Methods of fertility control in cats

Abstract

Overview:

Fertility control is important for population management of owned and unowned cats, provides health benefits at the individual level and can reduce unwanted sexually dimorphic behaviors such as roaming, aggression, spraying and calling. This article reviews the available evidence regarding European and American veterinarian, owner and pedigree cat breeder attitudes toward both surgical sterilization and non-surgical fertility control. It additionally presents new data on veterinarians’ and pedigree cat breeders’ use of, and attitudes toward, alternative modalities of fertility control.

Proportion of cats that are neutered:

Within the United States and Europe, the proportion of cats reported to be sterilized varies widely. Published estimates range from 27–93% for owned cats and 2–5% for cats trapped as part of a trap–neuter–return (TNR) program. In some regions and populations of cats, non-surgical fertility control is also used. Social context, cultural norms, individual preferences, economic considerations, legislation and professional organizations may all influence fertility control decisions for cats.

Non-surgical methods of fertility control:

Particularly in Europe, a limited number of non-surgical temporary contraceptives are available for cats; these include products with regulatory approval for cats as well as some used ‘off label’. Non-surgical methods remove the risk of complications related to surgery and offer potential to treat more animals in less time and at lower cost; they may also appeal to pedigree cat breeders seeking temporary contraception. However, concerns over efficacy, delivery methods, target species safety, duration and side effects exist with current non-surgical options. Research is under way to develop new methods to control fertility in cats without surgery. US and European veterinarians place high value on three perceived benefits of surgical sterilization: permanence, behavioral benefits and health benefits. Non-surgical options will likely need to share these benefits to be widely accepted by the veterinary community.

Introduction

Fertility control is widely acknowledged as necessary to prevent reproduction in individual cats and to manage populations. Surgical sterilization is a well established and permanent method of fertility control. Most commonly, it entails castration of toms and ovariohysterectomy of queens, but it can also include vasectomy and ovariectomy, respectively. Non-surgical fertility control approaches are used in a much smaller proportion of cats, with notable geographic variation and, overall, greater use in Europe than in the United States.

Fertility control of cats depends on a range of factors that include the attitudes and behavior of owners/caretakers/feeders/shelter staff, plus the interactions these individuals have with veterinary professionals. Cultural norms, social influences, individual attitudes and economic considerations may all influence fertility control decisions.

Understanding the behaviors, attitudes and circumstances of different communities, regions and stakeholders is important for advancing fertility control options that effectively meet the needs of cats and their caretakers. This article is divided into three sections. The first reviews published research on surgical sterilization rates in the US and Europe, and the second reviews existing literature on factors that influence surgical sterilization decision-making and outcomes for cats. The third section discusses previously unpublished results of surveys from multiple stakeholder groups (European and US general practice veterinarians, US shelter-focused veterinarians, and pedigree cat breeders) on attitudes toward non-surgical ‘tools’ that exist today or that may be future options.

Where are we now? Sterilization rates by country and region

The proportions of surgically neutered cats in different countries provide a measure of neutering behavior within these populations. In the United Kingdom, recent national estimates of the percentage of neutered adult cats have varied from 67–93%.^{1 –3} Elsewhere in Europe, the percentage of pet cats reported as sterilized has ranged from 43% in a study carried out in Teramo, Italy, to 61% for cats attending a vaccination clinic in France and 76% for cats belonging to households in Ireland.^{4 –6} While data on sterilization numbers are not published, in Sweden, Norway, Denmark, Finland and Germany dogs are not routinely neutered; owners are responsible for maintaining good control of animals and preventing uncontrolled breeding. ⁷ Published research is not available on cat sterilization rates and owner responsibility in these aforementioned European countries.

