ABSTRACT
Congenital cardiac malformations most often involve either a valve (or valve region) or an abnormal communication between the systemic and pulmonary circulations; valve malformations can cause insufficiency, stenosis, or both. Other cardiac defects occur sporadically. Multiple anomalies sometimes occur in the same patient. Certain breed predispositions are recognized (Table 51)1, 2. Most congenital cardiac defects cause an audible murmur (see Chapter 6), but some do not. Murmur intensity (loudness) as well as clinical signs commonly relate to the defect’s severity, although other factors can modify this. Some serious anomalies have no associated murmur. ‘Innocent’ murmurs are also relatively common in young animals1. Innocent murmurs are usually soft, systolic ejection-type murmurs heard best at the left heart base; their intensity may vary with heart rate or body position. Innocent murmurs diminish with time and
generally disappear by about 4 months of age. Murmurs associated with congenital disease usually persist and some get louder as the animal grows (e.g. subaortic stenosis). Careful evaluation at full maturity is especially important in animals that might be used for breeding. Radiographic and ECG findings can be useful, but echocardiography with Doppler provides greater diagnostic accuracy3.
