Variola affects horses, cattle, sheep, and dogs. It is of ancient history and widely extended occurrence. Sheep pox and smallpox (of man) are rather dissimilar to the others and were probably brought to us from the extreme East.
Causes. It is a contagious infective fever accompanied by a
rash which ultimately produces larger or smaller pustules that, in the end, form scabs and drop or are rubbed off. The contagion is both direct from a sick animal or through the air in infected premises. It is contained in the pustules, the scabs, blood, secretions, excretions, expired air, and the scurf from the skin. The contagious principle remains active for a considerable time and, in sheep particularly, may be carried comparatively long distances. One attack is all that the same animal may be expected to have.
General Symptoms. The disorder will begin to show itself in about one week after it has been "taken," when there will be a marked feverish attack, accompanied by some signs of nasal catarrh and general redness of the skin. Suddenly, upon this red surface, little red spots will begin to be shown which soon look like pimples; these, growing harder, get to be about the size of a millet seed or a little, smaller, and are surrounded by a red ring. After a few days the tops of the little pimples lose the hardness and bright red color and take on the appearance of small blisters of a bluish white color. This eruptive stage takes from six to eight days and, with the filled blisters, the pocks are fully matured. Following this, the blisters turn into pustules; this preparation takes place within two or three days, at the end of which the fever, which disappeared in a marked degree with the beginning of the eruption, now reappears. The pustules dry up little by little into, first, yellowish crusts, afterward becoming dark brown scales, which fall off leaving behind white, glossy, or brownish red scars. This last process lasts from three to five days.
Horse pox is not as commonly seen as formerly, and when it makes its appearance does so in certain districts, not in single cases. It may be transmitted to sheep, cows, and men.
Symptoms. There is at first a rise of temperature and loss of appetite. This is soon followed by a swollen, hot skin at the back of the pastern bones, under the fetlock, that may, in certain instances, extend upward to some little extent. This same appearance of the skin may also be rarely noticed on other parts of the body, especially in the neighborhood of the nose and lips, sometimes extending into the mouth and nostrils. With the swelling of the skin at the pasterns the animal becomes quite lame and if made to move lifts his feet high off the ground. After a little the blisters appear and the disorder progresses as described. The whole process will occupy some three or four weeks when all will, generally, be right again.
Cowpox. The contagious principle is not so easily and widely spread as that of sheep, and is mainly carried by the hands of the milkers going from diseased animals to the healthy ones. There is also some reason for believing that a person, recently vaccinated against smallpox, may convey the disorder to cows by milking them. Cowpox can be transmitted to sheep, horses, and men.
Symptoms. Fever is absent or only slightly marked, there may be some slight disturbance of the general health, best shown by the decrease in the amount of milk given, and the milk may be thinner. It is possible that the slight decrease in the milk is because of the pain caused by handling the sore teats, in milking. The pimples may be larger but are less in number and vary somewhat in color in different skins. The whole process lasts about three weeks in a given animal, but its progress through a herd is slow, as all of the cows, with very few exceptions, will sooner or later be attacked. Bulls, oxen, and young cattle are less frequently affected.
Sheep pox is of more importance than that of any other animal. The infectious principles are conveyed in the air as well as being fixed; its vitality is so great that a building into which it has been introduced will remain infected for five or six months. It may be conveyed, by an animal that has had it, for six weeks after apparent recovery. The germs are also conveyed by infective sheep, by dogs, wool, skins, manure, fodder, the clothes of people, railroad cars, etc.
Symptoms. Within from four to seven days after exposure there is shivering, fever, depression, shown by a hanging head, considerable weakness, and loss of cud and appetite. The temperature rises to one hundred and four or one hundred and five, perhaps a little higher; pulse and breathing are more frequent than normal, in proportion to the fever present. In a day or two the red spots, etc., appear upon the skin where the wool is not thick, especially upon the head, near the eyes, nose, and mouth, or on the inner surface of the legs, chest, and belly; rarely, it may become more widely spread.
On the fifth day after the eruption the pimples become whiter and show the red ring; if they lie closely, as on the head and about the eyes, the neighboring skin becomes very much swollen. The temperature now falls and within a few days the pimples increase in size and contain fluid. On the sixth or seventh day after the eruption the pocks are "ripe," from which time onward the pimples become pustules; the temperature again rises, the symptoms of acute catarrh of the breathing apparatus and the eyelids appear, with a more or less abundant fluid discharge from both the nose and mouth, and there is difficulty in both swallowing and breathing; diarrhea may appear. The head becomes swollen, the skin has a bad smell, the pustules wither and dry up, the brown scales appear, finally leaving the white or red scars. The disorder continues in an ordinary case for about three weeks. Unfortunately there are many variations of the usual type, in this animal, some of which, not infrequently, cause a large death rate, which is not at all usual in the other animals. Several of the pocks may run together and form a large, unhealthy sore and the sheep die of blood poison. Lung or throat difficulties (croup) may appear and death be caused by suffocation, or if the animals Eve they are left greatly exhausted, in an unhealthy condition and perhaps lame or blind.
If the disorder is introduced into a herd, only two or three per cent escape infection; the mortality is from ten to twenty per cent under ordinary circumstance, and fifty or more per cent under unfavorable ones.
Dogs seldom have pox, although it is possible for them to do so. When it occurs the course is light, regular, and is followed by recovery in from two to three weeks.
Treatment. As the disorder runs a regular self limited course there is not much to be accomplished by curative measures. The skin can be kept clean and a little cooler by washing the diseased portions with saleratus (bicarbonate of soda) water; one tablespoonful of the saleratus to each one quart of water used; or with a solution of borax in water, as strong as it can be made, using the crystals of borax, not the powdered agent. In large flocks individual applications or administrations of any kind become practically impossible. In the few cases wherein throat, lung, or other complications arise, it may be possible to treat the disease which has been set up, under the general rule; as, for instance, the confluent variety, sometimes appearing among sheep, may receive the treatment laid down for septicemia, etc. The food should be sound, clean, and nourishing; the premises as well cleansed and disinfected as possible, and there is no better method for this purpose than that recommended in glanders, excepting that the carbolic acid must be used in the strength of six ounces of the pure acid to each gallon of the whitewash. It may be applied, one coat at a time, at intervals of a week or ten days, until after the last case has recovered; and in a sheep barn for a longer period, as already indicated, unless the formaldehyde gas can be used, which is extremely doubtful in this class of buildings. Protective inoculation, is possible.
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