Laparoscopic oviductal artificial insemination improves pregnancy success in exogenous gonadotropin-treated domestic cats as a model for endangered felids

Postmortem Collection of Gametes for the Conservation of Endangered Mammals: A Review of the Current State-of-the-Art

The collection of gametes from recently deceased domestic and wildlife mammals has been well documented in the literature. Through the utilization of gametes recovered postmortem, scientists have successfully produced embryos in 10 different wildlife species, while in 2 of those, offspring have also been born. Thus, the collection of gametes from recently deceased animals represents a valuable opportunity to increase genetic resource banks, obviating the requirement for invasive procedures. Despite the development of several protocols for gamete collection, the refinement of these techniques and the establishment of species-specific protocols are still required, taking into account both the limitations and the opportunities. In the case of wildlife, the optimization of such protocols is impeded by the scarcity of available animals, many of which have a high genetic value that must be protected rather than utilized for research purposes. Therefore, optimizing protocols for wildlife species by using domestic species as a model is crucial. In this review, we focused on the current advancements in the collection, preservation, and utilization of gametes, postmortem, in selected species belonging to Equidae, Bovidae, and Felidae, both domestic and wildlife.

The challenge of assisted reproduction for conservation of wild felids - A reality check

Threats to the Earth's biodiversity are increasing exponentially, driven by human population growth and resource consumption. As many as one million wildlife species may disappear within the next few decades due to this human-induced extinction event. This represents our current reality and has profound implications for wildlife conservation. Within this context, application of assisted reproductive technology (ART) to conservation management is unlikely to mitigate broad-scale species loss, but for select species, such as wild cats, ART may determine if populations survive or disappear. In North American and European zoos, 20 of the world's 38 wild felid species are managed within structured breeding programs, but most are not sustainable with natural breeding alone. Zoo-based breeding programs are facing tenuous futures due to triage-based responses to this growing sustainability crisis. Theoretically, ART could benefit conservation management, but only by recognizing and addressing its present challenges. The application of ART to wildlife has been rarely successful, with only 62 mammal species (including 15 cat species) ever propagated by AI, and just 35 of these species (6 cats) reproduced following frozen semen AI. Even this most basic form of ART has a minimal impact on wildlife sustainability. The drivers of this deficit include lack of species-specific reproductive knowledge and limited access to animals for study, but also is exacerbated by a science-conservation disconnect that attempts to apply advanced reproductive technologies to species in which basic ART remains unproven. For a few felid species, these scientific challenges have been overcome and AI with frozen semen is becoming feasible as a practical management tool; for other felids, further research is needed. Non-scientific issues also impair our ability to use ART to implement global management plans. Political dysfunction, regulatory barriers and societal indifference create inertia that interferes with achieving meaningful progress in applying ART to wildlife. Collectively, these challenges may seem insurmountable but human resiliency is essential if we are to resolve these issues in a systematic manner. It will require expanding collaborative efforts substantially and intensifying efforts to conserve wildlife species that are literally running out of time. Our goal is to create a new reality that includes a sustainable future for wild felids and other imperiled wildlife species.

Artificial Insemination in Queens in the Clinical Practice Setting: Protocols and challenges

PRACTICAL RELEVANCE

Despite substantial advances in assisted reproductive techniques having been recently reported in cats, the use of these is limited and routine application is still far from being a reality in veterinary clinics. Nevertheless, there is an increasing demand from domestic cat breeders for artificial insemination (AI) techniques that are already commonly used in dogs. Where natural breeding is not possible in tom cats and queens of high breeding value, AI could offer a solution. Clinical challenges: AI in cats is more difficult than in other species - both in terms of semen collection/handling and oestrous cycle management given that ovulation must be induced.

AIM

For practitioners wishing to perform AI in queens, there are challenges to overcome, and a good understanding of the techniques and procedures involved is pivotal. This review aims to contribute to improved knowledge by providing an overview of AI protocols, encompassing choice of breeding animals, procedures for semen collection, oestrus and ovulation induction, AI techniques and equipment.

EQUIPMENT AND TECHNICAL SKILLS

Depending on the animals involved and the specific AI technique chosen, essential equipment may include an artificial vagina, electroejaculator, endoscope (sialendoscope, which can be fairly expensive) and special catheters for transcervical insemination. Other instrumentation and materials needed are typically readily available in a veterinary clinic. In general, no particular skills are needed to perform the procedures described in this review, with the exception of endoscopic transcervical catheterisation, where the ability to use an endoscope is required.

EVIDENCE BASE

The information and advice/recommendations provided are based on specific feline research and reviews published in scientific peer-reviewed journals, animal reproduction textbooks, and presentations at national and international congresses. The authors also drew on their own clinical experience with regard to the choice of protocols and procedures presented in this review.

