Introduction

• Normal body temperature is 37.7°C to 39.2°C.
• Hypothermia exists when core body temperature is below this value.
• The most accurate measurement of core body temperature is made using an esophageal probe placed at the heart base.
• In conscious dogs, a rectal thermometer provides a rough estimation of core temperature.
• In anesthetized dogs rectal thermometers can be very inaccurate.

Causes of hypothermia

Small dogs and puppies with large surface area/volume ratios are particularly susceptible.

Anesthesia

• The main cause of hypothermia in dogs. Several factors are responsible for this:
  • Sedatives and general anesthetic agents cause vasodilation and inhibit thermoregulatory processes, eg shivering.
  • Excessive use of alcohol-based cleaning agents during preparation for surgery.
  • Cold environments.
  • Exposure of body cavities to ambient temperature.
  • Surgical blood loss.
  • IV administration of cold fluids.
  Occasional hypothermia is deliberately induced during anesthesia to prevent brain damage if blood supply to the CNS is likely to be compromised.

Other causes

• Neonates are at particular risk of hypothermia as they have poorly developed temperature regulation systems and large surface area to volume ratios.
• Cold environment.
• Severe hypothyroidism Hypothyroidism.
• Poisoning Poisoning: overview.
• Ivermectin toxicity Ivermectin toxicity.
• Septic shock Shock: septic.
• Cardiogenic shock Shock: cardiogenic.
• Decompensatory hypovolemic shock.
• Coma.

Effects of hypothermia

Prevention of hypothermia during surgery

Rewarming

Monitoring

Further Reading

Publications

Refereed papers

• Recent references from PubMed and VetMedResource.
• Cabell L W, Perkowski S Z, Gregor T et al (1997) The effects of active peripheral skin warming on peri-operative hypothermia in dogs. Vet Surg 26 (2), 79-85 PubMed.
• Dhupa N (1995) Hypothermia in dogs and cats. Comp Cont Ed Pract Vet 17 (1), 61-68 VetMedResource.
• Weirich W E (1994) Hypothermia for cardiac surgery. Semin in Vet Surg 9 (4), 206-209 PubMed.
• Dunlop C I, Duant D A & Haskins S C (1989) Thermal burns in 4 dogs during anesthesia. Vet Surg 18 (3), 242-246 PubMed.