Contraceptive implants used by cat breeders in France: a study of 140 purebred cats

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.

Efficacy and Safety of 4.7 mg Deslorelin Acetate Implants as a Neutering Option in Male Cats: A Large-Scale Multicentre Randomised Controlled Study

This multicenter-controlled, double-masked randomized European study was conduc-ted to confirm both the efficacy and safety of a deslorelin implant in controlling fertility and sexual behavior in a large population of tom cats over a 12-month period. Among the 225 screened individuals, a total of 205 privately owned indoor intact male cats, aged 3 months of age or older, were randomly allocated to a deslorelin implant (n = 154) or to a negative control group (n = 51). After the screening visit performed between day (D)-14 and D-7, six additional visits were sche-duled on D0, D45, D93, D186, D279 and D372. Effects on testosterone, sexual behaviors, penile spines, testicular volume and intact male cat urine odor were assessed at every visit under masked conditions as regards to the treatment group. In addition, phone calls from the investigators to the owners were scheduled on D7 and then on a monthly basis whenever no visit was scheduled. Success was defined as an individual serum testosterone concentration below or equal to 0.10 ng/mL and was 77.9% at D45, 83.1% at D93, 84.4% at D186 and D279, and 61.7% at D372 in the deslorelin group, and 3.9% at D45, 5.9% at D93, 3.9% at D186, 7.8% at D279 and 3.9% at D372 in the negative control group. Testing for superiority was made stepwise from D45 to D372 upwards; the difference in success rates was significant from D45 to D372 (p < 0.001 for each time point). The mean testosterone concentration dropped from baseline in the deslorelin group, remaining below the set threshold of 0.1 ng/mL until D372. From D7 onwards, the mean sum score for sexual behaviors (including vocalization, urine marking, aggression and intact male cat urine odor) was significantly lower at each observation time point in the deslorelin group compared to the control group, where no decrease in scores was observed. The mean percent change to baseline of the testicular volume and the percentage of cats with a decreased visibility and adult appearance of penile spines were significantly lower in the deslorelin group as soon as D45. No relevant safety concerns were reported during the course of the study. The deslorelin implant Suprelorin^® 4.7 mg (Virbac, Carros, France) is a safe and effective neutering option, inducing infertility over a 12-month period when administered to intact male cats aged between 3 months of age and 11 years of age. The implants also successfully reduced sexual behaviors (i.e., vocalization, urine marking, aggression), intact male cat urine odor, testicular volume and penile spine score for 1 year (372 ± 5 days).

Prevalence of lactational oestrus in cats and consequences for kittens

OBJECTIVES

Although lactation and suckling suppresses fertility in most mammals, some feline breeders have reported spontaneous oestrus during lactation, causing distress to kittens. This led the Official French Feline Pedigree Registry (Livre Officiel des Origines Félines - LOOF) to send a questionnaire to cat breeders requesting data on their last three litters. The aim of this study was to investigate the prevalence of lactational oestrus, its impact on litters and potential associations with litter size, age, parity, breed and seasonality.

METHODS

Answers from 108 breeders were collected, providing data on 238 litters in 23 different breeds. Data were also collected on successive litters from multiparous queens (n = 20) and were analysed separately from the 195 independent births.

RESULTS

Of the 195 independent births with complete data sets, 96 (49%) queens came into oestrus during lactation, 37 (38%) of which were associated with loss of maternal interest (n = 20), milk quality variation (n = 2), clotted milk (n = 3), reduced milk quantity (n = 13), which in kittens led to reduced weight (n = 6), diarrhoea (n = 9), vomiting (n = 4), nausea (n = 2) or death (n = 4), and bottle feeding (n = 2), early weaning (n = 4) or modified litter behaviour (n = 1). A significant association was found between small litter size (one or two kittens) and the onset of lactational oestrus (P = 0.007) and between births occurring in February, March and April and lactational oestrus (P = 0.005); there was no association with age or breed.

CONCLUSIONS AND RELEVANCE

Breeders perceived a relationship in 38% of cases of lactational oestrus with maternal disinterest, clotted milk, reduced milk yield and in kittens, weight loss, vomiting, diarrhoea or even death. An association between small litter size and lactational oestrus was found, as well as with births occurring between February and April. Breeders presenting with at-risk females should be warned. Conservative and preventive measures such as contraceptive options are discussed as a possible therapy.

Reversible Control of Reproduction In Queens: Mastering the use of reproductive drugs to manipulate cyclicity

BACKGROUND

The literature is full of papers reporting side effects of progestogens in cats; however, they are, in fact, safe drugs, as discussed in this article. Gonadotropin-releasing hormone (GnRH) agonists and melatonin are additionally a practical solution for controlling cyclicity in queens, but they also have some contraindications and need to be used carefully.

CLINICAL RELEVANCE

Mastering the use of reproductive drugs allows feline practitioners to handle many more clinical situations than can be solved using surgery. It is not necessary to be a specialist in reproduction to be able to halt cyclicity in a valuable breeding queen using hormones.

