Sperm evaluation of Jungle Cat ( Felis chaus ) obtained by urethral catheterization (CT) after medetomidine administration

Evaluation of the testicular artery Doppler velocimetry and its correlation with sperm defects in domestic cats

Several studies have demonstrated the correlation between Doppler velocimetric parameters of testicular artery and semen quality in domestic species, but in felines data are scarce. This study aimed to correlate the Doppler velocimetry of the testicular artery with sperm kinetics and sperm defects, in sedated and non-sedated cats. Forty tomcats were divided into two groups: sedated (SG; n=20) with dexmedetomidine (10 µm/kg) and ketamine (12 mg/kg), and non-sedated (NSG; n=20). The animals were subjected to ultrasound Doppler velocimetry of the distal supratesticular and marginal region of the testicular artery and subsequently orchiectomized. Epididymal tail spermatozoa were recovered and analyzed using a CASA system for motility, and morphology took place. Animals of SG presented a significantly higher velocity in the marginal region of the cat's testicular artery [peak systolic velocity (PSV) 11.51 cm/s; end-diastolic velocity (EDV) 7.72 cm/s] compared to NSG (PSV 7.72 cm/s, P < 0.001; EDV 4.93 cm/s, P < 0.001). Sedated cats presented higher pulsatility and resistivity indexes than non-sedated cats. The supratesticular PSV of NSG was moderately correlated with major (rs = 0621; P < 0.001) and total sperm defects (rs = 0614; P < 0001). Doppler velocimetry was fairly correlated with minor, major, and total sperm defects. In conclusion, Doppler velocimetric evaluation emerges as an important possibility in the reproductive evaluation of tomcats, once the testicular artery hemodynamics were associated with sperm defects. However, it is advisable to carry out this evaluation in non-sedated animals. If sedation is necessary, peripheral vasoconstriction should be considered.

Pharmacological semen collection in domestic and wild canids and felids: literature review

Semen collection methods vary greatly and rely on the practitioner's expertise, available materials, and the specific behavioral traits of the male animals involved. When it comes to domestic cats, wild felids, and canids, semen collection is particularly challenging. Thus, given the difficulty of semen collection in these species, pharmacological semen collection (PSC) stands out since it is a quick and straightforward method that does not require specific equipment. The PSC consists of administering α2-adrenergic receptor agonist drugs, mainly medetomidine, and dexmedetomidine, aiming semen release into the urethra with posterior urethral catheterization and sperm recovery. This technique was primarily described in domestic cats and wild felids, and despite the decreased seminal volume, the retrieved semen is highly concentrated and presents good quality. However, further studies are required to optimize semen collection in domestic dogs and wild canids. Therefore, the purpose of this review is to provide a comprehensive overview of the research developed on pharmacological semen collection (PSC) in the past few decades. The objective is to equip professionals with the essential knowledge required for the efficient application of this technique in both domestic and wild canids and felids and to make a valuable contribution to conservation efforts and the preservation of biodiversity, aligning with the principles of One Conservation.

Current knowledge in the biology of gametes and embryos from Carnivora

In addition to companion animals and laboratory species, about 270 carnivore species play fundamental ecological roles in different ecosystems. However, almost 40% of carnivore species are now threatened or endangered in the wild because of human activities. While protection of natural habitats is critical, it is equally important to better understand carnivore reproduction, including a solid knowledge in sperm, oocyte, and embryo biology, to maintain sustainable populations in the wild and in conservation breeding centers. Characterizing gamete and embryo biology is also needed to develop cryopreservation and assisted reproductive technologies to enhance conservation efforts. The objective of this review is to provide the most recent knowledge in the biology of sperm cells, oocytes, and early embryos across all carnivore families. Overall, most data originate from populations maintained in breeding centers or zoos. Characterizations of sperm biology and cryopreservation are far more advanced than for oocytes and embryos. Currently, sperm biology is mainly studied in Canids, Felids, Ursids, and Mustelids, with more emphasis on structural than functional properties. Importantly, fundamental studies of gamete and embryo biology in domestic dogs, cats, and ferrets have paved the way for more precise characterizations in wild counterparts as well as the development of cryopreservation and assisted reproductive technologies. A striking feature of spermatozoa across a wide range of Canids and Felids is the presence of teratospermia (>60% of abnormal sperm cells), which is related to the loss of genetic diversity in some populations. Although sperm structures differ across carnivore families, sperm biology remains difficult to compare because of the small amount of data in many species. Regarding oocyte biology and embryology, data are much scarcer than in sperm cells, with too few studies going beyond structural descriptions. More carnivore species and more individuals (especially from wild populations in addition to captive ones) must be studied to improve our understanding about comparative germplasm biology and develop adequate conservation breeding strategies including the use of cryobanking and assisted reproductive technologies.

