TOBA: Thoroughbred Owners and Breeders Association
Owner Education

Common Injuries and Ailments

EIPH or Bleeding

Exercise-Induced Pulmonary Hemorrhage (EIPH), commonly known as bleeding, has been known to afflict Thoroughbreds since the early 18th Century. Tom Biracree and Wendy Insinger point out in their book The Complete Book of Thoroughbred Horse Racing that reference to bleeding can be found in the name of the early 18th Century English stallion Bleeding Childers. Subsequently his name was changed to Bartlett's Childers. Bartlett's Childers is the great-grandsire of Eclipse, the horse which 80% of all modern Thoroughbreds trace their parentage.

EIPH is characterized by bleeding from the lungs after strenuous exercise. According to an article in the UC Davis Center for Equine Health's The Horse Report, recent studies suggest that anywhere from 70 to 100 percent of horses in racing and training experience EIPH. It is believed horses experience EIPH because during exercise they have unusually high blood pressures in the vessels that lead from the heart to the lungs and this high pressure causes the walls of the vessels to break and release blood into the airways.

The American Association of Equine Practitioners (AAEP) recommends for a horse to be declared ineligible to race for a minimum of 10 days after the first incident of EIPH. If a second incident occurs, recommended ineligibility is 20 days. Ineligibility for at least 60 days is recommended for third and subsequent incidents. After the third incident it is at the discretion of the track veterinarian in consultation with the practicing veterinarian and trainer when the horse is declared eligible to race.

HELPFUL TIPS: EIPH Facts vs. Fiction

Reprinted with permission from the UC Davis Center for Equine Health.

Fiction: If you can't see any blood in the nose after exercising, there was no bleeding (EIPH).

Fact: Most cases of EIPH occur internally with no external sign of bleeding. In Japan, researchers analyzed 250,000 racing starts and found that bleeding from the nose occurred in less than 0.2 percent of the racing starts. However, in studies using an endoscope, in which a tube is passed via the nose and the veterinarian looks into the airways, researchers found that 50-70 percent of all horses that race experience EIPH at some time. In studies that evaluated airway cellular debris, results suggest that perhaps 100 percent of racehorses experience EIPH.

Fiction: Only Thoroughbreds running flat races experience EIPH.

Fact: Bleeding can occur with almost any type of severe exercise in horses, even with draft animals pulling heavy loads. Some horses pull up and show evidence of bleeding immediately after sudden exertion (e.g., the start of a Quarterhorse sprint). Some evidence suggests that bleeding might be more frequent in shorter, higher intensity events. At UC Davis, horses on the treadmill have bled severely when simply changing from a trot to a canter.

Fiction: Lasix will prevent a horse from bleeding.

Fact: The diuretic Lasix can be legally administered four hours before a race to horses that have been documented with a history of bleeding. Although Lasix does lower blood pressures slightly, there is no proof that it reduces the incidence or severity of bleeding. Several studies have found evidence indicating that Lasix measurably improves racing performance; however, it dehydrates the horse prior to the race, as well as dilutes any drug residues that might be in the urine. Recent evidence indicates that Lasix causes only a slight improvement in racing performance.

How do I tell if my horse is bleeding?
In rare cases, a horse may spray blood from its nose while exercising or after abruptly pulling up. In other unusual cases, there may be a thin trickle of blood showing from one or both nostrils up to two hours after a workout. The most common way to diagnose EIPH is by passing a flexible endoscope into the horse's airways to view the blood that is being cleared from areas of the lungs where bleeding occurred. This is usually done one to two hours following exercise. Over time, repeated EIPH incidences will lead to changes in lung structure as a reaction to the blood in the airways. In extreme cases, large areas of the lung's upper rear portion may consolidate to become unusually solid which may be detectable with radiographic imaging.

Bowed Tendon

An inflammation and enlargement of the flexor tendon at the back of the front cannon bone. The general cause is severe strain. Back at the knees, long, weak pasterns, a long toe and low heel and improper shoeing are all predisposing causes. The bowed appearance is due to the formation of fibrinous tissue. Bows are classified as low, medium or high depending on location. Treatment usually requires long periods of rest; six months to a year on the farm is normal. The use of enzyme injections, laser and surgical procedures are all currently being used to try and treat this injury. Less than 50% of horses suffering a bowed tendon come back successfully.

