Introduction or Objectives: Benzylpenicillin G (BP) is one of the first-line antibiotics prescribed by equine practitioners. However, they encounter difficulties linked to several discrepancies between manufacturers' and scientific recommendations and guidelines regarding dosage regimens (doses and intervals). The objective of our study was to determine the pharmacokinetic (PK) parameters of BP using 4 different formulations, allowing determination of the appropriate dosing regimens. Materials and Methods: An experimental PK study was performed on six healthy horses (3 geldings, 3 mares; 8+/−3 yo; 503+/−40 kg) receiving commercial formulations of BP: Depocilline® (BP procaine), Duplocilline® (BP procaine and BP benzathine), Penetavet® (penethamate hydroiodide, a prodrug of BP) and BP sodium (BP-Na). Commercial formulations were administered intramuscularly following the manufacturer regimen for 3 days in a 3 × 3 crossover design (10.0 mg/kg BP q24h for Depocilline, 12.4 mg/kg BP q48h for Duplocilline, and 11.9 mg/kg BP 1st day SID then 6.0 mg/kg SID for Penetavet); in addition a single BP-Na dose of 12.4 mg/kg BP was administered intravenously. BP concentrations in blood samples were analyzed by UPLC (LOQ of 0.01 μg/mL) and a non-compartmental analysis was performed (Phoenix®WinNonlin®8.3). In addition, the PK/PD indice T > MIC was determined using MICs of target pathogens. Clinical parameters such as a swelling score, an induration score, a global pain score including clinical examination and lameness score were also measured. In addition, local muscle loss was estimated after quantification of plasmatic creatine kinase. Results: Except one horse that exhibited a minor neurological reaction at first Penetavet injection, all other injections were well tolerated, with a maximal observed pain score of 4/21. Estimated muscle lysis was more important with Penetavet compared to Depocilline or Duplocilline. BP PK parameters were consistent with those of the literature (clearance: 480 ± 56 mL/h/kg; Vss: 194 ± 18 mL/kg; t1/2: 1.49 ± 0.23 h). Bioavailabilities of BP were 104% for Depocilline, 64% for Duplocilline, and 58% for Penetavet. Discussion or Conclusion: Using the manufacturers dosing regimens, BP plasma concentrations ensured higher T > MIC values with Depocilline compared to Duplocilline and Penetavet. The combined knowledge of the BP PK profiles after the 3 commercial formulations, and of the MICs of the target bacteria, will allow to ascertain more adequate dosing regimens able to cure equine patients.