There are several different types of external parasites that can easily find a great place to live, feed and grow right on your horse. Good parasite control is simple, relatively low cost, and can prevent many types of anemia, secondary bacterial infections and even discomfort for your horse. Most external parasites that feed and live on horses also can affect other animals, including humans, so keeping your stables and horses free from parasites is helpful in several ways.
Some of the most common external parasites found on horses are mites. These small, microscopic parasites can live on the skin, under the skin or in the hair follicles themselves. Each type of mite will cause itching and discomfort for the horse as well as allergic reactions to the toxins they produce. Hair loss and secondary bacterial infections due to scratching and licking are often the first signs of a mite infection. Mites can also live in the ears and will cause a dry, scabby look to the ears and cause a dark, foul smelling waxy discharge from the ears. While not fatal themselves, a severe mite infection in an already compromised horse can be life-threatening.
Ticks are another problem for horses as they can, in severe infestations, cause anemia due to blood loss. Ticks can also carry sleeping sickness, Lyme disease and may be linked to Equine Infectious Anemia or EIA. Ticks will move from host to host so are capable or transmitting disease from wild and domestic animals, making control essential. Ticks in the ears can result in the horse becoming hypersensitive to being touched on the head and also producing droopy ears.
Lice may be one of two varieties, blood sucking or biting lice. The blood sucking louse is most problematic as it will cause anemia, hair loss and can even stunt growth and development of foals if found in great enough numbers. The biting louse feeds off hair and dead skin cells and will also cause hair loss, although it is less problematic than the blood sucking variety. Lice are more significant in horses in poor condition, although they are not directly linked to carrying any diseases.
There are many different types of flying parasites and insects that bother horses. Since the bites of these flies are painful, they cause the horses to constantly be on the move and irritated, often contributing to weight loss and anxiety in horses that are exposed to high fly populations. Horses may also become anemic in the summer months when flies are most numerous. Horse flies, stable flies, deer flies and mosquitoes all can be carriers of serious and potentially fatal diseases such as sleeping sickness, equine infectious anemia and swamp fever.
Non-disease carrying insects such as midges, horn flies, face flies and black flies can cause lesions, dermatitis and even secondary infections on the belly, around the eyes and the neck and between the legs of horses that can be very problematic.
Control of external parasites requires treatment with either spray or wipe on insecticides or powders on a routine basis during the fly and parasite seasons. Clean, dry bedding and good ventilation in stalls and stables will also help reduce fly populations. Steaming or disinfecting stalls, blankets and brushes can also help prevent spreading any parasites from horse to horse.