Are "normal" horse temperatures too high?

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A normal rectal temperature is a useful indicator of health. 

Along with heart rate (pulse) and respiratory rate, rectal temperature is one of the “vital signs” that can alert us to the presence of disease. Ideally temperature should be measured regularly - both to get the horse used to the procedure and to establish what is normal for that individual. 

But what is normal? A recently published study suggests that previously published ranges of “normal” temperatures may be too high.

Researchers from Nottingham Trent University (NTU) and the Royal Agricultural University investigated the use of body temperature in assessing equine health. They argue that current tradition-based guidelines may be inaccurate and require further investigation.

As part of the study Emily Hall, Dr Anne Carter and Dr Carol Hall from Nottingham Trent University, in collaboration with Dr Anne Stevenson from the Royal Agricultural University, researched the normal body temperature of horses on the NTU yard. Lubricated, digital thermometers were used and inserted to a standard depth of 5cm.

The findings showed that the upper limit of the published ranges (38.5°C) is typically 0.5°C higher than the results from clinically normal horses in this study. The researchers found the normal temperature range for horses on this yard was 36.0-38.0°C.

The research, led by the University's School of Animal, Rural and Environmental Sciences, included over 600 measurements from 41 healthy adult horses. The horses ranged in age from 2 - 23 years. 

A full report of the study is published in the Journal of Equine Veterinary Science.

Lead researcher, veterinary surgeon Emily Hall, said, "Due to factors such as antibiotic resistance, climate change, and ever-increasing movement of horses, it is increasingly important that early signs of ill-health or disease are picked up as early as possible.

“By establishing a reference range specific to the yard at NTU, we can now be more confident in identifying horses that are too hot, or too cold, and take appropriate action.”

The study found that the overall equine temperature reference ranges cited in textbooks may need reviewing and updating. The aim is to repeat this study on other equine yards around the UK in order to review the overall normal range for all horses across the country.

For more details, see:

Establishing a Yard-Specific Normal Rectal Temperature Reference Range for Horses

Emily J.Hall, Anne J.Carter, Anne Stevenson, Carol Hall

Journal of Equine Veterinary Science, (2019), Vol 74, pp 51-55

https://doi.org/10.1016/j.jevs.2018.12.023