Laboratory studies were conducted to determine the subacute toxicity and tolerance of the veterinary drug “BTF plus” on white rats, dogs, and guinea pigs. The “BTF plus” preparation is a complex vitamin and mineral preparation based on butophosphane, L-carnitine, and cyanocobalamin, which normalizes and corrects metabolic processes in animals and poultry. The drug is used for various types of animals and poultry as a stimulating, tonic and general strengthening agent for obstetric pathologies (difficult births, postpartum complications, paresis, eclampsia, sexual cycle disorders); metabolic disorders caused by irrational feeding, malnutrition, asthenic syndrome, etc.; anemia with helminthiasis; secondary anemias, as an additional means in the treatment of magnesium and calcium deficiency; to increase muscle activity, with significant loads, overstrain and exhaustion in animals; to increase the body's resistance to various pathogens; to stimulate growth, development and live weight gain in young animals and poultry; as an additional means in the treatment of diseases caused by various factors (infectious and non-infectious origin). When administered subcutaneously to rats, the drug “BTF plus” under the conditions of a subacute toxicological experiment in doses (by absolute weight of the drug) of 200.0, 1000.0, and 2000.0 mg/kg of body weight does not cause hemo-, hepato- and nephrotoxic effects on the body of laboratory animals, but on the contrary, stimulates hematopoietic processes and has a positive effect on metabolic processes in their body. Subcutaneous administration of the drug “BTF plus” to dogs in doses (by absolute weight of the drug) of 200.0, 1000.0, and 2000 mg/kg of body weight for ten days does not cause hepatotoxic and nephrotoxic effects on the body under the conditions of a subacute toxicological experiment, but on the contrary, stimulates hematopoietic processes and has a positive effect on metabolic processes in the body of target animals. The tolerance of guinea pigs to the drug “BTF plus” was studied. It was established that the drug does not hurt the body and behavior of ants when administered subcutaneously in doses (based on the absolute weight of the drug) (5000,0–15000,0) mg/kg of body weight. Further studies will be the next stage of pre-registration tests aimed at studying the embryotoxic and carcinogenic effect of “BTF plus”, which is mandatory material of the “Safety and residue studies” section of the dossier for this medicinal product.