Domestic cats are commonly housed indoors, in multi-cat groups, and with reduced enrichment opportunities compared to their solitary, outdoor, nocturnal origins. These changes may result in significant aggression between cats. Aggression may manifest as overt fighting between cats, but may also present as less aggressive actions (hissing, yowling, and chasing) or as more passive actions (such as hiding or inappropriate urination). This creates significant quality of life issues for the affected cats and owners and may result in physical injury, emotional stress, or surrender.
Pheromones are chemicals secreted by an animal and deposited into the environment. They are detected by other animals of the same species and result in physiological, emotional, or behavioural changes in that animal. Cats may secrete pheromones by rubbing or scratching, urinating, or in other secretions. Several pheromones (i.e. feline facial pheromone, feline interdigital pheromone) have been used commercially to alter feline behaviour. “Feline Appeasing Pheromone” (FAP) is secreted by mammary sebaceous glands during lactation and helps to establish bonds and positive relationships between kittens and queen. A synthetic version of this pheromone is available commercially with a claim of reducing signs of intra-cat aggression.
The purpose of this study was to determine if the use of FAP in a multi-cat household reduced intra-cat aggression. The study was designed as a prospective, randomized, double blinded, placebo controlled trial. 45 households containing between 2 and 5 cats were enrolled in the study. Each group had a recent history of intra-cat aggression issues including (but not limited to) biting, yowling, scratching, hissing, growling, and others. Cats were at least 6 months old and sexually intact males were excluded. Cats with extreme aggression to cats or humans, concurrent medical issues, or treatment with any psychotropic medications were excluded.
Households were randomized to receive 2 plug-in diffusers containing either pheromone or placebo. Owners were instructed to run these within the house for 28 days. Owners received training on feline behaviour and were instructed to keep a daily diary of aggression including the use of a numerical scale. Weekly phone interviews were also held with a more detailed scaling system (OFSIS-Aggression). There were also trained on the use to behavioural modification techniques including classical conditioning and redirection.
45 cats were enrolled in the study, of which 42 completed it as per protocol. 17 were treated with the active pheromone, and 25 with placebo.
No treatment related adverse effects were noted over the course of the study. At day 0 there were no differences in behaviour scores noted between groups. In the initial 7-day enrollment period, OFSIS scores decreased similarly in both groups. Over the 28 day treatment period, scores decreased in both groups, but at a faster rate in the treatment group. Differences reached significance at day 21 and maintained a difference until the end of the trial.
After the end of the treatment, monitoring was continued for an additional 2 weeks. During this period, the treatment group remained stable while the placebo group regressed.
An OFSIS-Harmony score was also established. This measured the presence of affiliative or “positive” behaviours between cats. While there was a trend towards increased values in the treatment group, the difference did not reach significance.
At the end of the study, all households were asked “‘Generally, do you find that your cats are getting along better?” 84.2% of treatment group households answered “yes” compared to only 64% in the control group, a statistically significant difference.
Interestingly, the authors noted a trend towards higher rates of aggression in declawed cats compared to cats who were not. While this has little relevance to the current study, it suggests there may be a positive correlation between declawing and aggression.
The authors postulate that not only was the pheromone more effective in initially reducing aggression, but it increased that ability of the cats to learn and remodulate their behaviour, resulting in a more lasting benefit.
Many confounding factors were present in this study, including the number, sex, and ag of cats in each household, size of each house, and specifics of the intra-cat dynamics. Many of these would be difficult if not impossible to control for. The length of follow-up was also relatively short, without data on long-term effects of therapy. Cats with severe aggression were excluded from the study, meaning that the efficacy in the most extreme cases is unknown.
The authors concluded that there is evidence for the efficacy of a Feline Appeasing Pheromone analogue in managing aggression between cats. While further work is needed to determine the exact role of this product, it may prove to be a minimally invasive, low risk option for helping to control aggressive behaviour.
Related articles of interest on the topic of feline aggression:
Intercat Aggression: Restoring Harmony in the Home: A Guide for Practitioners
Feline Aggression Toward Family Members: A Guide for Practitioners
