Cardiovascular Diseases of Horses

CARDIOVASCULAR DISEASES OF HORSES A horse's heart weigh's approximately 9 to 20 g/kg (19.8 to 44 Ibs) 0.9 to 1% of it's body mass. Trained and elite horses can have heart weights of 1.1% and 2.2%, respectively. -4g/kg (8.5 lbs) PRIMARY OBSERVED SIGNS Increased heartrate Poor Performance Collapse Ventral oedema Respiratory distress Nasal discharge Coughing Sudden death Cold extremities Depression Loss of appetite Cyanosis Ataxia Jugular pulses COMMON HEART CONDITIONS Cardiac arrhythmias Heart murmurs Myocardial disease An irregular heartbeat is an arrhythmia A heart murmur is an extra or unusal Bacterial/viral myocarditis/Endocarditis (dysrhythmia). Arrhythmias may be caused sound heard during a heartbeat. may be linked with respiratory infections. by many different factors including: Many are harmless, which are r Myocardial degeneration and necrosis can be eferred to as "innocent". vitamin E/selenium deficiency or toxicity, • Electrolyte imbalances in the blood thrombo-embolic events, acute ischaemia, Changes in the heart muscle • Severe cardiac disease atypical myopathy, rattlesnake bites, • Can also occur in “normal, healthy" ingestion of ionophores in feed, blister hearts beetles, or cardiac glycoside containing plants. Congenital heart defects Mitral regurgitation Aortic insufficiency These are abnormalities that horse's are Mitral regurgitation (MR) is often Aortic insufficiency (Al) occurs commonly born with. Some of these include: discovered in horses presented for in middle-aged to older horses (>10 years heart failure. It is the most common of age). The condition usually progresses Ventricular septal defects (VSD) Patent ductus arteriosus (PDA) cause of heart failure syndrome in slowly, however once signs are evident, Atrial septal defect (ASD) horses. It is important to check for the horse should immediately be retired f Tetralogy of Fallot this during a pre-purchase exam. rom ridden exercise. Tricuspid atresia Truncus arteriosus DIAGNOSIS History Physical exam Auscultation Echocardiogram Electrocardiogram TREATMENT OPTIONS ACE inhibitors They are a type of vasodilator that is used to treat high blood pressure and heart failure. Anti-arrhythmics Used to control the horse's heart rhythm. Anticoagulants Known as blood thinners. They prolong the clotting time of the horse's blood. Diuretics Used to remove the excess fluid from the tissues and blood stream to reduce the symptoms of heart failure. Transvenous electrical Recently introduced alternate treatment for horse's with atrial fibrillation. cardioversion (TVEC) Vasodilators Used to help lessen the amount of work the horse's heart has to do. SOURCES McGurrin MK, Physick-Sheard PW, Kenney DG, Kerr C, Hanna WJ. Transvenous electrical cardioversion of equine atrial fibrillation: technical considerations. 2005. Journal of Veterinary Internal Medicine. Chapter 7: Cardiovascular system. Equine Medicine and Surgery HorseDVM Chapter 31: Heart and vessels function during exercise and training adaptations, Equine Sports Medicine and Surgery Chapter 32: Diseases of the heart and vessels, Equine Sports Medicine and Surgery