Forty sows were utilized in a study to determine the plasma concentration profile and tissue residues of procaine penicillin G after injection by two methods (20 sows each method). A target dose of 33,000 IU/kg (5 ml/100 lbs) of a 300,000 IU/ml commercially available procaine penicillin G suspension was injected by either conventional intramuscular injection with a needle (CI) or injection by needle-free device (NF) in the hip. Live animal work including treatment and tissue collection was conducted at Iowa State University and is reported here. Sample analysis and pharmacokinetic work was conducted a Kansas State University and is reported elsewhere.

For the plasma concentration study, 15 plasma samples were taken over 24 hours from 8 pigs in each of the two treatment groups. In the tissue residue study, samples of kidney, liver, fat, muscle, and injection site were collected at 2, 4, 6, and 8 days post-injection. In swine tissues, the accepted tolerance is no detectable concentration in the United States and 50 PPB in many of the export markets. There were no statistically significant differences in the injection sites by microscopic examination. Gross evaluation of muscle, fat, kidney and liver did not reveal significant differences in the frequency or severity of lesions. When tissues were evaluated microscopically, there were no statistically significant differences in the frequency or type of lesion.