https://www.mdpi.com/2076-393X/7/3/116/pdf

Role of Antisperm Antibodies in Infertility, Pregnancy, and Potential forContraceptive and Antifertility Vaccine Designs: Research Progress and Pioneering Vision.

Contagious equine metritis: artificial reproduction changes the epidemiologic paradigm.

Ovarian dysfunction associated with zona pellucida–based immunocontraceptive vaccines

Context Fertility control is seen as an attractive alternative to lethal methods for control of population size and genetic diversity in managed animal populations. Immunocontraceptive vaccines have emerged as the most promising agents for inducing long-term infertility in individual animals. However, after over 20 years of scientific testing of immunocontraceptive vaccines in the horse, the scientific consensus is that their application as a sole management approach for reducing population size is not an effective strategy. Aims The purpose of this review is to evaluate currently available non-lethal fertility-control methods that have been tested for their contraceptive efficacy in Equidae, and to assess their suitability for effective management of wild (feral) horses in an Australian setting. Key results (1) Fertility-control agents, particularly injectable immunocontraceptive vaccines based on porcine zona pellucida (PZP) or gonadotrophin-releasing hormone (GnRH), can induce multi-year infertility (up to 3 years) in the horse. Some formulations require annual or biennial booster treatments. Remote dart delivery (on foot) to horses is possible, although the efficacy of this approach when applied to large numbers of animals is yet to be determined. (2) The proportion of females that must be treated with a fertility-control agent, as well as the frequency of treatment required to achieve defined management outcomes (i.e. halting population growth in the short term and reducing population size in the long term) is likely to be >50% per annum. In national parks, treatment of a large number of wild horses over such a broad area would be challenging and impractical. (3) Fertility control for wild horses could be beneficial, but only if employed in conjunction with other broad-scale population-control practices to achieve population reduction and to minimise environmental impacts. Conclusions In Australia, most populations of wild horses are large, dispersed over varied and difficult-to-access terrain, are timid to approach and open to immigration and introductions. These factors make accessing and effectively managing animals logistically difficult. If application of fertility control could be achieved in more than 50% of the females, it could be used to slow the rate of increase in a population to zero (2–5 years), but it will take more than 10–20 years before population size will begin to decline without further intervention. Thus, use of fertility control as the sole technique for halting population growth is not feasible in Australia.

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Could current fertility control methods be effective for landscape-scale management of populations of wild horses (Equus caballus) in Australia?

The safety of an anaesthetic protocol consisting of medetomidine hydrochloride (7 μg/kg iv) as premedicant, propofol, (1–2 mg/kg iv) as induction agent and sevoflurane, at 2% in oxygen for maintenance of anaesthesia was studied in 292 elective CSs and 2232 puppies delivered. Medetomidine effects were reversed using atipamezole hydrochloride at 50 μg/puppy sc immediately following delivery and in the bitch iv immediately following surgery. The protocol’s safety for puppies was expressed using survival immediately-, 2 hand 7 d after delivery, and Apgar scores (measurement starting 15 min after delivery of the last puppy). The maternal survival rate was established immediately-, 2 hand 7 d after CS. The CSs included 148 on Boerboel-, 84 on English Bulldogand 60 on other purebred bitches, which resulted in 1378, 541 and 313 puppies, respectively. Boerboel, English Bulldog and other purebred bitches yielded 97.39%, 96.67% and 91.69% live puppies at delivery, 95.43%, 88.35% and 89.78% alive by 2 h and 89.19%, 79.11% and 84.03% alive by 7 d. Sixteen (1.16%), 32 (5.59%) and four (1.28%) malformed Boerboel-, English Bulldogand other purebred puppies were euthanized. Thirty-five, 18 and 26, Boerboel-, English Bulldogand other purebred puppies were stillborn respectively, of which 12, 9 and 15, respectively had been discovered dead upon ultrasound examination immediately before CS. After correction for foetuses found dead on ultrasound examination and malformed euthanized puppies, 98.21%, 95.60% and 94.30% of Boerboel-, English Bulldogand other purebred puppies survived until 2 h and 91.78%, 87.17% and 88.26% until 7 d. Two-hour survival rates were negatively correlated to the proportion of puppies in a litter with scores of eight or below © University of Pretoria 188 (r = 0.14, P = 0.01, n = 292 litters) and tends to be positively correlated to the lowest Apgar score in a litter (r = 0.11, P = 0.05, n = 292 litters). This study shows that medetomidine hydrochloride in the protocol used is a safe premedicant in bitches prior to CS and is associated with good puppy vigour as well as 2 h and 7 d puppy survival rates. The use of medetomidine as premedicant permitted use of less than half the dose of propofol usually required as induction agent.

