Cats which die from heartworms can be clinically normal 1 hour before death. All cats with peracute death in heartworm endemic areas should be examined for heartworm disease. In acute cases as few as 1 worm has been found accompanied by severe pulmonary congestion, infarction and edema. The worms in the acute syndrome are not always found embolizing the main pulmonary arteries. Vomiting and respiratory signs are the predominate complaints in chronic clinical cases, although it is unusual for an infected cat to exhibit both symptoms concurrently.
Vomiting tends to be sporadic.
The etiology of vomiting in heartworm cats is unknown although the release of inflammatory mediators from the lungs which stimulate the chemoreceptor trigger zone has been hypothesized. The vomitus generally contains food or foam and is rarely bile stained. Retching and severe paroxysmal vomiting is a rare historical findings. Heartworm disease in endemic areas should be included in the differential diagnosis of chronic emesis in the cat. The most common respiratory complaints are coughing and intermittent dyspnea.