Assessment of subchronic systemic toxicity of a novel veterinary drug against eimerasis

Coccidiosis, caused by parasites of the genus Eimeria, represents one of the most serious infectious threats in broiler poultry farming, leading to significant economic losses. In the context of veterinary drug import substitution, the safety assessment of new domestic coccidiostats gains particular relevance. This paper presents the results of a preclinical investigation into the subchronic systemic toxicity of a novel domestic veterinary drug, containing monensin sodium as the active pharmaceutical ingredient (400 mg/g). The study was conducted on Wistar laboratory rats over 28 days of daily oral administration at doses equivalent to 1/10, 1/5, and an intermediate fraction of the LD50 (36.8, 55.2, and 73.5 mg/kg body weight, respectively), followed by a sevenday post-observation period. Comprehensive analysis included monitoring of clinical status, body weight dynamics, complete blood count, biochemical blood analysis, and pathological examination of organs. It was established that the drug did not cause lethality, showed no pronounced local irritant effect on the gastrointestinal tract, and did not lead to statistically significant morphological changes in internal organs. However, a dose-dependent, reversible inhibition of body weight gain was observed, particularly evident in female animals: at high doses (55.2 and 73.5 mg/kg), a significant decrease in weight gain rates and a moderate, but statistically significant, reduction in hemoglobin, leukocyte, and platelet counts in the peripheral blood of females were noted. Importantly, all observed hematological abnormalities completely resolved seven days after cessation of drug administration, indicating a reversible, adaptive nature of its effects. The obtained data confirm the relative safety of the drug when used at the recommended dose. It is particularly important to note that the effect of the drug on female rats was more significant compared to males.