What is Exercise-Induced Pulmonary Hemorrhage ?
The term bleeder is commonly applied to a horse which produces blood through the nostrils following a race or other activity involving heavy exertion at high speeds. The bleeding can occur during or after the race, and can take weeks to resolve in some horses. This condition can be the reason some horses perform poorly in such competitions. It is generally noted in Thoroughbred and Standardbred racehorses and is rarely seen in draft horses or those bred and used for endurance tasks and work. The theory seems to indicate the more extreme the exercise and faster the horse must run, the greater the opportunity for more horses to experience blood in the airways and lungs.
Exercise-induced pulmonary hemorrhage is the veterinary term for an equine who experiences blood moving into the airways and lungs during periods of extreme exertion, such as when racing.
Symptoms of Exercise-Induced Pulmonary Hemorrhage in Horses
You will know if your horse suffers from exercise-induced pulmonary hemorrhage or bleeding by the visual and auditory observations of these symptoms:
- The flow of blood from either or both nostrils following extreme exertion
- Mucous tinged with blood oozing from the horse’s nose
- Small amounts of blood noted on the horse’s feed bin - this can be noted as long as 24 to 36 hours after the race or activity of extreme exertion
- Unusual breathing noises like roaring or whistling while breathing deeply after exertion
- Unusual choking sounds when the horse is being exercised for longer periods of time
- Repeated swallowing within 15 to 30 minutes of having finished a race - this might also be coupled with signs of distress or uneasiness
If your horse displays any of the above symptoms, you might also take note of these things which could also support the presence of exercise-induced pulmonary hemorrhage in your horse:
- Your horse may display a hesitation to engage in normal activities for perhaps 3 or 4 days, displaying a slower recovery from the race or activities of extreme exertion for which the above symptoms were noted
- When the horse does participate in racing or working activities, higher speeds may not be sustainable and he may fall back
- Issues in regard to stride rhythms when the horse is urged to complete the race
Exercise-induced pulmonary hemorrhage or bleeding in horses seems to fall into two categories, each of which has specific causes and root issues:
- Bleeding from the lungs - A type which involves the blood actually coming from the capillaries in the lung - this can result in blood being seen coming from the nostrils but not always; this is the more prevalent of the two types, some estimates are as high as 75%
- Bleeding from the nose - A type which involves blood vessels located in the nasal airways that don’t necessarily involve the blood vessels in the lung - the percentage of horses suffering from this type is estimated to be approximately 5%
Causes of Exercise-Induced Pulmonary Hemorrhage in Horses
While there has not been a definitive cause established for this pulmonary hemorrhage condition, there is a process which is taking place inside the lungs which is believed to be the immediate reason for the bleeding or presence of blood in the airways of the horse.
- Increased activity requires an increase in the pumping function of the heart as well as an increased volume of blood required by the entire body of the horse to achieve the strength and endurance for the increased activity
- This increased pumping and volume of blood creates pressure within the blood vessels, raising blood pressure, raising the heart rate from 25 to 30 beats per minute at rest to 220 to 230 beats per minute during strenuous activity
- It is believed that the increased pressures within the blood vessels cause the capillaries to burst, allowing blood hemorrhages to get into the alveoli (air sacs in which the blood and gas exchange takes place in the lungs), eventually into the airways and into the nasal passages to flow from the nose
- This is the equine’s circulatory response to the stress that is placed on the equine during strenuous exercise, most often in the form of racing or running at high speeds
Diagnosis of Exercise-Induced Pulmonary Hemorrhage in Horses
Because there can be a number of root issues which can contribute to this condition, your veterinarian will need to get some specific information and do specific testing:
- Blood work
- A complete history will be needed from you about what you’ve noticed in your contact with the equine
An additional test that may be utilized is the endoscopic examination in which your veterinarian will use an endoscope to look into the airways of your horse. This endoscopic examination will provide more information if it is done within a 30 to 90 minute window after exercise. This procedure will help to eliminate other possible sources of upper respiratory hemorrhages like guttural pouch mycosis (a disease in the air sacs that are located in the neck that results from a fungal infection) and ethmoid hematoma (progressive and destructive masses of the nasal passages and paranasal sinuses).
As well, cytopathology, which is an examination of tissue samples, will be utilized to identify abnormalities within the various tissues in the pulmonary system. Other tests may be suggested:
- Scintigraphy, another imaging method which is similar to a bone scan, may be needed to get a multi-dimensional image of some of the tissues involved
- Radiography or x-ray will likely be utilized as well to identify the clinical signs and root issue causing the bleeding
Once a preliminary root cause can be established (or others ruled out), a treatment plan can be developed and initiated.
Treatment of Exercise-Induced Pulmonary Hemorrhage in Horses
The best treatment for exercise-induced pulmonary hemorrhage in horses is simply to reduce the repeat episodes. The more often the condition occurs, the more opportunity for scarring to occur which will eventually affect the equine’s performance and productivity, thus making this step in the treatment vital to the health of your horse. Here are some suggestions for treatments which have been helpful in treating this condition:
- Assess the horse’s environment for allergens, mold spores and fungi to reduce the exposure to these substances
- Take steps to assure good ventilation to provide fresher, cleaner air
- Assess the quality of the hay that is being fed - try to maintain good quality and avoid possible contaminates in the hay
- Avoid keeping the horse in its stall for many hours or days - turning the horse out for several hours a day allows the equine the ability to breathe fresh air and to graze in a more natural environment
- Clean the stall regularly and often to remove the possibility of inhalation and the subsequent irritation caused by the ammonia from urine
- For some horses, avoiding the feeding of a hay that is considered high protein, like alfalfa hay for example, is recommended as some vets feel the digestive process of proteins adds more ammonia to be excreted in the urine which exposes your horse to more of it to inhale
- Allow your equine to graze in a more natural position, i.e. with the head and neck down to avoid the possible inhalation of spores and dust from the hay that can occur when feeding is done at eye-level in a feeding bin
- Exercise the horse based on its individual needs and condition versus what might to needed to get ready for a particular race. This will likely require a step-by-step format to build strength and endurance in a healthy way for the horse
- Allow plenty of rest for your horse after a bleeding episode as some of these situations can take 4 to 6 weeks or more to heal properly
- Your vet may begin a course of Lasix (diuretic also known as furosemide) to be used before a race to help to reduce high blood pressure but even this isn’t a cure nor is it a guarantee that the bleeding episode will not be repeated
Recovery of Exercise-Induced Pulmonary Hemorrhage in Horses
Basically, there is no real treatment for exercise-induced pulmonary hemorrhage in horses but instead involves a supportive regimen being initiated and maintained not only after the bleeding episode but also may require changes to the environment, feeding and exercise habits of the equine to attempt to reduce the future episodes of bleeding with exercise. Generally, once a horse has had one episode, one should assume that it will be repeated. It is in this vein that it is recommended to assess the living conditions and all things environmental surrounding the horse to reduce the future episodes. Future episodes will only cause scarring which will, over time, reduce the performance and productivity of your horse.
Blood work can be performed by your vet that can show the propensity for hidden bleeding in your horse. The prognosis is not good for those horses having severe episodes of bleeding after exercise. If your horse is found in this category after this testing is done, you may be advised to allow 2 to 3 months of rest for those severely affected horses before training can be resumed in an attempt to reduce the chance of permanent lung damage being done.