Seasonal changes in testicular cell morphology in domestic male cats (Felis catus)

Reversible control of reproduction in tom cats: medical options for manipulating libido and fertility

BACKGROUND

There has been a growing interest in alternatives to surgery for controlling reproduction in tom cats, and the resultant medical options add to a practitioner's toolbox when handling these cases in clinical practice. It is important, however, that when suggesting these drugs, veterinarians have a good understanding of their mode of action, and their correct use and dosage.

CLINICAL RELEVANCE

Breeders increasingly wish to be able to switch on/off the reproductive ability of their tom cats in a controlled manner. In addition, in small animal medicine, there has been concern from some academics, and a growing number of pet cat owners, about potential long-term effects of surgical sterilisation. Further, for some cats surgical castration may not be possible due to health conditions that mean anaesthesia is unsafe. In all of these scenarios, medical alternatives to surgery can prove useful.

EQUIPMENT AND TECHNICAL SKILLS

No special equipment or technical skills are required. A good knowledge of the medical alternatives to surgical sterilisation for controlling reproduction in a tom, and making sure the patient is a suitable candidate, are, however, important for ensuring the cat's health during and after treatment and the owner's satisfaction.

AUDIENCE

This review is aimed principally (but not exclusively) at veterinary practitioners working with cat breeders who seek a temporary arrest in their tom cat's reproduction. It may also help practitioners with clients who would like an alternative to surgery or with cats where anaesthesia for surgical castration is not possible.

EVIDENCE BASE

Advances in reproductive feline medicine have resulted in improved knowledge of medical contraception. This review draws on scientific evidence-based papers that report on the mode of action, length of efficacy and potential side effects of different methods of medical contraception, as well as the authors' own clinical experience.

Proliferation and Apoptosis of Cat (Felis catus) Male Germ Cells during Breeding and Non-Breeding Seasons

Simple Summary

Spermatogenesis is a complex process through which male gametes, spermatozoa, are produced starting from stem germ cells called spermatogonia. The existing information on cat spermatogenesis is limited and somewhat contradictory. In fact, although this species is considered a long-day breeder with a reproduction period starting when the day length increases and ending in late autumn, spermatogenesis and sperm production occur throughout the year. In order to assess whether cat spermatogenesis is modulated according to a season pattern, we analyzed testes taken from feral cats orchiectomized during reproductive (February–July) and non-reproductive (November and December) periods. The results of the analyses carried out in the present study showed that spermatogonial proliferation was more intense during the reproductive period and germ cell death via apoptosis (a programmed form of cell death) increased during the non-reproductive period. Our results confirm the hypothesis that cat spermatogenesis is seasonally modulated through changes of germ cell proliferation and apoptosis, according to a common paradigm of seasonally breeding species.

Abstract

The domestic cat (Felis catus) is a seasonal-breeding species whose reproductive period starts when the day length increases. Since the existing information on cat spermatogenesis is limited and somewhat contradictory, in the present study, germ cell proliferation and apoptosis in feral adult tomcats orchiectomized during reproductive (reproductive group, RG; February–July) and non-reproductive (non-reproductive group, NRG; November and December) seasons were compared. Cross-sections taken from the middle third of the left testis were chemically fixed and embedded in paraffin wax. Histological sections were processed for the immunohistochemical detection of proliferating germ cells (PCNA) and for the identification of apoptotic cells (TUNEL method). The percentage of PCNA-positive spermatogonia was higher in the RG than in the NRG. On the contrary, germ cell apoptosis was higher in the NRG than in the RG. Our results confirm that cat spermatogenesis is modulated on a seasonal basis and suggests that spermatogenesis control involves changes in germ cell proliferation and apoptosis according to a common paradigm of seasonally breeding species.

Effect of cat seminal plasma and purified llama ovulation-inducing factor (β-NGF) on ovarian function in queens

The present study aimed to determine the effect of cat seminal plasma and purified llama ovulation-inducing factor (β-NGF) on ovarian activity in queens. Queens (n = 6) were used for all the treatments in a crossover design with an interval time between treatments of three interestrus intervals. Forty-eight hours after the detection of an estrus vaginal cytology, queens were given cat seminal plasma (subcutaneous or intramuscular), purified llama ovulation-inducing factor (15 or 35 μg), hCG (75 UI), saline, or were mated with a male. A total of 192 estrous cycles were observed. Estrus length and serum estradiol concentration were 6 ± 1 days (range 2-10 d) and 38 pg/mL (range 10-75 pg/mL), respectively. Queens mated and given hCG showed higher serum progesterone concentration and longer interestrus interval (47 ± 5 d) than that of controls (10 ± 3 d). Sixty-seven percent of queens (4/6) treated with subcutaneous cat seminal plasma, and 17% of those treated with purified llama β-NGF showed high serum progesterone concentrations along with prolonged interestrus. However, intramuscular administration of cat seminal plasma produced interestrus intervals similar to controls (15 ± 5 d) and basal serum progesterone concentration (<0.50 ng/mL). This study demonstrates that the subcutaneous administration of cat seminal plasma induced ovulation in queens. Therefore, molecules present in cat seminal plasma, contribute to the induction of ovulation in queens. Identifying those molecules will improve the knowledge of queen's reproductive physiology. Also, it could offer a physiologic alternative to induce ovulation in queens when reproductive biotechnologies are used.

Radiographic lumbosacral vertebral abnormalities and constipation in cats

Background and Aim:

Lumbosacral intervertebral disk disease (IVDD) in cats usually develops concurrent with constipation, spondylosis deformans, and sacralization. However, the prevalence of lumbar IVDD in cats was considered low, and there was less information on the incidence of non-traumatic lumbosacral vertebral abnormalities that may affect large bowel dysfunction. This study aimed to retrospectively investigate the relationship between non-traumatic lumbosacral vertebral abnormalities, both congenital and acquired, and large bowel dysfunction in cats.

