SCIENCE OF CATS
Stress and multi-cat households: Is there safety in numbers or is it better to go it alone? Dr Lauren Finka takes a closer look at the evidence.
Dr Lauren Finka explains the latest scientific research into multi-cat households.
For many of us cat enthusiasts, it can be difficult to stop at owning just one! No two cats are the same. This means that we form slightly different — but equally rewarding — relationships with each cat for which we care. Therefore, the more cats we surround ourselves with, the more we may be able to sample this rich tapestry of feline companionship.
Indeed, multi-cat households appear to be common place around the globe, with surveys suggesting numbers range from 41.7 per cent of cat-owning households in the UK, to 73.6 per cent in Italy. However, before we get too carried away, it’s important that we consider the other crucial stakeholder in this equation: Are the cats we want to share our lives with happy to share with each other? Essentially, do we have a situation of multi-cat harmony or multi-cat hell?
WHY CAN MULTI-CAT ENVIRONMENTS BE CHALLENGING?
Cats were domesticated from solitary wildcats that were not motivated to live in groups — quite the opposite, in fact. This is coupled with the fact that during cats’ process of domestication, there has been no intense genetic selection for them to exhibit greater levels of affinity towards each other. At a species level therefore, the domestic cat doesn’t necessarily need or want to live in a group with others.
Having said this, under certain conditions, group living can provide various benefits to its members in the form of predator detection, communal raising of offspring, and access to
Multi-cat households
are not guaranteed
to be harmonious.
an area of plentiful resources. Indeed, we can often see free-roaming or feral cats living together in colonies, seemingly of their own choice.The key point to note here though is that these colonies tend to have a very specific make up: they are focused around a resource of some kind (usually a good food supply), with core group members comprising mostly related females. Additionally, even under these specific conditions, relationships between cats and associated levels of affection can vary between individuals, meaning that perhaps not all group members appreciate the company of others equally. Very importantly, these cats are also free to leave the group and go their own way if they choose.
Thinking back to our typical multi-cat domestic home then, the composition of group members is usually very far removed from that of these free-forming outdoor groups. We are typically the ones who decide which cats will live together and we may opt to introduce unrelated cats to our multi-cat home at different points in time, meaning these cats do not grow up together as would usually occur in the outdoor colonies. Especially if we keep our cats strictly indoors, we also limit their ability to ‘leave’ the group, or at least maintain ample distance from each other where needed. We might also create competition between our cats by not providing them with sufficiently plentiful resources around the home.
For all these reasons, and more, the cats within our multi-cat homes can potentially struggle to live happily alongside each other, and in the process may experience compromises to their well-being. Indeed, a study surveying cat
owners in the USA found that a whopping 70 per cent reported their cats exhibited signs of conflict from the time that they were initially introduced to each other. Additionally, slightly over 50 per cent of owners reported that the nature of their cats’ relationships remained stable over the course of their cohabiting, meaning that for many of the cats that didn’t get on well to begin with, their relationships did not improve over time. This hopefully presents a compelling case for why multi-cat households are not guaranteed to be harmonious, but instead why they may need careful management to ensure all members have a good level of well-being.
ARE MULTI-CAT ENVIRONMENTS MORE STRESSFUL? WHAT DOES THE SCIENCE SAY?
Interestingly however, the scientific evidence fails to paint a clear picture regarding whether multi-cat environments are more or less stressful for cats than single-cat homes, or whether larger multi-cat groups are more stressful than smaller groups. There are potentially several important reasons for this, which myself and trusted colleague and PhD student Rae sought to highlight in our recent study.
Our aims for this study
were to critically review all the relevant research on this topic to summarise key findings and identify important limitations.We were also keen to identify any other additional factors (aside from the numbers of cats living together) that might be linked to cats’ well-being in the domestic home. Lastly, we also wanted to highlight what’s still missing research-wise and to provide recommendations for future studies, with the goal being to help us better understand the relationship between multi-cat environments and their impact on cat well-being.
HOW DID WE UNDERTAKE THE REVIEW?
We conducted a systematic search of the scientific literature using special databases and key search terms. We initially returned over 1000 unique scientific articles, which we then filtered following a systematic process until we were left with 15 papers that contained relevant information regarding links between numbers of cats in the domestic home and aspects of cat well-being. We then critically evaluated these studies in order to help us understand this topic.
