Aspirin Dosage Chart for Cats: Risks, Side Effects, Dosage, and More

Occasionally, our feline friends experience painful injuries. As they get older, they may develop arthritis or other painful conditions. Humans commonly reach for aspirin to relieve fever or head/body aches. Also known as acetylsalicylic acid (ASA), aspirin is a non-steroidal anti-inflammatory drug (NSAID) that has been around for many years. However, is aspirin safe to use for your cat?

By and large, the answer is no. Dr. Julie Parks, a veterinarian at Northwood Hills Animal Hospital in Gulfport, MS told AZ Animals, “I wouldn’t use aspirin in cats. It has too many potential side effects and [a] cat’s GI tract, liver, and kidneys are too sensitive. It takes 7 days to clear the liver so you can’t give anything else in that time period.” Her statement confirmed the extreme danger of giving aspirin to cats. There are very few conditions where this medication may be indicated.

With this information in hand, we remind anyone reading this article that giving medication of any kind to your pet requires a veterinarian’s advice and direction. This article does not replace veterinary advice. Failure to consult a veterinarian before giving medication to your cat could result in major side effects up to and including death.

What is Aspirin Used for in Cats?

Although the risk of poisoning is high, some conditions do require the use of aspirin in cats. However, due to the potential side effects, veterinarians prescribe it only when absolutely necessary. Let’s learn about one condition that requires treatment with aspirin in cats!

Feline Aortic Thromboembolism (FATE)

FATE (also called saddle thrombus) results when a blood clot travels through the aorta (the main artery of the body) and then gets stuck. The clot lodges at the area where the aorta splits into two pieces and travels into the rear legs. Often occurring as a side effect of hypertrophic cardiomyopathy (HCM), the blood clot reduces blood flow to the rear legs causing sudden paralysis. The disease is nearly 100% fatal.

One study reports that the success of treatment depends on early diagnosis and treatment, usually within six hours of onset. Treatment includes hospitalization, intravenous fluids, and administration of multiple medications (such as aspirin) in an attempt to dissolve the clot and prevent new ones from forming. Cats who survive will likely continue aspirin therapy for several months. Reoccurrence is common with FATE. Any underlying medical conditions (like HCM) must also be accounted for and treated.

Side Effects and Aspirin Poisoning in Cats

The use of any medication comes with the risk of side effects. Aspirin in cats produces dangerous side effects which can result in death. If you think your cat may have accidentally ingested aspirin, contact the Pet Poison Helpline immediately and take your cat to the nearest emergency veterinary hospital.

Possible side effects/symptoms of aspirin poisoning include:

• Fever
• Vomiting
• Diarrhea
• Abdominal pain
• Decreased appetite
• Increased breathing rate
• GI tract ulcers
• Pale gums
• Weakness/tiredness (lethargy)
• Wobbly walking (ataxia)
• Internal bleeding
• Anemia
• Low Blood Protein
• Acidosis (too much acid in the blood)
• Increased blood clotting times
• Lung damage
• Renal (kidney) failure
• Hepatic (liver) failure
• Tremors
• Seizures
• Coma
• Death

Contact your veterinarian immediately if you notice any of these signs. While they may not be related to aspirin poisoning, seeking medical help right away could save your cat’s life!

When Should Cats Not Take Aspirin?

We’ve already learned that cats should only take aspirin when specifically prescribed by a veterinarian. However, there are some medications and other conditions that may prevent a veterinarian from using it in a cat under any circumstances. Also, as Dr. Parks said, it takes aspirin a long time to be eliminated from a cat’s body. That means if they do need to go to the vet, your veterinarian will not be able to give other medications that could really help them feel better!

Medications Your Cat Cannot Take With Aspirin

VCA Animal Hospital’s article about aspirin use in pets lists a huge variety of medications, supplements, etc., that may be contraindicated for cats who need to take aspirin. Here’s the list (along with some examples/what they are used for):

• ACE inhibitors (enalapril, captopril, etc.)
• Alendronate (used in cats to treat high calcium, bone cancer, and FORLs)
• SSRI antidepressants (fluoxetine, sertraline)
• Blood glucose lowering agents (insulin)
• Calcium channel blockers (amlodipine)
• Corticosteroids (prednisolone)
• Carbonic anhydrase inhibitors (dichlorphenamide)
• Digoxin (controls heart rate and rhythm)
• Furosemide (helps pull fluid away from the area around the heart)
• Glucosamine (joint supplement)
• Heparin (anticoagulant used for abnormal clots)
• Oral anticoagulants (clopidogrel)
• Hyaluronidase (used to treat the negative side effects of chemotherapy)
• Methotrexate (treats some autoimmune diseases)
• Other NSAIDs (robenacoxib, meloxicam)
• Pentosane polysulfate sodium (treatment for joint pain/osteoarthritis)
• Phenobarbital (seizure medication)
• Probenecid (reduces bladder stone formation)
• Sulfinpyrazone (reduces blood clotting)
• Spironolactone (increases urine production)
• Tetracycline (antibiotic)
• Tiludronate (treats bone disorders)
• Urinary acidifying or alkalinizing drugs (diethylstilbestrol)
• Valproate products (a group of seizure mediations)
• Vitamin E (used for vitamin E deficiencies)

Now, that’s a long list of possible drugs that interact with aspirin for cats! Some of them are not even medications but supplements like vitamin E and glucosamine. That’s why it is so crucial for your veterinarian to know every single thing you are giving your cat before they treat them.