Successful Laparoscopic Oviductal Artificial Insemination in the Endangered Tsushima Leopard Cat (Prionailurus bengalensis euptilurus)

Simple Summary

The Tsushima leopard cat is an endangered wild felid that lives solely on Tsushima Island, Nagasaki, Japan. Approximately, only 100 Tsushima leopard cats can be found in the wild, and there are concerns that the population will further reduce due to habitat degradation and traffic accidents. In 1994, Japan’s Ministry of the Environment (MOE) developed a conservation and breeding project for the Tsushima leopard cat. The MOE is working with the Japanese Association of Zoo and Aquariums for ex situ conservation of this species. However, considering genetic diversity, it is difficult to conduct captive breeding programs using only natural breeding; hence, assisted reproductive technologies are required. This study aimed to breed Tsushima leopard cats using artificial insemination (AI) by depositing sperms into the oviducts. Ovulation was artificially induced in two females, laparoscopically inseminated with fresh sperms into the oviducts. The pregnancies were monitored via fecal levels of progestogens and radiography. One female had spontaneous delivery of a female kitten 66 days post-AI. This is the first successful case of AI in a Tsushima leopard cat.

Abstract

The Tsushima leopard cat (Prionailurus bengalensis euptilurus) is an endangered wild felid that lives solely on Tsushima Island, Nagasaki, Japan. Japan’s Ministry of the Environment is working with the Japanese Association of Zoo and Aquariums for ex situ conservation of this species. However, considering genetic diversity, it is difficult to conduct captive breeding programs by natural breeding alone; hence, assisted reproductive technologies are required. This study aimed to breed Tsushima leopard cats, which otherwise cannot be paired, using laparoscopic oviductal artificial insemination (AI). Female Tsushima leopard cats (female 1, aged 7 years; female 2, aged 6 years) were treated with 200 IU equine chorionic gonadotropin, followed by administration of 1000 IU porcine luteinizing hormone (pLH) after 96 h to induce ovulation. Laparoscopic AI was performed 32 h post-pLH administration. Females 1 and 2 were inseminated in the oviduct with 2.4 × 10⁶ and 3.3 × 10⁶ motile spermatozoa, respectively, collected from two males. Pregnancy was confirmed by radiography 45 and 51 days post-AI in females 1 and 2, respectively; one fetus was found in female 2. Moreover, female 2 had spontaneous delivery of a female kitten 66 days post-AI. This is the first successful case of AI in a Tsushima leopard cat.

Assisted reproductive technologies for endangered species conservation: developing sophisticated protocols with limited access to animals with unique reproductive mechanisms

Assisted reproductive technologies (ARTs) have been proposed as a means of overcoming the significant challenges of managing small, isolated populations of endangered species in zoos. However, efficient protocols for ARTs do not exist for most endangered species. This review will focus on research efforts to characterize unique reproductive mechanisms and develop species-specific ARTs. Central to these studies are assays to measure steroid metabolites in urine or feces and/or training programs to allow unrestrained blood collections and ultrasound evaluations. The resulting information about estrous cycle dynamics, combined with studies of semen collection and processing, provides the foundation for the development of artificial insemination (AI). In vitro fertilization and embryo transfer are also discussed in relation to the advantages these techniques could provide relative to AI, as well as the significant challenges involved with technologies that require oocytes and embryos. Finally, an argument is made for additional research of nontraditional model species (e.g., domestic cats and dogs) and the development of novel models representing unique taxa. Whether these species are studied by zoo-based researchers with the expressed intent of developing ARTs for conservation or academic scientists interested in basic biology, the resulting information will provide a unique, evolutionary perspective on reproduction that could have wide-reaching benefits. The more information we have available, the better our chances will be of developing effective ARTs and making a difference in conservation efforts for endangered species.

Reproductive biology and biotechnologies in wild felids

Conservation strategies in natural habitats as well as in breeding centers are necessary for maintaining and reinforcing viable populations of wild felids. Among the fundamental knowledge that is required for conservation breeding, a solid understanding of reproductive biology is critical for improving natural breeding and enhance genetic diversity. Additionally, it offers the opportunity to develop assisted reproductive technologies (ARTs) in threatened and endangered species. Conservation breeding and reproductive biotechnologies of wild felids have advanced in the past decade. It has been clearly shown that female felids have species and individual patterns of reproductive cycles and respond differently to exogenous hormones. In males, several species still have poor semen quality often due to the loss of genetic diversity in small populations. To overcome the challenges of natural breeding (incompatibility between individuals or suboptimal environment) and mitigate inbreeding, artificial insemination, embryo production and embryo transfer have been further developed in 24 wild cat species. Major factors limiting ART success are inconsistent responses to ovarian stimulation, variable quality of gametes and embryos, and preparation of recipient females. Additional approaches including stem cell technologies have been explored for future medical applications. However, there still is a critical need for better knowledge of feline reproductive biology and improvement of ARTs efficiency to increase the genetic diversity and create sustainable populations of wild felids.

