Chorioptic mange, or "leg mange," is quite common in draft horses with long hair or feathers on their legs. Caused by tiny, burrowing mites, it first appears as pustules and, as it advances, there is hair loss, crusting and thickening of the skin. Typically chorioptic mange occurs on the feet and fetlocks of the distal limbs, but it can affect the body and base of the tail. Symptoms of chorioptic mange subside during warm weather but will flare up again when the weather turns cold. If left untreated, this condition will become chronic, but fortunately, there are many treatments available for your horse.
In a study conducted at Glasgow Veterinary School (2007), Dr. David Rendle and colleagues concluded that two injections of doramectin given 14 days apart is an effective treatment for chorioptic mange. No discernible side effects were seen.
The same Glasgow study also concluded that a fipronil solution, sprayed directly onto the affected areas, was equally as effective as doramectin. There were no notable side effects.
Researchers at Tanat University in Egypt (2006) concluded that administering oral moxidectin gel is an "effective and good alternative" for the treatment of chorioptic mange.
According to Dr. Bob Judd, a veterinarian, horse caretakers should first clip the hair from the affected areas, then apply an antibiotic paste mixed with liquid ivermectin to heal infection and kill mites.
Lime Sulfur Dip
Judd also suggests using a lime sulphur solution on the affected areas of the horse. Lime sulphur solutions are effective for killing mites, so if there are secondary infections present, oral antibiotics will be required.
Oral Ivermectin Paste
A 1995 study conducted by Dr. J.D. Littlewood, Dr. J.F. Rose and Dr. S. Paterson concluded that oral ivermectin paste, although unable to completely eradicate mite infestation on horses, produced a "statistically significant reduction" in the number of mites present.