There are more options today for treating systemic fungal infections in foals and horses, but owners should be prepared for a long haul–treatment takes a long time, it's expensive, and the infection can reoccur.

Fungal infections can cause a host of systemic problems, such as pneumonia, meningitis, and aggressive sinusitis and rhinitis, and they can cause abortions in pregnant mares. Some diseases are so aggressive, horses have to be euthanized.

Early treatment is best, but clinical signs can be vague, and the infection might not be diagnosed until the horse is very ill and teaming with fungi.

"Often the first signs are weight loss, anorexia, fever, and diarrhea," said Allison J. Stewart, BVSc (hons), MS, Dipl. ACVIM, Dipl. ACVECC, of Auburn University, at the ACVIM Forum 2010 veterinary meeting held in Anaheim, Calif