Assisted reproduction mediated resurrection of a feline model for Chediak-Higashi syndrome caused by a large duplication in LYST

Chediak-Higashi Syndrome (CHS) is a well-characterized, autosomal recessively inherited lysosomal disease caused by mutations in lysosomal trafficking regulator (LYST). The feline model for CHS was originally maintained for ~20 years. However, the colonies were disbanded and the CHS cat model was lost to the research community before the causative mutation was identified. To resurrect the cat model, semen was collected and cryopreserved from a lone, fertile,  CHS carrier male. Using cryopreserved semen, laparoscopic oviductal artificial insemination was performed on three queens, two queens produced 11 viable kittens. To identify the causative mutation, a fibroblast cell line, derived from an affected cat from the original colony, was whole genome sequenced. Visual inspection of the sequence data identified a candidate causal variant as a ~20 kb tandem duplication within LYST, spanning exons 30 through to 38 (NM_001290242.1:c.8347-2422_9548 + 1749dup). PCR genotyping of the produced offspring demonstrated three individuals inherited the mutant allele from the CHS carrier male. This study demonstrated the successful use of cryopreservation and assisted reproduction to maintain and resurrect biomedical models and has defined the variant causing Chediak-Higashi syndrome in the domestic cat.

Responsiveness of the cheetah (Acinonyx jubatus) ovary to exogenous gonadotropins after preemptive oral progestin treatment

Control of ovarian function in cheetahs is sub-optimal, which currently limits the integration of assisted reproductive techniques into the genetic management of that endangered species. The objective of this study was to determine the effect of preemptive progestin treatment on the quality of ovarian responses after exogenous gonadotropin stimulation in cheetahs. Adult females received either 1) 200 IU equine chorionic gonadotropin (eCG) followed with 3,000 IU porcine luteinizing hormone (pLH) (intramuscular route) (n = 5; control group) or 2) similar eCG/pLH administration preceded by a 7-day treatment with oral progestin (0.1 mg/kg altrenogest; ALT group; n = 7). At 42 h post-pLH administration, a series of metrics was assessed via laparoscopy (number of follicles ≥ 2 mm, number of corpora lutea, oviduct and uterine cornua diameter and overall vascularization). Concentrations of fecal estradiol, progesterone and glucocorticoid metabolites (FEM, FPM, and FGM, respectively) were measured by enzyme immunoassay for 3 wk before ALT treatment (Period 1), 7 d during ovarian suppression period (Period 2), throughout eCG/LH treatment and laparoscopy (Period 3), and 6 wk following laparoscopy (Period 4). Overall, nine out of 12 cheetahs (4/5 in control and 5/7 ALT group) had freshly-formed corpora lutea at the time of laparoscopy. Mean follicle and corpora lutea numbers in the control versus ALT group were not different (P > 0.05). Overall measurements and vascularization scores also did not differ (P > 0.05) among groups. FEM average concentrations increased (P ≤ 0.05) in response to eCG for the ALT-treated females between Periods 2 and 3 and were sustained during Period 4. However, FEM average concentrations did not vary (P > 0.05) for control females throughout Periods 1-4. Post-ovulatory FPM average concentrations (Period 4) did not differ (P > 0.05) between the ALT-treated females and controls. FPM average concentration from both groups increased in Period 4 compared to Periods 1-3 (P ≤ 0.05). Females receiving the ALT treatment also had lower (P ≤ 0.05) FGM metabolite average concentrations than control females during ovarian suppression (suggesting adrenal suppression). Collective results suggest that ovarian response to gonadotropin treatment in the cheetah was improved following oral progestin administration due to the normative increase in estradiol following stimulation for these females compared with control. This treatment should lead to more effective timed assisted reproduction procedures for this species.

Practical application of laparoscopic oviductal artificial insemination for the propagation of domestic cats and wild felids

AI was first reported in cats almost 50 years ago but, unlike AI in other domesticated animals (e.g. dogs, cattle, horses), has not been widely used for routine propagation by veterinarians or breeders. Anatomical and physiological challenges with cats have hindered the efficiency of AI using standardised transcervical approaches applied to other species. Development of laparoscopic oviductal AI (LO-AI) has helped overcome some of these barriers and, during the past 7 years, produced high pregnancy percentages (>70%) in domestic cats using both fresh collected and frozen-thawed semen and resulted in the birth of full-term offspring in three cat hereditary disease models and six wild cat species (ocelot, Pallas's cat, fishing cat, sand cat, tiger, clouded leopard). The standard approach involves exogenous gonadotrophin treatment (typically equine chorionic gonadotrophin followed by porcine LH) to induce ovarian follicular growth and ovulation, with laparoscopic visualisation of the oviductal ostium for direct intraluminal insemination with low numbers of spermatozoa. Similar ovarian synchronisation and insemination approaches have been used with wild felids, but frequently must be refined on a species-by-species basis. From a practical perspective, LO-AI in domestic cats now has adequate efficiency for applied use as a reproductive service in veterinary practices that possess basic laparoscopy expertise.

