Researchers investigated the “recognition and quantification of pain in horses” with the goal of creating a new pain scale that could be put into use in equine veterinary practice. They first identified what is considered normal horse behavior and compared it to pain-related behavior by comparing non-painful horses with those that were considered to be in pain while in a box stall.
In general, horses that are not painful will eat, drink, rest/sleep, and are attentive to their surroundings. They will generally stand at the front or middle of the box stall, allowing them to interact with humans or neighboring horses. It is important that someone familiar with the horse should do the pain assessment when the horse is in an unfamiliar environment (like a hospital). A painful horse will exhibit behavior depending on what type of pain he is experiencing. Acute pain may cause the horse to withdraw or try to escape. Subacute pain can cause a horse to protect the painful area to help encourage healing. General pain may cause restlessness or depression, while orthopedic pain may show up as decreased weight bearing of the limb.
Colic pain may cause a horse to paw, look at the flank area, or roll. Horses that are painful will often stand with their head lowered and spend more time at the back of the stall. Facial expression can also be used to assess pain, with attention paid to the ear position, tension above the eyes, staring, nostrils, and tension in the muzzle and chewing muscles. Heart rate, respiratory rate, blood pressure, cortisol, and body temperature were just a few of the physiological measurements that were evaluated.
The information gathered from all of the studies that were reviewed was used to formulate a pain scale that can be used by veterinarians to evaluate pain in their equine patients. The researchers state, “the overall goal of pain evaluation is alleviating pain for improved welfare, optimal healing, and convalescence.”
Review Article: Gleerup, KB and Lindegaard, C. Recognition and quantification of pain in horses: A tutorial review.
Equine Veterinary Education AE Jan. 2016, pp. 47-57.