WHAT WERE THE MAIN FINDINGS?
Most of the papers we evaluated (11 out of the 15) dedicated only small sections of their studies to investigating relationships between cat group sizes and cat well-being, meaning this area of research remains largely neglected.
Overall, the reviewed papers did not consistently provide evidence to suggest that multi-cat living was associated with poorer welfare outcomes for cats (compared to single-cat living), or that living in larger multi-cat groups was more stressful for cats than living in smaller groups. For example, some studies reported that owners of cats living in multi-cat households (compared to single households) or larger multi-cat groups (compared to smaller ones) were more likely to report that their cats exhibited behaviour problems and anxiety, in addition to increased house soiling and cat-to-cat conflict and aggression. On the other hand, some studies reported no differences in reported cat behaviour problems, house soiling, levels of cats’ secreted stress hormones, or cat-to-cat conflict, based on number of cats in the home. Finally, some studies reported better relationships with humans, less problem behaviours, increased cat-to-cat affiliative behaviour, and lower levels of secreted stress hormones (but
only among younger cats) with increased numbers of cats in the home.
A range of other social and environmental factors were also associated with cat well-being. These included the amount of space and resources available to the cat, their age, sex and neuter status, house location, and various demographic features of the owners. However, some of the studies produced conflicting results regarding these factors. For example, some studies found that cats given access to the outdoors displayed less problem or stress-linked behaviours, while other studies suggested cats given outdoor access displayed more of these behaviours.
These inconsistencies in findings are likely due to the vast differences in the methodologies used by the various studies and limitations in their approaches, including the way data was collected, analysed, and reported, and how aspects of cat welfare were being measured. These limitations are unsurprising however, given that most of the studies did not set out to investigate the links between cat group sizes and cat well-being as their primary aim.
Interestingly, several of the studies revealed that humans’ behaviour, both that directed towards the cat and towards other humans, were frequently linked to well-being outcomes for cats. However, as with other findings, the results between studies were mixed. For example, cats receiving fewer daily interactions with humans and being left alone for longer periods were more likely to be reported by their owners as displaying behaviour problems and anxiety respectively. In other studies, higher levels of human social activity and increased human presence in the home were actually associated with greater levels of cats’ secreted stress hormones. Additionally, higher levels of stress hormones were detected among cats described as ‘tolerating’ rather than ‘liking’ or ‘disliking’ being petted by their owners.
While not necessarily conclusive, these findings do suggest that in addition to considering the welfare impact of a cat having to share its home with other cats, we should also think about how our behaviour might be impacting our cats’ well-being.
WHAT ARE THE TAKE-HOME MESSAGES?
When experts or professionals provide recommendations to support the optimal care of cats in the home, it’s important that these recommendations are evidence-based wherever possible. This can be tricky however, when the particular topic in question has not been thoroughly investigated, and the current research is contradictory or of insufficient quality to help us draw any firm conclusions.
What our review highlights is the potentially very complex, multi-factorial relationships between a cats’ well-being and their environment. Due to the great diversity in the types of cats we may choose to
No two multi-cat homes are likely to be the same...
home together and the sorts of homes we may provide those cats with, it’s important to bear in mind that no two multi-cat homes are likely to be the same. While living in a multi-cat group certainly has the potential to cause a cat stress, the devil is probably all in the details. These details might be as, if not more, important to consider than simply the absolute number of cats living together.
FOR EXAMPLE, WHETHER MULTI-CAT ENVIRONMENTS CAUSE CATS STRESS OR NOT MAY COME DOWN TO:
The individual qualities of the cats (their ages, personality, health, previous experiences with other cats).
The dynamics of the group and how each cat behaves towards the others.
Whether the cats are related to each other and/or grew up together as kittens.
How unrelated cats were initially introduced (whether this was done suddenly or gradually and carefully).
The nature of the cats’ physical environment
(space availability, amount and location of resources, opportunities for positive enrichment but also hiding and escape).
Our behaviour and choices (predictability of our routines, level of commotion in the home, and the social pressure
might place on our cats). All of these important factors were not thoroughly taken into consideration or controlled across the various studies. This means that further, more detail-focused research is needed in order to help us better isolate the impact of group size on cat well-being and to tease apart the roles these other variables might also play. Such investigations will hopefully help us to be able to provide further evidencebased recommendations for the optimal management of cats in the home.