OBJECTIVE: Perioperative hypothermia is a common problem that must not be underestimated. There are plenty of methods to prevent or reduce heat loss during anaesthesia. The aim of this study was to evaluate the influence of warmed intravenous (IV) infusions to the perioperative decrease of body temperature of anaesthetized cats. MATERIAL AND METHODS: In this randomly designed study 30 cats undergoing surgical procedures were anaesthetized with a standardized anaesthesia protocol. Fifteen cats received IV infusions with room temperature; the IV infusion of the other 15 cats was constantly warmed to 38-39°C using a fluid warming device. The development of body temperature within the first 60 minutes of anaesthesia of both groups was compared and analysed. Additionally the influence of the room temperature on the body temperature and the influence of body temperature at the end of anaesthesia on the recovery period were evaluated. RESULTS: After 60 minutes of anaesthesia cats receiving warmed IV infusions had a significant higher body temperature than cats receiving IV infusions with room temperature. Room temperatures lower than 26°C had a significant influence on the development of perioperative hypothermia. The evaluation of the recovery period showed a significant correlation between low body temperature at the end of anaesthesia and prolonged time until extubation on the one hand and postoperative shivering on the other hand. CONCLUSION AND CLINICAL RELEVANCE: The present study shows that warmed IV infusions have a significant influence on the reduction of perioperative heat loss in cats. Nevertheless other additional methods to prevent heat loss are necessary to keep the patient in a normothermic range. Room temperatures play an essential role in decreasing hypothermia and should be at least 26°C. Low body temperature at the end of anaesthesia prolongs the recovery periode and enhances postoperative shivering.