Objectives: To evaluate population characteristics, clinical signs and simple echocardiographic measurements of a general practice population of cats, in identifying characteristics that reliably distinguish cats with heart disease from others, including those with respiratory disease, using widely available techniques.

Methods: Cats presented with heart disease (n=103), respiratory disease (n=19) and a normal group (n=29) were prospectively recruited. All cats were subject to full clinical examination, echocardiography and additional diagnostic procedures as appropriate to establish definitive diagnosis. Cats were classified as Group 1: no heart disease ± respiratory disease; Group 2: heart disease with no clinical signs; Group 3: heart disease with clinical signs. Murmur, gallop sound and arrhythmia prevalence and left atrial size were compared between the groups.

Results: Low heart rates prevailed in Group 3. Murmurs were prevalent in Group 2, but in Group 3 prevalence was significantly lower. Dyspnoea, gallop sounds, arrhythmias and left atrial diameter were significantly different between groups.

Clinical Significance: Heart rate is unreliable for diagnosing heart failure in cats. Absence of murmur is prevalent in cats with clinical signs of heart failure, but arrhythmia and gallop sounds are prevalent. Echocardiographic measurement of left atrial diameter >16.5 mm may distinguish heart failure from respiratory disease in general practice.