Hair cortisol as a new biological marker for stress in cats

Abstract

Cortisol concentrations have been measured in a variety of sources, including blood, saliva, urine and faeces. A novel method is hair cortisol measurement, which is non-invasive, reflects long-term circulating cortisol concentrations, is insensitive to momentary stressors and is less sensitive to individual circadian patterns. The objectives of the present study were to create reference ranges for cats (Felis catus) and to investigate whether breed, coat colour, age and different locations on the body have a significant influence on hair cortisol values. A total of 106 cats from three different breeds (European Shorthair, Burmese and Maine Coon) were used. Cortisol concentration of hair samples from the ventral neck and abdomen was determined using High-performance liquid chromatography (HPLC). There was a significant difference (ANOVA, p = 0.004) between the breeds for abdominal hair; between the Burmese and the Maine Coon (p = 0.003) and between the European Shorthair and the Burmese (p = 0.049). Overall reference ranges were established at 1.38-4.95 pg/mg and 1.38-5.64 pg/mg for the ventral neck and abdomen cortisol value, respectively. Because of the significant difference between breeds, reference ranges were also established for each breed for abdomen hair cortisol. Coat colour did not show a significant difference, while age had a significant (p = 0.038) but weak correlation with neck hair cortisol (R2 = 0,032). After making three age groups, this significant difference was no longer seen. Thanks to this study, it is shown that hair cortisol can be determined reliably and with the established reference ranges it will possible to study factors that may result in long-term stress in cats in a non-invasive way.