Serum oxytetracycline levels in free-ranging male African elephants (Loxodonta africana) injected with a long-acting formulation

Thirteen adult free-living male African elephants (Loxodonta africana) were anesthetized and given 20-100 g of a long-acting oxytetracycline (OTC) preparation either i.m. or i.v. Five dosages were established based on body measurements (the sum of the body length and the girth in centimeters). Serum concentrations of OTC were measured 48 hr after injection. Serum concentrations ≥0.5 μg/ml were measured in 11 of 12 elephants receiving OTC dosages of 52-133 mg/cm either i.v. or i.m. The i.m. administration route produced serum concentrations from 0.75-1.6 μg/ml in four of four elephants. A dosage of 60-80 mg/cm i.m. or i.v. should provide a therapeutic serum concentration of OTC for at least 48 hr. The use of an i.v. catheter avoids multiple i.m. injections of large drug volumes.