Non-Parasitic Skin Disease in Sheep

Non-Parasitic Skin Conditions

Dermatophilosis (lumpy wool, mycotic dermatitis, rain scald):

·         Common skin disease worldwide. Not much of a problem in the UK, where there is little high quality wool production. Caused by Dermatophilus congolensis which is spread during wet conditions and close contact during gathering etc.

·         Clinical presentation: in the UK it is encountered along the dorsum in short-wooled breeds. It causes serum exudation and scab formation at the base of the wool fibres, which then slowly grows out. Usually encountered during summers when there is high rainfall after shearing. Discrete 3 – 5 mm “bottle-brush” lesions are often found around the muzzle and on the margins of the ears.

Photosensitization (yellowses, plochteach, alveld, facial eczema)

·         Typically, white-faced lambs aged 2 – 6 months are affected during summer months. In sheep, it occurs as a primary condition or secondary to liver damage. Primary condition follows ingestion of photodynamic agents; eg. Hypericin (Hypericum perforatum) which is a drug synthesised from a chemical found in the plant ‘St. John’s Wort’.

·         Clinical presentation: initially, affected animals are dull and seek shade. The ears are particularly affected, becoming swollen and pendulous. The face, eyelids, lips and lower limbs may also become oedematous. There is frequent head-shaking and often self-trauma to the head by rubbing against objects. Necrosis of the ear tips develop within a few days, which give a “curled-up” appearance.

·         Treatment: affected sheep should be confined in the shade to prevent further exposure. Corticosteroids are helpful during the early stages to reduce associated oedema. Topical antiobiotic and fly control powders can be helpful.

Periorbital Eczema

·         Common skin condition when sheep have too little space when feeding at troughs.

·         Clinical presentation is that sheep have swollen and painful eyelids blocking vision in that eye.

·         Treatment: single intramuscular injection of procaine penicillin affects a rapid response within 24 hours. Ewes with impaired vision in both eyes should be kept inside. Provide more space at feed troughs.