Horse Health and Pastures
by Dr. R. Dean Scoggins, Equine Extension Veterinarian, Univ. of Illinois College of Vet Medicine
The most important health issue concerning horses on pasture is internal parasites. The strongyle type of intestinal worms develop and are protected by the grass and the dew or rain on the forage. Horses should be dewormed with a broad spectrum anthelmintic before being turned out on pasture and retreated appropriately during the time they are on pasture, eight week intervals being the common recommendation. Horses coming off pasture should be treated for bots and tapeworms as well.
Pastures should be inspected for toxic plants and have them removed before tuning horses out. While many are not highly palatable, intensive grazing may reduce forage to the point that horses will graze toxic plants. White snakeroot, deadly nightshade wild onion, red maple trees, black walnut, and locust seed pods plus numerous other plants are capable of causing illness and death especially in old established permanent type pastures with low wet areas and or wood lots.
Pastured horses should be kept on a good vaccination schedule, especially with protection against E&W encephalomyelitis, tetanus and rabies. In the Midwest, skunks are the primary carrier of rabies and the horses natural curiosity causes them to lower their heads to investigate strange objects or animals resulting in their being bitten on the nose. Rabies is always fatal in any warm blooded animal that contracts it, so there are no options. Annual vaccination is the only protection.
Protection against biting insects is helpful in maintaining the normal health and condition of pastured horses. Fly tags in manes and tails, pour-on materials that provide some residual effect and environmental aspects are all helpful. For safety reasons, NO HORSE should be turned out with its halter on, so repellant products should not be placed on the halters. Face fly masks should be of the break-away variety so if hoses get the mask caught, they can get loose.
Horses are continuous grazers and do best when pastures are a grass mix with minimal legume. Fescue is not considered a safe pasture for pregnant or nursing mares, but is quite satisfactory for non-pregnant mares and geldings. By keeping it mowed and preventing the presence of seed heads,
the danger of endophyte toxicity is reduced. By proper management and preventing any grass to reach the seed head stage, any risk of ergot toxicity is likewise avoided.
The avoidance of clovers in a pasture mix avoids other problems. The white clovers, especially alsike tends to cause a condition called photosensitivity dermatitis. This affects the liver and the unpigmented areas of the horses' body. This can be a mild rash to a very severe "sunburn" with sloughing of the skin. The answer is to spray the pastures to control the clover. Red clover is occasionally infected with mold that contains slafranin. This is a toxin that infects the plant and is active in either green forage or in hay. It`s a powerful irritant that causes horses to salivate excessively resulting in their drooling large volumes of saliva. While not dangerous, it's a nuisance and a mess.
Health issues cover several areas of horse management. Pre-planning allows the owner to prevent and avoid problems rather than having to deal with them later.
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