Bucked Shins

An enlargement on the front of the cannon bone between the knee and the fetlock joints. This enlargement is due to trauma to the periosteum (thin sheathing which covers the bone), most often caused by concussion. Generally, the condition is confined to soreness, but if a periostitis (calcium deposit) occurs new bone growth can result that gives one the perceived look of a "bucked" shin. This injury occurs most often in young horses in heavy training.

The goal of treatment of a bucked shin is to thicken the front cortex of the cannon bone. This can be done by continued light training with a gradual increase in intensity or pin firing. Pin firing is a therapy whereby a red-hot probe is used to cauterize the affected area to produce a serous inflammatory response. The serum appears to flush out the other inflammation in the area. A horse that has been pin fired usually requires two to three months of rest before training can resume. The benefits of pin firing are open to debate, with some vets believing there is little or no benefit to the practice. Once healed bucked shins rarely recur.


A calcification or bony growth, usually occurring on the inside of the cannon bone or splint bones. It typically results from a tear of the interosseous ligament that binds the splint bone to the cannon bone, but can result from any inflammation of the periosteum. This condition is most commonly caused by concussion with a hard surface. Blistering (a therapy similar to pin firing), surgery and rest are all treatments.

Torn Suspensory Ligament

The suspensory ligaments run from the top end of the back side of the cannon bone (and knee or hock) down to the sesamoids and the pastern bone. These are among the most stressed of all tissues in the racehorse's body, and are therefore one of the most common sites of injury. The treatment is usually six to nine months of rest and an additional three to four months of re-training.

Bone chip in the knee or ankle

Pieces of broken bone off the knee or ankle (usually from racing stress). If chips remain attached they may not interfere with the action of the horse's leg, but can be extremely painful and usually require removal by arthroscopic surgery. If it is determined that the chip should be removed, arthroscopic surgery is performed followed by three months of rest and an additional three to four months of re-training. The cost of the surgery is approximately $2,000.

Slab Fracture

A break in the knee whereby the "slab" of a carpal bone splits and the front part becomes detached. This can often be repaired surgically. While a slab fracture does not necessarily mean the end of a horse's career, it is a serious injury. See Fractured Leg.

Condylar Fracture

A fracture of the condyle of the cannon bone. The condyle is the bulbous bottom or distal end of the cannon bone that fits into the fetlock joint. Condylar fractures can be repaired surgically. The prognosis for survival and a return to racing soundness is dependent on the severity of injury. In uncomplicated cases, after surgery to fix an uncomplicated condylar fractures, the horse normally is given stall rest for one month, followed by stall rest and hand-walking for another month. After this 60-day period, follow-up x-rays are taken to determine the rate of healing. If all is going well, there likely is another two to four weeks of paddock exercise before the horse might resume training. In the case of more severe fractures, the recovery period could encompass many months before the horse is ready to return to training. See Fractured Leg.

Sesamoid Fracture

The sesamoids are two small, delicate bones located at the back of the fetlock, held in place only by ligaments. These little bones located just behind the pastern serve as pulleys over which the deep digital flexor tendons pass. A fracture to the sesamoids usually involves an injury to the suspensory apparatus. Depending on the severity of the injury, surgery can be performed to treat the fracture. See Fractured Leg.

Fractured Leg

A fractured leg requiring the placement of screws in the cannon bone or pastern will cost from $2,000 to $3,500, depending upon the complexity of the fracture. In addition, the horse will require four to eight months of rest and another three to four months of re-training.


A hard enlargement on the rear of the cannon bone immediately below the hock. It begins as an inflammation of the plantar ligament and the inflammation leads to a thickening of the ligament.

Grabbed Quarter

While running, the horse "grabbed" one of its front hooves with a rear hoof, tearing skin and tissue. Cost and amount of training time lost depends on the extent of the injury.

Quarter Crack

Under stress, or if improperly shod, the hard substance of the hoof (similar to the human fingernail) can crack and become a source of pain - sometimes including the development of an infection in the exposed soft tissue underneath. This ailment can be corrected with a fiberglass or epoxy patch, and shoeing. Cost and amount of training time lost, if any, depends on the extent of the injury.


Colic is a general term used to describe pain in the gastrointestinal tract of a horse. Colic can happen any time to any horse and has many causes. It is the number one killer of horses. Treatments vary depending on the type of colic and its severity. A "simple" colic may cost around $100 for treatment. More severe or prolonged colics can cost several hundred dollars to treat. If the colic is severe enough to require surgery, the cost of treatment can be several thousand dollars.

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