Dogs normally have a core body temperature of 37.8°C to 39.3°C (100.4°F–102.74°F). Hypothermia (<37.8oC) occurs with increased heat loss, decreased heat production, or a combination of both. Although mild hypothermia during surgery may be beneficial, severe hypothermia can lead to life-threatening complications.

This study evaluated the effect of 3 active warming devices on the body temperature of patients undergoing prolonged surgery. Group A dogs (n = 119) underwent celiotomy procedures (exploratory laparotomy, ovariohysterectomy); group B dogs (n = 119) underwent nonceliotomy procedures (skin mass excisions, orthopedic procedures, orchidectomy).

Dogs in each group were assigned to 1 of 3 subgroups: subgroup 1 dogs were placed on a circulating water blanket with a forced-air warming blanket over the abdomen or thorax, subgroup 2 on forced-air warming blankets only, and subgroup 3 on 2 warming panels. Body temperatures before anesthetic induction were measured with a rectal thermometer and after induction with an esophageal temperature probe. All dogs had a significant drop in temperature within 45 minutes from time of induction (38.1°C ± 0.64°C; 100.6°F ± 1.2°F) to start of surgery (36.7°C ± 0.95°C; 98.1°F ± 1.7°F). Body temperatures were maintained once the warming units were started, but there was a significant difference in patient temperature by surgery types in subgroups 1 and 2. All warming systems were able to preserve body temperatures.

Commentary
This article is a good general review of why patients develop hypothermia and how warming devices work. It discussed the advantages and potential dangers (eg, thermal injury) of various devices available; however, the authors failed to evaluate conductive fabric models, which are commonly used. In addition, there were several limitations, such as not having a control group and not comparing active warming systems to each other.—Justine A. Lee, DVM, DACVECC, DABT

Source
Comparison of three intraoperative patient warming systems. Franklin MA, Rochat MC, Payton ME, et al. JAAHA 48:18-24, 2012.