When the abscess has opened, and the dead tissue separated, the abscess cavity or wound should be regularly washed out with a disinfecting solution, to prevent complications, in case fragments of necrotic tissue have been retained. If, however, complications have occurred, no hesitation should be felt in freely incising the parts, and, if necessary, in removing one or both phalanges. When both joints of one foot are affected, and arthritis threatens to or has set in, there is no object in treating the animal, and early slaughter is to be recommended.
In cases where the disease follows foot-and-mouth disease, and threatens to become enzootic, it can generally be prevented spreading by keeping the foot-and-mouth subjects on very clean beds, and frequently washing the feet with antiseptic solutions. Disinfection of the sheds is also very desirable.
FOOT ROT.
Foot rot is a disease of sheep, and, like canker, is confined to the claws.
Thanks to the progress of hygiene, it tends to become rarer, but is still seen in the enzootic form in some portions of England and Scotland, in the mountains of Vivarais, the Cévennes, and the Pyrenees.
It affects large numbers of animals at once, animals belonging to one flock or to neighbouring flocks in one locality, and when it invades a sheep farm, all the animals may successively be attacked at intervals, according to the local conditions.
Symptoms. The disease develops rather insidiously, and the patients always retain an excellent appetite. It begins with lameness, which is at first slight, later becomes accentuated, and in the last periods is very intense. On examination, the coronet and lower part of the limb as high as the fetlock are found to be swollen. Palpation reveals exaggerated sensibility, and on direct examination, a fœtid discharge is discovered in the interdigital space. This discharge, which is peculiar to the onset of the disease, only continues for a week or two, and is succeeded by a caseous exudate which is always offensive, which moistens and macerates the horn, the skin, the tissues in the interdigital space, and the region of the heels. From the 20th to the 30th day after onset the claw separates above in the interdigital space. The separation extends towards the heel, then to the toe, exposing ulceration of the subjacent podophyllous tissue.
From this time the patients experience very severe pain, and, as in other diseases of the feet, remain lying for long periods. Movement becomes extremely painful, and the animals frequently walk on the knees. The subungual lesions become aggravated, separation of the claw extends, necrosis of the podophyllous tissue and of subjacent tissue becomes more extensive, and the inter-phalangeal ligaments and the extensor or flexor tendons become involved. Finally, the claws are lost, and synovitis and arthritis are added to the complications already existing.
In an infected locality the development is always the same. The animals lose flesh, become anæmic, and, unless vigorously treated, soon die. The ordinary duration of the disease is from five to eight months, sometimes more. If, however, patients are isolated and well treated they recover.
Causation. The specific cause of foot rot still remains to be discovered, although everything points to the conclusion that it consists in an organism capable of cultivation in manure, litter, etc., for foot rot is transmissible by cohabitation, by mediate contagion through infected pasture, by direct contact and by inoculation.