Overview of Heart Disease in Cats
Heart disease is one of the most common serious health problems in cats. According to research published in the Journal of Veterinary Internal Medicine (Payne et al., 2015), approximately 15% of cats have some form of cardiac abnormality, and many cases show no obvious symptoms before serious complications develop. Unlike dogs, where valvular disease predominates, the primary form of heart disease in cats is cardiomyopathy, with hypertrophic cardiomyopathy (HCM) being the most common.
Classification of Feline Heart Disease
| Type | Characteristics | Prevalence |
|---|---|---|
| Hypertrophic Cardiomyopathy (HCM) | Abnormal thickening of the ventricular wall, impaired diastolic function | Approximately 58–68% |
| Restrictive Cardiomyopathy (RCM) | Myocardial fibrosis leading to restricted diastolic filling | Approximately 10–15% |
| Dilated Cardiomyopathy (DCM) | Ventricular dilation with decreased contractility (often associated with taurine deficiency) | Approximately 5–10% |
| Unclassified Cardiomyopathy (UCM) | Cardiomyopathies that do not fit any of the above classifications | Approximately 10% |
Hypertrophic Cardiomyopathy (HCM) in Detail
HCM is the most common heart disease in cats, characterized by abnormal thickening of the left ventricular wall and/or interventricular septum (typically > 6mm), resulting in a reduced ventricular chamber size and impaired diastolic function. According to the ACVIM consensus statement (Luis Fuentes et al., 2020), diagnosing HCM requires ruling out conditions that may cause secondary myocardial hypertrophy, such as hyperthyroidism and systemic hypertension. HCM is highly heritable, and specific gene mutations (such as MYBPC3) have been identified in certain breeds.
Symptoms of Heart Disease
The most challenging aspect of feline heart disease is that there are often no symptoms in the early stages. According to ISFM guidelines, when the following signs appear, the disease has usually progressed to a moderate or advanced stage:
- Rapid or labored breathing: A resting respiratory rate > 40 breaths per minute is a significant warning sign
- Open-mouth breathing: Unlike dogs, cats do not pant; open-mouth breathing typically indicates severe respiratory distress
- Decreased activity: Reluctance to jump or play
- Hind limb paralysis: Arterial thromboembolism (ATE) can cause sudden hind limb weakness, pain, and cold extremities
- Fainting: Brief loss of consciousness due to arrhythmia or insufficient cardiac output
Important tip: Monitoring the sleeping respiratory rate (SRR) at home is an effective tool for early detection of cardiac decompensation. A normal cat's resting respiratory rate should be below 30 breaths per minute.
Diagnostic Methods
According to the ACVIM consensus statement, echocardiography is the gold standardfor diagnosing feline cardiomyopathy. Other supplementary tests include:
- Echocardiography: Measures ventricular wall thickness, left atrial size, and assesses diastolic and systolic function
- NT-proBNP blood test: Released when the myocardium is under stress; can serve as a screening tool
- Chest X-ray: Evaluates cardiac silhouette size, pulmonary edema, and pleural effusion
- Electrocardiogram (ECG): Detects arrhythmias
- Blood pressure measurement: Rules out secondary myocardial hypertrophy caused by hypertension
Treatment and Management
Asymptomatic Stage
For asymptomatic cats with HCM, there is currently no definitive evidence that early drug intervention improves prognosis. However, according to the FATCAT study published in theJournal of Veterinary Internal Medicine (Hogan et al., 2015), for cats with significantly enlarged left atria, clopidogrel can reduce the risk of thromboembolism.
Congestive Heart Failure (CHF)
- Furosemide: A diuretic to reduce fluid accumulation
- ACE inhibitors: Such as Benazepril, to reduce cardiac afterload
- Clopidogrel: To prevent blood clot formation
- Thoracocentesis: Drainage of pleural effusion when significant fluid accumulation is present
Prognosis
Prognosis varies depending on disease severity. According to data from the Journal of Veterinary Internal Medicine (Fox et al., 2018): asymptomatic HCM cats with normal left atrial size have a median survival time exceeding 5 years; once CHF develops, median survival time is approximately 12–18 months; if ATE occurs, the prognosis is poorer, with a median survival time of approximately2–6 months.
Breed Predisposition
| Breed | Notes |
|---|---|
| Maine Coon | MYBPC3 gene mutation A31P; genetic testing available |
| Ragdoll | MYBPC3 gene mutation R820W; genetic testing available |
| British Shorthair | Higher prevalence; specific gene mutation not yet identified |
| Persian | Higher prevalence |
| Sphynx | Higher prevalence |
References
- Payne, J.R. et al. (2015). Prevalence of cardiomyopathy in apparently healthy cats. Journal of Veterinary Internal Medicine, 29(5), 1366-1375.
- Luis Fuentes, V. et al. (2020). ACVIM consensus statement guidelines for the classification, diagnosis, and management of cardiomyopathies in cats. Journal of Veterinary Internal Medicine, 34(1), 3-17.
- Hogan, D.F. et al. (2015). Secondary prevention of cardiogenic arterial thromboembolism in the cat: The double-blind, randomized, positive-controlled feline arterial thromboembolism; clopidogrel vs. aspirin trial (FAT CAT). Journal of Veterinary Cardiology, 17, S306-S317.
- Fox, P.R. et al. (2018). International collaborative study to assess cardiovascular risk and evaluate long-term health in cats with preclinical hypertrophic cardiomyopathy. Journal of Veterinary Internal Medicine, 32(3), 1009-1021.
- ISFM. (2020). ISFM Guidelines on feline heart disease screening and management.