Hypothermia is the most common anesthesia complication: over 80% of dogs and nearly all cats become hypothermic during anesthesia. Anesthetic agents impair thermoregulation, blood vessels dilate, and small patients lose heat rapidly. The consequences are serious — slower drug metabolism, prolonged recovery, coagulopathy, cardiac arrhythmias, and even a threefold increase in infection risk.
Consequences of Hypothermia
A 1 °C drop in body temperature slows metabolism by approximately 10%. Anesthetic agents are eliminated more slowly, prolonging recovery and increasing the risk of relative overdose. Coagulation factor function deteriorates, increasing surgical bleeding. Myocardial irritability increases, and below 31 °C serious arrhythmias become likely. In human medicine, it has been shown that even a 2 °C drop triples the risk of surgical site infection.
Active Warming — The Superiority of Forced Air Warmers
At our clinic, we have three active forced air warmers, which are considered the gold standard of warming methods. The device blows heated air evenly around the patient through a disposable blanket — without the burn risk associated with electric heating pads. Studies show that heated IV fluids alone do not prevent hypothermia in dogs or cats. Passive insulation (blankets, socks) reduces heat loss by only 30%. Active forced air warming combined with warm fluids and insulation is the most effective combination.
Recovery Phase Monitoring
The majority of anesthesia-related deaths occur during the recovery phase — 47–81% in dogs and 61–75% in cats. At our clinic, we continue active warming and monitoring throughout recovery. We monitor temperature, oxygen saturation, and blood pressure until the patient is fully awake and has reached normal body temperature.
Safe Warming
Electric heating pads and hot water bottles designed for humans are dangerous for anesthetized animals — the patient cannot move away from an overheated surface or express pain. Documented burn cases have been reported. According to AAHA guidelines, heating pads and cage dryers must not be used for warming anesthetized patients. Forced air warmers and purpose-designed conductive warming mats are the safest options.