Toxicity and therapeutic trials using
Cymelarsan (an arsenical compound) against Trypanosoma evansi
infection were carried out using chronically infected goats. For the toxicity trial, 40 goats were divided into four groups of 10 animals each; the first three groups received s.c.
injections of 5, 10, and 15 mg/kg bw of
Cymelarsan, respectively, and the last one served as control. No systemic reaction was observed in any goat throughout the experiment. For the therapeutic trial, 15 adult female goats were inoculated intravenously with at least 1 x 10(5)T. evansi isolated in the Canary Islands. Six months after inoculation, the animals were treated with
Cymelarsan at single dose of 0.3 mg/kg (5 animals), 0.5 mg/kg (5 animals), and 0.625 mg/kg (5 animals). At 4 and 6 weeks
after treatment, two goats belonging to 0.3 mg/kg group showed recurrence of trypanosomes.
Parasitemia, however, was negative in all animals belonging to 0.5 and 0.625 mg/kg groups until the end of the experiment (6 months
after treatment). Thus, it can be concluded that
Cymelarsan is a safe trypanocidal
drug for goats and that the curative dose is 0.5 mg/kg or above.