Meanwhile, recent national estimates of pet cats sterilized in the United States range from 77–91%.^{8 –11} However, research has found notable regional and community variations in feline sterilization rates. ¹¹ A Massachusetts study estimated that 94% of owned cats were sterilized, ¹² and a survey in a Florida community found a 91% cat sterilization rate. ¹³ By contrast, a 27% feline sterilization rate was reported for a community on the Texas– Mexico border. ¹⁴

Differences in survey findings, particularly those carried out within the same country, might be attributable to differences in cat-related (eg, breed) or owner-related (eg, affluence) characteristics. There is evidence that older and purebred cats are more likely to be sterilized than their younger and mixed-breed counterparts.^2,11 In two US studies, male pet cats were slightly more likely to be sterilized than females,^10,11 whereas a study in Ireland found the opposite. ⁶ Studies of cats recruited through veterinary practices are likely to report higher sterilization rates than studies of cats with little or no veterinary contact.^2,15 Sterilization rates may also be associated with the geographical (eg, urban vs rural) location of study samples. ¹⁶

Estimating numbers of sterilized unowned (feral/community/street/stray) cats is considerably more challenging than estimating proportions of sterilized owned (pet) cats. In addition to challenges with observation and counting methodology, there is potential to incorrectly ‘categorize’ an individual animal – for example, cats that roam freely can be owned, semi-owned or unowned. ¹⁷ These challenges notwithstanding, two large US studies estimated that 2–5% of cats trapped during trap–neuter–return (TNR) programs had been previously sterilized.^18,19

Factors influencing attitudes and behaviors toward surgically sterilizing cats

Studies in countries across the globe have explored factors that influence owners’ and caretakers’ attitudes and behaviors toward sterilizing cats and dogs. Several of these studies have focused on dogs, or on the species combined. Recognizing that owner attitudes and behaviors are often species- and location-specific, this review is limited to research that distinguishes cats and dogs, and that took place within a US or European context. Studies implemented within these parameters suggest that a variety of factors are associated with cat sterilization attitudes and behaviors at individual, community and national levels.

Owner beliefs, knowledge and awareness

Studies of US, UK and other European residents suggest that, although cost is an important factor in the decision to sterilize (discussed below), beliefs and knowledge can strongly influence decision-making.

A 2007 cross-sectional telephone (landline) survey of US households revealed that the most common explanations for not sterilizing cats were the belief that their female should have one litter first (41%), the procedure costing too much (39%) and the plan to breed the cat (20%). ⁹ A second national study found three times as many unplanned litters of kittens as puppies born in US households. ²⁰ Cost was most often reported in that study as the reason for not sterilizing a queen, followed by the procedure being inconvenient, not knowing the cat was in heat, thinking the cat was too young, not believing in neutering animals, and ‘other’ reasons (eg, the owner adopted a pregnant stray cat, the owner wanted kittens). ²⁰

A 2013 UK study found that the most common reason owners gave for not neutering their cat was that they ‘don’t believe in it’, cited by 16% of respondents, with nearly as many (15%) saying they ‘haven’t thought about it’. ³ A cross-sectional telephone (landline) study of UK cat-owning households revealed frequent misinformation about feline reproduction: 26% of cat owners believed that female cats could not conceive before 1 year of age; 23% believed that they should have a litter before being neutered; while a further 26% were uncertain if they should have a litter prior to neutering. ²¹

A focus group with Irish cat and dog owners, all recruited through private veterinary clinics, cited three primary reasons for not neutering. The first was financial cost. The second was the belief that owners had enough control over their pets to prevent accidental reproduction; however, this belief differed according to species, as cats were perceived as more difficult to control than dogs. The third was perceived negative health and welfare effects of neutering. ²²

These data indicate that certain beliefs and knowledge levels, including the preferred time to sterilize (discussed below), may contribute significantly to feline reproductive outcomes.

Owner demographics

Although multiple studies have looked at the demographics of cat owners, a relatively limited number have explored how owner characteristics such as ethnicity, sex and religion are associated with decisions to sterilize one’s cat. Understanding variability in owner demographics and characteristics is very important, particularly when considering targeted strategies for increasing sterilization rates or pet-owner populations who might respond more or less positively to non-surgical fertility control options.

