Aspirin Toxicity in Dogs

Dog laying down with pills on floor

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When our pets are in pain, it is only natural to want to find a way to alleviate it. When they experience pain from an injury or arthritis, our first thought may be to give them something that helps us. For people, aspirin may provide some pain relief. However, this may not be the best option for your dog. H In recent years, safer options to aspirin have become available for pet use. Here we will discuss how aspirin can affect dogs, how to prevent over-exposure, and alternative options for lameness and arthritic pain.


If your pet has ingested aspirin, seek veterinary attention immediately! If you know the amount and time it was taken, make sure to share this with your veterinarian.

What Is Aspirin Toxicity?

Aspirin, also known as Acetylsalicylic Acid, is a non-steroidal anti-inflammatory drug. It inhibits an enzyme called cyclooxygenase, which is involved in the production of inflammatory chemicals called prostaglandins. Arachidonic acid, a fatty acid essential in the diets of cats and dogs, is necessary to develop cell membranes. When the inflammatory cascade is active, cells begin to convert their arachidonic acid into prostaglandins. Aspirin stops this process.

The problem? There is more than one form of cyclooxygenase. Some make both inflammatory and non-inflammatory prostaglandins. Some prostaglandins have important functions. Unfortunately, aspirin does not distinguish between different forms of cyclooxygenase and inhibits them all. So, when an unknowing owner gives their dog aspirin, it is potentially harmful, if it's not the proper dose. Veterinary assistance should be sought out immediately.

Clinical Signs of Aspirin Toxicity

  • Lethargy
  • Vomiting (Sometimes with blood)
  • Diarrhea
  • Black-tarry Stool
  • Inappetence
  • Increased Heart Rate
  • Change in Thirst or Urination
  • Fever
  • Hypoglycemia (Low blood sugar)
  • Muscular Weakness
  • Ataxia (Instability)
  • Coma
  • Death

The most common clinical signs of aspirin toxicity are vomiting (sometimes with blood) and loss of appetite. Stomach ulcers may develop when there is significant gastrointestinal irritation. As a result, owners may notice their dog's stool is black and tarry-like. As the condition progresses, increased heart rate, fever, muscular weakness, and ataxia may develop. In severe cases, acute kidney failure, liver failure, and bone marrow suppression may occur. If medical intervention is delayed or absent, toxic doses can cause your dog to become comatose. Death may eventually follow.


Toxic doses require aggressive treatment. This includes gastric decontamination (inducing vomiting, gastric lavage, activated charcoal) and gastrointestinal protectants. Symptomatic and supportive care, fluid and blood work monitoring are also recommended. Prognosis is based on the severity of clinical signs, and the timing of treatment. Administering activated charcoal early on can be crucial to survival.

If your dog has been given aspirin, contact your veterinarian immediately. Sometimes, you may be asked to contact animal poison control. If your veterinarian's office is closed, contact the ASPCA Animal Poison Control Center or the Pet Poison Helpline. These are the most widely used poison centers in the United States. There is a consulting fee. But they will provide initial instructions and advise whether you should go to an emergency hospital. These experienced agents are also available to speak with your primary care or emergency veterinarian.

How to Prevent Aspirin Toxicity

As with all medications, the best way to prevent an overdose of aspirin is to keep it out of your dog's reach. If your dog appears to be in pain, consult with your veterinarian before giving over-the-counter medications. They may suggest a treatment most likely approved by the FDA for dog use. Don't assume it's ok for you and your dog to take the same medication. What might be ok for you can be potentially deadly for them.


Do not give aspirin without specific instructions from your veterinarian.

Alternatives to Aspirin for Lameness and Arthritic Pain

Over the years, newer and safer options to aspirin, have been created for lameness and arthritis. There are also non-medication options that your veterinarian may recommend, like joint supplements and nutritional therapy. Acupuncture, laser therapy, and other rehabilitation modalities are commonly recommended although there is an overall lack of studies to prove any benefit. Your veterinarian will help decide which options are best.


  • Brooks, DVM, DABVP, Wendy. "Aspirin - Veterinary Partner - VIN". Veterinarypartner.Vin.Com, 2016,
  • "Smith Jr., DVM, DiplACVIM, Francis W. K. and Tilley, DVM, DiplACVIM, Larry P. et al". Blackwell's Five-Minute Veterinary Consult: Canine and Feline 5th Edition. John Wiley and Sons, Inc. 2011. West Sussex, UK. Kindle file
If you suspect your pet is sick, call your vet immediately. For health-related questions, always consult your veterinarian, as they have examined your pet, know the pet's health history, and can make the best recommendations for your pet.
Article Sources
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  1. Analgesics (Toxicity). Merck Veterinary Manual

  2. Analgesics (Toxicity). Merck Veterinary Manual

  3. Osteoarthritis in Dogs. American College of Veterinary Surgeons