Preventing Equine Ailments with Fly Control

Horses are susceptible to many ailments spread or made worse by flies. Prevention in the form of a solid Integrated Pest Management (IPM) program goes a long way in protecting horses from diseasecarrying flies.

There are many ailments attributable to flies that can be mitigated with IPM. Many of these ailments are endemic to certain areas of the country, so problems in one state may not be a problem or as severe in another.

Some common ailments attributable to flies include: Pigeon Fever is caused by a bacterium called Cornebacterium pseudotuberculosis that lives in soil and dust and is more common in dry, arid regions, particularly in the western United States. It can be carried and spread by horn flies (Haematobia irritans), house flies (Musca domestica) and stable flies (Stomoxys calcitrans). These flies act as mechanical vectors by picking up the bacteria from the soil and carrying it on their bodies where it is transferred to the horse when the flies feed on the horse. The bacteria can also infect open wounds and mucous membranes if the horse is laying or feeding on contaminated soils or bedding. A third means of transmission is directly from horse to horse via physical touch (infected horse chews his own infected wound, and then grooms another horse, etc). The most notable symptom is the development of abscesses in the chest and midline that cause swelling resembling a pigeon’s breast.

Summer sores (Habronemiasis) are caused by the larvae of stomach worms, primarily those in the genera Habronema and Draschia. Summer sores are most common in warm, humid regions of the United States. These worms primarily live in the stomachs of horses where they cause few problems. However, when the adults begin to breed, larvae of the worms are deposited in the horse’s manure. Adult house flies and stable flies then pick up the larvae when feeding on manure and transfer the larvae to any open wounds, mucous membranes, eyes of horses they subsequently land on. When the worm larvae are deposited in these areas, it can lead to an inflammatory reaction that leads to the development of summer sores. The most notable characteristic of summer sores are granulomatous lesions that have

a greasy appearance, may have yellowish discharge, and are slow to heal.

Eye worms

are caused by the nematode Thelazia and is medically known as Thelaziosis. Eye worms are most common in areas with high humidity and high fly populations. These worms are parasites that live in the conjunctival sac of the horse’s eye. When the adults release larvae, they are picked up by flies feeding around the eyes. The worm larva matures inside the fly and the new adult worm is then transferred back into another horse’s eye while the fly is feeding. These are spread primarily by face flies (Musca autumnalis) and house flies (Musca domestica). Eye worms can cause excessive tearing, conjunctivitis, and corneal ulcers.

Sweet itch

is an allergic reaction in horses caused by the bites of insects, primarily the Culicoides midge but can also be triggered by black flies (Simuliidae), mosquitoes, and other biting insects. Symptoms of Sweet itch include severe itchiness, especially around the mane, tail, withers and back. This can lead to excessive rubbing, biting, and scratching of affected areas and lead to hair loss and skin thickening.

In addition to the ailments above, wound healing can also be delayed if flies are not kept away from the wound. Serious wounds could result in myiasis (maggots in the wound) from blow flies (Calliphoridae). Flies like house flies, stable flies, horse flies and deer flies (Tabanidae), and eye gnats as well as others can all cause slow wound healing due to increased feeding behavior on or near the wound which can also lead to secondary bacterial infections.

Fly Predators kill one of the main species that transmits eye worms, which is house flies (Musca domestic) and can kill the species most responsible for the transmission of pigeon fever and summer sores, said Spalding Labs Chief Science Officer Jessica Starcevich. That makes them a key part of an effective IPM program. JESSICA STARCEVICH

All of the above diseases and ailments vectored by house flies and stable flies in particular can be managed on a property by using a good IPM program that includes:

good manure management to reduce fly breeding locations

traps along perimeters to intercept migrating flies

using Fly Predators® for biological control to kill developing flies

using an effective repellent like Bye Bye Insects®

using fly sheets on animals

To learn more about upgrading a current IPM program to include Fly Predators® and other Spalding Labs fly control solutions, visit Spalding-Labs.com