Coming to Terms with Common Ailments

Anyone new to the horse world will hear many terms that may be confusing or unfamiliar. Following are basic explanations of some terms that refer to health conditions. For more detailed information, check with a veterinarian or an experienced horse owner.

Abscess: An infection in any location can cause an abscess, which is a collection of pus within tissues. Often refers to an infection within the hoof caused by bruising or other injury. Usually results in severe lameness, treated by cutting into the sole to release pressure and to clean out the infection.

Bleeding: Also called exercise-induced pulmonary hemorrhage or EIPH. Blood that originates in the lungs is visible in the upper airway passages and occasionally the nostrils after exercise, and affected horses are called “bleeders.” It is estimated that at least 70% and possibly close to 100% of Thoroughbreds have some amount of bleeding after hard exercise. Incidence is somewhat lower in other breeds. Exact causes, including elevated blood pressure in the lungs, are still being studied. Bleeding can be treated with diuretics (medications that increase urination). Some racetracks do not allow horses to race while on medication for bleeding.

Colic: Abdominal or intestinal discomfort, ranging from mild to severe. Signs may include pawing, nipping or kicking at the flanks and belly, sweating, or repeated lying down and getting up. There is a variety of causes including stress, parasites, change of feed, moldy hay or feed, toxic plants, gastric ulcers, medications, or a buildup of gas. Horses are not able to relieve discomfort by burping or vomiting. While mild colic may resolve without treatment or with the administration of pain medications, colic caused by impaction or torsion (twisted intestines) may require surgical intervention. Colic can be a serious or fatal condition, so examination by a veterinarian is recommended to determine cause and treatment.

EPM: Equine protozoal myeloencephalitis, a neurologic disease caused by protozoal infection. Signs can be mild (occasional stumbling) or severe (collapse). Spread when horses ingest hay, grass, or grain contaminated by waste from infected opossums and some other animals. Treatment may be expensive, long-term, and not completely effective.

Founder/laminitis: These terms are often used interchangeably to describe inflammation of the laminae, the layers of tissue that join the hoof wall to the primary bone within the hoof. Signs include reluctance to move, obvious discomfort when moving, hooves that are warmer than usual, and a leaning-back posture to take weight off front feet. Many causative factors including overconsumption of carbohydrates in feed or grass. May follow foaling or other stress. Injury to one leg may cause founder in the opposite leg due to increased weight-bearing. Founder is more common in the front feet, but may affect any or all hooves. Severe founder is life-threatening; early treatment minimizes damage to hoof structures.

Heaves: Restriction of airflow, somewhat similar to asthma in humans. Heaves is caused by an allergic reaction to dust, mold, or other particles the horse inhales. Signs may include exercise intolerance, coughing, a thin clear nasal discharge, and a visible effort to exhale. Horses sensitive to airborne particles in the barn or stall often improve when turned out, while those sensitive to pasture mold may get better when kept in the barn. Management changes and medication may be included in treatment.

Lame, “three-legged” lame: A horse that shows any deviation from normal free movement is a lame horse. Gait abnormality may be a result of pain or stiffness in the neck, back, or legs. It may be extremely subtle or quite obvious. A horse that won’t put weight on one leg is “three-legged” lame. Lameness is often most obvious when the horse is trotting. Sometimes mild lameness can be most easily detected by listening for changes in gait rhythm when a horse is trotted on a hard surface. Many causes and many associated treatments.

Laminitis. See Founder.

Navicular syndrome: The navicular bone is located above the frog at the rear of the horse’s hoof. Pain in this area is often diagnosed as navicular syndrome. Navicular pain may be suspected if the horse develops a short, stilted gait. Theories related to cause include conformation, overuse, arthritic changes in the navicular bone, and irritation of the deep digital flexor tendon that runs across the navicular bone before attaching to the coffin bone. No single theory fits every case. Treatment may involve corrective trimming and shoeing as well as medication to control pain. Severe cases may be treated by neurectomy (severing the nerves to the area so the horse no longer feels discomfort).

Slobbers: Every time the horse opens his mouth, what looks like pints of saliva drain out. This horse “has the slobbers.” A likely cause is ingestion of an irritant like a common fungus that grows on red clover and other legumes. Usually not as serious as it looks, although in extreme cases the horse can become somewhat dehydrated. Provide plenty of fresh drinking water.

Sound, unsound, pasture-sound: While some people use “unsound” and “lame” as synonyms, “sound” technically refers to all body systems while “lame” refers to gait. Therefore, a horse is certified “sound in wind and limb” to denote proper and normal function of respiratory and musculoskeletal systems. A horse with heaves, for example, might be unsound although it is not lame. A horse that isn’t visibly lame but won’t hold up to training or work, possibly due to an old injury like a bowed tendon, might be described as “pasture-sound.” Such an animal can stay comfortable if it is turned out or lightly ridden, but its days of steady hard work are over.

Splint: A bump on the inside, and less commonly on the outside, of the leg below the knee or hock. Causes can include conformation, exercise, and injury. Though they may be painful at first, many splints heal and do not cause further problems.

Strangles: A highly contagious respiratory disease (not the same as “choke” in which a horse’s esophagus becomes engorged with grain).

Tying-up: A condition characterized by severe cramping of the muscles in the horse’s loin, croup, and hindquarters. There are several causes including genetic factors. Many horses that tie up find relief on a diet that limits carbohydrates and supplies energy from fat and fermentable fiber.

West Nile virus: In 1999, some horses on the east coast of the United States developed a low fever, dullness, and mild neurologic signs. A few horses became very ill, and a small number died. The cause was West Nile virus, spread by the bite of an infected mosquito. The disease has moved across the country in the intervening years.Eliminating places where mosquitoes can breed is an important prevention measure. A vaccine is available to protect horses.