HYDROPHOBIA (from Greek words meaning °fear of water"), an acute or subacute infectious disease, particularly of canine animals. It is usually communicated by a bite of the afflicted animal, and the contagion, the exact nature of which is still under discussion, is resident for the most part in the saliva, al though it has been found in the peripheral nerves, the pancreas and the suprarenal gland. It is frequently communicated to man, although the dog, wolf, fox, deer, cat, cow and skunk are the animals most frequently affected; it has been known to occur also in the horse, pig, birds and other animals. Nine-tenths of all the are contracted through .he bites of rabid dogs. Hydrophobia may be however, by wounds occurring during the dissection of rabid animals. it is said to have been caused by eating the flesh of animals that have died of the disease; and the milk of sucklings, animal and human, is thought to contain the virus. This poison has been found to be active in a dog 44. days buried, and in a rabbit buried 21 days.
In dogs the disease is comparatively common. In 1900 D. E. Salmon, chief of the United States Bureau of Animal Industry, determined that the disease was prevalent throughout the United States, and largely on the increase. The chief symptoms in dogs may be divided into two classes. Dogs suffer from furious rabies, and from dumb rabies. In the former Pasteur thought that the brain was involved ; in the latter, the spinal cord. The furious form of the disease shows (1) a period of melancholy or depression; (2) a period of irritation; (3) a period of paralysis. The first varies from a few hours to two days. During this period the anxious and restless dog may also be cross. He hides from his master, obeys sullenly and changes his position frequently. His appetite may not be at first affected, but it soon fails; he may lick everything in sight, or bite every thing within reach, swallowing all sorts of foreign bodies. The period of irritation usually persists three or four days, during which the dog is spasmodically mad; restlessness increases, and the animal has an irresistible impulse to run away. During the running spells dogs may bite at everything.in sight ; at such times they usually seem fearless, and rarely avoid other dogs or people. If caged, they tear and chew on the bars, even breaking their teeth or fracturing their jaws. The bark is modified into a peculiar
howl. During the third or paralytic period the dog is subdued and more sullen; the lower jaw becomes paralyzed and hangs down, saliva dripping from the mouth; the gait is staggering; from the fourth to the eighth day after the onset he dies of paralysis or exhaustion.
In dumb rabies the characteristic second stage may be entirely absent. The most persistent feature of dumb rabies is the dropped lower jaw, the paralysis of the jaw in the later stages preventing the dog from biting.. Veterinarians see many cases of dumb rabies in dogs brought to them by owners who think that the trouble is caused by a bone in the throat. Beware of a dog that becomes listless and dull aud hides away; is always on the go, prowling about and restless; one that is sullen and walks with his head down like a bear. A dog that scrapes in cessantly and tears things up, and one that sud denly becomes excessively fond of its master, desiring to lick his hands and face, should be watched and guarded. A dog that has trouble in swallowing, that seems to have a bone in his throat, or, having wandered away from home, returns covered with dirt, exhausted and miser able, should be put under lock and key.
So far as the water-test is concerned, it is nonsense. The mad dog is often very fond of water; he is thirsty and rushes into water, thrusts his head into it • but he may have great difficulty in swallowing it, the act of swallowing usually bringing about severe convulsions, In man the disease may go through some what similar stages, but the course is greatly modified; males are more likely to be affected than females, the difference in dress and ex posure accounting for this; and two-fifths of the subjects are below the age of 15. Bites on the face, neck and hands are thought to be the most liable to develop the disease, and punctured wounds are more dangerous than lacerated wounds because of the difficulty in cleansing their. In man the period of incubation varies widely, from 20 to 60 days is the usual range, but six months may represent an extreme limit. In exceptional instances the period of incuba tion seems to have been greatly prolonged. The pathological changes recently discovered are found to be extremely characteristic, so that it is now even possible to diagnose rabies in a dog within a reasonable time after his death.