Research on owner ethnicity and relationships with companion animals is limited, and the most extensive work on this topic has focused on US residents self-identifying as having Hispanic, Spanish or Latino origins.^{14,23 –25} These studies have found that persons of Hispanic, Spanish or Latino origin are less likely to report ownership of sterilized cats compared with cat owners of non-Hispanic background.^{14,23 –25} (They are also less likely than other groups to own cats and more likely to say that they get a sense of personal safety from their pet.)^{14,23 –25}

A study of Romanian pet owners found a significant difference between male and female owners’ attitudes toward neutering male cats and dogs, with men being more resistant. In contrast, the owner’s sex did not influence attitudes toward sterilizing females. ²⁶ There was no significant association between level of attachment to pets and attitudes toward sterilization in this ²⁶ or another, US-based study, ²⁷ suggesting that other factors may be mediating or moderating the decision.

Albeit a small sample, one Massachusetts study found that Catholic pet owners were less likely to sterilize their pets (cats and dogs) than were owners of other religions. ²⁸

These limited studies indicate that demographic factors can be associated with attitudes toward and decisions about sterilization. Further research on this topic is needed.

Cost of sterilization

Although owners report myriad reasons for not sterilizing their cats, the cost of the procedure is considered an important concern. Subsidized sterilization is common in the US and available in multiple European countries in an effort to make sterilization economically feasible.^7,29 While research has shown the complicated relationship between cost and sterilization behavior across pet populations, US national and regional studies suggest that cost is more often the limiting factor for sterilizing cats than it is for dogs.^12,20,30,31

Moreover, studies in the US and UK have found strong correlations between income levels and sterilization decisions. A US random-digit-dial phone survey found that annual family income was the strongest predictor of whether a pet cat was sterilized. ⁹ The differences were dramatic: whereas 96% of cats in households with family incomes of $75,000 or higher were neutered, the percentage dropped to 51% of cats in households with annual family incomes below $35,000. ⁹ In another US survey, 53% of respondents stated that they would choose low-cost veterinary care if available. ²⁷ These owners tended to have an annual household income below $40,000 (as well as describe a weak owner–pet or client–vet bond). ²⁷ Even with a subsidized spay/neuter clinic available, a study in one US community found that 45% of cat owners were still unable to pay for surgery, indicating the extent of financial need or priorities among certain populations. ³²

One UK study found that cat-owning householders with low annual incomes (£10,000 or below) were less likely than higher income counterparts to report that their cats were neutered by 6 months of age. ³³

Cat ‘lifestyle’

Higher sterilization rates have been reported for pets (cats/dogs combined) in urban compared with rural areas, which indirectly may be related to indoor–outdoor access. ¹⁶ Studies in Italy and the UK have documented that free-roaming pet cats not permitted inside their owner’s home were significantly less likely to be sterilized than cats with indoor access.^2,4 In turn, decisions on indoor–outdoor lifestyle vary over time and between countries. For example, US pet cats kept strictly indoors have increased (33% in 1993, 49% in 2005); and, compared with the US, a lower percentage of cats is reported to be kept strictly indoors in Italy (30%) and in the UK (9%).^4,34

A limited number of studies have evaluated the extent to which those who feed unowned cats (as distinguished from formal colony caretakers) also take responsibility for neutering them. Recent research in the US has found that only 5.5–14% of persons who feed free-roaming cats at their home or place of work, in their community or at a local park, also sterilize them.^13,18,35 This suggests a disconnect between feeders’ commitment to feeding cats and their perceived responsibilities toward population control. It is also consistent with findings that only 2–5% of cats trapped as part of TNR programs were already spayed or neutered.^18,19

Recommendations about the appropriate age for sterilization

Age of sterilization is important to population control, and the appropriate age to spay or neuter a cat has been the subject of veterinary attention and research. ³⁶ The positions of veterinary and animal welfare organizations on appropriate sterilization age may affect recommendations given by veterinarians and ultimately decisions of cat owners regarding the procedure.

