Clopidogrel is an irreversible platelet aggregation inhibitor that is used in the prevention of arterial thromboembolism. Clopidogrel does not treat thromboembolism but may help prevent the formation of new clots during the course of a patient’s disease.

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Mechanism of action/pharmacokinetics

  • Clopidogrel is a pro-drug that is metabolized in the liver and cytochrome p450 to an unstable active metabolite
  • Inhibits the binding of ADP to the P2Y12 receptor on platelets, which prevents activation of the GPIIb/IIIa complex. The ADP receptor is permanently altered on the platelet affected.
  • No pharmacokinetic data are available in veterinary species. In humans, bioavailability is 50% and food does not affect absorption.

Adverse Effects

  • Mild, self-limiting diarrhea
  • Hemorrhage, especially if coupled with other anticoagulants


  • Thromboprophylaxis in dogs
    • IMHA (alone or dual therapy with aspirin)
    • Aortic thromboembolism
    • Cardiac disease spontaneous contrast visible within the left atrium
    • Endocarditis
    • SIRS/Sepsis
    • Pulmonary thromboembolism
    • Uncontrolled Cushing’s disease
  • Thromboprophylaxis in cats
    • Recurrent aortic thromboembolism (ATE)
    • ATE in cats with asymptomatic hypertrophic cardiomyopathy who are at high risk (based on dilated left atrial size) or those with spontaneous contrast visible within the left atrium

Dosing suggestions/guidelines

  • Dogs: 1-5 mg/kg PO q24hrs
  • Cats: 18.75mg/cat PO q24hrs
  • Commonly combined with aspirin therapy

Dosage forms

  • 75mg tablet
  • Can be compounded to suspension for smaller animals


  • Hogan DF, Fox PR, Jacob K, et al. Secondary prevention of cardiogenic arterial thromboembolism in the cat: the double-blind, randomized, positive controlled feline arterial thromboembolism; clopidogrel vs. aspirin trial (FAT CAT). J Vet Cardiol 2015;17:S306-17. Download article
  • Mellet AM, Nakamura RK, Bianco D. A prospective study of clopidogrel therapy in dogs with primary immune-mediated hemolytic anemia. J Vet Intern Med 2011;25:71-5. Download article

Additional resources

Last updated: 2018-03-28