Common Diseases of Farm Animals

by Robert Alexander Craig

The hair varies in length, thickness and coarseness in the different species, and the different regions of the body. In addition, breeding, care, heat and cold may cause marked variations in the thickness of the coat. Exposure to cold causes the coat to thicken. High temperatures cause the short hairs to drop out and the coat to become thin.

Diseases of the skin may be classified as parasitic and non-parasitic. Parasitic skin diseases are caused by animal and vegetable parasites. Non-parasitic skin diseases are caused by irritation to the skin and internal causes. Irritation to the skin may be either chemical, thermic or mechanical. The internal causes may be due to an individual predisposition together with digestive disturbances and the eating of feeds too rich in protein. In this chapter parasitic skin diseases produced by insects will not be discussed.

FALLING OUT OF THE HAIR AND FEATHERS.—Falling out of the hair and feathers frequently occurs independent of parasitic diseases. This condition does not occur as an independent disorder, but as a secondary affection. It is due to faulty nutrition, and irritation to the skin. Intestinal diseases, insufficient feed and feed of bad quality are common causes. Animals that are fed a heavy ration, or that lie on dirty, wet bedding frequently lose large patches of hair. Sheep that are dipped in late fall and early winter, or exposed to wet, cold weather may lose a part of their fleece. It is not uncommon for animals toward the latter period of pregnancy, or that sweat freely, to lose patches of hair.

Falling out of the hair heals of itself within a few weeks.

The preventive measures are of special importance in sheep and horses. This consists in avoiding conditions that may lead to alopecia and in correcting the diet. In horses the regions of the mane and tail should be washed with soap, or rubbed with alcohol and spirits of camphor, equal parts. Treatment should be persisted in for a long period if necessary.

URTICARIA, "NETTLERASH."—Urticaria is characterized by roundish elevations that appear quickly and become scattered over a part or the whole surface of the skin. They are caused by an inflammatory infiltration of the deeper layers of the skin. Horses and hogs are most frequently affected.

The causes of urticaria are irritating juices of certain plants, secretions of flies, ants and some caterpillars, irritating drugs, scratching, sweating and the action of cold on a warm skin. It has been observed in connection with the feeding of certain leguminous feeds and digestive disturbances. Horses that are fat, or putting on flesh rapidly, seem to be predisposed to this disorder. Urticaria may occur in certain infectious diseases.

The characteristic symptom is the formation on the skin of roundish elevations or "hives." There may be an elevation of body temperature and partial loss of appetite. Small animals may act restless and show evidence of itching or pain. This symptom is very common in hogs. The eruption may last only a few hours or a few days, or, because of the animal's scratching or rubbing the part, the skin may become scabby and small pustules form.

An important preventive measure is to avoid the use of agents capable of irritating the skin and producing urticaria when treating parasitic skin diseases. It is very advisable to give the animal a saline cathartic (Epsom or Glauber's salts). The skin may be washed with cold water, or a weak water solution of permanganate of potassium.

ACNE, "SUMMER RASH."—In this skin disease the oil glands and hair follicles are inflamed and sometimes infected with pus germs. This results in skin eruptions varying in size from the point of a pin to about a quarter of an inch in diameter. This inflammation is most prominent during the warm weather.