Four dogs harboring Dirofilarits immitis were treated with three mercury compounds—mercury cyanide, mercury oxycyanide, and jnercury succinimide. In spite of the fact that the dosage proved to be toxic, no therapeutic action was observed either on the microfilariae or adult worms.
Preliminary investigations with trivalent antimony compounds indicated that the most favorable schedule of treatment consisted in the intravenous administration of six doses per week, each dose containing 08 mgm. of antimony per kilogram of body weight. With this schedule, the employment of 16 different antimonyl compounds resulted in the elimination of microfilariae from the peripheral circulation of 28 of 29 dogs infected with D. immitis with no recurrence during an observation period of two to six months. Some of the adult worms were killed by the treatment; changes were evident in the uterine contents of living worms recovered at autopsy.
Cotton rats infected with Litomosoides carinii were treated with nine antimonyl compounds. Five of these compounds in a dose rate of 3.3 mgm. of antimony per kilogram of body weight were well tolerated and were effective in killing the adult parasites.