Diagnosis overview
After a consideration of the signalment and history, a thorough physical examination, including all body systems, should be performed. A provisional diagnosis of cardiac disease can often be made following auscultation of the heart and lungs.
Further diagnostic procedures including radiography, electrocardiography and blood tests may then be carried out to establish whether heart failure is present, what the likely cause is, how severe it is and whether any complicating factors are present. Radiography should be carried out in every patient with suspected heart failure. Other tests are ideally carried out, but may not be possible or indicated in every case.
The American College of Veterinary Internal Medicine (ACVIM) has provided guidelines for classification and diagnosis of chronic valvular heart disease1, which provide some useful guidance.
ACVIM diagnosis recommendations for chronic valvular heart disease (CVHD)1
| Stage | Description |
| A (at risk) | Annual auscultation Breeding dogs to participate in breed schemes (where available) |
| B (disease, no signs) | Thoracic radiography (all patients) Blood pressure (all patients) Echocardiography: - small breeds: only if cause of murmur is not clear - large breeds: all dogs, as murmur more likely due to other diseases than CVHD Basic laboratory work (blood tests) |
| C (heart failure) | Thoracic radiography, especially to exclude tracheobronchial disease (all patients) Echocardiography is preferred Basic laboratory tests are preferred |
| D (refractory) | As for ‘C’ above |
Classification systems of heart failure
There are various classification systems to assess the severity of heart failure. In general, these measure the clinical severity of disease (i.e. how bad are the clinical signs). They do not necessarily measure the severity of the underlying disease. With treatment, the stage of heart failure may improve. The most commonly used classification systems are:
- ACVIM Consensus Panel
- ISACHC (International Small Animal Cardiac Health Council)
- Modified NYHA (New York Heart Association)
ACVIM Consensus Panel classification1
ISACHC (International Small Animal Cardiac Health Council)2
| Class | Criteria |
| IA | Heart disease present No clinical signs No signs of compensation (no left ventricle volume overload) |
| IB | Heart disease present No clinical signs Signs of compensation on echocardiography or radiography (e.g. left ventricle volume overload or left atrial enlargement) |
| II | Mild to moderate heart failure Clinical signs at rest or mild exercise At rest, no evidence of hypoperfusion |
| IIIA | Advanced heart failure Clinical signs immediately obvious Death or severe debilitation likely without treatment. Home treatment possible |
| IIIB | Advanced heart failure Clinical signs immediately obvious Death or severe debilitation likely without treatment. Hospitalisation mandatory (e.g. cardiogenic shock, life threatening pulmonary oedema |
Modified NYHA (New York Heart Association)1
| Class 1 | Heart disease on clinical examination No clinical signs |
| Class 2 | Clinical signs during strenuous exercise Normal at rest |
| Class 3 | Clinical signs during normal activity or mild exercise |
| Class 4 | Severe clinical signs, even at rest |
References: 1. C. Atkins et al. (2009) JVIM, 23: 1142-1150. 2. BENCH (1999). JVC, 1(1): 7-18.