Cryopreservation of jaguar (Panthera onca) sperm cells using different cryoprotectants and different thawing temperatures

The cryopreservation of jaguar semen must be improved to produce high-quality biobanking doses. Until now, the rare studies of semen freezing in the species have only evaluated glycerol, always with a significant reduction in sperm quality in thawed semen. The purpose of this study was to assess the efficacy of three cryoprotectants, dimethylsulfoxide (DMSO), glycerol (GLY), and methanol (MET), in the cryopreservation of jaguar semen in an LDL-based extender, as well as the effect of thawing temperature on dosage quality. Five mature males with a history of reproduction were used. On the males, an infrared thermal image (IRT) was captured, the spicules and testes were analyzed, and the CASA system was used to evaluate the quality of fresh and thawed sperm. The superficial IRT was 4.6 ± 1.2 °C cooler than the anal sphincter, and the semen measured between 27.3 and 28.7 °C shortly after exiting the urethra. The total motility of fresh sperm was 55.3 ± 22.6%, and progressive motility was 36.3 ± 18%. The total motility of thawed sperm was 5.28 ± 2.51%, 4.49 ± %2.49, and 0.51 ± 0.62% for DMSO, GLY, and MET, respectively. DMSO and GLY performed better than MET, and there was no difference in thawing temperature (37°C 30 s vs. 50°C 12 s). All animals exhibit a considerable level of morphological changes in sperm. Low amounts of total and progressive motility were found in the thawed sperm. Males with a high level of sperm morphological changes were found to be fertile, but the lone male with normospermia was infertile. Thus, we contest the applicability of the commonly used morphological classification for bovines to felid species.

How Can We Introduce ART into Wild Felid Conservation in Practice? Joint Experience in Semen Collection from Captive Wild Felids in Europe

Simple Summary

Artificial reproductive techniques (ART), such as cryopreservation of sperm cells and artificial insemination, are useful tools for species conservation. However, there is relatively little information published about their introduction into clinical practice for wild felids. The aim of this paper was to describe how those techniques were applied by three European teams in various species of wild felids. In total, this article presents 22 semen collection attempts in 12 species of wild felids, 15 of which were successful and resulted in the collection of at least one million spermatozoa. The failures in obtaining spermatozoa were most probably due to (1) male infertility, (2) wrong age/non-breeding season, or (3) recent multiple copulations. The cases presented in the article confirm that although ART have been introduced into clinical practice, they are mostly used in cases of infertility, not as routine breeding tools. Greater involvement of zoological gardens and private breeders is required, as many chances for preservation of valuable material are lost.

Abstract

Although artificial reproductive techniques (ART) are considered to be a valuable tool for species conservation, information about their introduction into clinical practice for wild felids is limited. The aim of this paper was to jointly describe cases of non-experimental sperm collection from males of various species of wild felids, performed by three European centers focused on feline reproduction. In total, the article presents 22 attempts of semen collection in 12 species of wild felids. The reasons for semen collection were: fertility assessment (10 cases), artificial insemination (5 cases), sperm rescue (postmortem collection for cryopreservation, 5 cases), and sperm banking (in vivo collection for cryopreservation, 2 cases). Semen collection was successful (defined as at least 1 × 10⁶ spermatozoa) in 15 cases. The failures in obtaining spermatozoa were most probably due to (1) male infertility, (2) wrong age/non-breeding season, or (3) recent multiple copulations. The cases presented here confirm that although ART have been introduced into clinical practice, they are mostly used in cases of infertility, not as routine breeding tools. Higher involvement of zoological gardens and private breeders is required, as many chances for preservation of valuable material are lost.

