Chorioptic mange, due to a species of mite different from that causing common cattle mange, is confined almost entirely to the region at the root of the tail and if not treated may persist for years. The treatment is the same as for psoroptic mange.
SARCOPTIC MANGE.
Sarcoptic mange, frequently called "barn itch," is caused by a mite very similar to that which causes itch in human beings. It commonly affects the head and neck, but may also occur on various other parts of the body. Bulls are particularly liable to be affected with this form of mange. Cattle may become infected not only from other cattle, but also from horses, goats, dogs, sheep, and hogs. As a rule sarcoptic mange in any species of animal, if acquired from an animal of another species, is likely to run a short course and tend toward a spontaneous recovery.
The treatment likely to be most efficacious is that of dipping in a crude-petroleum dip, one treatment as a rule being sufficient. If lime-sulphur dip is used, four or five successive treatments, or even more, at weekly intervals, may be necessary before a cure is effected.
DEMODECTIC MANGE.
Demodectic mange, which is caused by a small parasite that lives in the hair follicles, causing pustules, especially on the neck and shoulders, occurs occasionally among cattle in this country and is of importance on account of the injury to the hide. When tanned, hides infested by this parasite are pitted, the pits, in some cases, being so deep that they form holes. No practicable treatment is known for this disease.
TICKS.[18]
About 10 species of ticks have been reported as parasites of cattle in the United States. The most common and most important is the species known as Margaropus annulatus, which transmits Texas fever. Information concerning this tick and Texas fever has been given elsewhere in this volume ([p. 475]).
The spinose ear tick (Ornithodoros megnini) is frequently found in the ears of cattle in the western part of the United States, and is of common occurrence also in the ears of horses, dogs, cats, etc.
When its parasitic stage of development is completed the ear tick leaves its host. Mating between the sexes occurs after the ticks have cast their skins following the abandonment of their host. They usually crawl up some distance from the ground and secrete themselves in cracks and crevices in trees, walls of buildings, etc., where the females deposit their eggs.