It can be overwhelming, and a little scary, when your cat is diagnosed with a condition which requires medication. Clopidogrel is an anti-platelet drug, used in cats who are considered at risk of forming a clot, or who are recovering from the effects of a clot. It is usually given in tablet form, and can be quite bitter tasting; which can cause some cats to drool a lot after taking it.
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What is clopidogrel?
You may know clopidogrel by one of its brand names. This medication targets the platelet cells in your cat’s bloodstream. Platelets are small cells in the blood, and they help blood to clot by attracting other platelets if they find a damaged area, and then sticking together. Clopidogrel is an anti-clotting drug, and works by reducing the ability of these platelets in the blood to stick together.
Why is it needed?
The ability of the blood to clot is usually a good thing, as these clots can plug wounds and damaged areas of blood vessels. However, there are some health conditions in cats that can predispose them to form clots which aren’t necessary. These abnormal clots (thrombi) can then break off and lodge in narrow parts of blood vessels. The stuck clot then restricts blood flow to wherever the narrow vessel was taking it, leading to pain and injury. This is called thromboembolism.
The prevalence of thromboembolism in cats is around 0.3-0.6%1,2, which is higher than in many other species. This is likely because cats are prone to heart disease, especially a type called hypertrophic cardiomyopathy (HCM), which leads to enlargement of the left atrium chamber of the heart – the most common reason for a clot (thrombus) to form. Other (much less common) causes of thrombus formation include infection of the heart valves and lung tumours.
The most common place for a clot to get stuck (embolise) is in the aorta
Typically, it sticks just where it divides at the level of the cat’s pelvis. Affected cats will have paralysis of one or both of their hindlimbs, and will often be very distressed, as the condition is known to be painful. The onset is very sudden and can happen at any time. Clots can also lodge in the brachial arteries of the forelimbs, or in areas of the lungs, brain or other parts of the body.
As heart disease is a known risk factor for clot formation1, cats who have been diagnosed with certain types of cardiac disease may be prescribed clopidogrel to reduce the risk of thrombus formation. It may also be used as part of a treatment plan in cases where a clot is known, or suspected, to be already present. Aspirin was historically used in these cases, but clopidogrel has been shown to significantly reduce the likelihood of arterial thromboembolism compared to aspirin use2.
How is it given?
Clopidogrel is usually given in tablet form, to be given orally once a day. The usual dose is significantly less than one tablet per cat, per day, but always follow the directions on your prescribed veterinary medication. The tablets can be bitter, causing some cats to salivate a lot, and can be placed into plain gelatine capsules if this causes difficulties with medicating.
Are there side effects?
Some cats will get an upset tummy when on clopidogrel – poor appetite, vomiting and diarrhoea being the most common signs. These symptoms are often mild, and improve when the clopidogrel is given with food as opposed to on an empty stomach.
Anti-clotting medications all carry a risk of bleeding and anaemia. Internal bleeding in cats may present as bruising, blood in the stools or vomit, or breathing difficulties. These are serious side effects, but very uncommon.
If you think your cat may be suffering from side effects to a medication, or having an adverse reaction, contact your vet.
Clopidogrel cannot be given alongside certain other drugs. Always let your vet know if your cat is on any medications, supplements, or herbal remedies that they may not be aware of.
Help! I’ve given the wrong amount to my cat!
Think you’ve accidentally given the wrong dose of clopidogrel to your cat? Don’t panic!
If you forget a dose, continue the next day as normal. Do not double up on doses if one was missed.
If you’ve given too much clopidogrel, contact your veterinary surgeon for advice. Depending on the overdose, your cat may be able to be monitored at home, or they may need to attend the veterinary surgery for further treatment.
Clopidogrel: a summary
Clopidogrel is an anti-clotting medication. It is often prescribed to cats who are at a higher risk of forming an unwanted clot (a thrombus), such as those with heart disease. It may also be used in cats who are recovering from a thrombic event. It’s usually given once daily in an oral form, and any side effects are usually mid and gastrointestinal in nature. If you are unsure about any medication prescribed to your pet, speak to your vet.
References
- Borgeat K, Wright J, Garrod O. (2014) ‘Arterial thromboembolism in 250 cats in general practice: 2004-2012’. J Vet Intern Med ;28(1):102–108.
- Hogan, D.F., Fox, P.R., Jacob, K., Keene, B., Laste, N. & Rosenthal, S. (2015) ‘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 17(1) pp.306-317
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