Preparturient caesarean section in the bitch : justification, timing, execution and outcome evaluation

Reasons for performing study: Few studies have investigated ovarian function in the mare undergoing porcine zona pellucida (pZP) immunocontraception despite reported ovarian dysfunction in other species.

Objectives: This study aimed to describe ovarian function and oestrous cyclicity in pony mares following treatment with either the conventional pZP vaccine or a novel recombinant form of the vaccine derived from porcine ZP3 and ZP4 (reZP). In addition, the contraceptive efficacy of pZP versus reZP was assessed. 

Study Design: Mares (n=21) were randomized into three groups of seven: Group I received the conventional pZP vaccine, with a booster five weeks later; Group II received the reZP vaccine, with a booster five weeks later; and Group III (controls) received two treatments, five weeks apart, of saline and adjuvant alone. Data were collected over a 24 week period coinciding with the physiological breeding season, with treatments commencing in week four. 

Methods: Mares underwent weekly monitoring via trans-rectal palpation and ultrasound examination of the reproductive tract, with daily monitoring during oestrus. Serum samples were obtained for antibody titres and ovarian steroid level analyses at seven day intervals. Cycling mares were bred via fresh semen artificial inseminations, over a maximum of two consecutive oestrous cycles that commenced five weeks post booster vaccination. 

Results: Control mares cycled throughout the trial. Post-treatment, six of seven pZP mares (86%) and one reZP mare (14%) had extended anoestrus that correlated with basal serum oestradiol and progesterone levels. All mares resumed cyclicity by ten months post treatment. Pregnancies were diagnosed in all controls, four reZP- (57%) and none of the pZP- immunized mares. 

Conclusions: The current study demonstrates the reversible suppression of ovarian function in pony mares following treatment with pZP. The effect of the reZP vaccine on pregnancy outcome requires further investigation.

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Ovarian function and pregnancy outcome in pony mares following immunocontraception with native and recombinant porcine zona pellucida vaccines.

Disorders of sex development (DSD) have long been documented in domestic animal species including horses. However, there is only a single report of an androgen receptor (AR) mutation causative of such a DSD syndrome in a horse pedigree. Here, we present a new familial AR mutation in horses. A missense mutation (c.2042G>C) at AR exon 4 explains the segregation of the DSD in a Thoroughbred horse pedigree. The mutation, expected to affect the ligand-binding domain of the AR protein, led to complete androgen insensitivity of 64,XY SRY+, testicular DSD individuals. Additionally, the design of a PCR-RFLP technique provided an accurate molecular test for the identification of horses carrying the mutation.

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Missense Mutation in the Ligand-Binding Domain of the Horse Androgen Receptor Gene in a Thoroughbred Family with Inherited 64,XY (SRY+) Disorder of Sex Development

Two full-term canine fetuses were found to share a placenta during Caesarean section. The fetuses were of discordant gender, with apparently normal male and female external genitalia. Genetic analysis of whole-blood samples obtained from each fetus revealed identical DNA profiles, with more than two alleles detected at six loci. Subsequent genetic analysis of myocardial tissue samples revealed dissimilar DNA profiles, with at most two alleles detected per locus. Superimposition of the tissue-derived profiles matched that derived from the blood samples exactly, except for two loci failing to amplify, and hence demonstrated blood chimaerism. Dissection of the abdomen of the male fetus revealed delayed descent of the testes towards the inguinal canals. Macroscopically, the gonads, uterus and vagina were not identifiable on dissection of the female fetus, although vestigial ovarian tissue and a vagina were detected microscopically. The hypoplastic internal reproductive tract of the female fetus was suggestive of freemartinism and is believed to be the first report of this condition in the canine.

Dizygotic monochorionic canine fetuses with blood chimaerism and suspected freemartinism.

Monozygotic twinning has not previously been genetically confirmed in the dog. This case report describes the finding of two viable male monozygotic foetuses within one placental site during caesarean section. Their umbilical cords attached to a single placenta. Genetic profiling using a total of 38 microsatellite markers, as well as amelogenin and SRY for sex determination, revealed identical DNA profiles, whether derived from blood or tissue (buccal swabs) samples. To the best of our knowledge, this is the first report of monozygotic twinning in the dog confirmed using DNA profiling.

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Carolynne J. Joone

Papers

Ovarian function and pregnancy outcome in pony mares following immunocontraception with native and recombinant porcine zona pellucida vaccines.

Ovarian dysfunction associated with zona pellucida–based immunocontraceptive vaccines

Missense Mutation in the Ligand-Binding Domain of the Horse Androgen Receptor Gene in a Thoroughbred Family with Inherited 64,XY (SRY+) Disorder of Sex Development

Dizygotic monochorionic canine fetuses with blood chimaerism and suspected freemartinism.

The first case of genetically confirmed monozygotic twinning in the dog