The hog louse (Haematopinus suis) is the only louse to affect pigs. It is a large sucking louse (order Anoplura) measuring up to 5-6mm. The nymphal stages often are found deep inside the ears, around the ears, elbows and between the legs. Adult lice may be found in the scurfy skin layer anywhere on the body. The lice are irritant to their host, causing reduced voluntary feed intake and Daily Live Weight Gain. The lice are also considered to be a vector for the spread of swine pox. Transmission tends to occur by pig to pig contact, although ova can survive in warm environments for up to 3 weeks. Buildings vacated by infested stock should be thoroughly cleansed prior to next use. The Avermectin class of anthelmintics (eg. Ivermectin) are effective against lice. Routine use is often given to sows on entry to the farrowing house. An eradication dosing programme would require the whole herd to be treated twice, 3 weeks apart.
The species of ringworm which affects pigs is Trichophyton mentagrophytes. The clinical signs are brown, circular, slowly enlarging areas on back, flank and behind ears with low level pruritus (itchiness) and alopecia (hairloss). These lesions are found across all age groups, since environmental spores are the main source of infection. The condition is probably unimportant to the pig but infection can pass to humans, and care should be taken when handling infected animals. The disease is self-limiting, although progression through a herd may take weeks or months. Lesions can be washed with chlorhexidine, or off-license use of Imaverol wash.
Mange in pigs is most commonly of the Sarcoptic form, caused by infestation with Sarcoptes scabei var suis, which are burrowing mites. The result of infestation is intense pruritus (itchiness) which causes self-excoriation and loss of condition due to reduced feed intake. The lesions will appear a few weeks after initial infestation. The lesions develop from raw patches, particularly around the eyes, snout and in the axillae (armpits). Scabs and crustiness of this skin results from excoriation as a result of the itching. Hair loss is common and may be the most noticeable feature. Aural haematomas can result from head shaking. Avermectins are given subcutaneously and will clear mites over a period of 1-2 weeks. If severe crusty lesions are present in the ears of animals, the treatment should be repeated after 14 days to ensure coverage of mites which are found in the ear wax. Avermectins can also be used in control, with treatment most effectively given prior to entry into the farrowing accommodation, to prevent infestation of the piglets.