Lack of inhibitory effect of acetylsalicylic acid and meloxicam on whole blood platelet aggregation in cats


  • Curtis J. Cathcart DVM,

  • Benjamin M. Brainard VMD, DACVA, DACVECC,

    Corresponding author
    • Department of Small Animal Medicine and Surgery, College of Veterinary Medicine, University of Georgia, Athens, GA
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  • Lisa R. Reynolds BSc,

  • Sami Al-Nadaf BSc,

  • Steven C. Budsberg DVM, MS, DACVS

  • Dr. Brainard is an assistant editor for the journal and did not participate in the peer review process other than as an author.

  • The authors declare no other conflict of interest.

  • Portions of this study were presented as abstracts at the 2010 ACVIM Forum, June 2010, Anaheim, CA.

Address correspondence and reprint requests to

Dr. Benjamin Brainard, Department of Small Animal Medicine and Surgery, College of Veterinary Medicine, University of Georgia, 501 D.W. Brooks Dr, Athens, GA 30602-0001, USA.




To determine the effects of acetylsalicylic acid (ASA) and meloxicam on feline platelet aggregation and associated platelet thromboxane production and serotonin release.


Prospective interventional study.


University research facility.


Eight healthy male castrated domestic short hair cats from a research colony.


Oral medications were administered to 8 cats for 14 days in a randomized, placebo-controlled, crossover design. Treatment groups included: aspirin (ASA) (5 mg/kg q 48 h), meloxicam (0.05 mg/kg q 24 h), and placebo (0.5 mL of water q 24 h). Thromboxane assays (TXB2) and whole blood (impedance) aggregometry (WBA) were performed on samples collected before drug administration, and on days 7, 15, and 17, using adenosine diphosphate (ADP; 10 μM) and collagen (5 μg/mL) as agonists for WBA. Serotonin release was assayed on postaggregation plasma. Oral mucosal bleeding time (OMBT) and complete blood cell counts were measured on days 0 and 15.

Measurements and Main Results

Neither medication affected WBA at any time point. OMBT decreased in the ASA group relative to baseline. No differences were detected in WBA and OMBT baseline between any groups. No difference was detected in serotonin secretion at any time point. TXB2 was significantly decreased in the ASA group at all times after initiation of treatment but no change was noted in the meloxicam or placebo groups.


At the doses studied, neither meloxicam nor ASA had an inhibitory effect on WBA or OMBT in cats. Thromboxane concentrations were significantly decreased with ASA treatment.