In preliminary investigation of the pharmacokinetics of aspirin in dogs it became apparent that the drug was well absorbed following oral ingestion with food. Multiple dosing appeared to lead to a substantial increase in half-life; a twice daily dosage regimen would, therefore, be adequate for maintenance of therapeutic levels in dogs. The marked variation in pharmacokinetic parameters observed suggested that therapeutic drug monitoring would be benefit in the control of canine inflammatory conditions using aspirin. Therapeutic monitoring of dogs (n = 20) showed that clinical improvement paralleled plasma salicylate concentrations and the therapeutic concentrations so determined were within the range considered therapeutic in humans. No overt gastric irritation was noted in this study over a period of a year which suggests that aspirin can be successfully used to treat canine inflammatory disorders, routine monitoring of plasma salicylate being recommended to ensure therapeutic success.