In an effort to reduce unplanned litters, the American Veterinary Medical Association (AVMA) supports ‘the concept of paediatric spay/neuter in dogs and cats’, ³⁷ and the British Small Animal Veterinary Association (BSAVA) supports The Cat Group policy that recommends neutering at 4 months of age.^38,39 Despite these recommendations, veterinarian and owner surveys indicate that the practice of prepubertal neutering has not become widespread in the US or UK.^33,40,41 However, recent developments, including but not limited to the Cats Protection Early Neutering Register and publication of spay–neuter program guidelines by the Association of Shelter Veterinarians (ASV), suggest that awareness and the practice of prepubertal neutering is increasing.^42,43

In 2006 and 2007, the then World Society for the Protection of Animals (WSPA) and the Royal Society for the Prevention of Cruelty to Animals International (RSPCA International) distributed questionnaires to member societies and associated organizations in Europe. The results indicated variable practice of ‘early-age’ sterilization; however, ‘early-age’ was not defined in the questionnaire. Groups in Bulgaria, Croatia, Estonia, Germany, Hungary, Italy, Malta, Serbia and the Ukraine reported early-age sterilization of cats. Responses suggested that early-age sterilization was not practiced in the majority of countries in 2006–07. ⁷

Influence of professional associations, legislation and policies

Beyond influencing the age at which cats are sterilized, professional organizations may influence countries’ overall sterilization rates. So, too, may spay/neuter legislation and policies for companion animals.

Although veterinary associations of some countries (eg, the AVMA and British Veterinary Association)^44,45 and most veterinarians within these countries recommend neutering cats not intended for breeding, limited legislation exists to support these recommendations. The 1987 European Convention for the Protection of Pet Animals states that neutering should be promoted to reduce unplanned breeding of stray cats and dogs, and that there is a need to discourage unplanned breeding. ⁴⁶ However, this document has been signed by only 23 of 47 European member states. ⁴⁷ In Norway, routine surgical sterilization is prohibited by the Animal Welfare Act; in Sweden, Denmark, Finland and Germany, surgical sterilization is not prohibited but removal of organs for the purpose of convenience to humans is discouraged.^48,49 In contrast, since September 2014 it has been obligatory to neuter all cats (excluding breeding cats) that are sold in Belgium. ⁵⁰ This variance suggests mixed sentiments by the professional organizations and legislative authorities across Europe, which likely influence veterinarians’ recommendations and pet sterilization outcomes.

With regard to unowned, free-roaming cats, surveys of groups in 31 European countries found that the majority of countries perform TNR in conjunction with culling or catch-and-removal to control populations; only Belgian and Greek groups reported using TNR exclusively. ⁷

Stakeholder attitudes toward present and future non-surgical fertility control options

For a variety of reasons, as outlined in the box above, research is under way to develop new methods to control feline reproduction,^54,55 many of which are discussed in accompanying articles in this Special Issue. Already, progestin contraceptives (eg, medroxyprogesterone acetate, proligestone, hydroxyprogesterone, megestrol acetate, chlormadinone acetate, levonorgestrel and altrenogest) and the long-acting gonadotropin-releasing hormone (GnRH) agonist deslorelin are being used in cats (J Miller, unpublished data; J Murray, unpublished data). ⁵⁶ Some, but not all, progestins have regulatory approval for cats in certain countries, and surveys reveal that these contraceptives are more widely used in Europe than in the US (J Murray, unpublished data; J Miller, unpublished data). ⁵⁶

Non-surgical ‘tools’ have the potential to benefit individual cats by removing postoperative recovery and risks associated with surgical sterilization; they may also be more affordable, easier and faster. At the same time, non-surgical methods present challenges, concerns and questions. There is no permanent sterilant currently available; all options require repeated treatments. Any product given orally, particularly to unowned, free-roaming cats using a bait system, prompts concerns about proper dosing and safety for non-target species. ⁵⁵ Certain existing products, notably progestins used long term and/or in high doses (see accompanying article in this Special Issue), ⁵⁷ have yielded reports of adverse side effects such as endometrial hyperplasia or endometrial cancer, pyometra, glucose intolerance and diabetes mellitus, adrenocortical suppression and mammary tumors.^55,58,59

To follow are summaries of original research conducted with veterinarians and pedigree cat breeders to gauge attitudes toward, and use of, non-surgical feline fertility control. Some questions have inquired about use of products currently available (often used off label); others have presented theoretical future pharmaceuticals to gauge what features are, and are not, attractive to stakeholders.