Materials and Methods:

Of 3108 cats that were presented to the Diagnostic Imaging Unit, the Small Animal Teaching Hospital, Faculty of Veterinary Science, Chulalongkorn University, between March 2016 and February 2018, 1365 cats met the inclusion criteria. All abdominal radiographs were reviewed, and all subsequent data were recorded, including the presence of congenital or acquired lumbosacral lesions, number of lumbar vertebrae, and length of the second, fifth, and last lumbar vertebrae, including the type of lumbar abnormalities. Moreover, radiographic information relating to constipation and megacolon was also collected.

Results:

Non-traumatic lumbosacral vertebral abnormalities were observed in 29.74% of cats. The most common congenital lumbosacral vertebral abnormalities were six lumbar vertebrae, sacralization, and lumbarization, whereas most common acquired lumbosacral abnormalities were bone spur, narrowing disk space, spondylosis deformans, and lumbosacral degeneration, respectively. Cats with abnormal lumbosacral vertebrae are prone to have more problems with the large bowel (p=0.0057; odds ratio=1.731). Moreover, congenital and acquired lumbosacral abnormalities were also at risk of large bowel abnormalities (p=0.0069; odds ratio=1.920 and p<0.0001; odds ratio=4.107, respectively).

Conclusion:

This study revealed the evidence and distribution of the variation in feline lumbar anatomy and also elucidated that cats with abnormal lumbar vertebral columns were more likely to have problems with distal gastrointestinal tracts than those without.

Relationship between semen quality and seminal plasma cholesterol, triacylglycerols and proteins in the domestic cat

OBJECTIVES

The current study aimed to evaluate the relationship between specific seminal plasma components - cholesterol (CHOL), triacylglycerols (TAG) and total protein (PROT) concentrations - and semen quality in cats. A further aim was to determine the relationship between specific seminal protein bands and semen quality.

METHODS

Thirteen toms, 2-5 years of age, were included. Semen collection was performed by electroejaculation every 4 weeks. Fifty-eight ejaculates were assessed for motility, velocity, volume, sperm concentration, total sperm count, viability, acrosome integrity, plasma membrane integrity and sperm morphology. Samples were divided into two groups: good semen quality (GSQ) and poor semen quality (PSQ). After evaluation, seminal plasma was separated from the sperm by centrifugation and stored at -20°C. CHOL, TAG and PROT concentrations were then assessed and seminal plasma protein profile was determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE).

RESULTS

Seminal plasma CHOL and TAG concentrations, motility, velocity, sperm concentration, total sperm count and sperm morphology were significantly higher in GSQ cats compared with PSQ cats (P <0.01). Moreover, seminal plasma SDS-PAGE analysis showed an identifiable extra band exclusively in the GSQ group.

CONCLUSIONS AND RELEVANCE

Data obtained in this study showed that seminal plasma CHOL and TAG concentrations and specific protein bands could be used to improve semen evaluation in toms. In this sense, the 14 kDa protein band could be a valuable marker for semen quality in the cat and should be further investigated. However, more studies are necessary to determine its relationship with fertility.

Alternative methods for feline fertility control: Use of melatonin to suppress reproduction

PRACTICAL RELEVANCE

Reversible contraceptives are highly desired by purebred cat breeders for managing estrous cycles and by scientists managing assisted reproduction programs. A variety of alternative medicine approaches have been explored as methods to control feline fertility.

SCOPE

In the field of veterinary homeopathy, wild carrot seed and papaya have been used for centuries. Both appear to be safe, but their efficacy as feline contraceptives remains anecdotal. In contrast, the use of melatonin in cats has been investigated in a number of studies, findings from which are reviewed in this article.

RATIONALE

Cats are seasonally polyestrous (they cycle several times during their breeding season) and are described as long-day breeders because endogenous melatonin negatively regulates estrous cyclicity. Exogenous melatonin administered parenterally also suppresses ovarian activity in cats, and long-term oral or subcutaneous melatonin administration is safe.

CHALLENGES

The therapeutic use of melatonin is limited by its short biological half-life (15-20 mins), its poor oral bioavailability and its central effects in reducing wakefulness. Research is required to determine whether higher doses, longer-release formulations, repeated administration or combination implants might overcome these limitations.

Variation of spermatogenic and Sertoli cell number detected by fine needle aspiration cytology (FNAC) in Iberian red deer during and out of the breeding season

The aim of the present study was to evaluate spermatogenesis in Iberian red deer, a short-day seasonal breeder, using the fine needle aspiration cytology (FNAC) technique. Reports on spermatogenesis in deer are limited and here, for the first time, FNAC has been used to evaluate changes in such physiological process during and out of the breeding season. Testes were collected from 51 stags from November 2010 to February 2011. The Sertoli index and spermatic index were significantly higher during the breeding season than out of the breeding season (P = 0.0477 and P = 0.0125, respectively). A similar pattern was described by histological analysis, in which both Sertoli cell number per tubular cross-section and Johnsen score decreased significantly from the breeding season to the non-breeding season (P = 0.0131 and P = 0.0010, respectively). Data provided by FNAC were correlated with histology: the Sertoli index was positively correlated with Sertoli cell number per tubular cross-section (P = 0.0015), whereas the spermatic index was correlated with the Johnsen score (P = 0.0497). The results of the present study indicate that FNAC is a reliable technique to evaluate spermatogenesis in Iberian red deer and suggest that Sertoli cell number is not stable in these species, reaching highest values during the breeding season.