Conditions or ailments that are the cause of a problem that you see - your observation.

Your vet may diagnose

Dermatophilosis, Rain Rot

Synonyms: Rain Scald, Cutaneous Streptothricosis, Dermatophilus Congolensis


This is a common bacterial skin infection that causes very distinctive "paintbrush crusts" to form on the skin. It is most commonly seen on the topline and lower limbs. The bacterial infection and inflammation causes the skin to ooze serum that sticks the hairs together in the classic way. These peel off together in a shape akin to a broad paintbrush stroke, leaving pink skin underneath.

This condition is more common in situations where the skin stays moist for extended periods of time. It is easily transmitted horse to horse via tack and grooming equipment, human handlers and insects.

The organism can live in removed hair crusts for a very long time so disposal of these is advised. The condition is not typically itchy (pruritic) but severely affected horses may be in discomfort from it, and removal of crusts may be painful. It is seen commonly in horses that are debilitated and immune suppressed from other causes.

my vet's role


Prognosis is usually very good with removal of the crusts and direct treatment with antibacterial shampoos. Ten minutes contact time is always advised with any skin treatment.

further reading & resources

Related References:

Higgins AJ, Snyder JR eds. The Equine Manual. 2nd Ed. Edinburgh: Elsevier Saunders 2006.

Author: Doug Thal DVM Dipl. ABVP