Mange is a parasitic disease of the skin caused by one of two mites either Sarcoptes scabiei or Demodex phylloides. Sarcoptic mange (sometimes called scabies) is by far the most common and important because it is irritant and uncomfortable for the pig, causing it to rub and damage the skin which becomes unsightly. It significantly depresses growth rate and feed efficiency. The life cycle is direct and takes 14-15 days from adult to adult to complete. The mite dies out quickly away from the pig, under most farm conditions, in less than five days. This is an important factor in control. If a herd is free from mange, it is one of the easiest of diseases to keep out because it can only be introduced by carrier pigs. However, once it is introduced it tends to become permanently endemic unless control measures are taken.
Symptoms
Piglets
- Skin irritation after 7 days.
Sows
In acute disease:
- Ear shaking.
- Severe rubbing of the skin against the sides of the pen causing reddening. Approximately three to eight weeks after initial infection the skin may become sensitised to the mite protein. A severe allergy may develop in some pigs with very tiny red pimples covering the whole of the skin.
- Intense irritation and rubbing to the point where bleeding may occur.
In chronic disease:
- Thick asbestos-like lesions on the ear, along the sides of the neck, the elbows, the front parts of the hocks and along the top of the neck.
Weaners & Growers
- Its presence affects food conversion and daily gain, particularly if the weight of infection is heavy.
- Tiny red pimples over the skin.
- Irritation and rubbing/scratching.
- Ear shaking.
- Chronic condition – Thick asbestos like scabs, mainly on the ears, often with slight bleeding and constant rubbing.
- Poor growth.
Causes / Contributing factors
- The mite spreads directly from pig to pig, either by close skin contact or contact with recently contaminated surfaces.
- The boar helps to maintain infection in the herd because he is constantly in direct skin contact with breeding females and he remains a chronic carrier.
- If pigs are housed in groups there is increased opportunity for spread.
- Newly purchased pigs.
- Disease is more easily spread where sows are group housed.
- Continually housed pens.
Diagnosis
This is confirmed by demonstrating the presence of the mite. Scrapings are taken from suspicious lesions on the skin and particularly inside the ears. A teaspoon is an ideal instrument to scarify material from the interior of the ear. This material can be spread onto a piece of black paper and left for ten minutes. Mange mites which are rounded in shape and only 0.5mm in length may be just visible to the naked eye. However to positively identify the mite the scrapings should be submitted to a laboratory for microscopic examination. An ELISA blood test is also available.