Semen collection, evaluation, and cryopreservation in the bonobo (Pan paniscus)

Background

Captive breeding of bonobos (Pan paniscus) has proven to be successful, but maintaining genetic diversity remains a challenge. Cryopreservation of semen is an important potential tool to maintain genetic diversity by preserving current genetic material for future use, as well as facilitating the transport and exchange of genetic material. This study aimed to develop a protocol for semen collection and cryopreservation in the bonobo. Semen was collected from four healthy adult bonobos under general anesthesia during management translocation procedures. Semen collection utilizing urethral catheterization was not successful (n = 1), however, all males (n = 4) responded well to rectal probe electro-ejaculation. Immediately after collection, ejaculates were evaluated for color and admixtures, volume, motility, and concentration. Eosin-Nigrosin staining was prepared to evaluate morphology and viability. Ejaculates were split into two equal volumes and cryopreserved in two different extenders, using a one-step and a two-step approach. Ejaculates were gradually cooled to 4 °C in two hours, subsequently stored in liquid nitrogen vapor for twenty minutes (0.25 ml straws), and finally dropped into liquid nitrogen.

Results

Pre-freeze evaluation showed thick, white samples with an average ejaculate volume of 450 µl (100-1000 µl), total motility of 59% (40–80%), viability of 69% (38–85%) and 58% (46–72%) normal spermatozoa. Mainly head (22%) and tail (19%) defects were detected on the Eosin-Nigrosin stain. Ejaculates were highly concentrated, nevertheless, due to the coagulum that caused high viscosity and non-homogenous fractions, only estimations of concentration could be made (1000 million/ml). After 24 h of storage, the post-thaw evaluation showed a loss of quality with an average post-thaw total motility of 15% (5–25%) using the one-step freezing medium, and 19% (5–30%) using the two-step medium. Average post-thaw viability was 15% (4–24%) and 21% (15–29%), respectively.

Conclusions

This report on ejaculates from bonobos obtained by rectal probe electro-ejaculation shows that semen parameters of this species are not completely similar to those of its sibling species, the chimpanzee. Further studies are necessary to develop an optimal protocol for the processing and cryopreservation of bonobo spermatozoa.

Spermatic profile of captive giant anteaters (Myrmecophaga tridactyla): Knowing more to preserve better

The giant anteater (Myrmecophaga tridactyla) is being threatened by natural habitat destruction and fragmentation, illegal hunting and road kills. In this context, the generation of basic information on the reproductive parameters of this species is vital, aiming to improve reproductive management via, amongst others, assisted reproductive technologies. This study aimed to describe the morphological and functional features of semen collected from captive giant anteaters. Electroejaculation was performed in 13 animals housed in zoos located in São Paulo state, Brazil. Semen samples were collected from 13 animals in 16 procedures. Samples were evaluated for volume, motility, vigor, pH, concentration, sperm morphology, and functional tests. The following mean values were obtained: volume 1.28 ± 0.27 mL; motility 28.3 ± 6.2%; vigor 2.4 ± 0.25; concentration 129.4 ± 36.1 × 10⁶ sperm/mL; pH 7.4 ± 0.2. Total acrosome, head, midpiece, and tail sperm abnormalities were 3.2 ± 0.8%, 25.4 ± 3.6%, 20.7 ± 3.2%, and 14.7 ± 2.6%, respectively. Intact acrosome was found in 83.7 ± 3.1% and intact membrane in 81.1 ± 4.0% of all samples collected. Mitochondrial activity was 66.4 ± 6.0% (Class I), 18.7 ± 2.9% (Class II), 8.0 ± 2.0% (Class III), 3.9 ± 1.0% (Class IV), and 3.0 ± 0.9% (Class V). Sperm DNA fragmentation rate was 13.2 ± 3.7%. These results indicated that electroejaculation is a feasible method for semen collection in giant anteaters, allowing a more detailed description of the semen in this species.

