Responsible ownership and care of domestic cats in Scotland: report

4. What are the welfare harms/issues associated with owned and unowned (stray and feral) cats?

Welfare issues of owned cats

As shown in Table 1 above, the majority of cats in Scotland are owned cats. This is also the group where there is the most information about welfare status and current ownership practices. Survey data from PDSA^[8] and Cats Protection^[1,3] provide annual reports on owner activities, particularly with respect to accessing veterinary treatments and responsible ownership behaviours, and the scientific literature also provides some analysis of common welfare issues.

A UK-based study in 2019 used expert opinion to identify the 118 welfare concerns for pet cats and determined the priority areas of most concern^[33]. Of these, the areas that were considered a priority were an inappropriate home environment, leading to behavioural problems and chronic stress, obesity, old age and delayed euthanasia, and neglect or hoarding. Failure to seek required veterinary care was also of concern. Lack of owner knowledge and understanding of cat behaviour, health requirements and welfare needs, as well as concerns about differing professional views on cat welfare issues (including neutering), were included in the overall list of welfare concerns.

This report cannot address all aspects of owned cat welfare, but several of the welfare concerns raised by this study are related to responsible cat ownership, particularly accessing veterinary care, preventing over-population of cats, and understanding cat behaviour.

In Scotland in 2023, 92% of pet cats were registered with a veterinarian, 62% visited the vet annually and 45% were insured against the costs of veterinary treatments^[1]. Most cats were reported by their owners to be fully vaccinated against common causes of ill health in cats (76%), and 13% had had some vaccinations, although 5% had not been vaccinated at all. Note these data are derived from owner-reported activities and may not be accurate (see above). Cats living with owners in lower socioeconomic groups were less likely to have been vaccinated. Just over half of owners protected their cats from internal (worms: 56%) and external parasites (fleas: 54%).

Dental disease and obesity were the most commonly reported health issues for pet cats in 2023 (3% for each), with hypertension, obesity and allergic skin conditions also reported. Pet cats are also at high risk of sustaining injuries (24% of owners reported that their cats had been injured), which were most likely to be related to fights with cats or other animals^[1].

In 2023, 45% of pet cats in Scotland were reported to live only indoors (which is higher than the rest of the UK), and only 2% lived only outdoors^[1]. This follows trends in other countries, where owners are increasingly keeping cats exclusively indoors for various reasons (e.g., reducing impacts on native fauna, reducing risks of injuries and accident, reducing nuisance to others). This high rate of indoor management is suggested to be an explanation for the relatively low use of parasitic prophylactic treatments in Scottish cats.

Although cats can be successfully kept indoors without impacts on their welfare, this does require a significant commitment from owners to provide high-quality resources that allow the cats to express natural behaviours, such as those that mimic hunting, and to allow sufficient numbers of resources to allow choice and reduce stress. UK-wide data suggest that 39% of indoor-only cats have a climbing frame and 80% spend some time playing with toys, which is greater than the resources offered to cats with outdoor access^[8]. Behaviours associated with stress (such as inappropriate elimination, hiding or aggression) were commonly reported, suggesting that some aspects of management may not be optimal for cat welfare^[3].

The Cats Protection Scotland 2023^[1] report cites a rate of neutering of 87% of owned cats in Scotland, which is in line with the UK overall and a slight increase on 2022. Recent figures span the changes imposed by response to the COVID pandemic and may not be a true reflection of long-lasting trends in behaviour by cat owners.

If approximately 13% of pet cats are not neutered, this means that 108,000 fertile cats could potentially contribute to the overpopulation of cats and add to the burden of stray and unowned cats. The top five reasons given in 2023^[1] for not neutering were that the cat did not go outside (21%), that the owner wanted the cat to have kittens (13% - an increase on 9% in 2022), the owner had not yet got around to it (12%), felt that the cat was too young (12%), or simply had not thought about it (12%).

