THE MERCK VETERINARY MANUAL
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Mange in Pigs

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Sarcoptic mange (Sarcoptes scabiei var suis) is the only form of any importance in pigs. Mange mites are typically introduced to a herd after the purchase of infested breeding stock, and spread after direct contact is rapid. Unless SPF derived or following mange eradication, all pig herds must be considered potentially infected even if acaricides are used routinely in some groups of animals. Survival of the mite eggs away from the host is limited; however, exposure for as little as 24 hr to pens that have been immediately vacated by previously infested pigs has resulted in infestation. Laboratory experiments indicate that mites did not survive >96 hr at temperatures <25°C or >24 hr at 20–30°C. Survival was <1 hr at temperatures >30°C.

S scabiei suis infestations are negatively correlated with daily weight gains and feed conversion in pigs. The lesions usually start on the head, especially the ears, then spread over the body, tail, and legs. Itching is usually intense and associated with a hypersensitivity reaction to the mites. As the hypersensitivity subsides, usually after several months, the thickened, rough, dry skin is covered with grayish crusts and thrown into large folds.

Diagnosis is best performed by combining different approaches: dermatitis score recorded at slaughter, scratching index, observation of clinical signs of mange, ear or skin scrapings for microscopic examination, and ELISA for detection of specific antibodies. The usefulness of each criterion may vary according to the group age. This global approach is particularly useful during an eradication campaign.

Spraying with lindane (0.05–0.1%) or malathion (0.05%) is effective; chlordane solution (0.25%) also has been used. (Use of some or all of these on food-producing animals is prohibited in some countries.) Ivermectin and doramectin (300 μg/kg, SC) are also effective. Due to the major economic impact of sarcoptic mange on the pig industry, local, regional, and national eradication programs have been developed. These are very cost effective and typically include 2 injections of ivermectin or doramectin (300 μg/kg, SC) given to all pigs in the herd on days 0 and 14. On day 7, piglets born during the previous week are also treated. Alternatively, an in-feed medication (ivermectin premix, 100 μg/kg) can be administered for 2 wk. In this case, suckling piglets or diseased pigs are injected twice at a 14-day interval at the start and end of the feed medication (ivermectin or doramectin, 300 μg/kg). An application of acaricide to the premises is not usually required. After treatment, a certification protocol is followed. It is based on a combination of clinical (scratching and dermatitis indices), parasitologic (ear and skin scrapings), and serologic data from a representative number of animals belonging to different age groups.

Demodectic mange is also seen in pigs, causing skin lesions similar to those seen in other large animals. There is no reliable treatment.

Last full review/revision July 2011 by Bertrand J. Losson, DVM, PhD, DEVPC; Bernard Mignon, DVM, PhD, DEVPC

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