Sperm evaluation and morphological description of male genitalia of meerkats (Suricata suricatta)

In ex situ conditions, little is known about the reproductive biology of meerkats. The aim of present study was to describe the morphological aspects of male genital organs and accessory glands using macroscopic evaluation, ultrasonography, and radiography, as well as describing semen characteristics post-electroejaculation. The results indicated anatomical characteristics of meerkats are very similar to those of cats, having a prostate, accessory bulbourethral glands, and an elongated and radiopaque structure in the penis, which is indicative of there being a baculum. The testicular volume was 0.81 cm³ (± 0.10) and the relative testis weight was 1.37 cm³/kg (± 0.15). Both testicles are present in the scrotum, which has an ellipsoidal shape, homogeneous texture, hypoechoic parenchyma and are encased in a hyperechoic tunica albuginea. Electroejaculation was effectively induced in all animals for semen collection with utilization of medetomidine and ketamine. The values semen samples variables were as follows for volume - 0.125 ± 0.193 mL, motility - 19.8 ± 18.6 %, vigor - 1.9 ± 1.0, concentration - 40.5 ± 25.2 × 10⁶ sperm/mL and morphologically normal sperm - 10.8 ± 6.6 %. This is the first study in which there is a description of morphological and imaging aspects of the male reproductive tracts of meerkats, as well as the seminal characteristics after using electroejaculation for semen collection. Knowledge of anatomical and seminal characteristics is essential for implementation of assisted reproduction programs, as well as reproductive management in the species.

Urethral catheterization as an alternative method for collecting sperm in the black-footed ferret (Mustela nigripes)

The endangered black-footed ferret (BFF; Mustela nigripes) is an important example of the benefits of assisted reproduction in species conservation with both semen evaluation and artificial insemination using fresh and frozen sperm being successfully incorporated into the breeding program. Currently, electroejaculation (EE) is routinely utilized for semen collection in BFFs, a technique that requires custom equipment and experienced operators, and does not consistently yield viable samples in this species. In this case study, we evaluated the feasibility of urethral catheterization (UC) for semen collection, a method predominately tested in domestic and non-domestic felids, on four occasions (three BFF males). After general anesthesia with a combination of ketamine, midazolam and α2-agonist dexmedetomidine (thought to promote semen release into the urethra), a lightly lubricated, flexible feeding tube was passed into the urethral opening and advanced ~7-8 cm into the urethra. A syringe attached to the feeding tube was used to apply mild negative pressure to collect sperm. Semen samples were successfully collected on all four attempts. Sperm characteristics ranged as follows: 10.5-26.0 × 10⁶ sperm/ml concentration, 50-90% motility and 36-61% normal sperm morphology. This is the first report of the use of UC as a potential alternative to EE in the BFF, a more field-friendly technique that is less invasive and more consistent for obtaining samples free of urine contamination.

Coleta de sêmen em Leopardus guttulus pelo método do cateterismo uretral

RESUMO Considerando a realidade conservacionista dos animais mantidos em cativeiro, em especial os pequenos felídeos silvestres, objetivou-se, com este estudo, descrever o método de coleta de sêmen por cateterismo uretral em Leopardus guttulus cativos, anestesiados com cetamina-dexmedetomidina. Inicialmente foram utilizados 13 animais para coleta de sêmen por cateterismo mediante o uso de diferentes doses de cetamina-dexmedetomidina. Após determinação da dose anestésica ideal para coleta de sêmen nessa espécie, cinco L. guttulus machos foram submetidos a coletas seriadas de sêmen pelo método do cateterismo. A dose ideal para coleta de sêmen foi de 0,008mg/kg de dexmedetomidina e 10mg/kg de cetamina. Os valores médios para volume e concentração foram de 35,9µL e 552,8x106sptz/mL. Com média de 71% de motilidade e 3,1 de vigor, 68% dos espermatozoides apresentaram vitalidade (integridade de membrana) e 77% integridade acrossomal. Sobre as patologias espermáticas, obteve-se uma média de 28% de espermatozoides com defeitos maiores, 6% com defeitos menores e 67% normais. As vantagens do método, como a facilidade e o baixo custo, fazem recomendar sua utilização em L. guttulus, pois foram apresentados bons resultados quanto à concentração espermática, à motilidade, ao vigor, à viabilidade espermática e à integridade acrossomal, sendo uma técnica promissora para utilização em felinos selvagens.