Scotland has the highest proportion of indoor-only cats in the UK^[1], which suggests that many owners may use this as their main method of reducing cat reproduction, since this was the most common reason given for not neutering. This can provide its own welfare issues, particularly in multi-cat households, but does suggest that there are alternative strategies to managing cat reproduction being implemented, particularly by younger cat owners. The effectiveness of cat containment as a reproductive management strategy is largely unexplored, with most literature focused on impacts on wildlife populations and preventing risky behaviour in cats by containment. However, risks of accidental pregnancies for escaped cats, and a higher risk of pyometra and mammary cancers in entire females may be issues that owners of indoor cats have not considered in their decision making. In the UK 7% of owners of un-neutered female cats said they were waiting for their cats to have their first season, and up to 49% of owners believed a cat should have a litter of kittens before being neutered. However, although some owners may choose to have a litter of kittens, there is evidence that 80% of all cat pregnancies are accidental and poor owner knowledge of cat reproduction is considered to be the main risk factor for cat pregnancies^[43].

Overall, 71% of the Scottish cat population was reported to be microchipped in 2023, an increase on 67% in 2022^[1]. Ability to access veterinary care has also been considered an issue in Scotland, with 36% of cat owners reporting difficulty in getting an appointment in 2022 and 25% in 2023.

A third of Scottish cat owners have two cats or more^[1]. Although cats can be friendly towards other cats, behaviourally they are solitary hunters and prefer to eat and urinate/defaecate apart from other cats, even if these are familiar. Failure to provide sufficient resources for the number of cats in a household can be a cause of stress, and may contribute to the incidence of behavioural problems, and cat relinquishment to shelters^[44]. Friendly associations between pet cats kept together are probably more likely to be successful between mothers and daughters and between sisters.

Concern is also growing about the welfare of cats bred to demonstrate exotic (e.g., Bengal or Savannah cats – derived from crosses between domestic cats and wild cat species) or extreme phenotypes (e.g., Scottish Fold, Munchkin, extreme brachycephalic Persian cats). Some of these breeds or types may suffer pain or physical impairment requiring specialist care^[45] or exhibit behavioural requirements that can be difficult for owners to accommodate^[41]. As with breeding of extreme phenotypes in dogs, there is an increased interest in cats bred to display particular aesthetic features that some owners find desirable^[3], and selection for these traits may lead to an increase in welfare problems for the cats. The Animal Welfare (Licensing of Activities involving Animals) (Scotland) Regulations 2021 include cat breeding and provide limitations on the numbers of animals that can be bred without licensing. Although this legislation does not specifically prohibit the breeding of cats with extreme phenotypes, there are powers for licensing authorities to assess the suitability of the breeder before granting a licence and one of the specific licence conditions is that no cat may be kept for breeding if it can be reasonably expected, on the basis of its genotype, conformation, behaviour or state of health, that breeding from it could have a detrimental effect on its health or welfare, or the health or welfare of its offspring. There is associated guidance on cat welfare for breeders, including of exotic or extreme breeds^[46].

Welfare issues of farm cats (semi-feral Felis catus)

Farm cats are a particular population of rural-dwelling cats, which are a halfway position between owned and feral cats in their association with and care for by people. These cats are at least partially dependent on humans for food (through deliberate resource provision as well as accidental) and are typically considered ‘part of the farm’, playing a role in rodent population management. Various studies suggest that cats are present on 80-95% of UK farms. The degree of human management of these animals (provision of food, shelter, neutering status, vaccination, etc.) is highly variable, but typically at a lower level compared to pet cats, even on the same farm. For example, neutering rates were only half those of pet cats living on farms^[47], and infection rates (presence of antibodies) for endemic cat diseases were higher than for pet cats with outdoor access or indoor-only cats^[48]. Similarly, farm cats had higher gastrointestinal parasite burdens than pet cats, although these were lower than for feral cats in a Spanish study^[49]. Estimates of rates and causes of mortality, prevalence of hunger, hypothermia, and other welfare concerns are hard to find compared to other groups of cats.

Some farm cats can be well socialised with humans, and may act and be treated much as a pet cat, which happens to live outside. The farm survey by Roberts et al. (2018)^[47] suggested that farm cats are typically fed on most days, and shelter is provided via outbuildings or other means. Farm cats may also scavenge or be fed ‘accidentally’ from sources available about the farm.

