the TT scores extracted five main dimensions (explaining 70.8% of variance), with high internal consistency (alpha > 0.65) and being broadly consistent with existing research. Behavioural components that were extracted from the fake dog experiment showed that dogs are likely to show signs of anxiety and fear toward both the real and fake dog. Dogs’ responses towards a real vs. fake stimulus were significantly correlated (p < 0.05) and they were not affected by the size of the stimulus (p > 0.05). We discuss the importance of interpreting these data with caution and use behavioural tests as a partial screening tool to be used in conjunction with more extensive behavioural and welfare monitoring.

Gonadotrophin-Releasing Hormone Agonists and Other Contraceptive Medications in Exotic Companion Animals

The use of a gonadotrophin-releasing hormone agonist slow-release implant (GnRH A-SRI) has become increasingly popular as an alternative for surgical contraception in many species. Although these implants have proven to be very effective in some species (eg, ferrets, rats, chicken, psittacines, and iguanas), they have been found less effective in other species (eg, male guinea pigs and rabbits, veiled chameleons, slider turtles, and leopard geckos). This review provides an overview of the available literature on the effects of GnRH A-SRIs in companion exotic animals.

Reproductive Medicine in Ferrets

In the United States, desexing is performed routinely in ferrets at the age of 6 weeks, therefore reproductive tract diseases are not so common. However, in Europe most ferrets are desexed when they are several months old, or they are kept as intact animals. For this reason, diseases of the reproductive organs and a prolonged estrus are far more frequent in Europe than in the United States. This article summarizes and reviews the anatomy, reproductive physiology, management of reproduction (including surgical and hormonal contraception) and reproductive tract diseases in male and female ferrets.

Assisted colonisation trial of the eastern barred bandicoot (Perameles gunnii) to a fox-free island

Context Assisted colonisation has the potential to protect species from intractable threats within their historical ranges. The Australian mainland subspecies of the eastern barred bandicoot (Perameles gunnii) is extinct in the wild, with surviving populations restricted to small sites protected by predator–barrier fences. PVA modelling shows that a self-sustaining bandicoot population would require an area free of the introduced red fox (Vulpes vulpes) of at least 2500ha. French Island is outside the historic range of the species, but is fox-free and contains around 9000ha of potentially suitable habitat. Aims This study will assess the suitability of French Island as a potential site for a self-sustaining eastern barred bandicoot population by conducting a 1-year assisted colonisation trial to assess habitat use, body condition and survival. Methods Between July and September 2012, 18 adult bandicoots were released. We radio-tracked bandicoots using intraperitoneal radio-transmitters for up to 122 days and trapped fortnightly. Key results The release group met the three measures of success: (1) appropriate habitat use; (2) recovery of post-release bodyweight; and (3) founder survival exceeding 100 days. Habitat use and body condition throughout the trial reflected that of mainland populations, and seven bandicoots survived longer than 100 days. Mortality was greatest in the first month, with veterinary investigations confirming two deaths due to cat predation, two deaths from toxoplasmosis and one unknown cause of death. Bandicoots that survived longer than 100 days occupied higher, drier ground than those that did not. Toxoplasmosis cases were associated with lower topographic position on the site. Conclusions Our results suggest that French Island provides suitable habitat for the establishment of a population of eastern barred bandicoots. On French Island, toxoplasmosis was identified as an important source of mortality in addition to cat predation, and warrants further investigation. Implications Given the costs and challenges of predator control and the maintenance of predator exclusion fences, assisted colonisation to one or more fox-free islands remains the most viable option to establish self-sustaining bandicoot populations. Our results highlight the value in conducting trial releases ahead of major translocations.

Play in juvenile mink: litter effects, stability over time, and motivational heterogeneity

Mink are potentially ideal for investigating the functions of play: deleterious effects of early social isolation suggest a crucial developmental role for play; and huge numbers of highly playful juvenile subjects can be studied on farms. We collected descriptive data on 186 pairs from 93 litters, half provided with play-eliciting environmental enrichment objects in their home cages, to test three hypotheses: (1) play frequency is subject to litter effects; (2) relative playfulness is stable over time; (3) play sub-types share a single, common motivational basis. We found weak litter effects that were driven by stronger litter effects on general activity, and weakly stable individual differences in both total and rough-and-tumble play. Experimentally increasing object play did not inhibit rough-and-tumble play, showing these sub-types are not motivational substitutes. Frequencies of these sub-types were also uncorrelated, and changed differently with time of day and age, further supporting this conclusion.

