By Dr. David Gross
Pain is a part of life. All living things experience pain in some form. Pain perception is well-documented in living animals and a similar type of response may even occur in plants. Pay heed, you vegans.
Most of us who live in close proximity to animals will know it when our pet/companion/friend/family member/however you identify the animal that lives with you, is experiencing acute pain. When the animal cries out or limps, looking at you with pitiful eyes, you know it. Animals that experience chronic pain, even if it is relatively severe, sometimes cover it up. In the wild, this covering up of pain can be a survival strategy. Animals in obvious pain are easy targets for predators.
Dogs and cats in pain will usually demonstrate a change in behavior or temperament. Some individuals will vocalize, whimpering, crying, meowing, etc. I’ve known some cats that didn’t suffer stoically — they vocalized and let me know they were hurting. Perhaps this was the origin of “caterwauling”?
If your pet is normally gregarious, happy and affectionate but becomes irritable and avoids being held or petted, that could be a sign of chronic pain. If your normally rambunctious golden retriever sits or lies around and avoids contact with you, something is up. Many species adopted as pets will lick, scratch or bite at the part of their body causing pain. When this happens, the frequent outcome is self-inflicted injury. Thus we have those ridiculous-looking Elizabeth collars, affixed around the neck of your pet by your veterinarian, to prevent exacerbating the condition.
Horses show pain by restlessness, pawing at the ground or looking at the painful area. They may try to kick at the painful place, especially if their abdomen or thorax is the source. If the pain is severe, especially abdominal pain, horses may go down and roll on the ground. This is very dangerous because the rolling can results in twisting of the intestines on themselves resulting in death of the tissue and, without surgery, death of the animal. Some horses in severe pain may refuse to move and just stand, depressed, with their head drooping.
Cattle, sheep and goats frequently grind their teeth when in pain, vocalize by groaning or whimpering, and look and/or bite at the painful spot.
Birds will often pluck feathers from a painful area. Iguanas and other exotic species may try to bite at the offending stimulus. Almost all animals will respond by withdrawing when you palpate a sore area and some may bite or strike at you in response. Almost all animals in pain will stop eating and this may be the first sign.
As it is in us humans, the threshold for pain can and does vary with individuals and in the same individual at different times. Avoid giving your animal human pain medication unless your veterinarian has specifically recommended it and explained the proper dose.
Dr. David Gross graduated from Colorado State University’s veterinary school in 1960 and was in private practice for ten years. He enrolled in graduate school at Ohio State University earning a M.Sc. degree in 1972 and a Ph.D. degree in 1974. He retired in 2006 as Professor and Head of Veterinary Biosciences, at the University of Illinois, Urbana-Champaign. Dr. Gross is a Fellow of the Cardiovascular Section of the American Physiological Society. During his academic career, he published over 90 papers in refereed scientific journals and over 100 abstracts in proceedings of scientific meetings.