Stable individual differences in vocalisation and motor activity during acute stress in the domestic cat

The behavioural assessment of individual animals in stressful situations should consider measures which are consistent across repeated testing, and therefore truly representative of an individual's behaviour. Here we report a study conducted on 40 neutered adult cats (Felis silvestris catus) of both sexes, originating from two animal shelters in Mexico and Hungary. We recorded the responses of the cats to repeated brief confinement trials that mimicked a common situation (confinement in a pet carrier). This test was repeated three times, leaving one week between trials, to assess short-term repeatability. Stable inter-individual differences in two behavioural measures, the number of separation calls and the duration of motor activity, were found, although the inter-individual differences in vocalisation were more pronounced than they were for motor activity. Additionally, the overall number of vocalisations emitted remained stable despite repeated testing, whereas motor activity tended to decrease week to week. There was a negative effect of age on vocalisation rate, and no effect of sex on either behaviour. No correlation between the two behavioural measures was found. We suggest that, in adult cats, vocalisation may be more reliable than motor activity as a behavioural measure of stress.