Attitudes and awareness among US general practice and shelter veterinarians

In 2007 and 2008, 200 general/private practice and 240 ASV member veterinarians were surveyed about attitudes toward and awareness of non-surgical fertility control for cats and dogs.^60,61

The overwhelming majority of general practice and ASV member veterinarians (96% and 98%, respectively) agreed ‘strongly’ or ‘somewhat’ that unplanned litters contributed significantly to numbers of unwanted pets (cats and dogs) in their community. The cohorts differed, however, in their beliefs about the potential for non-surgical options to reduce unwanted populations. Sixty percent of ASV members perceived a need for non-surgical sterilization in their shelter or clinic, while only 32% of general practitioners believed there was such a need in their practice. The latter recognized the value of non-surgical options for pets that cannot undergo surgery, and for clients who resist surgery or cannot afford its cost. However, the majority of private practice veterinarians felt that surgical sterilization worked well and offered behavioral and health benefits; 65% also felt that spay and neuter was important for attracting new clients to the practice.

Using mean ratings, both veterinary cohorts perceived that female cats were most in need of a non-surgical alternative to sterilization, followed by male cats. In their opinion, the need for non-surgical options was also greater for cats than for dogs. However, while 62% of ASV member veterinarians rated the need for female cats as 6 or 7 on a 7-point scale (1 = no need at all and 7 = a very great need), only 22% of general practice veterinarians assigned a rating of 6 or 7 for female cats.

Although ASV member veterinarians viewed female cats as the group that would benefit most from non-surgical options, they did not strongly support the idea of a multi-year contraceptive as a solution. When presented with a hypothetical single-injection 3-year contraceptive for female cats, veterinarians in general practice were more likely than ASV member veterinarians to say they would recommend the product to their clients (52% versus 30%, respectively). However, even general practice veterinarians who supported the hypothetical product were concerned that owners would fail to repeat the treatment. When asked about the relative value of a contraceptive for pet versus feral cats, both veterinary cohorts thought that such a contraceptive had the potential to be most useful for the latter population.

Survey findings offer valuable insights on different veterinary perspectives regarding non-surgical fertility control. Differences exist between the contexts in which veterinarians work and their perceptions of the need for, and benefit of, non-surgical options. This variability warrants consideration, particularly for potential early adopters of new technologies.

US and European veterinary perspectives

A 2014 survey, distributed via International Cat Care (iCatCare) and the American Association of Feline Practitioners (AAFP) listservs, was modelled loosely on the aforementioned surveys^60,61 (J Murray, unpublished data). It sought to gauge veterinarian attitudes toward and use of fertility control, both surgical and non-surgical, in Europe and the United States. The survey yielded 169 responses from veterinarians who worked in predominantly small animal veterinary practice and/or who engaged in activities related to feline population control. Respondents included 115 European veterinarians, 59 of whom practiced in the UK; in total 18 European countries were represented. Fifty-four US veterinarians completed the survey.

The findings, which are summarized in the box below, suggest geographic heterogeneity in veterinarian attitudes toward, and priorities for, non-surgical fertility control. This variety warrants attention, as it will influence receptiveness to new products.

This survey also indicates the weight that veterinarians place on the health and behavioral effects of sterilization and alternative fertility control methods; in this way, it is consistent with the earlier study of two US veterinary cohorts.^60,61 This survey also reflects veterinarians’ strong desire for permanent versus temporary sterilization methods for pet and unowned, free-roaming cats. It is notable that, relative to other features of non-surgical fertility control, study participants did not place great importance on its potential economic benefits for the veterinary practice.

