By Dr Andrew Tucker – CS Vets
Mange is caused by Sarcoptes scabiei, a small burrowing mite 0.5 mm in length. These mites burrow into the skin and feed on skin cells. The burrowing and feeding activities cause itchiness and then scratching causes the release of fluid (serum) near the mite burrows. This fluid forms the crusts that then form on the skin. Thickening of the skin also occurs in infected areas and secondary bacterial infection is possible.
The life cycle is typically as short as 14 to 15 days. The female lays ±50 eggs in the burrow where they hatch and mature. Spread of the mite is via direct pig to pig contact e.g. sow to piglets or sow to sow in the gestation housing. Mites can survive off the host for up to three weeks under laboratory conditions, but they have only been shown to live for up to 12 days under farm conditions and this becomes even shorter in warmer climates.
How do you know if it’s on your farm?
Affected pigs scratch and this is often the first sign. Small red inflamed lumps (smaller then mosquito bites) are the first lesions seen. These then develop after scratching into brownish scabs. The skin later becomes wrinkled, thickened and covered in brown crusts. Lesions can be anywhere but are mainly in areas where the skin is thinner e.g. axillae (area between front legs), on front and inside of hind legs, on the abdomen and the inside the ears.
Production figures will drop in moderate/severe cases with weaning weight dropping as much as ten percent, sow feed usage increasing five to ten percent and growth rate in the finishers decreasing five percent or more.
Clinical signs are indicative of the disease and various laboratory tests are available to confirm the diagnosis.
How do you treat or prevent it?
Ivermectin and Doramectin are the typical products used worldwide to treat mange, although others are also available. Treatment can be via subcutaneous injection. In-feed medication options as well as topical pour on products are also possibilities.
Control requires regular treatments at specific key times. Please take note of the withdrawal period when using products to treat/control mange. Eradication is possible by treating the whole herd simultaneously twice with an appropriate interval. Housing may in certain instances also have to be washed, treated or rested to ensure the success of the eradication.
Pig Diseases – D.J. Taylor; Diseases of Swine – Straw, Zimmerman, D’Allaire, Taylor