News from Your Equine Health Care Provider | Vol. 2 |2014
Medical Reasons for Poor Performance By: Bonnie Barr, VMD DACVIM
IN THIS ISSUE EQUINE HEALTH
Medical Reasons for Poor Performance Demystifying the Lameness Exam NEWS
2014 Hats Off Day 2014 Kentucky Experience 2014 National Horse Show 2014 TOBA Sport Horse of the Year Around the Practice
The most common reason for poor performance is lameness, but performance issues can also result from medical problems. Problems of the lower respiratory tract, such as inflammatory airway disease, can result in poor performance. Inflammatory airway disease (IAD) is characterized by poor performance, exercise intolerance, coughing, and nasal discharge. Any age can be affected but this is a syndrome of predominately young horses. IAD is probably due to several factors such as low-grade persistent infection, inhaled allergens or reaction to blood in the airways secondary to exercise induced pulmonary hemorrhage (EIPH). Diagnosis is best made by ruling out other causes of respiratory disease. Endoscopic examination of the trachea is used to identify increased mucoid airway secretions. Bronchoalveolar lavage (BAL) is then recommended for all horses with suspected IAD. This procedure can be performed in a sedated horse, using a 2 or 3 meter endoscope or special BAL tubing. The endoscope or BAL tubing is passed through the nasal passage, into the trachea and into to the airways. Warm saline is placed into the lungs, then immediately drawn out for analysis under the microscope. Horses with IAD will have increased inflammatory cells, such as neutrophils, eosinophils and mast cells, but no evidence of an infection. Treatment involves environmental alterations to decrease exposure to allergens and administration of anti-inflammatory agents. Fig 1:ECG/EKG of Atrial Fibrillation. Exercise-induced pulmonary hemorrhage (EIPH) is a condition affecting all horses during intense exercise. Common presenting complaints include poor performance and bleeding from the nostrils (epistaxis). The development of EIPH is believed to be due to rupture of blood vessels deep in the lung resulting in blood in the airways. The usual method of diagnosis is endoscopic detection of blood within the trachea shortly after a race or strenuous exercise. Another indicator of bleeding is the presence of red blood cell breakdown product (hemosiderin) in inflammatory cells within the lungs when a transtracheal wash or BAL has been performed. There are many proposed treatments for EIPH although none are universally successful. Often, after an episode, horses are rested and monitored Fig 2: Gastric Ulcer. for secondary complications. Administration of furosemide (also known as Lasix™ or Salix™) is the most common method of prevention, although this is not without controversy. Abnormal heart rhythm can also result in poor performance and exercise intolerance. Atrial fibrillation (AF) is the most common abnormal heart rhythm affecting performance. During AF, the heart’s upper chambers beat irregularly and out of coordination with the lower chambers, which results in poor blood flow to the body. The diagnosis of AF is by listening to the heart with a stethoscope and noting the characteristic irregularly irregular heart rhythm. An ECG/EKG confirms the diagnosis. AF can be caused by electrolyte abnormalities, infection or underlying heart disease. Occasionally the AF will be transient and resolve in 24-48 hours. Persistent AF treatment includes administration of medications or electrical stimulation to coordinate the heart chambers. Treatment is usually successful and recurrence is low. Gastric ulcers are a common medical condition in performance horses. Numerous publications have identified that up to 60% of show horses have ulcers and up to 90% of racehorses may develop gastric ulcers. Clinical signs associated with gastric ulcers are numerous and often vague. Typical symptoms include poor performance, poor hair coat, picky eating and colic. The gold standard of diagnosis is gastroscopy, which is visualization of the stomach with a 3 meter endoscope. The endoscope is inserted through the nose into the esophagus and then into the stomach. If gastroscopy is not available therapy can be started if gastric ulcers are strongly suspected and improvement suggests that the horse had gastric ulcers. Several risk factors have been identified that make a horse more prone to the development of gastric ulcers including confinement to the stall, feeding high grain diet, intermittent feeding, strenuous exercise and administration of non-steroidal anti-inflammatory drugs (ie Bute or banamine). The primary goal of treatment is to suppress gastric acid. The most commonly used product is omeprazole (GastroGard™), which is administered by mouth daily for 28 days. Other medications that are used to treat gastric ulcers include H2 blockers (ranitidine or cimetidine), antacids and gastric protectants. Environmental and dietary modifications may also be beneficial to facilitate ulcer healing and in prevention of gastric ulcers. Management changes include increasing the amount of roughage/forage in the diet, decreasing the amount of grain in the diet, feeding frequent small meals, increasing turn-out and limiting stress. Fig 3: Nasal Blood Excretion due to EIPH. So keep in mind if your horse is performing poorly it may not be due to lameness!