The influence of the seasons on the development of this disease has been well shown by Gerlach and Muller. The disease commences about the end of autumn, when the animals are stabled. It continues to extend until February, but diminishes as soon as the animals return to the fields in spring. The crusts fall, the hair again grows, and the animal appears to be cured, but the disease again revives during the autumn. The psoroptes lie hidden during the summer round the poll and the horns. The disease seldom attacks animals at grass and in good condition, or those over three years old. Calves, yearlings, and two-year-olds in poor condition suffer most.
When the disease is very extensive, the animals lose condition and may even die.
Diagnosis. Psoroptic mange in the ox may be mistaken for several cutaneous diseases, to which it has a certain resemblance, as for instance phthiriasis and the first stage of ringworm.
These different diseases, however, show their own distinctive symptoms on a careful examination.
The prognosis only becomes grave when the disease has been neglected and the animals are greatly reduced in condition. When recent, this form of mange can readily be cured by the application of parasiticides.
Treatment. As in dealing with all transmissible diseases, the animals must be isolated and washed with soap, and the diseased parts must be dressed with some parasiticide, such as sulphur ointment. The best preparations are: Benzine and petroleum in equal quantities; concentrated solution of sulphuret of potassium (8 ounces to the quart); Helmerich’s ointment; diluted creolin solution; decoctions of tobacco; ointment of pentasulphuret of potassium, and oil of cevadilla.
One or two applications are generally sufficient to effect a cure, and relapses are not likely to take place if the stable is disinfected. In America the disease is common in the West and North-West, where it is treated by the lime-and-sulphur bath recommended for sheep scab (which see). Large vats are constructed, and the oxen are lowered into these by means of a wooden cage controlled by machinery, which is operated either by a small engine or more frequently by a horse.
The food should be of good quality, for good general health plays a great part in resisting parasitic invasions.
CHORIOPTIC MANGE.
This disease has also been termed dermatophagic and symbiotic mange.