Causation. Sarcoptic mange in the pig is due to the presence of Sarcoptes scabiei (v. suis), although the pig may contract (temporarily) the sarcoptic mange of goats.
Contagion is favoured by poor condition, over-crowding, dirt and bad hygienic surroundings.
The primitive races of pigs resist the disease better than the improved races. This mange can be conveyed to man and to other animals.
Symptoms. It usually commences about the head, ears, and eyes, and extends to the quarters, internal surface of the thighs, etc. In the early phases it is impossible to discover the little galleries under the epidermis, but closely placed reddish papules may be seen. The active proliferation of the epidermis, together with discharge, causes the formation of dry crusts of a greyish-white, silvery tint, adherent while still thin, easy to detach at a later stage, and sometimes ⅜ of an inch in thickness. The skin becomes wrinkled, the bristles are shed or loosened in their follicles, and are glued together in little bunches before falling. As these patches extend over the whole surface of the body, the animal appears to be bespattered with dry guano (Muller).
Under the crusts the skin is rough, excoriated, and, about the thorax and abdomen, is indurated, and sometimes measures 1 to 1½ inches in thickness. In other parts, particularly at the base of the ears, the papillæ are hypertrophied; they become as large as a pea, or even a bean, and, lifting the crusts which cover them, assume the appearance of the warts sometimes found on the cheeks of dogs or the teats of cows. Sarcoptes may be found under these epidermic growths, though in order to obtain them the skin must be scraped until it almost bleeds.
The dimensions of these parasites render them visible to the naked eye. They are the largest variety of the sarcoptinæ, the egg-bearing female being half a millimètre in length. Guzzoni has found in the ears specimens of smaller size.
Mange in pigs develops slowly. When it affects the whole body, it prevents fattening and causes loss of condition.
Diagnosis. This is the only parasitic disease which affects the entire surface of the body and presents these peculiar powdery crusts.
Treatment. All the styes should first be carefully disinfected. Treatment is commenced by vigorously scrubbing the animal with a brush dipped in soap and water, and thus getting rid of the crusts as far as possible.
The animals are afterwards dressed with decoctions of tobacco, with Helmerich’s ointment, or the other mixtures above mentioned.