3.2.3 General medical history
A variety of previous problems may provide evidence of other conditions which may complicate, or which may have been mistaken for signs of cardiac disease. Therefore, a general medical history should always be recorded. In addition specific signs of potential cardiac disease which may be recognised by the owner should be known. These include exercise intolerance or prolonged recovery after exercise (see below), peripheral oedema formation, and even a pounding heart or irregular heart rhythm noted by the rider.
Respiratory signs are a particularly important subject for detailed questioning. It should be established whether a cough has been present at any stage. Although coughing is a relatively uncommon sign of cardiac disease, it can be seen in animals with pulmonary oedema, and may also have been caused by respiratory infections which can be associated with subsequent myocardial disease. For this reason, it should be established whether a viral illness has affected that individual or other horses in close proximity. Other infectious conditions such as bacterial pneumonias may also affect the animal and be mistaken for signs of cardiac disease. Allergic small airway disease is still an under-recognised cause of signs varying from coughing to poor athletic performance, and owners should be closely questioned about air hygiene. Dyspnoea and tachypnoea may be seen in animals with left-sided congestive heart failure (CHF) and pulmonary oedema, but can also result from respiratory disease. Epistaxis has been reported in a number of animals with cardiac disease. It is most commonly associated with arrhythmias such as atrial fibrillation and atrial premature complexes in athletic animals. However, exercise-induced pulmonary haemorrhage usually occurs without underlying heart disease.
Musculo-skeletal problems are a very significant cause of poor athletic perand should not be forgotten even in a horse which is suspected to have a cardiac disease. Mild bilateral lamenesses are most commonly overlooked. Myopathies associated with exercise are a potential cause of poor athletic per(see section 8.2.1). Aorto-iliac thrombosis is an uncommon cardiocause of ischaemic myopathy (see section 6.10.5).
Other problems such as colic, diarrhoea and any recent weight loss should also be noted. Occasionally these may result from cardiac disease. Diarrhoea and weight loss are often seen in animals with CHF. Weight loss is a common feature of endocarditis and may be the primary presenting complaint. Questioning about vaccination status and worming history may be important in some instances, for example where viral illness is suspected or when anaemia results in a haemic murmur.