Benzylpenicillin-G (BP-G) is one of human and veterinary medicine’s most widely used antibacterial drugs. It represents a large market for the Pharmaceutical Industry, and various combinations with frail pharmacological support have been made available to veterinarians. The crystalline sodium and potassium salts of BP-G and the benzathine salt of BP-G have been incorporated into many existing preparations, arguing that higher and more prolonged concentrations are obtained. However, there are not evidence published. Notwithstanding the above, these preparations are presented as sustained-release ones and capable of achieving therapeutic concentrations. There are no pharmacokinetic bases for such combinations of BP-G derivatives. It is unlikely that such combinations provide better serum profiles than those offered by an adequate dose of only procaine BP-G. The incorporation of the BP-G benzathine is prohibited in many countries. In Latin America, such combinations limit the amount of procaine BP-G that should be injected, ideally ≥ 20 000 IU/kg of body weight every 12-24 h. Within the framework of the rational use of antimicrobial drugs in veterinary medicine advanced by the World Health Organization (WHO) and based on pharmacological considerations, it is proposed that combinations of BP-G derivatives be restricted, allowing only BP-G procaine preparations. Also, formulations of BP-G incorporating other active principles should offer solid pharmacological support. To date, combined preparations of BP-G have shown no formal pharmacological support. Based on the information presented in this review, it is feasible to conclude that the only BP-G derivative that should be available for veterinary medicine is procaine BP-G.