Measurement of cortisol in dog hair: a noninvasive tool for the diagnosis of hypercortisolism

Abstract

The clinical signs of hyperadrenocorticism (hypercortisolism) in dogs are known to be caused by chronic overexposure to glucocorticoids. The quantification of cortisol in serum, saliva or urine reflects the cortisol concentration at the time of sample collection, but in suspected hyperadrenocorticism it may be preferable to examine a long-term parameter of cortisol production. There is a need for a noninvasive method to monitor the long-term production of cortisol in dogs. It seems possible that measuring cortisol levels in hair could represent such a method. Hair was collected from 12 dogs with hyperadrenocorticism and from 10 healthy control dogs. Immunoreactive cortisol, cortisone and corticosterone concentrations were determined by enzyme immunoassay. High-performance liquid chromatography was performed to test the validity of the cortisol assay. Levels of immunoreactive cortisol, cortisone and corticosterone were significantly higher in dogs with hyperadrenocorticism than in control dogs. The difference was most pronounced for the cortisol level. The determination of cortisol in hair offers the advantage that sampling is easier and less invasive than taking blood, urine, faeces or saliva. Measuring cortisol in hair may represent a valuable tool for the diagnosis of hyperadrenocorticism in dogs.