Dimetridazole, a Systemic Treatment for Bovine Venereal Trichomoniasis. II. Intravenous Administration

Abstract

Tritrichomonas foetus infections were eliminated from two bulls by injecting dimetridazole intravenously at the rate of 10 mg/kg body weight daily for 5 consecutive days. A single intravenous injection at 25 mg/kg was ineffective in one bull, but this animal was subsequently freed of the infection when the dosage was increased to 50 mg/kg body weight. The latter regimen, moreover, cleared T. foetus from nine of 10 additional bulls. The one animal that did not respond became and remained free of the infection when the drug level was raised to 100 mg/kg. Dimetridazole (1,2-dimethyl-5-nitroimidazole), administered orally, is effective against Tritrichomonas foetus in bulls (McLoughlin, 1963, 1964, 1965; Ribot and Uilenberg, 1965; Parez, 1966; Bareggi and Gasparini, 1966). Although there were some differences in the dosages employed, all of these investigators treated infected animals at daily intervals for 4 or 5 consecutive days. Such regimens for large animals at the dose levels used are both costly and time-consuming. In an attempt to minimize these disadvantages, intravenous injection of dimetridazole was tried. This report summarizes observations on the first 13 infected bulls treated intravenously. MATERIALS AND METHODS Experimentally infected bulls were used throughout. The animals were anesthetized, the penis withdrawn from the sheath, scarified, and then massaged with the trichomonad culture. The animals were examined 1 week after exposure to the parasite and were reexamined before treatment to verify the infection. In no instance was an established infection spontaneously lost. Preand posttreatment examinations were made by pipetting physiological saline into the prepuce, closing the opening by hand, and massaging for at least a minute. The washings were then collected, centrifuged, and portions of the sediment used to inoculate tubes of Diamond's medium (Diamond, 1957); other portions were examined microscopically for trichomonads. The cultures were examined after intervals of 48, 120, and 144 hr. The solubility of dimetridazole (supplied through the courtesy of Rhodia, Inc., New York, N. Y.) varies within limits, with the pH of the solvent. A 10% solution of sulfuric acid was used to dissolve the drug given to Bulls 130 A and 130 CE; 17 to 20% solutions of the acid were used for all other bulls. Each animal was weighed at the last pretreatment examination and the solution used for intravenous injection was adjusted so that 1.5 to Received for publication 10 May 1968. 3 ml contained the required amount of dimetridazole for each 25 pounds of body weight. Bulls 130 A and 130 CE were treated daily for 5 days; preputial washings were taken before each treatment, and four additional examinations were made during a 5-month posttreatment period. The other animals were given single injections of the chemical and examined at least six times during a 3to 8-month posttreatment period. Bulls 5061 and 5159 required a second treatment at a higher dose level.