Attitudes of pedigree cat breeders toward different fertility control methods

In 2013, The Cat Fanciers’ Association (CFA) distributed a survey to members seeking feedback on breeder contraception and sterilization methods (J Miller, unpublished data). Approximately 700 responses were recorded; the majority (81%) of respondents were pedigree cat breeders. Although 82% of survey respondents hailed from the US or Canada, 34 countries from across the globe were represented.

Ninety respondents reported that they had controlled heat cycles in their cats; 358 respondents had not (the remaining respondents did not answer the question). Breeders who controlled heat cycles most often cited use of progestins megestrol acetate and medroxyprogesterone acetate. Of note, breeders reported using highly varied dosages, even of the exact same compound. Smaller numbers of breeders reported using the GnRH agonist deslorelin or gonadorelin diacetate tetrahydrate. Some respondents indicated extended use of non-surgical fertility control, but most indicated short-term use to delay breeding a cat. The safety of a contraceptive and ability to eliminate secondary behavioral issues were viewed as primary considerations by cat breeders.

Whereas veterinarians have conveyed concern about the failure of cat owners to return for follow-up treatment with a long-term contraceptive, ⁶⁰ the possibility of postponing or temporarily preventing reproduction appealed to pedigree cat breeders. When asked if they would welcome an ‘FDA approved and proven safe, and reversible, contraceptive for female cats’, 90% of respondents answered ‘yes’. Those answering ‘no’ cited concerns about long-term safety and the need for extensive testing. Others resisted interfering with a cat’s normal reproductive cycle, often for fear of long-term health consequences (J Miller, unpublished data). Approximately equal proportions of respondents (34% and 35%, respectively) desired options that would allow their female to regain fertility 3 or 6 months following treatment; 24% were interested in options with a duration of 1 year.

Discussion and conclusion

Existing research shows that proportions of sterilized pet cats vary considerably across countries and communities. Unfortunately, prevalence estimates for many European countries are not available in the peer-reviewed literature, potentially reflecting low levels of interest in population control aspects of neutering, low numbers of unowned or unwanted cats, a dearth of active research on this topic or lack of active promotion of neutering in these countries.

Variations in reported sterilization rates can be attributed, at least in part, to owner attitudes, knowledge and demographic variables. Legislation, policies, veterinary training of undergraduates and positions adopted by veterinary organizations surely influence veterinarian recommendations and cat owner decisions, and over time they likely contribute to sterilization ‘norms’.

Human behavior, practices and attitudes provide important context for addressing questions about non-surgical fertility control for cats. Where is the greatest need, and could non-surgical options address that need? Which stakeholders are most open to non- surgical options? What features of non-surgical fertility control are most valuable to different groups?

Among pet owners, those wishing to breed their cat or for their female to have a litter prior to sterilization are unlikely to choose a non-surgical sterilant over surgery. Those who have not sterilized their cat due to perceived inconvenience are also unlikely to benefit from non-surgical options.

However, non-surgical fertility control could be attractive to owners who resist surgical sterilization for other reasons: perceived negative health effects, the invasiveness of surgery, or a cat that cannot safely be anesthetized. An injectable contraceptive or sterilant might also gain traction among owners who resist prepubertal sterilization, particularly if it was proven and perceived to be as safe as vaccines given as early as 6–8 weeks.

There is compelling evidence that although cost is not the sole factor discouraging owners from sterilizing their cats, it can be a deterrent, particularly for owners with limited economic resources. Less expensive non-surgical methods of fertility control could be attractive to this group; however, a comparison would need to be made between the desirability of non-surgical treatment and subsidized low-cost or free surgical neutering. For persons with limited resources, the ability to bring a non-surgical sterilant to the community (without the need for a mobile surgical unit) could be significant.

