Abstract
Recent reports indicate that sulfanilamide is ineffective in the treatment of several animal parasites. 1 , 2 However, as helminths vary so greatly in habitat, morphology and physiology, it appears possible that sulfanilamide may have a selective action upon certain species just as it appears to have on the coccal group of bacteria. Further, as the treatment of a number of helminthic infections is unsatisfactory, any therapeutic agent which may aid is welcome. Canine filariasis (heartworm) due to Dirofilaria immitis is a helminth infection which is very difficult and sometimes impossible to cure with the drugs now used. It was therefore thought worth while to test the value of sulfanilamide in Dirofilariasis.
Four infected dogs were treated with varying amounts of sulfanilamide† (para-amino-benzene-sulfonamide). The drug was administered orally for periods ranging from 15 to 36 days. It was given as a single daily dose. The dosage of sulfanilamide varied from 0.057 to 0.137 g per kilo weight of dog. These amounts were all well tolerated, no evidence of toxicity manifested, and all the dogs gained weight during the experiment. Microfilaria counts on 0.1 cc amounts of blood from the infected dogs were made before, during, and after treatment. In order to avoid variations due to periodicity of the parasite, blood for these counts was all secured at the same hour of the day.
In general it appears that the course of sulfanilamide treatment was without significant effect on the microfilaria content of the blood, Table I. The microfilaria count of dogs 1, 3, and 4 remained rather constant during and for as long as 10 days after the conclusion of the treatment. In the case of Dog 2, however, the microfilaria count fell approximately 45% after 9 days of treatment.
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