Diseases occurring in this class are limited to those in which pustules constitute the primary lesion. In the lower animal the affection which is known as ecthyma is the only disorder which may be considered a typical one. Furunculus, which means merely a boil, is of occasional occurrence in horses, and would naturally come under the same class.

Ecthyma commonly appears in the form of pustules of various sizes on an elevated patch of skin, which is extremely tender to the touch.

It may be simple or contagious; the latter form of the disease is the more prevalent, and is better known in this country as the "American Horse-pox" or the "American Horse Disease", and by some as "German Boil". These terms had no doubt their origin in its common occurrence among imported horses, especially those from America, Canada, and Germany. It is essentially a local disease, which spreads from animal to animal more especially by means of infected clothing and harness; it appears to be necessary that the contact of the skin with the contaminated article must be extremely close. The mere throwing of a soiled cloth over an animal's body is not alone sufficient to transmit the disease; but if it be ridden for a short distance while the infected cloth or saddle is on the back, the disease is almost certain to follow.

The appearance of the malady so often on the withers, the lay of the collar, and the back, is probably to be explained by the favourable influence which the heat and moisture generated in these parts exercise on the pro-pagation of the contagion.

Treatment

This being a local disease will depend mainly on local applications for its eradication. To commence with, it is desirable that all contaminated clothing should be removed and the employment of contaminated harness be discontinued. A ten-per-cent solution of carbolic acid should be freely applied on and around the pustules twice a day, not only to bring about speedy healing of the sores, but at the same time to destroy the contagion existing in the discharges. A little boracic acid and Hour dusted over the wounds two or three times a day may be used with the same object.

In severe cases the food ration should be diminished, and the state of the bowels may require the administration of a mild aperient.

Fig. 267. - Contagious Ecthyma, or American Boil.

To guard against its further spread, all soiled clothing, harness, brushes, cloths, sponges, and stable utensils should be thoroughly cleansed and disinfected, and the same should be done with regard to the stall-posts, partitions, and fittings of the box or stall occupied by the diseased horse.