During cold weather the mites burrow under the hair for protection causing itching. The symptoms reduce during the summer but the mite population does not die out completely, leaving a nucleus for re-infestation the following winter. Heavy draught horses and cobs are the most usual hosts and laboratory tests have revealed that the mite does not survive on Thoroughbred skin. Infected animals frequently stamp their feet in an effort to relieve the itching. Young foals have been known to be affected all over the body.
Veterinary treatment is necessary and skin samples taken for diagnosis.
It has only been recognised in horses in the last few years but is often fatal. Some of the first symptoms are facial paralysis, head tilting to one side and sometimes seizures. Veterinary treatment using sulfonamides and an antimalarial drug has been found to be successful in some cases. Vitamin E supplements have also been advised together with a monthly check on the affected animal's blood. New studies are being carried out in the hope of finding better treatment.