Effect of Prewarming on Perioperative Hypothermia in Small and Toy-breed Dogs


The purpose of this study is to determine and compare the effects of warming small dogs prior to anesthesia (termed prewarming) with small dogs that are not warmed prior to surgery.


Anesthesia decreases a dog’s ability to regulate temperature, and hypothermia has unwanted side effects, such as prolonged recovery from anesthesia, suppression of the immune system, and increased incidence of postoperative infections. Studies have documented postoperative hypothermia as a frequent occurrence in dogs. Prewarming has been studied extensively in humans for the prevention of postoperative hypothermia, but no studies have been done to evaluate prewarming in animals undergoing surgery. This study will provide valuable information that could make anesthesia safer for small dogs.

Inclusion criteria:

To qualify for enrollment for this study, dogs must:

  • Present for abdominal surgery, such as ovariohysterectomy, cystotomy, enterotomy, or cryptorchid castration.
  • Weigh less than 10 kg.
  • Have a healthy cardiovascular system.
  • Have no evidence of dehydration.

Exclusion criteria:

Dog will not qualify for this study if:

  • They are dehydrated.
  • Have previously diagnosed heart disease.
  • A heart murmur (greater than grade II/VI) is detected.
  • Other surgical or diagnostic procedures are planned during the anesthetic period.
  • The set protocol of anesthetic drugs is deemed inappropriate for that dog.

Study Design:

Once your dog has been deemed eligible to enter the study, he/she will be randomized to receive prewarming or no prewarming. In Group 1, dogs will be placed in an incubator for

20 minutes with no warming source. In Group 2, dogs will be placed in an incubator for 20 minutes with a warming source. Regardless of the treatment group, your dog will be monitored during this time. Body temperature will be measured and your dog will be anesthetized for its surgical procedure. Body temperature will be monitored throughout surgery. If your dog reaches a set temperature, a heat source will be turned on during surgery. After surgery is over, your dog’s temperature will continue to be monitored until recovery from anesthesia is complete.

Client Compensation:

Clients participating in this study will be given a one-time credit of $50 that can be applied towards the costs associated with the surgical management of your dog’s condition at The Ohio State University Veterinary Medical Center.

Contact Information:

Please contact The Clinical Trials Office at the Veterinary Medical Center for more information about this study.