EQUIPMENT AND TECHNICAL SKILLS

A sound knowledge of appropriate dosages and criteria for patient selection for all reproductive drugs currently used in feline reproduction is the best guarantee of owner satisfaction and of ensuring the queen's health. Availability of a serum progesterone assay, either in-house or via an external laboratory, is also important, in order to confirm a queen is at an appropriate stage of the reproductive cycle for treatment.

AUDIENCE

This article is aimed principally (but not exclusively) at veterinarians working with cat breeders and whose clientele is increasingly interested in alternative methods of controlling reproduction in pet queens. Surgery is no longer the only choice, and practitioners who manage to keep abreast of new developments will be able to address clients' needs in a modern, professional way.

EVIDENCE BASE

This review draws on a vast body of scientific evidence-based literature. Previously, personal (and sometimes misinformed) opinions, such as the proposed dangerous side effects of progestogens, have been perpetuated in the scientific literature. The papers cited in this review have therefore been carefully scrutinised to distinguish reliable information based on controlled studies from non-evidence-based information.

Reproductive Management in Catteries: Optimising health and wellbeing through veterinarian-breeder collaboration

PRACTICAL RELEVANCE

Many veterinarians - even those engaged in small animal reproduction - are uncomfortable with taking care of cat breeders or being in charge of catteries. Likely reasons for this are that feline reproduction is largely under-represented in undergraduate and graduate reproduction teaching, as well as in postgraduate education and science, whereas cat breeders themselves are often well informed and actively share knowledge with other cat breeders via the internet and social media.

CLINICAL CHALLENGES

A variety of problems can exist within a cattery, and collaboration between veterinarian and breeder to solve these is ultimately beneficial for the breeder, for the veterinarian, and for the health and wellbeing of the individual cats and of the cattery as a whole.

AIM

This review presents a comprehensive overview of aspects of cattery management that might negatively impact reproduction, including sanitation, hygiene and infectious disease control. It also discusses monitoring of reproductive performance, breeding recommendations, and the diagnostic and therapeutic approach to some common and specific problems.

EQUIPMENT AND TECHNICAL SKILLS

Reproductive management in the cattery requires no specialised equipment, as such. What it does need is an open mind, in terms of seeing how things are done, an open ear, for listening to the breeder, and the veterinarian's clinical skills in palpation, auscultation and, where required, further examination of the animals. Keeping abreast of the latest information on infectious diseases, disinfection and genetics ensures proper advice is provided.

EVIDENCE BASE

Current knowledge of reproductive management in catteries is summarised in order to apply an evidence-based approach, whenever possible. Notwithstanding, much of the information remains empirical.

Hyperplastic and atrophic changes in the genital tract of a female cat following repeated treatment with deslorelin acetate – a case report

This study aimed to investigate the morphological patterns of the genital tract after long-term treatment of deslorelin acetate in a female cat, a gonadotropin-releasing hormone agonist currently used in adult cats to obtain transient oestrus suppression. A 1-year-old Chartreux female cat was treated with 4.7 mg deslorelin acetate to suppress oestrus manifestations. The treatment was repeated for a total of × 3 every 2 years. After 8 years, the female cat came into oestrus again, but she was no more implanted, and an ovariohysterectomy was performed. Before surgery, an ultrasound examination was performed that showed a normal uterus and the presence of about 5 follicles in ovaries. Concentrations of oestradiol, progesterone, and vaginal smears were compatible with oestrus. During surgery, a very short ovarian pedicle was observed yet neither uterus nor ovaries presented appreciable alterations. At histology, the ovaries presented a juvenile appearance with numerous primordial and periovulatory follicles. The uterus showed marked endometrial hyperplasia with polypoid projection and atrophic myometrium. Based on this case report, deslorelin acetate is a powerful drug able to preserve ovarian function. However, the suppression of gonadotrophin, especially for a long period, has a detrimental atrophic effect on the target organs during treatment and, on the opposite, hyperplastic changes may occur after the restoring of normal cyclicity.

Interval between Removal of a 4.7 mg Deslorelin Implant after a 3-, 6-, and 9-Month Treatment and Restoration of Testicular Function in Tomcats

Deslorelin implants have been used to produce a reversible sterilization in several species. In cats, the prolonged duration (12-15 months in tomcats and 18-22 months in queen) is often too much for cat breeders who request early implant removal. The interval between implant removal and resumption of reproductive function in cats has never been investigated. Eighteen tomcats received a 4.7 mg deslorelin implant placed in the periumbilical area and surgically removed during all seasons of the year after 3, 6, or 9 months (n = 6, 6, and 6 cats, respectively). Following implant removal, all cats received a clinical exam every two weeks, including testicular ultrasonographic measurement, observation of penile spikes, and blood collection for serum testosterone assay. Restoration of serum testosterone secretion occurred after 23 ± 6, 23 ± 6, and 22 ± 7 days in the 3-, 6-, and 9-month groups, respectively. Restoration of testicular function was confirmed by histology in 13/15 cats undergoing orchiectomy at the end of the study while the owners of the remaining two cats opted to maintain their animals intact. Removal of a 4.7 mg deslorelin implant after 3, 6, or 9 months is followed by resumption of serum testosterone secretion after about 3 weeks independent of age or season.