We have seen a few cases of angiostrongylus (so called lung worm or french heart worm) recently. In all cases the dogs were referred for investigation of known heart disease that was not responding to the usual medications. The presenting signs may mimic congestive heart failure caused by common diseases such as mitral valve disease and dilated cardiomyopathy: breathing difficulties, pot belly, exercise intolerance, cough or can be associated with internal haemorrhage and anaemia. The parasite is spread by foxes and carried by slugs. It may be avoided by the uses of appropriate worming medication available from vets.