Urethral catheterization after pharmacological induction for semen collection in dog

The α-adrenergic agents are known to influence erection and ejaculation, and ejaculatory reflex is a primarily α-adrenergically mediated event. This paper aims to describe the urethral catheterization technique after pharmacological induction for semen collection in domestic dogs. For dose determination, semen collection was performed using increasing doses of dexmedetomidine (5 μg/kg, n = 2; 10 μg/kg, n = 2 and 15 μg/kg, n = 2) associated to 3 mg/kg ketamine in six animals. Once the dose was established, additional semen collection using association of 15 μg/kg dexmedetomidine and 3 mg/kg ketamine was carried out in eight dogs. After the procedure, sperm volume (0.092 ± 0.03 mL), total motility (58.33 ± 8.7%), vigor (1.89 ± 0.309), sperm concentration (1186.67 ± 304.667 × 10⁶ sperm/mL), sperm plasma membrane integrity (83.22 ± 4.82%), acrosomal integrity (73 ± 6.187%) and normal sperm morphology (53.22 ± 5.6%) were assessed. Thus, this study demonstrates that urethral catheterization after pharmacological ejaculation using dexmedetomidine-ketamine association can be performed in dogs and it may be possible to obtain good semen quality, despite urine contamination.

Colheita farmacológica de sêmen de onças-pardas (Puma concolor: Mammalia: Carnivora: Felidae)

RESUMO Objetivou-se, por meio do presente estudo, avaliar o método de colheita farmacológica de sêmen com sondagem uretral, em machos de onças-pardas (Puma concolor) mantidos em cativeiro. A técnica proposta (Cat; N=3) foi comparada com a eletroejaculação (EE; N=4). Para a colheita farmacológica, utilizou-se medetomidina para induzir a liberação de sêmen na uretra e sonda uretral para gatos, sem janela lateral, para colheita do sêmen por capilaridade. O método foi eficaz em todos os animais usados. Por meio dessa técnica, colheram-se amostras com menor volume (106,7±30,5aµL) e maior concentração (524,1±54,3b x 106 espermatozoides/mL) em relação à EE (450,0±0,1bµL e 205,0±141,8a x 106 espermatozoides/mL). As avaliações de vigor, motilidade e patologia espermática demonstraram que a técnica não afeta a qualidade do sêmen em relação à EE (P>0,05). Dessa forma, o método proposto consiste em uma técnica mais prática e eficiente para a colheita de sêmen com boa qualidade, dispensando o eletroejaculador.

Plasma Concentration Rise after the Intramuscular Administration of High Dose Medetomidine (0.13 mg/kg) for Semen Collection in Cats

High dose medetomidine 0.13 mg/kg can be used for semen collection in cats with variable results in terms of quantity and quality. Therefore, a variation in terms of distribution and elimination among patients has been hypothesised. The aim of the study was to characterise the pharmacokinetics of medetomidine (0.13 mg/kg) administered intramuscularly (IM) in healthy male cats. Eighteen male cats undergoing castration were included, and medetomidine (0.13 mg/kg) was administered IM. Venous blood samples were collected at 20, 30, 40, 50, 60, 75 and 90 minutes after medetomidine administration. Before orchiectomy, at T20, sperm collection was attempted. Plasma medetomidine concentrations were determined by liquid chromatography/mass spectrometry analysis. Semen collection was successful in 15/18 cats. The medetomidine plasma concentration following the IM administration of a bolus was best described using a non-compartment model. Time of maximum concentration was observed at 40 minutes (range 20–90); maximum concentration was 32.8 ng/mL (range 26.8–51.2). The median apparent clearance was 11.9 mL/kg/minute (range 0.7–43.8). In conclusion, medetomidine administered IM at 0.13 mg/kg reached its peak plasma concentration slowly and with variability among patients. In addition, it was characterised by low total body clearance probably due to the cardiovascular alterations associated with medetomidine administration.

