A rough coat can be the sign of a problem. Instead of lying flat, the hairs form an uneven surface. The ends of the hairs look dull and reddish, and they stand up. A buildup of dead skin, dirt, and loose hairs affect the appearance of the coat. Dermatitis, or inflammatory skin disease, can include signs such as cracks, lesions, nodules, and wheals.
Skin diseases can be bacterial, fungal, parasitic, allergic, or scaling.
Some common conditions include rain rot, seen in some climates during the summer. This condition is caused by the anaerobic bacterial organism Dermatophilus congolensis . It is not a fungus. Don't clip a horse with wet skin. Prevent transmitting the infection through isolating the horse's tack, blankets, and grooming tools.