Observations on the adverse reaction to diethylcarbamazine in Dirofilaria immitis-infected dogs.

The severity of the adverse reaction, as assessed by clinical, haematological, and biochemical abnormalities, following treatment of Dirofilaria immitis-infected dogs with diethylcarbamazine (DEC) was found to be related to the level of microfilaraemia. The magnitude of change in the blood constituents studied was proportional to the severity of the side reaction. The most notable alterations in dogs experiencing a moderate or severe adverse reaction were a decrease in platelet numbers and fibrinogen level, a rise in serum transaminases, and the appearance of fibrin monomers. The practical value of qualitatively and quantitatively characterizing the post DEC adverse reaction is discussed.