Pharmacokinetics and dosage of aspirin in cattle.

Sodium salicylate was given intravenously to clinically normal cows, and aspirin (acetylsalicylic acid) was given orally to arthritic and clinically normal cattle. Despite slow absorption (half-time of absorption, 2.91 hours) of orally administered aspirin and rapid elimination (biologic half-life, 32 minutes) of salicylates, oral dosage of 100 mg/kg every 12 hours maintained serum salicylate concentration greater than 30 mug/ml, which was considered to be therapeutically effective.