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