Pain in dogs is not always easy to recognize. Unlike humans, dogs lack the ability to communicate emotions with words, but this does not mean that they lack emotions. Overt and obvious signs of pain in dogs, such as vocalization and aggressive reactions in response to palpation or manipulation of a painful area, usually require an extreme painful experience in most dogs. This is perhaps the most easily detectable painful condition by dog owners, but it is just one of the several painful conditions that can occur in dogs. In fact, most painful conditions in dogs are characterized by subtle signs and often require careful observation of their behavior and proper interpretation before being detected. Therefore, it is important for pet owners to learn how to recognize pain in dogs to avoid unnecessary suffering for their companions.
The evaluation of pain in dogs mainly relies on the observation of their behavior, focusing on attitude, activity level, posture and locomotion, appetite, grooming, vocalization, facial expression, as well as self-guarding and self-awareness behaviors. Broadly speaking, dogs show three different types of behavioral changes in response to pain, depending on whether the pain is acute, sub-acute (or persistent), or chronic.
Recognizing Different Types of Pain in Dogs
In acute painful conditions (those immediately following a painful incident), dogs usually show avoidance or escape reactions, which become stronger as the severity of the painful stimulus increases. In the most severe cases, vocalization and sudden unusual aggression are common, especially when dogs are caught by surprise by the painful stimulus or incident. Vocalization may include howling, barking, growling, yelping, whining, or a combination of these. Aggressive reactions to palpation of the affected body part can include snarling or even an attempt to bite or attack humans or other animals.
As the pain becomes more persistent (sub-acute pain), such as that following an accidental trauma or surgical intervention, dogs typically start to show more protective behavior to minimize stimulation of the painful area. In this condition, many signs can indicate pain. There may be vocalizations such as whimpers and groans, which often stop when the dog is comforted. Protective and guarding behaviors may include frequent changes in body position to find the position that causes the least discomfort, as well as reluctance to use the painful body part, resulting in abnormal posture or gait. For example, dogs with a painful limb may limp to minimize weight-bearing on the affected part, while dogs with abdominal or thoracic pain may be reluctant to lie down and may stand for hours until exhaustion.
Changes in activity level may also appear as restlessness, agitation, and disturbed sleep patterns, or at the other extreme, lethargy, dullness, and a reluctance to move and play. Self-awareness behaviors such as protecting, licking, chewing, and looking at the painful area are always reliable indicators of pain. Changes in facial expression can also help recognize pain in some dogs. The dog may hold its ears in a down or back position, with wide-open eyes, dilated pupils, and sometimes a fixed, glazed stare. Alternatively, its eyes may be partially closed, with a tired, dull appearance. Furrowing of the brows and other unusual grimaces may also be signs of pain in dogs.
The matter of how to recognize pain in dogs becomes even more challenging when talking about chronic pain. Chronic pain is defined as pain lasting for more than three months, which can persist beyond or in the absence of the original noxious stimulus. It most often arises from less apparent chronic conditions, such as cancer and osteoarthritis. In this case, behavioral signs of pain are usually subtle, non-specific, and insidious in onset, often going unnoticed by the owner or being mistaken for signs of normal aging. Depression, irritability, reduced appetite, reduced activity level, failure to groom regularly, disturbed sleep, unresponsiveness to environmental stimuli, and poor interaction with the owner may all be signs of chronic pain in dogs. In the most advanced stages, chronic pain culminates in lethargy, withdrawal from surroundings and social interactions, weight loss, muscle wasting, and a complete loss of body condition.
Other typical signs of chronic pain include a lowered pain threshold, resulting in increased responses to painful stimuli and painful reactions to stimuli that do not normally cause pain. Due to the debilitating nature of chronic pain, it is important for pet owners to learn how to recognize pain in dogs to avoid the devastating consequences of this condition on their pets’ quality of life. It is also important for owners to track any suspicious behavioral changes in their dogs, as these are often only apparent in the home setting and can be masked by misleading behaviors during routine veterinary visits. This might be a demanding task for pet owners, but it is the best way to allow the veterinarian to diagnose chronic pain early and formulate an appropriate management plan aimed at maximizing the quality of life of dogs with chronic pain.
