Mar Vista Animal Medical Center

3850 Grand View Blvd.
Los Angeles, CA 90066




(for veterinary information only)



75 mg & 300 mg



There are many diseases that increase the body's tendency to form blood clots. This is a problem when abnormal blood clots form, break off, and lodge in places where their presence occludes normal blood flow. Further, the body's natural mechanisms to dissolve blood clots is inherently inflammatory and the resulting biochemicals can be dangerous if there are a large number of blood clots dissolving at once. The diseases that result from abnormal blood clotting, vessel occlusion with clots and inflammation from clot dissolution are called "thrombotic" or "thromboembolic" diseases.

Examples of such diseases in veterinary medicine would include the feline condition now known as FATE where a large blood clot forms in the heart, a small piece of the clot breaks off and then lodges in the aorta (the large artery that travels the length of the body) right where it branches to serve the rear legs. The circulation to the rear legs is painfully disrupted and while many cats survive this episode and regain function in their rear legs, they are at risk for future episodes. In cats with heart disease, there are certain findings on ultrasound which suggest that a cat is at risk for forming abnormal clots even when they have not done so heretofore. Either suggestion warrants medication to reduce clotting tendency.

In dogs, immune-mediated hemolytic anemia, where the immune system wrongly attacks the body's own red blood cells, carries a very high mortality rate because of thromboembolic disease. In these patients, medication to reduce blood clotting can be life-saving.

In the past, the only option was low dose aspirin to inactivate platelets, the blood cells responsible for clotting blood. There is still controversy as to whether the inexpensive decades old medication works just as well as the new drug. Both drugs inactivate platelets but they do so by different routes. A very large study of cats at risk for thromboembolic disease (the "FATCAT" study), however, clearly showed improved survival rates in the clopidogrel group over the aspirin group. Similar studies in canine disease are lacking but results of the FATCAT study has made this medication more popular in both dogs and cats for the treatment and prevention of thromboembolic disease.


This medication is used once daily in patients deemed at risk for thromboembolic disease. It may be given with or without food. If a dose is accidentally skipped, give it when it is remembered and time the next dose accordingly. Do not double up on the next dose.


The most common side effects relate to upset stomach (appetite loss, vomiting, diarrhea). Giving clopidogrel with food generally alleviates these symptoms.

Inappropriate bleeding is always possible with medications that reduce clotting. It is important to watch for black or bloody stools, bruising, nose bleeds.

Anemia (red blood cell deficiency) not associated with bleeding has been rarely reported as well.


Bleeding risk is increased when clopidogrel is combined with aspirin. Many patients take these medications together.

Concurrent use with either the antacid omeprazole or the antacid cimetidine may interfere with the activity of clopidogrel as can concurrent use with the antibiotic chloramphenicol or the anti-hypertension medication amlodipine.

Non-steroidal Anti-inflammatory medications may increase the risk of bleeding when combined with clopidogrel as can concurrent use of clopidogrel with serotonin re-uptake inhibitors (such as fluoxetine).


As noted above, if nausea or GI side effects result, try giving clopidogrel with food. If this does not help, notify your veterinarian.

If you think there is abnormal bleeding, discontinue the medication and notify your veterinarian.

Platelet function returns to normal 5-7 days after discontinuance of this medication.


Short version (to help us comply with "Lizzie's Law")

Page posted: 8/5/2016
Page last updated: 10/16/2021