Control of Pain in Dogs and Cats

The perception of pain is an extremely complex physiological phenomenon, the reaction possibly involving many systems of the body (14). Just how one particular species may respond to a noxious stimulus can be exhibited in different ways. There can also be a great deal of interspecies and individual variability so that one animal may respond quite differently than another. This variability among animals is decreased in some of the common laboratory animals, such as rats and mice, where generations of breeding for laboratory use have tended to produce animals that respond quite uniformly. Variability, however, is often accentuated in highly outbred populations such as dogs and cats. Some breeds of dogs, such as hounds, are noted for their hardiness and may be less likely to exhibit overt signs of pain to the same stimuli, whereas other breeds, such as poodles or pomeranians, may be more sensitive. Cats may only show visible signs of pain when the stress becomes more pronounced. Apparently, therefore, it is the tolerance to pain that is highly variable, even though pain thresholds are remarkably similar among animal species (12).