Gentamicin dosage in foals aged one month and three months.

The study investigates the effects of the antibiotic gentamicin on one-month and three-month-old foals, at two different dosage levels, to identify appropriate dosage recommendations for treating systemic infections in these young horses caused by microorganisms susceptible to gentamicin.

Study Methodology and Findings

• The researchers tested the absorption and disbursement kinetics (how the drug is absorbed and distributed throughout the body) of gentamicin at two different dosages: 2 and 4 mg/kg bodyweight (bwt) in both one-month and three-month-old foals.
• After the foals were given a single dose of 2 mg/kg via an intramuscular (im) injection, the drug was observed to have been absorbed rapidly, reaching its peak concentration in the serum at around half an hour.
• However, there was a high level of variation associated with both the amount of drug absorbed and the concentration of gentamicin in the serum when the higher dosage level was administered.
• Despite the variation in absorption and concentration, the half-life of gentamicin (the time taken for the drug’s concentration to halve in the body) was similar across both age groups and was not affected by the dosage given. The half-life was around 3.7 hours for one-month-old foals and 3.3 hours for three-month-old foals.
• Another significant finding was that the one-month-old foals did not show a deficiency in renal (kidney) excretion of gentamicin, suggesting that their bodies could effectively process and get rid of the drug.
• The minimum inhibitory concentration (MIC) – the lowest concentration of a drug that will prevent microbial growth – of gentamicin for Corynebacterium equi and certain other equine bacterial isolates was found to be less than 0.195 micrograms/ml.

Conclusions and Recommendations

• The researchers concluded that a dose of 2mg/kg administered through an im injection every 8 to 12 hours, depending on the severity of the infection, could be recommended for treating systemic infections in foals caused by microorganisms that are susceptible to gentamicin.
• This recommended dose is based on the drug’s absorption, distribution, half-life, and minimum inhibitory concentration (MIC) data collected from the study.
• This research provides important evidence for veterinarians in deciding on appropriate gentamicin dosage and administration frequency when treating young horses for systemic infections.