By Rania Gollakner, BS, DVM, MPH

What is clopidogrel?

Clopidogrel (brand name: Plavix®) is a platelet aggregation inhibitor used to prevent abnormal blood clot formation in dogs, cats, and sometimes horses. Certain conditions such as heart disease can predispose a dog or cat to blood clots, and these blood clots can lead to other problems such as paralysis, lung injury, or brain injury (stroke). In cats, this medication may also improve circulation in the lower limbs when used after a blood clot event.

Its use in cats and dogs to prevent blood clots is ‘off label’ or ‘extra label’. Many drugs are commonly prescribed for off label use in veterinary medicine. In these instances, follow your veterinarian’s directions and cautions very carefully as their directions may be significantly different from those on the label.

How is clopidogrel given?

Clopidogrel is given by mouth in the form of a tablet or compounded liquid. It may be given with or without food; however, if vomiting occurs after dosing on an empty stomach, give future doses with food. Measure liquid doses carefully. Because the medication is extremely bitter, the tablet can be put inside an empty gelatin capsule prior to administration.

This medication should take effect within 1 to 2 hours; however, effects may not be visibly obvious and therefore laboratory tests may need to be done to evaluate this medication’s effectiveness.

What if I miss giving my pet the medication?

If you miss a dose, give it when you remember, but if it is close to the time for the next dose, skip the dose you missed and give it at the next scheduled time, and return to the regular dosing schedule. Never give your pet two doses at once or give extra doses.

Are there any potential side effects?

Side effects may include stomach upset, such as vomiting, diarrhea, or lack of appetite. In cats receiving this medication long term, anemia may occur. Serious side effects may include bruising, difficulty breathing, or blood in vomit or feces (blood can appear red or black). In humans, the most common side effect is bleeding, and less commonly reported side effects include stomach upset and skin rashes.

This moderate-acting medication should stop working in several days, although effects can be longer in pets with liver or kidney disease.

Are there any risk factors for this medication?

Do not use this medication in pets that are allergic to it or in those with active bleeding problems. Clopidogrel should be used cautiously in pregnant or nursing pets.

In pets that need surgery, this medication should be stopped (if possible) approximately 7 days prior to surgery. In some pets, the risk of stopping this medication versus the risk of bleeding during surgery should be considered.

Are there any drug interactions I should be aware of?

The following medications should be used with caution when given with clopidogrel: aspirin, azole antifungals, calcium channel blockers, chloramphenicol, cimetidine, cyclosporine, heparin, nonsteroidal anti-inflammatories (NSAIDs), opioids, phenytoin, proton pump inhibitors, rifampin, rivaroxaban, selective serotonin reuptake inhibitors (SSRIs), telmisartan, torsemide, or warfarin.

Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking.

Is there any monitoring that needs to be done with this medication?

There is no specific monitoring that needs to be done while your pet is taking this medication. Your veterinarian may monitor your pet to be sure that the medication is working, which may include platelet function testing. Monitor your pet at home for side effects.

How do I store clopidogrel?

Store this medication at room temperature (77°F or 25°C), although the medication can withstand short stints between 59°F and 86°F (15°C and 30°C). Protect the tablets from moisture. Follow the specific storage instructions on the label for liquid formulations, as these may vary across pharmacies.

What should I do in case of emergency?

If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility.

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