Behavioural indicators for cats’ perception of food: a novel tool for development of veterinary pharmaceuticals

Administering oral medication to cats is often challenging to owners. Cats have a strong aversion to swallowing objects they perceive as non-food, and voluntary consumption of veterinary tablets by cats is typically below 50%. The pharmaceutical industry recognises the need to develop veterinary pharmaceuticals with a more acceptable smell, taste, size and consistency, but development is hindered by lack of research methods capable of detecting subtle differences in cats’ perceptions. Such methods could help determine which formulations under development are less aversive than others, so that they can be selected for further improvement. Existing palatability tests are based on the less informative dichotomous measure of whether or not the cat eats a tablet; and on assessments by owners, subject to bias. Behavioural indicators offer a promising window to more detailed information on cats’ perceptions. A set of behavioural indicators has previously been determined for two degrees of palatability of cat foods. The aim of this study was to identify an expanded set of behavioural indicators to measure subtle vs substantial degrees of palatability. A total of 34 pet cats were used in the study. The cats were presented with three types of edible items with a size of approx. 1 cm3, selected individually for each cat according to preferences reported by the owner. FF (favoured food) was defined as a food preferred by the cat and having a consistency that makes it possible to hide a small tablet in it. TFF (tablet in favoured food) was the same food as above, with a placebo mini-tablet hidden in it. NFF (non-favoured food) was defined as something edible that the cat is unlikely to eat. The edible items were presented one at a time in a pseudorandomized sequence. There were six trials per item, totalling 18 trials per cat, over a period of two days. Behaviour of cats before, during and after eating or refusing to eat was recorded on video. Two trained observers independently determined the prevalence of 16 behavioural patterns on the video recordings, blinded to the types of edible items. The data were analysed with a mixed logistic regression model. The following behavioural patterns were found to be more prevalent with NFF than with FF: a rapid ear flick backward (OR 12.6, P<0.001), a lick on the nose after not eating the item (OR 80.2, P<0.001), flicking of the tail (OR 7.3, P<0.001) and grooming of the body (OR 1.8, P<0.05). For the subtle difference between TFF and FF, the most promising indicator was the more prevalent dropping of food from the mouth while eating TFF (OR 2.0, P<0.001). These findings provide evidence of new behavioural indicators for objective assessment of food perception in cats, and they have practical applicability in designing a novel palatability test for developing veterinary pharmaceuticals with improved palatability for cats.