Effects of Handling and Physical Restraint on Rectal Temperature, Cortisol, Glucose and Leucocyte Counts in the Silver Fox (Vulpes vulpes)

Abstract

The present paper describes the effects of handling and one hour of physical restraint on rectal temperature (Trec), plasma Cortisol, plasma glucose and leucocyte counts in six 8-months old silver fox vixens (Vulpes vulpes). Mean Trec in silver foxes 5 min after capture was 40.1 °C and increased during restraint, showing a maximum of 40.8 °C at 30 min thereafter. Supplementary, deep body temperature (Tb) was recorded with surgically implanted biotelemetry devices in 6 adult silver fox vixens kept isolated from environmental disturbances in a barn. Mean Tb in these foxes ranged between 38.0-38.4°C, showing a diurnal variation and being at the lowest between 0700-1600 hour. When a person approached a fox and was present for 5 min, Tb increased rapidly. The results indicated that a stress-induced hyperthermia (SIH) was evoked rapidly within the first registration at 5 min after capture, and that this response continued during one hour of physical restraint. Plasma glucose and plasma Cortisol levels increased during one hour of physical restraint, whereas numbers of lymphocytes, total white blood cell counts, and total granulocytes decreased. Furthermore, previously reported base levels of plasma Cortisol and plasma glucose were exceeded. The results indicate that the hypothalamic-pituitary-adrenal (HPA) axis and the sympathoadrenal medullary (SAM) system were activated within 5 min of handling and restraint. Furthermore, hyperthermia is a promising indicator of acute stress in silver foxes.