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What is congestive heart failure (CHF) in dogs and cats

Congestive heart failure (CHF) in dogs and cats occurs when the heart can't pump enough blood to meet the body's needs, leading to fluid build-up in the lungs, abdomen or both.  

Causes in dogs: mitral valve disease (leaky valve), dilated cardiomyopathy (heart muscle weakens), and congenital defects.  
 
Causes in cats: hypertrophic cardiomyopathy (thickened heart muscle), thyroid disease (hyperthyroidism).  



Written by Dr. Mariella Roberts, Veterinary Surgeon, Animal Trust Vets CIC | Published May 2025 | Review date May 2027 | This advice is for UK pets only and is not a replacement for seeing a vet

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Symptoms  

  • Coughing: persistent coughing, especially at rest or after exercise, can be a major sign of CHF, often due to fluid buildup in the lungs.  

  • Difficulty breathing: your pet may struggle to breathe, pant excessively, or have a rapid breathing (respiratory) rate, even at rest.  

  • Fatigue and exercise intolerance: dogs and cats may tire easily, be reluctant to exercise, or show decreased energy levels.  

  • Blue or gray gums: a bluish or grayish tint to the gums indicates a lack of oxygen in the blood, a common sign of severe heart failure.  

  • Distended abdomen: fluid buildup in the abdomen (ascites) can cause the belly to swell.  

  • Fainting: some dogs may faint due to reduced blood flow to the brain, especially after effort.  

When to contact your vet

If your dog or cat shows signs of difficulty breathing, coughing, or lethargy, particularly if these symptoms are worsening or accompanied by changes in gum color or appetite, contact your vet immediately. These could be signs of congestive heart failure (CHF) and require prompt veterinary care. 

Diagnosis

  • History and physical exam 

  • Chest X-rays: these can reveal heart enlargement, fluid in the lungs (pulmonary oedema), or other abnormalities.  

  • Echocardiogram (ultrasound of the heart): provides detailed images of the heart's structure and function, allowing for a more precise diagnosis and assessment of heart disease severity.  

  • Blood tests: can help identify underlying conditions or rule out other causes of symptoms.  

  • Urine tests: can assess kidney function and help rule out other conditions.  

  • Electrocardiogram (ECG): measures the heart's electrical activity and can detect heart rhythm problems.  

  • Holter monitor: a portable ECG that can record heart activity for 24-48 hours to detect irregular heartbeats or other rhythm disturbances.  

Treatment for congestive heart failure (CHF) in dogs and cats

Congestive heart failure (CHF) in dogs and cats is managed primarily through medications, dietary changes, and monitoring for signs of disease progression.  

  • Medications: diuretics (water tablets) to help remove excess fluid from the body, particularly in the lungs.  

  • ACE inhibitors: help reduce blood pressure and improve heart function.  

  • Pimobendan: improves heart muscle contraction and dilates blood vessels, helping the heart pump more efficiently.  

Other medications may be used to control heart rhythm and improve heart function, depending on the specific case  

Dietary and lifestyle changes:  

  • Low-sodium diet: limiting sodium intake can help reduce fluid buildup in the body.  

  • Limited activity: restricting exercise can help reduce strain on the heart.  

  • Supplements: vitamins, minerals, and antioxidants may be recommended to support heart health, but should be discussed with your vet.  

Prevention  

  • Regular veterinary check-ups: annual check-ups allow your vet to monitor heart health, identify potential issues early, and catch heart murmurs or arrhythmias, which can be early signs of heart disease.  

  • Weight management: maintaining a healthy weight through a balanced diet and regular exercise is crucial for overall heart health and reduces the risk of heart disease.  

  • Nutritious diet: feeding a balanced, high-quality diet, and potentially supplementing it with fatty acids and antioxidants, can support heart health.  

  • Parasite prevention: In areas with heartworms, regular preventative medication is essential. In the UK, you should also ensure your dog/cat is not exposed to slugs and snails, as they are carriers of lungworm.  

  • Breed awareness: some breeds are genetically predisposed to certain heart conditions, so you should be aware of the risks and seek early veterinary care for any concerns.  

  • Monitoring: you can also monitor your pet’s resting respiratory rate to identify changes in his/her need for oxygen. 

Outlook

The prognosis for dogs and cats with congestive heart failure (CHF) varies depending on the underlying cause and severity of the condition. Generally, survival time can range from a few months to several years. Early detection, proper medical care, and management of the underlying disease are crucial for improving the outlook and quality of life for affected animals.