Because of the many popular misconceptions concerning rabies, it seems advisable to consider a few general facts about the disease and its spread before taking up specific symptoms.
Rabies is a virus disease transmissible to almost all kinds of warm-blooded dogs.
Not all dogs bitten by a rabid dog develop rabies. Of dogs bitten by rabid dogs, 40 percent die; with horses, the percentage is also 40; hogs,30 percent, and cattle, 30 percent. Only about 15 percent of the humans in one study who took no treatments to protect themselves after being bitten developed the disease. In the past, when rabid wolves bit humans, a higher percentage died.
It is the saliva of the rabid dog that is dangerous. The bite drives the virus in the saliva deep into the victim’s tissues, where, being a neurotropic virus, it attaches itself to nerves and grows. (If the virus can attach itself to a nerve after the dog has been bitten, the dog has rabies. If the dog’s body is capable of destroying the virus, the dog does not have rabies.) It is not dangerous on unbroken skin. When a dog is bitten, there is no certainty about how long the virus will take to grow up the nerves until it reaches the huge mass of nerve tissue called the brain. The position of the bite has some effect. If a dog is bitten on a back foot, the virus will have quite a distance to travel before it reaches the brain; whereas with a bite in the jaw, the elapsed time would be much less. From 15 to 285 days are the extremes found in a study to determine how long it takes.
What we think of as rabies is merely the manifestation of brain inflammation encephalitis and the dog may exhibit any of several typical forms of that malady. Thus present-day students of rabies have come to hold concepts of the disease completely different from those of our forefathers. Even the old name, hydrophobia, is no longer used. The conceptions of dumb and furious rabies have been dropped because the symptoms these terms describe are only two manifestations of encephalitides. In rabies, dogs do not have fits and then recover, as they may with other diseases. Once the symptoms appear, it is a downhill drag until death ensues.
SYMPTOMS: The earliest sign of rabies may be what seems to be a perverted appetite, but this may be due to hunger coupled with the dimming of the sense of taste that anything will be chewed and swallowed. Another sign may be restlessness, excitability, or a desire to move which becomes accentuated as the virus grows in the brain. Complete character reversals are frequent. Some ugly dogs become docile, while some lovable, kindly dogs may become ferocious. As the disease progresses, a whole range of symptoms from drowsiness to such violent reactions to exciting disturbances that the dog appears wild.
A startled look haunts the eyes. Some dogs may be paralyzed and stupid and quiet, giving rise to the idea of “dumb rabies.” Other dogs may become fearless and run about, head down, biting anything that moves. Since its peripheral nerves are partially or completely paralyzed, the dog Inas little sense of feeling when bitten. In fights with dogs that refuse to run, the rabid dog can stand terrific punishment. When confined to a cage, it may break its teeth on the bars without apparent pain.
Probably the paralysis of the throat causes panic because the helpless feeling of not being able to swallow drives the dog wild. Rabid dogs do not have a phobia, or fear, of water; they simply cannot manage to swallow it, try as they may, and after many attempts to drink naturally, they behave queerly toward it.
In the paralytic form, the lower jaw may hang; it is not held open by muscle power but rather from want of it. The frothing from the mouth in some cases is well known to all who have heard about mad dogs. Indeed, the common conception of a mad dog is of a dog miming about with froth drooling from its mouth. This misconception should be corrected. That type of behavior is far from being the typical form of rabies, and because this fact is not generally recognized, many people have died.
In all forms of rabies, once the severe encephalitis symptoms appear, death generally ensues in less than a week, sometimes in three days. The dog’s bite can be infectious three days before anyone knows it is sick. One dog was found to have infected saliva eight days before it showed the typical symptoms.
Diagnosis beyond the suspicion created by the symptoms is possible only by microscopic and biological means. To do this, the suspected dog must is destroyed and a portion of the brain examined for inclusion bodies by a test called a fluorescent antibody test.
You wish you have space to tell of the many cases we have seen of encephalitis following virus diseases and how exactly some followed the course of rabies encephalitis. Thousands of dogs that died of other virus diseases have been suspected of having rabies. We have suspected at least a dozen to such an extent that we had the brains examined. One dog bent heavy wire in its cage front, snatched a one-inch-square stick out of someone’s hand, chewed and swallowed some of it, ate the metal of feed pans, ate the equivalent of a newspaper that was on the floor of its cage, and died with legs in rigid extension. Its brain was sectioned but the tests were negative for rabies. The next step in diagnosis was to inject some of the tissue into mice, and they, too, showed that the dog was not infected with rabies. If a dog dies in the early stages of rabies, no inclusion bodies have developed, so mouse tests are used as standard procedures in diagnosis.
PREVENTION AND CONTROL: Suppose you think your dog may be rabid. What should you do? Confine it in a veterinary hospital or dog pound. Give it time to develop characteristic symptoms. If it does have rabies, have it destroyed, have the brain examined, and put yourself in the hands of your veterinarian.
These questions are often asked. Why don’t veterinarians try to cure dogs affected by rabies? If dogs can’t drink, why aren’t they given water by vein? Isn’t there any serum for rabies? The answer to all these questions is that human beings don’t want to handle rabid dogs, practically nothing has been done in the way of treatment.
Prevention is the keynote in rabies control. It can be made more effective by keeping all dogs under supervision and by rigid enforcement of the regulations requiring dog wardens to pick up all strays. Prevention consists of dog vaccination. These are made very expensive in some states by subsidies and veterinary volunteers.
If there is a possibility that infected saliva or other excretion from a rabid dog has entered a cut or abrasion, a person can be given treatment, which, if taken in time, causes the human body to develop immunity in the blood, and the immune bodies in turn attack the virus growing on the nerves and destroy it.
What chance have you of owning a rabid dog? Since we have set down in some detail the dangers of this disease to man and his pets and warned dog owners of the precautions to be taken, a more cheerful note may well be struck.
As of this writing, the outbreaks of epizootics in raccoons seem to be the most serious reservoir of the disease but rabid house cats also are increasing in numbers. House cats should all be inoculated.
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