Canine and feline dirofilariasis: prophylaxis, treatment, and complications of treatment.

Several agents are available for the prevention of heartworm infection. Melarsomine is up to 96% efficacious (after two doses) as a heartworm adulticide in infected dogs. However, treatment of dogs infected with D. immitis can be expensive, and adulticide therapy in patients with moderate to severe heartworm disease can be associated with life-threatening complications. Patients with clinical signs associated with pneumonitis benefit from short-term therapy with antiinflammatory doses of corticosteroids before and after adulticide treatment. Strict cage rest for 4 to 6 weeks is mandatory after adulticide administration. Microfilaricide therapy is indicated for microfilaremic patients. The prognosis is good in patients with mild to moderate infection, fair to guarded in severe cases, and poor to grave (even with treatment) in patients with caval syndrome, severe pulmonary thromboembolism, or congestive heart failure.