Coat and claws as new matrices for non-invasive long-term cortisol assessment in dogs from birth up to 30 days of age

The last stage of foetal development and the neonatal period represent the most critical phases for the mammals offspring. In the dog, the knowledge about the final intrauterine foetal development and biology, as well as about the neonatal physiology, remains scarce. Hormonal changes occurring in the last intrauterine foetal phase and during the early neonatal age are still not completely clear, probably because of the invasiveness related to the collection of the more common biological matrix, represented by circulating blood.Toward term of pregnancy, during parturition and after birth, the hypothalamic--pituitary-adrenal axis is a key system regulating several physiologic processes, and its activity was previously investigated by blood analysis, considered an invasive procedure providing a single point measurement. In respect to animal welfare, and for a more correct long-termretrospective investigation, non-invasive hormonal studies were performed firstly on the hair of humans and coat of animals and, more recently, in the nails of human-beings. This study was aimed to assess cortisol (C) in coat and claws of newborn puppies, and to evaluate the possible influence of the newborn gender, breed body size, and age on coat and claws C concentrations. The results obtained from 165 newborn puppies evidenced that coat and claws C levels were highly correlated each other (P<0.0001), although the C accumulation in the two matrices was different in relation to the class of age. Moreover, the puppies age influenced both coat and claws C concentrations (P<0.05), with premature puppies showing higher values when compared to term born-dead puppies or puppies dead between 1 and 30 days of age. The present study demonstrated that C is quantifiable in coat and claws of newborn dogs. Moreover, both matrices appear as useful tools for new, non-invasive, long -term perinatal and neonatal researches also in canine species.