Why Can't I Give My Dog Baby Aspirin?

“Can I give my dog baby aspirin?” Well, before you do, consider this statement by Paracelsus, a fifteenth century Australian physician/alchemist, “What is there that is not a poison? All things are poisonous; the dose determines that a thing is not a poison.”¹

The reality is all drugs have the potential to be life-threatening if used improperly or in the wrong dose. Here we discuss the dangers of giving dogs medications that are formulated for humans, and provide you with facts so you can answer this question for yourself.

Baby aspirin is one of a group of drugs classified as nonsteroidal anti-inflammatory drugs (NSAID), which are used to relieve pain and to reduce inflammation. One baby aspirin tablet contains 81 mg. of aspirin, while one aspirin tablet contains 325 mg. of aspirin.

Dogs and humans metabolize drugs differently. An 81 mg. dose of aspirin is not eliminated from the dog’s body as quickly as it is from the human's so there is a greater risk of the drug accumulating in an organ like the kidney and leading to toxicity. According to a report in the Merck Veterinary Manual, “the elimination half-life of aspirin in dogs is 7.5 hours.”²

Factors like the size of the dog, the weight, the age, and the overall health contribute to the risk factors. For instance, one baby aspirin tablet does not have the same effect on a Saint Bernard as it does on a Chihuahua.

Your vet considers all these factors and rules out other diseases before he or she decides to use a NSAID as a treatment for pain. Because he or she is acquainted with your pet's total health history and state of health, they are in the best position to decide upon the appropriate treatment and dosage amounts.

The Merck Veterinary Manual states, “Gastric ulcers were seen by day 30 in 66% of dogs given aspirin at 35 mg/kg, PO, TID.”³

Gastric ulcers and kidney failure are the most common adverse side effects of NSAID toxicity in canines. Symptoms of aspirin toxicity include but are not limited to diarrhea, vomiting, bloody stools, seizures or death.

Vets may prescribe baby aspirin for dogs to relieve pain from sprained muscles or joint pain from conditions like arthritis. It is sometimes used post operatively to treat pain. However, they may prefer to use one of the safer canine-formulated NSAIDs like Rimadyl ® or Deramaxx ®.

Deciding on the proper dose is best left up to the vet because determining the proper amount of aspirin in relation to the dog’s weight is difficult.

According to an article by Dr. Mike Richards, the recommended dosage range is between 5 to 15 mg per pound of body weight.

Given that baby aspirin is sold in 81 mg. tablets, it is easy to imagine how difficult it is to calculate the effective dose, and then cut the pill into precisely the right milligram dose.

Going back to the Merck Veterinary Manual, we find: "Because aspirin is not approved for veterinary use, definitive efficacy studies have not been performed to establish effective dosages.”³

Clearly, trying to decide whether or not to give a dog aspirin is a complicated decision, which is probably better left to a professional.

Now that you know the facts, you are in a better position to answer the question “Can I give my dog baby aspirin?” and you realize why you shouldn't.

It's really important to know what you are doing before you give any first aid treatment to your pets.

1 - Veterinary Medicine Teaching Hospital, University of California, Davis, Animal Pharm News, August 2004, Toxicology for Companion Animals, accessed 10/20/2010

2 & 3 - Merck Veterinary Manual, Specific Nonsteroidal Anti-Inflammatory Drugs, Aspirin, 2008, accessed 10/20/2010

Vet Info, Aspirin Tolerance, Mike Richards, DVM, accessed 10/20/2010