Tetralogy of Fallot

Tetralogy of Fallot is a structural condition of the heart that is present from birth, involving four connected abnormalities that together affect how blood flows through the heart and out to the body. The core issue is that oxygen-poor blood may bypass the lungs and mix with oxygen-rich blood, meaning the body receives less oxygen than it would in a normally formed heart. Owners most often notice this condition in young animals, particularly puppies, who may tire more easily during play, breathe more rapidly at rest, or appear less vigorous than their littermates. In some cases, the mucous membranes—gums, tongue—can take on a bluish tint, particularly after exertion. The severity can vary; some animals show signs early in life, whilst others may cope reasonably well for a period before limitations become apparent. This page explores the patterns that can appear, what is happening structurally inside the heart, how the condition is investigated through examination and imaging, and the range of approaches that exist for managing it. Each animal presents differently, and the course depends on the degree of abnormality and how the body adapts over time.