However, other farm cats can be poorly socialised and afraid of humans, and behave in a similar manner to truly feral cats. Whilst these animals are considered to be part of the farm, playing a role in rodent control and being provided with food to support the colony, they should also be provided with similar health and welfare provisions as other owned cats. The estimation in a 2018 study that 55% of these cats may not be neutered suggests that these cats may be a significant source of animals for the feral cat population^[47]. Although the median number of farm cats per farm was two, the range of farm cats was from 1 to 27 cats, suggesting that some large colonies of cats are present on farms.

Welfare issues of unowned (stray, feral and some farm) cats

In addition to the owned pet cat population, there is an additional unowned cat population, which is the same species as owned cats (Felis catus) and is a separate species from the wildcat (Felis silvestris).

Obtaining accurate figures on the numbers of unowned cats in Scotland is problematic, and the dynamics of movement of cats living in human homes, cats living in shelters or free-roaming, and unowned cats is poorly understood. This is particularly an issue in the UK, where most owned cats are provided with either continual or partial outdoor access.

A recent modelling estimate of the size of the urban, unowned cat population in Scotland^[50] suggested a population of 21,218 cats (range of 13,418 to 31,418 for 95% Credible Intervals). This study suggested that the main determinants of the unowned cat population were the density of the human population, and the degree of deprivation of the area (an increase in unowned cat abundance in the most deprived areas). The Scottish unowned cat population also includes a substantial rural population, reflecting the distributed nature of the human population in rural communities.

A small survey study in 2018 suggested that 92.5% of UK farms had cats living on them, either as pets (49%), ‘farm cats’ (cats which live outside and derive some of their food from hunting; 65%) or feral cats (15%). Of these only 45% of farm cats were reported to be neutered, compared to 92.9% of pet cats^[47]. Extrapolating these results to Scotland only (as the study reports no difference between countries in the UK and a median number of farm or feral cats of two per farm) with an estimated 51,000 farms, suggests there may be 66,300 farm cats and 15,300 feral cats in rural locations in Scotland (with the proviso that these estimates should be treated with caution as the survey sample was small). The estimate of 21,000 unowned urban cats^[50] suggests that the majority of Scottish unowned cats are thus living in rural locations, if farm cats are considered to be unowned.

Previous studies have suggested larger numbers of feral cats (e.g., at least 100,000 feral cats living in Scotland^[51]). This is broadly in agreement with our estimates, if this figure includes farm cats, but may be an over-estimation of the number of truly feral cats. However, this also reflects the difficulty in acquiring accurate figures of rural cat populations, and the farm survey method used to determine rural feral cats may underestimate feral cats living far from the farm. The dynamics of movement of cats between different ownership types and classes may also contribute to the difficulty in assigning cats to different ownership classes.

Owing to difficulties in separating stray cats (once owned by humans and now living without human intervention) from feral (usually considered to be unsocialised with humans), these two groups of cats will be considered together and may experience similar welfare issues. The issues apply despite the fact that stray cats may technically still be owned by someone, as shown in Table 1. Although the unique flexibility of cats means that they can live without human intervention as well as being commensal with humans^[2], it is important to note here that feral cats are the same species as owned pet cats (Felis catus) and distinct from wildcats (Felis silvestris). Felis catus is derived from populations of the African wildcat (Felis lybica) the Middle East and/or Egypt^[52] and has morphological features suggesting adaptation to a warm and dry climate (such as an ability to survive on low water intake and tolerate high temperatures). Although prolonged cold exposure can lead to some adaptation through an increase in cold-induced metabolic response and fur insulation^[53], generally domestic cats are poorly suited to survival in the cold and wet Scottish climate. This is in contrast to the wildcat, which has adaptations (such as higher density of fur and larger body size) to promote survival in a cold environment.

Finding accurate statistics on the rates of mortality and other welfare issues in feral cats is challenging, and most data are confined to urban feral cats. Feral cat mortality can be high, and the life expectancy of a feral cat has been estimated to be less than five years^[54], approximately a third to a quarter of the life of an owned cat. Some data suggest that kitten mortality can be up to 75-90% of all animals before the age of six months, especially in areas of high feral cat population density^[55]. Feral cats are vulnerable to high levels of infectious disease, including zoonoses^[56], and engage in life-threatening behaviours such as crossing roads, fighting with other cats, eating and drinking substances found in the environment, and entering drains, crawlspaces and other containment areas where they can become trapped^[57]. Some examples of the threats to feral cat welfare have also been provided by Cats Liberation.

