Horses can be prone go chorioptic mange

By Gary Sliworsky
OMAFRA Rep.

Following is the latest Horse News and Views which is prepared by Dr. Bob Wright, Animal Health and Welfare, OMAFRA, in cooperation with the staff and researchers of the University of Guelph.
The monthly column highlights research topics, extension resources, reminders of common poisonings, disease or production concerns and coming events and is placed on our website, http://www.omafra.gov.on.ca/english/livestock/horses/news.html.
A surprising finding in horse pastures this summer was flax with its sparkling blue flowers. The seed is very small for chewing; most of it goes undigested through the horse’s digestive system and is deposited back on the pasture to grow again next year. The feeding of flax can be a concern since it contains a source of cyanogenic glycosides. Researchers at the University of Guelph, however, in a study to reduce the effects of the recurrent seasonal pruritus known as “sweet itch” in horses, fed milled (crushed) flaxseed at 1 lb. per 1000 lb. of body weight per day for 42 days with no negative side effects. (Ref: O’Neil, et al. Flaxseed (Linum usitatissimum) supplementation associated with reduced skin test lesional area in horses with Culicoides hypersensitivity. Can J Vet Res 2002; 66(4):272-277.)
Horse breeds, especially those with feathers (the long hair around the fetlock and pastern areas of the legs), are prone to chorioptic mange. It is caused by a mange mite, Chorioptes equi. Mites can be identified by applying “Scotch Tape” to the skin and viewing them under a microscope. Clinical signs include irregular skin lesions, severe itching and sometimes biting of affected skin areas, and decreased feed consumption. The skin lesions start mainly as an erythematous area (redness of the skin), followed by the development of papules (small swellings) and crust formation. Horses often traumatize their legs as a result of the severe itchiness. Consult your veterinarian as to diagnosis and treatment. (Ref: 1. Rendle DI, et al. Doramectin and fipronil in the treatment of equine chorioptic mange. Vet Rec 2007; 161(10):335-338. 2. Osman SA, Hanafy A. Clinical and therapeutic studies on mange in horses. Amer SE Vet Parasitol 2006 Oct 10; 141(1-2):191-195. Epub 2006 Jun 19.)

For further information, contact Dr. Bob Wright (519) 846-3412 or visit our
website: http://www.omafra.gov.on.ca/english/