From: American Heartworm Society. http://www.heartwormsociety.org/ 

New guidelines for the diagnosis, prevention, and management of heartworm (Dirofilaria immitis) infection in cats have been released by the American Heartworm Society (www.heartwormsociety.org/heart.htm). Heartworm disease in cats is different from the disease in dogs, but it is still a serious problem. Even a small number of worms can be life-threatening. The adult worms may not be found in the heart but may be found in aberrant places, and they do not need to reach a mature adult state to cause respiratory disease. A syndrome called heartworm-associated respiratory disease has been described. There are demonstrable histopathologic lesions of occlusive medial hypertrophy of the small pulmonary arterioles. Other changes are also noted in the bronchi, bronchioles, alveoli, and pulmonary arteries. Clinical signs are nonspecific and include intermittent vomiting, coughing, asthma-like attacks, and lack of appetite or weight loss. Sudden acute signs of collapse and death may also occur.

COMMENTARY: The American Heartworm Society and the American Association of Feline Practitioners have announced a joint campaign (funded by an educational grant from Pfizer) to promote the awareness of the serious nature of heartworm disease in cats. More information, including the "Five Myths and Misunderstandings of Feline Heartworm Disease" can be found at www.knowheartworms.org.

Guidelines for the diagnosis, treatment and prevention of heartworm (Dirofilaria immitis) infection in cats. American Heartworm Society. www.heartwormsociety.org/AHS%20Guidelines-Feline2007.htm