A study of urban feral cat colonies assessed cat welfare at feeding sites in Austria and found that approximately 80% of cats had been neutered. Most cats were in good health, but approximately 1.7% were classed as very thin (and this increased with a low percentage of clean feeding places), between 1-3% had visible injuries and a similar number had missing body parts (tail)^[58]. There was a relationship between neutering and health as intact males were more likely than neutered to have visible injuries, and intact females were more likely to have health issues than neutered females. Although published data on feral cat welfare in Scotland is hard to find, it seems likely that similar rates of high adult and kitten mortality would occur. The frequency of thin cats may be higher (the data quoted above were taken from feeding stations, so cats were actively being provided with food). Although concerns for predation by domestic cats on wildlife is often quoted, domestic cats can also be preyed upon themselves by foxes, dogs and avian predators. The implications of neutering for improved health, body condition and a reduction in injuries is also likely to be relevant to rural feral cats as well as urban animals.

Overall, feral cats are poorly adapted to live in Scotland, have very high rates of mortality, particularly of kittens, and are likely to experience high levels of disease and poor welfare. Although feeding of feral cats may improve some aspects of their welfare and survival, bringing large numbers of cats into the same area may contribute to spreading of infectious diseases (in a largely unvaccinated population), and, if these cats are unneutered, the improved body condition of female cats may lead to larger litters of kittens and exacerbate the issues. Feeding of feral cats in the wild is only likely to improve cat welfare, if this is accompanied by a programme of neutering and vaccination, but it could also lead to population growth unless the animals are neutered.

Welfare and conservation issues affecting wildcats

The wildcat, Felis silvestris, is Britain’s only remaining native felid^[59]. The domestic cat, F. catus, is derived from the North African wildcat, F. l. lybica, and hence is an introduced species^[52,60]. Recent genetic data show that these two species diverged more than one million years ago, but when wildcats and domestic cats are sympatric they may hybridise, producing fully fertile offspring^[60]. While levels of hybridisation in Europe have remained generally low^[52,61], hybridisation in Scotland has been extensive, resulting in the effective extinction of wildcats in the wild^[62,63]. Recently published genetic research has shown that hybridisation in Scotland increased significantly since the end of the 1950s/beginning of the 1960s, which also corresponds to a breakdown in the pelage phenotype of the wildcat^[63,64,65].

Wildcats have suffered from three main threats from hybrid cats, and feral and owned domestic cats. Firstly, direct competition for prey and home ranges could have impacted on wildcats, resulting in them occupying less favourable habitats with low prey population densities^[66,67]. Secondly, recent radio-tracking studies have shown that outbuildings and barns may be important resting sites for wildcats, especially in poor weather, so that the presence of domestic cats, which may occur in large social groups, may prevent this, thereby impacting on their welfare^[68]. Thirdly, domestic cats may be a reservoir of important domestic cat diseases, which has resulted in the complete replacement of the major-histo-compatibility complex (MHC) of the wildcat by that of the domestic cat^[65]. The very strong selection for the domestic cat MHC in wildcats as a result of hybridisation shows that exposure of wildcats to domestic cat diseases probably had a devastating effect on the wildcat population. Currently, the wildcat is being reintroduced to the Cairngorms Connect area of the Cairngorms National Park, using captive-bred wildcats. However, the captive population of wildcats is inbred and all have some domestic cat ancestry, so that it is intended to improve the genetics of the captive population for reintroduction by the addition of wildcats from western Europe. The welfare of the progeny of these wildcats that are released into the wild could be compromised if they have the wildcat MHC, which could make them vulnerable to domestic cat diseases.