Effectiveness of urethral catheterization under ultrasound guidance for semen collection from Asiatic black bears (Ursus thibetanus)

The Asiatic black bear (ABB; Ursus thibetanus ussuricus) is a globally endangered species, and measures to help increase their population are necessary. For the successful restoration of this species, artificial breeding as well as conservation translocation are considered important. The aims of the present study were to evaluate the feasibility and effectiveness of urethral catheterization (UC), which is effectively used in feline species, for semen collection from ABBs and establish the optimal protocol for semen collection via this technique. Seven clinically healthy, adult male ABBs (age, 6-13 years; weight, 130-180 kg) housed at the Species Restoration Technology Institute, Korea were included in this study. All study procedures were performed during the breeding season (June to August) over 3 consecutive years. Semen samples were collected once or three times from all bears by ultrasound-guided UC or electroejaculation (EE) under general anesthesia, and their characteristics, including sperm motility, were evaluated. The day of semen collection was defined as Day 0. The semen collected by the UC method was stored at 4 °C, and sperm motility was evaluated at the same time every day for 16 days. The successful collection rates for the UC and EE methods were 92.3% and 53.8%, respectively. The sperm concentration (4718.9 ± 1526.1 vs. 185.0 ± 34.2 × 10⁶/ml), total sperm count (1196.6 ± 955.5 vs. 100.9 ± 70.0 × 10⁶), sperm motility score (4.39 ± 0.78 vs. 3.00 ± 1.73), viability (98.2 ± 2.3 vs. 82.7 ± 19.6), and the proportion of spermatozoa with intact acrosomes (92.2% ± 9.3% vs. 75.6% ± 10.6%) were higher with the UC method than with the EE method, whereas the proportion of spermatozoa with an abnormal morphology (23.1% ± 4.6% vs. 45.6% ± 19.5%) was lower with the former than with the latter. Over the course of cool storage, there was an overall decrease in the total motility, progressive motility, and viability, although viability was >50% until Day 10. These findings suggest that ultrasound-guided UC is a useful and feasible tool for the collection of high-quality semen from ABBs. The collected semen remains viable for up to 10 days, with high sperm motility maintained for up to 7 days, when stored at 4 °C.

Characterization and cryopreservation of Amur leopard cats (Prionailurus bengalensis euptilurus) semen collected by urethral catheterization

The Amur leopard cat (Prionailurus bengalensis euptilurus) is a globally endangered species, and there is thus an urgent need to increase its population. The objectives of this study were to: (1) confirm the utility of urethral catheterization (UC) for semen collection from Amur leopard cats; (2) investigate proper dilution media for fresh semen; and (3) investigate the effectiveness of sperm cryopreservation, including examining the effect of glycerol concentration. Six adult males in captivity (mean weight 5.03 ± 0.44 kg, aged 2-6 years) were included. All study procedures were performed during the breeding season (February to April) over two consecutive years. Semen samples (n = 28) were collected four or five times from each animal (four times for two animals and five times for four animals) by UC under general anaesthesia, and their characteristics (including sperm motility) were evaluated. First, the sperm motility in semen diluted in Ham's F-10 or phosphate buffer saline (PBS) was compared. Next, semen diluted with TEST-yolk buffer containing 2%, 4%, or 6% glycerol was frozen in a liquid nitrogen tank, and sperm motility and acrosome integrity were evaluated after thawing. No difference in motility was observed between sperm diluted in Ham's F-10 and PBS. The percentages of sperm motility and kinetic values in semen frozen in 2% or 4% glycerol were higher than those in semen stored in 6% glycerol. In conclusion, the UC method for semen collection is recommendable for Amur leopard cats and should be useful for artificial insemination. Although sperm motility decreased after thawing, samples thus preserved may be usable for advanced reproductive techniques, such as intracytoplasmic sperm injection or in-vitro fertilization.

Comparison of semen samples collected from wild and captive jaguars (Panthera onca) by urethral catheterization after pharmacological induction

This study was designed to evaluate the efficiency of medetomidine anesthesia for semen collection through urethral catheter in wild and captive jaguars. Six captive and five wild jaguars were chemically restrained with a combination of medetomidine (0.08-0.1 mg/kg) and ketamine (5 mg/kg). After medetomidine administration the urethra was catheterized using a urinary tomcat catheter (1 mm diameter × 130 mm length) to collect semen from all animals. By using this technique, we could collect an average of 347.2 μl of semen containing 2,635.2 sperm/ml. Forward progressive motility, sperm progressive motility, and sperm morphology analysis demonstrated that the methodology did not affect sperm quality. Thus, urethral catheterization after medetomidine administration is a practical and efficient method to collect high-quality semen from wild and captive jaguars; this will enable the development of reproductive assisted technologies for jaguars.