Prolonged depression of thermoregulation after xylazine administration to cats

Xylazine administered subcutaneously (s.c.; 1–4 mg/kg) or intravenously (i.v.; 0.5‐2 mg/kg) to cats consistently caused dose‐related decreases in body temperature which were maximal 3–4 h after injection and lasted for at least 12 h. Otherwise the animals appeared to have recovered fully from the central nervous system effects of the drug within 1.5–3.5 h. Xylazine‐induced hypothermia developed more rapidly in cats placed in a 4°C environment and, in contrast, was replaced by a hyperthermic response in cats placed in a 32°C environment. These changes in body temperature were not opposed by compensatory thermoregulatory effector activity such as shivering or tachypnea. This pattern of responses at varied environmental temperatures is indicative of a general depression of the thermo‐regulation. Thus, animals given xylazine should not be exposed to extreme heat or cold for several hours to avoid development of hyper‐ or hypothermia.