To date, there is no registered injectable dosage form of levocarnitine for veterinary use on the territory of the Russian Federation. The purpose of our work was to conduct preclinical studies of l-carnitine for veterinary use, in particular acute toxicity, in laboratory animals and to establish the class of acute toxicity. Acute toxicity studies were conducted on outbred rats in October 2021 at the vivarium of the St. Petersburg State University of Veterinary Medicine. When studying acute toxicity after intragastric administration, l-carnitine was administered at an initial dose of 2 ml / kg of animal weight. When studying acute toxicity after intramuscular and subcutaneous administration, lcarnitine was administered at an initial dose of 2 ml / kg of animal weight. During three days of observations, the death of animals was not revealed. After the expiration of three days, we introduced the drug in the same dose and by the same routes of administration to other animals (three animals for each route of administration). During 14 days of observation, the death of the animals was not detected, other disorders of the general condition and any signs indicating the toxic effect of the studied drug were absent. As a result of acute toxicity studies on laboratory animals of the drug l-carnitine for veterinary use with intragastric, subcutaneous and intramuscular administration, it was found that a dose of 2 ml/kg did not cause death of experimental animals. The investigated drug l-carnitine, according to GOST 32644-2014, can be classified as hazard class V in accordance with the globally agreed system of hazard classification and labeling of chemical products or in class V in accordance with the toxicity classification according to Hodge and Sterner.