The Approach to Cases of Feline CHF: A Summary for Veterinarians

Feline heart disease is a significant concern in veterinary cardiology, requiring timely diagnosis and effective management to improve outcomes. As a progressive and often silent condition, it can lead to severe complications, including feline congestive heart failure (CHF) and cardiogenic shock, if not promptly addressed. This guide provides a concise summary of causes, treatments, and management strategies for clinicians in general practice.  

Recognizing feline CHF in cats with respiratory distress 

Respiratory distress is a common presentation in cats with CHF, but other causes of breathing difficulties must also be considered. Observing the respiratory pattern is critical for narrowing the differential diagnoses and can be done hands-off in cats in respiratory distress. 

Respiratory patterns and postures 

Cats with cardiogenic respiratory distress often exhibit a restrictive breathing pattern, with rapid and shallow breaths. In contrast, lower airway diseases like asthma tend to produce an obstructive pattern with prolonged expiration. 

• Postural adaptations, such as sternal recumbency with an extended neck and abducted elbows, signal significant respiratory effort. 

• Persistent open-mouth breathing is rare and typically indicates a grave condition requiring immediate stabilization.
   

Taking a thorough history 

Gathering detailed information about the onset, duration, and progression of symptoms is invaluable. For example: 

• A chronic cough is more indicative of lower airway disease or neoplasia than CHF, CHF rarely presents with a cough in cats. 

• Gagging or retching points to upper airway or nasopharyngeal issues. 

• Syncope or episodic weakness can hint at cardiac arrhythmias.
   

Physical examination: 

When you move on to a physical examination, take extreme care not to stress the cat. Don’t forget: 

• Mucous membrane color and capillary refill time. 

• Thoracic auscultation for murmurs, gallop sounds, or arrhythmias. 
• Palpation and percussion of the thorax and abdomen for pleural effusion or diaphragmatic rupture. 

Diagnostic tools:  

Focused thoracic ultrasound to assess left atrial size and NT-proBNP testing can help confirm cardiac involvement. Cats with CHF typically have significant left atrial enlargement. 

How to stabilize feline CHF cases in the hospital 

When it comes to stabilization, veterinarians need to act quickly. The goal is to alleviate respiratory distress while minimizing further stress.  

• Oxygen therapy: Ideally, use an oxygen cage to administer oxygen, as masks can be stressful and flow-by is less effective. Flow-by can be used during the physical examination but shouldn’t be used long-term. 

• Furosemide administration: Intravenous administration is preferred for its quick action, but intramuscular routes are often chosen for cats in severe respiratory distress to reduce stress. Typical dosages range from 1–2 mg/kg every 1–2 hours until respiratory rate improves. 

• Light sedation: Butorphanol (0.1–0.2 mg/kg IM) is commonly used to reduce stress in distressed cats, avoiding heavy sedation that could suppress cardiac and respiratory function. 

Monitoring is essential throughout stabilization, and cats should transition to oral medications once their condition has improved. 

The causes of feline heart failure 

The most common cause of feline congestive heart failure is hypertrophic cardiomyopathy (HCM), which can sometimes be accompanied by systolic anterior motion (SAM) of the mitral valve. This complication should be carefully considered when planning therapy. Other notable causes include: 

• Restrictive cardiomyopathy, dilated cardiomyopathy, and arrhythmogenic right ventricular cardiomyopathy. 

• Congenital heart disease  

• Systemic conditions like hyperthyroidism and anemia. 

• Drug-induced heart failure, such as from corticosteroids or intravenous fluids. 

• Transient myocardial thickening (TMT): A condition resembling HCM caused by myocardial swelling, often linked to catecholamine toxicity and stress. Careful history-taking can help differentiate TMT from other causes, as it is often preceded by a stressful event within two weeks. While cats with TMT may initially present in critical condition, their long-term prognosis is excellent with appropriate treatment. 

A detailed workup, including imaging and blood tests, is critical for identifying the root cause and guiding management. 

Medications for Long-Term Management 

Managing feline CHF over the long term involves a combination of medications tailored to the individual case: 

• Antithrombotics: Clopidogrel is recommended to prevent aortic thromboembolism. 

• Inotropic drugs: Pimobendan can improve outcomes in HCM but should be avoided in cases of SAM. 

• Diuretics: Torsemide is a potent alternative for cats with furosemide resistance or difficulty with frequent dosing. 

• Electrolyte management: Address hypokalemia with potassium supplements or spironolactone as needed. 

• Antiarrhythmics: Diltiazem and low-dose lidocaine can manage atrial fibrillation and ventricular arrhythmias, respectively. 

Routine monitoring of renal function and electrolytes is essential to minimize adverse effects. 

Home management of feline heart failure 

Client education is vital for successful at-home care. Key points include:

1. Monitoring respiratory rates: Owners should count sleeping respiratory rates, with fewer than 30 breaths per minute considered normal. Rates above 40 may indicate pulmonary edema. 
2. Emergency measures: Provide instructions for administering furosemide (1–2 mg/kg every 12 hours) if signs of CHF recur. Follow-up at the clinic is recommended if symptoms persist. 
3. Regular rechecks: Cats should be reevaluated within 1–2 weeks of an acute episode, with renal and electrolyte panels checked periodically. 

Prognosis in feline CHF cases 

Survival times for cats with feline heart failure can vary widely, ranging from days to several years. The heterogeneity of underlying causes plays a significant role in this variability. On average, survival ranges between six months to a year. Cats with structural heart disease may experience recurrent episodes of feline CHF, necessitating lifelong therapy. 

Client communication and quality of life 

Educating owners about feline CHF is essential for effective management. Explain the prognosis, treatment goals, and potential complications clearly. For cats with poor appetite or medication tolerance, prioritize diuresis to maintain comfort. Options such as pill pockets and appetite stimulants like mirtazapine may help improve compliance. 

Quality of life should remain the primary focus, as longevity can be secondary in advanced cases. Consistent communication with one veterinarian ensures continuity and tailored care. 

Conclusion 

Feline heart failure presents unique challenges for veterinarians, but early detection and individualized treatment can significantly improve outcomes. By focusing on proactive care and effective client communication, veterinarians can help ensure the best possible quality of life for affected cats. 

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