Feline
heartworm disease is a very different clinical entity from canine
heartworm disease. In cats, the arrival and death of immature heartworms in the pulmonary arteries can cause coughing and
dyspnea as early as 3 months postinfection. Adult heartworms suppress the function of pulmonary intravascular macrophages and thus reduce clinical disease in chronic feline heartworm
infection. Approximately 80% of asymptomatic cats self-cure. Median survival time for symptomatic cats is 1.5 years, or 4 years if only cats living beyond the day of presentation are considered. Aberrant worm migration is more frequent than it is in dogs, and
sudden death can occur with no prior clinical signs. The bacterial endosymbiont Wolbachia likely contributes to the inflammatory pathology of
heartworm disease, but its role is not yet fully clear. Unfortunately, the diagnosis, treatment, and management of feline
heartworm disease are far from simple. Antemortem diagnosis is hampered by low worm burdens, the frequency of all-male
infections, and nonspecific radiographic lesions. It is up to the veterinarian to determine the correct index of suspicion and choose the right combination of diagnostic tests to achieve an answer. Treatment is symptomatic because adulticide
therapy is risky and does not increase survival time. Despite the dangers of feline
heartworm disease, less than 5% of cats in the United States are on
chemoprophylaxis. It is important for veterinarians to take a proactive preventive stance because heartworm
infection in cats is a multisystemic disease that has no easy cure.