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The treatment options for trichomonas species of animal health importance are limited, due to a lack of authorised products and the increasing emergence of resistance. Tritrichomonas foetus is a protracted infection in cats causing diarrhoea of colonic origin, often developing into a lifelong chronic infection. The only adequately effective treatment is the nitroimidazole agent ronidazole, which is not licensed for cats and may cause neurological symptoms as an adverse reaction in some individuals. Metronidazole and tinidazole do not fully eradicate the parasite. Cattle abortions caused by Tritrichomonas foetus cause significant economic losses worldwide, but the use of nitroimidazoles in food producing animals is banned due to their potential carcinogenicity. In view of the above, new alternative treatments are needed.

The aim of the present study is to determine the efficacy of propolis tincture of Hungarian origin and nitroimidazole active substances as reference in Tritrichomonas foetus isolates of feline and bovine origin. We investigated the effects of the active substances propolis tincture, ronidazole, metronidazole, tinidazole and secnidazole on the parasite by using a two-based dilution series with a minimum inhibitory concentration (MIC) determination method. In addition, the possible influence of the same dilution series of ethanol and DMSO solutions used as solvents was investigated in parallel.

It was shown that the indigenous propolis tincture was effective in killing Tritrichomonas foetus protozoa, with a concentration of 1.25 mg/ml for the feline strain and 0.63 mg/ml for the bovine strain. The ethanol used as a solvent for propolis was better tolerated by the feline strain (96 mg/ml), whereas the bovine strain was more sensitive (48 mg/ml). The feline strain was much less sensitive to ronidazole (32 µg/ml) than the bovine strain (1 µg/ml). The effect of dimethyl sulphoxide (DMSO) used to dissolve the nitroimidazoles was negligible in the case of the feline strain but killed the parasites up to a concentration of 1% in the case of the bovine strain.

The efficacy of propolis tincture suggests that further in vitro studies with several strains and several propolis extracts; and in vivo studies to investigate its efficacy and pharmacokinetic properties are worthwhile.