Scottish Wildcat Action, 2015-2020, attempted to encourage the natural recovery of wildcat populations in five (originally six) priority areas^[69], including the trap-neuter-vaccinate-release (TNVR) of hybrids and feral domestic cats in these areas, to prevent hybridisation and the spread of diseases. However, the levels of neutering required for population reduction were never achieved^[70] and vaccinations must be repeated to have a long-term effect. Moreover, surveys coupled with genetic and morphological analyses concluded that there were too few, if any, wildcats surviving in the priority areas^[62,69]. The Saving Wildcats project led by RZSS, which is currently reintroducing wildcats, also uses TNVR within the release area, but even if successful neutered cats remain as possible competitors and reservoirs of disease and may compromise wildcat welfare.

The wider adoption of responsible domestic cat ownership, including neutering and regular vaccinations, would not only benefit the welfare of owned cats, but also the welfare of the wildcat as the population begins to recover following reintroduction.

Welfare and conservation issues affecting other wildlife – impact of domestic cat predation

With an estimated 11 million owned domestic cats in Britain, of which 0.8 million are in Scotland^[1] and around 247,000 urban feral cats in Britain^[50] but potentially as many as 100,000 feral cats including rural cats^[51], there is a huge potential impact of domestic cats on wild animals, including birds, small mammals, reptiles and amphibians.

Various studies have tried to estimate or reviewed the impact of owned and feral cats on wild animal populations, especially in the UK^[71-77]. In the UK it has been estimated that 57 million mammals, 27 million birds and five million reptiles and amphibians are brought home to pet owners each year by their cats, even though only 50-80% of free-ranging cats actually hunt^[71,77]. Given that only a proportion of prey are brought home (ranging from 10-50%^[75]) and 60% of pet cats never bring prey home, the actual number of wild prey killed could reach at least 700 million vertebrates per year in the UK. Hunting in cats is not driven by hunger; it has been estimated that 96% of an owned cat’s diet is pet food and only the remainder is wild prey^[77].

While the killing of prey by a cat may not necessarily be regarded as a welfare issue, domestic cats have a tendency to play with their prey and bring back live often injured prey to their owners. There appear to be no data on the proportion of cats that play with their prey and what proportion of captured prey is subject to play. In a study of birds recovered alive from pet cats, which were brought to RSPCA rescue centres, 78% died overall and 62% died or were euthanised on average after three days^[78]. It was estimated that when pet owners released apparently uninjured birds caught by their cats, this resulted in the deaths of 300,000 birds annually soon after release. It should be noted that wildcats have been observed playing with prey and wildcat mothers may bring back live often injured prey to their kittens so that they can practise killing and hunting^[79]. However, the numbers of live prey that are subject to post-capture play by domestic cats is far greater than would have occurred in an indigenous wildcat population. In the Mesolithic, when habitats were more or less intact across much of Britain, it has been estimated that the wildcat’s population was about 66,000 individuals^[80], which is only about half of the estimated feral cat population in Scotland today and only about 8% of the current Scottish domestic cat population^[1]. In urban areas population densities of domestic cats have been recorded as high as 348/km^[2], which is far greater than recorded for abundant wildcat populations in Scotland (0.33/km^[2])^[81]. Therefore, there are considerable welfare issues caused by post-capture play with wild prey by owned domestic cats coupled with release and rapid post-capture mortality of birds ‘rescued’ by pet cat owners.

Domestic cats can also have indirect impacts on wild species, resulting in high levels of stress and impacting negatively on reproductive success and levels of abundance. For example, in a study of swallows, Hirundo rustica, in Denmark the presence of predators (85% domestic cats) led to rapid reproductive senescence^[82]. Bonnington et al. (2013)^[83] investigated the impact of a taxidermy domestic cat specimen on the behaviour and reproduction of blackbirds, Turdus merula. The presence of the taxidermy cat led to a reduction of provisioning of food to nestlings by one third, because of increased vigilance and warning calls, but also led to increased vulnerability of nestlings to other predators, such as corvids. Preisser et al. (2005)^[84] modelled the impact of nonlethal effects on potential prey species and calculated that the impact on potential prey populations was as great as that of direct predation. Two studies have shown that the presence of domestic cats increases the time it takes for birds to discover new bird feeders and that if the cat is facing the feeder, this extends this period further^[85,86]. Beckermann et al. (2007)^[87] estimated that even if domestic cats caused <1% direct mortality of songbirds, reducing fecundity by <1 chick per year, owing to sublethal effects, led to population reductions of up to 95% caused by their presence.