Debility, ringworm, nodular hair. Hair bursts with brush like end. Cases in horse like singed hair. Causes: infection probable, disturbed innervation, dry air, impaired nutrition. Treatment: shave, oil, vaseline, petroleum, cantharides, sulphur, tar, favor shedding coat.

In a variety of conditions the hairs split up and break, leading to bristling or baldness. In debilitated conditions, when the hair is badly nourished, in ringworm when it is invaded by a cryptogam, and in the various nodular or ringed conditions of the hair this brittleness and splitting appears. The term Trichorrhexis (rexis a bursting forth) has been applied to one of these affections, in which the hair swells and bursts into a number of filaments giving it a broom-like termination. Trofimo describes this as affecting two-thirds of the horses of an artillery brigade, and showing upon the back, croup, mane and tail in isolated patches. Megnin, Trasbot and Roy have observed similar cases. The affected hair a short distance from the skin swells into a grayish white nodule and breaks across, leaving a tuft of fine filaments. The patches look to the naked eye as if singed, but when the hair is magnified the difference is easily made out, as there may be several nodular enlargements on the same hair, and the brushlike spread of filaments at the broken end is entirely unlike the solid node on the end of a singed hair.

The causes of the affection have not been demonstrated, though indications point to an infection which gradually extends from the first point of attack. This extension is not limited to the area presided over by particular nerves, and there is no other indication of disordered innervation. Trasbot has seen the disease transmitted from horse to horse by the use in common of combs, brushes and rubbers, and in other cases experimentally by rubbing the scurf from a diseased animal on the skin of a healthy one. From observations on the human subject Montgomery looks on it as a result of extreme dryness and brittleness of the hair, and charges dry climates and seasons, and an abuse of soap in washing as conducive causes. Debility and impaired nutrition of the hair may operate in the same way. No specific microbe has been constantly found in these cases and until such factor can be proved, it may be held that among the etiological agents impaired nutrition and dry air are important.

In the way of treatment shaving of the affected parts and oily or vaseline applications may be tried, together with such slight cutaneous stimulants as petroleum, weak tincture of cantharides, sulphur, tar ointment, etc. Roy noticed that cases that had lasted all winter recovered after shedding of the coat. It might be assumed that the evulsion of the infected hair, and the vascular stimulus necessary to the new growth contributed to the result.