Aspirin is widely used in food animal production for pain relief and fever reduction due to the current lack of antiviral drugs, the inexpensive cost, and the over-thecounter availability. However, there is no reported information on dosage or achievable plasma or serum concentrations when acetylsalicylic acid or sodium salicylate products are administered via water medicator dosing systems typically used in swine production facilities.

Significant differences are reported in the solubility of aspirin and sodium salicylate in water. These differences potentially impact the amount of each product that can be provided to pigs via water medication systems. Additionally, dose data for the oral route of administration is based on the provision of a daily dose in a single oral gavage. This differs from the typical application in swine where a daily dose is consumed over a 24 hour period via the drinking water.

Reported differences in solubility were confirmed in the first phase of this trial. The second phase selected the most soluble product (sodium salicylate) and administered four concentrations to commercial swine for 72 hours. Serum plasma levels were analyzed by HPLC from 10 randomly selected pigs in each group including controls at 0, 24, 60, and 72 hours post administration. Sodium salicylate reached peak serum levels 24 hours post administration and exhibited a dose dependent trend.

This study provided information necessary to perform future challenge trials for dose determination.