Eight dogs were enrolled in a randomized, cross-over study that used optical aggregometry and a platelet function analyzer to evaluate platelet function before and after the administration of 5 aspirin dosages: 0.5 mg/kg q24h, 1 mg/kg q24h, 2 mg/kg q24h, 4 mg/kg q24h and 10 mg/kg q12h. Urine 11-dehydro-thromboxane-B2 (11-dTXB2) and 6-keto-prostaglandin-F1alpha (6-keto-PGF1alpha), were measured. Compared to pre-treatment, there were significant decreases in maximum aggregometry amplitude and increases in PFA-100 closure times for all doses except 0.5 mg/kg q24h. There was no difference in amplitude or closure time between the 2 mg/kg, 4 mg/kg, and 10 mg/kg q12h dosages. At 2 mg/kg q24h, 100 percent (aggregometry) of dogs were aspirin responders. There was a significant decrease in urinary 11-dTXB2- and 6-keto-PGF1alpha-to-creatinine ratios with aspirin administration. An aspirin dosage of 2 mg/kg q24h consistently inhibits platelet function in healthy dogs without decreasing prostacyclin synthesis significantly more than lower aspirin dosages.

Enoxaparin, a low-molecular-weight heparin, is commonly used as an anticoagulant in dogs, and is currently dosed at 0.8mg/kg every 6 hours. With an increase in individual enoxaparin doses, less frequent dosing may be possible, thereby reducing owner inconvenience and expense. The three phases of this study investigated the appropriate dose (Phase one- 0.8mg/kg, SQ once; Phase two- 2mg/kg, SQ once; Phase three- 1.3 mg/kg, SQ q8h for 7 total doses) and dosing interval needed for maximum effectiveness of enoxaparin. A Sonoclot® analyzer and factor Xa activity were used to assess level of anticoagulation in six healthy dogs. Anticoagulation was inconsistent at the 0.8mg/kg dose, while the 2mg/kg dose showed a high level of anticoagulation, and the 1.3mg/kg dose provided more reliable anticoagulation than the other dosages and dosing intervals. Small sample size and the use of same-breed healthy dogs potentially affected the strength of the results.