What it is
Blood returning from the body passes through the right side of the heart, which pumps it through the pulmonary valve into the lungs to pick up oxygen. When that valve or the passage around it is narrowed, the right ventricle has to squeeze much harder to push the blood through. Over time its muscular wall thickens, and the blood rushing through the tight opening makes the turbulent sound a vet hears as a murmur.
The defect is present from birth and is linked to inheritance. A puppy with a mild narrowing can grow up looking completely normal.
How the defect affects daily life depends on how tight the narrowing is. A dog with a more severe form may tire sooner, pant harder after play or need more rest. Noticing how much exercise your dog enjoys, and whether that changes, helps you spot when the heart is struggling.
Signs you may notice
- Tires quickly on walks
- Heavy breathing after exercise
- Swollen belly
- Fainting or collapsing
- Reluctant to play
A mild form may cause no signs at all, and a vet may simply hear a heart murmur at a puppy check. With a more severe one the dog tires quickly, breathes heavily after exercise, may develop a swollen belly or faint, and if the dog faints it needs a vet immediately.
When to see a vet
If your dog faints or collapses, it needs a vet immediately. Tiring sooner than before, breathing harder after mild effort or a swelling belly is worth booking a visit for.
This is general information, not veterinary advice. For your own dog's health, tests and treatment, see a vet.