Clinical use of deslorelin (GnRH agonist) in companion animals: a review

Over the years, many contraceptive medications have been developed for companion animals, but many secondary adverse effects have limited their use. A major advancement was achieved with the use of gonadotropin-releasing hormone (GnRH) analogues, mainly GnRH agonists, which mimic the effects of native GnRH. The development of effective low-dose, slow-release implants with potent agonists such as deslorelin (Suprelorin®, Virbac) have allowed their use to become widespread in recent years, with many potential benefits in companion animals. While the major application of deslorelin was initially male contraception, due to its two differing actions, either the stimulation of oestrus or the sterilization of fertility, its use has been increasing in the bitch as well. The aim of this study is to review the applications of deslorelin GnRH agonist implants in companion animal, such as dogs, cats and some exotic pets.

Inhibition of the reproductive system by deslorelin in male and female pigeons (Columba livia)

Veterinary practitioners frequently encounter disorders of the reproductive system in avian patients. Management of these disorders relies on manipulating reproduction by modifying the environment, diet, and social interactions, and by the use of pharmacologic agents and surgery, with varying levels of success and side effects. An alternative is to use the gonadotropin-releasing hormone (GnRH) agonist deslorelin to suppress the pituitary-gonadal axis. To determine the efficacy of deslorelin in domestic pigeons (Columba livia), male (n = 10) and female (n = 10) birds each were implanted intramuscularly with a single long-acting implant containing 4.7 mg deslorelin. Untreated males (n = 11) and females (n = 10) were used as controls. The baseline serum concentration of luteinizing hormone (LH) was assayed at 7, 28, 56, and 84 days after treatment, and egg production was recorded weekly. In females, deslorelin administration significantly reduced serum LH concentrations compared to pretreatment levels at 7, 28, 56, and 84 days (P < .05). In males, deslorelin significantly reduced LH concentrations at 7, 28, and 56 days (P < .05). Female birds treated with deslorelin laid significantly fewer eggs over the course of the study (mean = 1.46, SEM = 0.84) compared with controls (mean = 5.54, SEM = 0.88). Deslorelin treatment had no discernible effect on body weight. Deslorelin is effective for controlling egg laying in female pigeons for at least 49 days, but further research is required to determine the effects on male fertility and the duration of action in both sexes.

Use of a GnRH agonist implant as alternative for surgical neutering in pet ferrets

In the current study, the duration of effectiveness, owner satisfaction and side effects of a gonadotrophin releasing hormone-agonist (deslorelin) implant were investigated during a two-year follow-up study in which 61 male and 69 female entire pet ferrets were given a 4.7 mg deslorelin implant as alternative to surgical neutering. In 27 participating non-oestrous jills, a double-blind placebo controlled study was performed to investigate whether a single low dose of medroxyprogesterone (2 mg orally) four days preceding placement of the implant could prevent oestrus induction. The duration of effectiveness of the implant ranged from 301 days to over 1339 days (mean 1012±38 days), with no sex difference present. Over 90 per cent of owners were pleased with the effects of the implant. Minor local side effects were noted in less than 20 per cent of ferrets, which all resolved within a week without treatment. Oestrus was induced in 77 per cent of jills receiving medroxyprogesterone and 50 per cent of jills receiving the placebo, indicating that administration of a low-dose progestogen cannot prevent postimplant oestrus. Based on the minimum duration of effectiveness, it is advised to place a new implant on a yearly basis to guarantee continuous gonadal suppression, although biannual replacement may be sufficient in the majority of ferrets.

Pain management in ferrets

The growing popularity of ferrets as pets has created the demand for advanced veterinary care for these patients. Pain is associated with a broad range of conditions, including acute or chronic inflammatory disease, neoplasia, and trauma, as well as iatrogenic causes, such as surgery and diagnostic procedures. Effective pain management requires knowledge and skills to assess pain, good understanding of the pathophysiology of pain, and general knowledge of pharmacologic and pharmacodynamic principles. Unfortunately, scientific studies on efficacy, pharmacokinetics, pharmacodynamics, and safety of analgesic drugs in the ferret are limited. However, basic rules on the treatment of pain and mechanisms of action, safety, and efficacy of analgesic drugs in other species can be adapted and applied to pain management in ferrets. This article aims to make an inventory of what is known on the recognition of pain in ferrets, what analgesic drugs are currently used in ferrets, and how they can be adopted in a patient-orientated pain management plan to provide effective pain relief while reducing and monitoring for unwanted side effects.