Conditions That Prevent Your Cat From Taking Aspirin

Not only does a cat’s current medication potentially make aspirin dangerous for them, but there are conditions that cats can have that prevent them from taking aspirin. Here’s the list, along with brief explanations:

• Bleeding disorders: Blood-thinning aspirin can worsen these conditions
• Bleeding ulcers: As with bleeding disorders, thin blood means heavier bleeding
• Diabetes: Aspirin affects the efficacy of insulin
• Asthma: Aspirin can affect lung function. If your cat’s lungs already suffer from asthma, aspirin can make the condition worse.
• Kidney disease: Aspirin can cause renal failure by reducing blood flow to the kidneys
• Liver disease: Aspirin is processed through the liver and can build up, thereby causing liver failure
• Upcoming surgical procedure: That’s right! Your cat cannot take aspirin within 7 days of any surgical procedure because it thins the blood. That means even a simple surgery like a spay or neuter could result in your cat bleeding out!

Dosage Chart for Aspirin in Cats

Always follow your veterinarian’s instructions exactly and finish the prescribed course unless otherwise instructed, even if your cat appears to be feeling 100% better. The typical aspirin dose for cats outside of cases of FATE is 5 mg per pound every other day. It is important to note that aspirin should never be given to kittens or pregnant/nursing mothers.

Alternatives to Aspirin for Cats

There are safer alternatives out there for cats instead of giving them aspirin. The risks far outweigh the rewards unless your cat is suffering from FATE. Most of the time, humans take aspirin to treat pain. Remember, always ask your veterinarian before starting any medications or supplements. Did you know that most cats over the age of six experience some sort of arthritic pain? Let’s explore a few other options for pain relief in cats!

Glucosamine and Fish Oil

Supplements can be a great alternative to aspirin for cats. Glucosamine is a supplement made from shellfish. It’s also found naturally in cartilage. Giving your cat glucosamine can help ensure their cartilage stays healthy and cushions their joints properly. You can even give glucosamine to your cat before they develop joint issues! This supplement has been shown to keep joints healthier and reduce the need for pain medications in both cats and dogs.

Fish oil is another great supplement for joint health. Cats require omega 3, 6, and 9 to help their joints, muscles, and skin to remain healthy. Many cat foods already contain these ingredients, but you can ask your veterinarian about supplementing if your cat is suffering from arthritis. The best part is both glucosamine and fish oil supplements come in tasty treats you can give your cat!

NSAIDs

Previously, there were few options for cats with inflammation and pain. As Dr. Parks told us, cats are very sensitive to these types of medications, especially aspirin. In 2016, the world of cat pain medication changed! Pet product manufacturer Elanco brought Onsior® to the U.S. market. It had previously been approved in Europe in 2008. Robenacoxib, the active ingredient, has been studied extensively. The FDA approved it for the use of post-surgical pain relief in cats. However, it cannot be taken for more than three days in a row. Occasionally, veterinarians will prescribe this medication after an injury. That’s so the cat can have some pain-free days while they heal!

The New Kid on the Block: Solensia™

In January 2022, the FDA approved a new kind of treatment for feline osteoarthritis (FOA) pain. Zoetis Petcare sought a way to help cats with this pain since medications like meloxicam and aspirin aren’t really safe for them. That’s how Solensia™ came about. This once-a-month injection for cats suffering from FOA proves to be an effective alternative. Studies showed at least 67% of cat owners saw an improvement in their cat’s pain levels in just one dose!

The best thing about this product is that it’s not a medication. It’s actually a special type of protein specific to cats called a monoclonal antibody. Essentially, it works just like your cat’s own antibodies.

It reduces pain by blocking the signals from the joints that tell the brain, “Hey, that hurts!” Of course, blocking the signals does not cure the problem. However, since FOA has no cure, reducing the pain your cat feels is the best that can be offered.

This product is the safest one on the market at the time of writing because it does not have to be processed through your cat’s liver or kidneys. This is especially awesome since many cats with FOA pain are elderly and may have other diseases, as well. Unfortunately, this medication is not available for dogs as it is a cat-specific protein. Dogs might be out of luck here, but this is a great alternative to aspirin for cats!

Final Thoughts on Aspirin for Cats

Giving your cat aspirin might seem like a great idea when they’re experiencing pain, but it is very dangerous to them. We discussed the possible side effects, including internal bleeding, irreversible kidney and liver damage, seizures, and even death. From our point of view, it’s just not worth the risk.

As always, if you’re concerned about your pet for any reason, please take them to the veterinarian! Many human medications are not safe for pets and can result in the loss of your pet. Your veterinarian is the best person to work with you and your pet to figure out what medications are best for them.

The photo featured at the top of this post is © Lightspruch/Shutterstock.com