A Comparison of Serum Concentrations of Penicillin After Intramuscular Injection and Subcutaneous and Deep Injection into the Dewlap in Cattle

Using an aqueous solution of sodium benzyl penicillin as the model substance, a comparison was made in cattle between absorption after intramuscular injection, and after subcutaneous and deep injection into the dewlap.The duration of supposed therapeutically effective serum concentrations using the 2 dewlap routes was longer than for the intramuscular route, although maximum concentrations were lower. The applicability of injection into the dewlap, especially the subcutaneous route, is discussed in relation to intramuscular injection.