Dog Rabies: Signs And Symptoms

Dog rabies is an age-old scourge which has been recognized as a dread disease since ancient times. Though it is primarily a disease of the dog, many other species, including man, are susceptible to infection. It has been reported in the cat, cow, horse, mule, sheep, goat, hog, wolf, fox, coyote, hyena, skunk, monkey, deer, antelope, camel, bear, elk, polecat, bat, squir­rel, hare, rabbit, rat, mouse, jackal, marmot, woodchuck, porcupine, weasel, hedgehog, gopher, raccoon, owl, hawk, chicken, pigeon, and stork. It is fairly common throughout the world, though Great Britain, Denmark, Norway, and Sweden have been free from it for several decades and it has not been reported in Australia.

Dog rabies may occur in the furious and the dumb forms. In the furious form, the dog usually first shows a marked change in disposition. Later the animal has a tendency to wander, and may return home exhausted after a day or two. The animal seems to become vicious and has an abnormal tend­ency to bite. This is because, at this time, the animal suffers impairment of vision, and, because of fear of its sur­roundings, the animal will bite at anything in reach that crosses its line of vision. As the disease progresses the animal develops a peculiar hoarseness of voice, shows signs of stag­gering, paralysis of the lower jaw, partial paralysis of the limbs, excitability, convulsions, and finally complete paralysis and death.

In the dumb form, there may simply be a marked depres­sion and then death, but more commonly the main symptom is paralysis of the lower jaw. The animal may or may not show a change in disposition, has no tendency to roam or bite, and is not excitable. The dropped-jaw appearance often arouses the erroneous contention that a foreign body might be lodged in the throat. Since the saliva carries the rabies virus, caution should always be used in approaching the mouth of an animal that presents such a symptom. The animal eventually de­velops complete paralysis and dies. In both furious and dumb rabies in dogs, once the symptoms appear the animal usually dies within three to seven days. The disease has been pre­sented here in its most typical forms. It may occur in many atypical forms, which means that one must always be aware of its possibility.

The term "hydrophobia," commonly associated with this disease, is a misnomer. The affected animal has no fear of water as the word implies. It simply cannot drink because of the paralysis of the lower jaw and the swallowing mechanism. The term may have its origin in the fact that humans with rabies develop convulsions due to unsuccessful efforts to drink, and later even the thought of drinking water may bring on convulsions. Thus a dread of drinking water be­comes established in many human patients.
Rabies is caused by a filterable virus, is positively diagnosed by the demonstration of certain structures called Negri bodies on microscopic examination of brain tissue, and is trans­mitted mainly by the bite of rabid dogs, though it has been transmitted experimentally by the feeding of the meat and milk of rabid animals. Dog rabies is invariably fatal in the animal and man as well particularly when untreated. In dogs, the disease may be prevented by vaccination, a single vaccination confering immunity for one year. A newer vaccine is claimed to give protection for at least three years. As a precautionary measure, all bite cases should be reported to the local Board of Health, and the animals involved should be examined to determine whether they have the disease.

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