Urethral catheterization and sperm vitrification for simplified semen banking in felids

Semen banking of domestic cats and wild felids represents a vital resource for their long-term conservation, but current methods require access to advanced training and specialized equipment. A newer method of semen collection, urethral catheterization of medetomidine-treated cats, allows recovery of high sperm numbers, but it is unclear if this approach permits maximal sperm recovery or is feasible using less expensive alpha-2 agonists. Similarly, a newer sperm preservation approach, vitrification, offers advantages of simplicity and minimal equipment needs, but its efficacy in combination with urethral catheterization has not been investigated. Our specific objectives were to (i) evaluate sequential semen recovery with urethral catheterization and electroejaculation in domestic cats, (ii) assess the effectiveness of a weak (xylazine) versus strong (dexmedetomidine) alpha-2 agonist for inducing sperm release, and (iii) compare post-thaw sperm motility, acrosome status and fertilizing capacity of catheter-recovered samples after vitrification or straw freezing. Results indicated that electroejaculation following repeated catheterization allowed recovery of additional spermatozoa (range, 11-32 × 10⁶  sperm/male) and that xylazine was ineffective for inducing meaningful sperm release (range, 0-0.4 × 10⁶ sperm/male). Post-thaw motility and acrosome status of vitrified catheter samples did not differ (p > .05) from that of straw frozen samples. Preliminary results indicated that in vitro fertilization success (9/30, 30%) of vitrified catheter sperm did not differ (p > .05) from that observed with straw frozen samples (17/30, 57%). In conclusion, urethral catheterization of dexmedetomidine-treated cats allows recovery of substantial sperm numbers but electroejaculation still may be warranted for maximal sperm recovery. Xylazine is not suitable as an inexpensive alternative to dexmedetomidine for catheterization. Vitrification of catheter samples results in comparable post-thaw parameters to straw freezing and may be adequate for use with oviductal insemination procedures.

Intrauterine insemination with fresh semen in Amur leopard cat (Pionailurus bengalensis eutilura) during non-breeding season

Equine and human chorionic gonadotropins were administered to two female Amur leopard cats to induce estrus and ovulation during non-breeding season. Fresh semen collected from male cats was surgically inseminated into the uterine horn of the females. In one animal, two fetal sacs without heartbeats were observed on abdominal ultrasonography 31 days after insemination, which indicated that embryo death had occurred. In the other animal, fetal heartbeats were detected in two fetal sacs 29 days after insemination, which confirmed as pregnancy. This animal delivered two newborns 68 days after insemination; the one of the kittens was assumed to be stillbirth, and the other grew normally. In this study, we successfully obtained a kitten from an Amur leopard cat by artificial breeding for the first time in Japan.

Enzyme immunoassays as a method for quantifying hair reproductive hormones in two felid species

Non-invasive monitoring of wild felid reproductive states is important, given that many species reproduce poorly in captivity. Despite extensive work in faecal hormone analysis in felids, continued development of techniques is necessary, particularly with wild populations. In this study, our aims were as follows: (i) biochemical validation of enzyme immunoassays for estrogen, testosterone and progesterone in Canada lynx and domestic cat hair extracts; (ii) assessment of the use of hair reproductive hormones to differentiate between reproductive states (intact, estrus, pregnant and spayed/neutered), using domestic cats as a model; and (iii) assessment of the use of hair reproductive hormones to differentiate between age and sex, accounting for potential regional variability in wild lynx populations. Analysis of hair hormone levels showed prospective value in detecting pregnancy states, with pregnant domestic cats having higher levels of progesterone than spayed females. However, intact and pregnant cats did not differ in progesterone levels. Yet, two female domestic cats had higher levels of hair progesterone following a 38-day oral progestin treatment, perhaps providing a preliminary pharmacological validation of the method. Estrogen and testosterone did not differ statistically according to reproductive states of domestic cats, although intact males had higher levels of hair testosterone than neutered males. When we applied these techniques to lynx fur, we determined that hormone levels were not sufficiently precise to differentiate age classes. Hair reproductive hormone ratios differed between sexes, with the estrogen-to-progesterone ratio demonstrating the highest accuracy in differentiating males from females. Hair hormone levels differed regionally for wild lynx, indicating that spatial variability should be a consideration in wildlife hormone studies spanning large spatial scales. We conclude that use of hair hormone analysis by enzyme immunoassay may hold promise for differentiating sex in felids, but the technique will require further refinement and validation before it can be applied broadly and reliably.