Surgical technique for long-term cecal cannulation in the Yucatan minipig (Sus scrofa domestica).

Measurements of standardized ileal digestibility yield more useful results than do those of fecal digestibility. To that end, cecal cannulation of the pig has been performed extensively in an attempt to model the digestive processes of humans. Here we introduce a technique for the placement of a permanent cecal cannula with a silicon port that is larger in diameter than those previously described in the literature. A large lumen offers several advantages, most notably ease in collection of larger samples and introduction of materials into the cecum. To date, this technique has been used successfully to cannulate 39 Yucatan minipigs at our institution. Long-term, there have been no major complications with the procedure or cannulas.

Controlled release of oxytetracycline in sheep.

A novel biodegradable injectable formulation of oxytetracycline (OTC) was administered subcutaneously to sheep at a dose of 40 mg/kg. Blood samples were collected from the jugular vein at predetermined time intervals. The concentration of OTC in plasma was analyzed by an HPLC method. The concentrations of OTC in plasma were maintained at or above 0.5 microg/ml (minimum inhibitory concentration) for approximately 6 days. The pharmacokinetic parameters of OTC in sheep were also determined by monitoring the plasma concentration of OTC after a single intravenous injection of a commercially available OTC formulation at 10 mg/kg body weight. The in vivo release profiles of OTC from the biodegradable injectable formulations in sheep were determined from the plasma concentration time profiles by the deconvolution method using PCDCON software. The in vitro release of OTC from the biodegradable injectable formulation was tested in phosphate buffer (pH 7.4), containing 0.686% w/v of sodium sulfite as antioxidant. The correlation between the in vitro and in vivo release of OTC from the injectable formulation was also evaluated. The results of the in vivo evaluation of the formulation in sheep indicated that a controlled release biodegradable injectable dosage form of OTC for food animals is feasible.