Hair Follicle Growth Arrest in Austrian Icelandic Horses

In a study conducted in 2003, 20 out of 70 Icelandic horses in Austria experienced seasonal hair loss and scaling, primarily on the ear base, temporal eye canthus, dorsal neck, and occasionally the cranial shoulder, with minimal itching. The condition first appeared in November 2001 after the herd was relocated and persisted until hair shedding in May/June 2002, reappearing in November 2002. Despite normal health otherwise, diagnostic tests for dermatophytes and ectoparasites were largely ineffective, and histopathology showed hair follicles entering a growth arrest phase. Blood tests were mostly normal, and feed analysis showed adequate mineral content. Supplementing the horses' diet with vitamins, iodine, cobalt, and selenium in 2003 successfully prevented the recurrence of hair follicle growth arrest during the following winter.