Low Rectal Temperature Linked to Death in Pet Rabbits

A study published in the Journal of the American Veterinary Medical Association has found that low rectal temperature at the time of hospital admission is a significant predictor of death in pet rabbits.

In human patients, studies have shown that nontherapeutic hypothermia is associated with an increased risk of death, and may therefore be a valuable prognostic indicator in a variety of clinical situations, including in patients with burns, congestive heart failure, or blunt trauma.

Among veterinary patients, because of their high body surface-area-to-volume ratio, rabbits may be more at risk of developing hypothermia than larger pets such as dogs and cats. However, the usefulness of measuring rectal temperature in pet rabbits is still controversial: some studies have offered that this practice has little clinical value, while others have suggested that sick rabbits do have a low body temperature. Indeed, a definitive rectal temperature reference range has not even been established in rabbits, although values of 38.0°C to 40.0°C have been considered normal.

When Nicola Di Girolamo, DVM, MSc, University of Bologna, Bologna, Italy, and colleagues conducted a systematic review of the veterinary literature, they found that, overall, clinical studies examining the effect of body temperature as a useful predictor of death or poor clinical outcomes in pet rabbits are lacking—as are studies documenting the body temperature of pet rabbits admitted to veterinary hospitals.

The researchers therefore performed a clinical study to examine whether rectal temperature at the time of hospital admission was associated with mortality risk in pet rabbits. In the study, they recorded the rectal temperature of 316 pet rabbits that were admitted to the animal hospital—typically for surgical procedures, intensive care, or both—over the course of about 1 year. Normal body temperature range was considered to be from 38.0°C through 39.9°C.

The median rectal temperature of the rabbits at the time of admission was 38.2°C (range, 32.0°C to 41.6°C); 37% of the rabbits had hypothermia, 2% had hyperthermia, and 61% had a normal body temperature. And 30% of all the rabbits in the study died either during hospitalization or within one week after discharge. The median rectal temperature at admission of rabbits that died was 37.2°C (range, 32.0°C to 40.2°C), while that of rabbits that survived was 38.5°C (range, 35.0°C to 41.6°C).

They researchers found that rabbits with hypothermia at admission had a 3-times greater risk of death than rabbits without hypothermia. Furthermore, each 1°C decrease in rectal temperature doubled the odds of death. Rabbits that were older, had gastrointestinal stasis, or were suspected to have a systemic disease were also more likely to die during hospitalization.

“For many years, the clinical value of measuring rectal temperature in client-owned rabbits has been criticized,” the authors write. However, “on the basis of results of the present study, rectal temperature at hospital admission was found to be a relevant prognostic factor in client-owned rabbits.”

Because of the size of the effect in particular, the researchers emphasize that this association should be considered clinically important. “Rectal temperature should be considered a major prognostic predictor in client-owned rabbits, and should always be measured during a physical examination.” the authors conclude.

Dr. Parry graduated from the University of Liverpool, England in 1997 and is a board-certified veterinary pathologist. After 13 years working in academia, she founded Midwest Veterinary Pathology, LLC where she now works as a private consultant. She is passionate about veterinary education and serves on the Indiana Veterinary Medical Association’s Continuing Education Committee. She regularly writes continuing education articles for veterinary organizations and journals, and has also served on the American College of Veterinary Pathologists’ Examination Committee and Education Committee.