Veterinary professionals will, without question, influence the success of non-surgical fertility control in private practice, animal shelters and TNR programs. US veterinarians, in particular, believed that non-surgical options could have value for pets that cannot undergo surgery, for clients who resist or cannot afford surgery, and for shelters and communities seeking to increase sterilization numbers (J Murray, unpublished data). It remains to be seen if the veterinary community will support a product without all the highly desired features (permanence and behavioral/health benefits) if such a product could help in these areas of veterinarian-identified need.

US veterinarians’ overall response to a hypothetical 3 year contraceptive was tepid at best, and there were some notable differences between veterinary cohorts. ASV members were less likely than their private practice colleagues to recommend a 3 year contraceptive to their clients, possibly due to the assumption that shelters will have only a single opportunity to treat a cat. Both US veterinary cohorts thought that a 3 year contraceptive had greatest potential for feral cat populations.^61,62 Although they were not asked to explain their reasons for having a greater interest in feral cat applications, potential explanations might include the required resources and stress to animals involved in trapping and transporting feral cats for TNR, as well as indications that, in comparison with pet cats, many feral and free-roaming cats have, on average, relatively short lifespans.^{15,62 –64}

In the 2014 online survey of US and European veterinarians (see box on page 795) a minority of respondents reported that they would be likely to recommend a 3 year contraceptive to their cat-owning clients (J Murray, unpublished data). However, whereas US veterinarians reported being equally likely to recommend such a product to clients and to organizations performing TNR, European veterinarians indicated being nearly twice as likely to recommend to cat owners than to TNR charities (J Murray, unpublished data).

Feedback on a multi-year contraceptive might be attributed, at least in part, to survey structure; namely, the contraceptive was presented as an alternative to permanent sterilization (surgical or non-surgical), and veterinarians were asked which option they would recommend for owned and unowned cohorts of male and female cats. Future surveys might explore contexts in which veterinarians would entertain using a 3 year contraceptive to complement or supplement permanent sterilization, and whether veterinarians believe there are circumstances in which a ‘combination approach’ could benefit fertility and population control efforts.

Veterinary attitudes toward a multi-year contraceptive are particularly relevant given that a GnRH-hemocyanin conjugate immunocontraceptive vaccine has shown promising results in cats (see accompanying article in this Special Issue). ⁶⁵ The challenges of pharmaceutical development are such that a long-lasting contraceptive for female cats will almost certainly become commercially available before a permanent sterilant. The potential market for such a product, particularly for the unowned female cats deemed most in need of new fertility control options, remains of interest.

As new technologies become available to control feline reproduction, it will continue to be important to gauge attitudes, perceptions and behaviors of diverse stakeholders (eg, veterinarians, cat owners, pedigree cat breeders and shelter professionals) across countries, communities and demographics. Humans arguably are – and will continue to be – the most important factor influencing feline veterinary care and fertility control outcomes.

Key Points

• Different countries and populations report highly varied sterilization rates for cats. Social context, cultural norms, individual preferences, economic factors, legislation and professional organizations may all influence fertility control decisions. Attitudes and behaviors may also vary among stakeholder populations (eg, veterinarians, pet owners and pedigree cat breeders).

• Understanding human behavior, practices and attitudes is important when attempting to increase the number of sterilized cats.

• When considering development of non-surgical fertility control options, areas of interest include identifying populations of greatest need; stakeholders most open to non-surgical options; and the features of non-surgical fertility control that are most desired by different groups.

• Veterinary professionals will influence the success of non-surgical fertility control in private veterinary practices, animal shelters and trap–neuter–return (TNR) programs. An online survey of US and European veterinarians found that US veterinarians, in particular, believe that non-surgical options could have value for pets that cannot undergo surgery, for clients who resist or cannot afford surgery, and for shelters and communities seeking to increase sterilization numbers. Veterinarians were overall not supportive of a hypothetical multi-year non-surgical contraceptive, although attitudes varied by country and the cohort of cats (owned or unowned) receiving the product.