Click to Skip Ahead Aspirin Overview How Aspirin Work Reasons Why Aspirin Isn’t Safe Signs of Aspirin Toxicity Diagnosis of Toxicity Treatment for Toxicity Alternatives Aspirin’s Drug Interactions One of the most common questions a veterinarian will get is, “What can I give my dog for pain?” While we have many pain medication options for dogs available via prescription, owners usually mean what over-the-counter pain medications they can find in their cabinet to give their dog in an emergency. For a long time, the best and safest pain medication available for people or dogs was aspirin, but if you ask a veterinarian this question now, they’ll say there are no safe over-the-counter pain medications for dogs. Why is this? Aspirin presents a high risk of toxicity for dogs, and there are just so many safer alternative options that it’s rare to recommend aspirin for any purpose. What Is Aspirin? Aspirin, also known as acetylsalicylic acid (say that five times fast), is a pain medication part of the NSAID family (Nonsteroidal Anti-Inflammatory Drug). NSAIDs are used for the following purposes: Pain control Lowering inflammation Decreasing clotting Fever reducer Aspirin’s long name is because it’s one of many salicylates, which are chemical compounds found in various products. Some examples would be: Pepto-Bismol (bismuth subsalicylate) Pain creams (Bengay, Icy Hot) Some foundations and concealers Some topical acne products Wintergreen oil All these salicylates are NSAIDs but have varying levels of toxicity to dogs. How Does Aspirin Work? As an NSAID, aspirin works by blocking an enzyme—cyclooxygenase—from forming a chemical compound called prostaglandins. Prostaglandins do a lot of jobs in the body, such as triggering fevers, causing inflammation and pain, and helping platelets clot at the site of cuts. So, aspirin works to block this, thereby lowering fevers, treating pain and inflammation, and decreasing the body’s ability to clot. Image Credit: JF4, Shutterstock Why Isn’t Aspirin Safe in Dogs? There are many different types of prostaglandins in the body, each doing those different jobs. Ideally, aspirin would only inhibit the production of the prostaglandins that cause pain, inflammation, and fevers while not triggering other side effects. When we talk about a medication like aspirin that inhibits everything like this, it’s called a non-selective COX inhibitor. Aspirin has been replaced by many other NSAIDs or NSAID alternatives that more selectively inhibit the production of the prostaglandins we want to inhibit so that there is a lower risk of unwanted side effects. The most common problem with aspirin, and what it is specifically worse for than the other NSAIDs, is that it will cause a lack of blood flow to the stomach cells, leading to cell death and the creation of stomach ulcers. Life-threatening bleeding into the GI tract can occur, but lack of blood flow to the kidney can also cause kidney damage, and other organs can also be affected. You can imagine how dangerous it is to pair a risk of bleeding with a risk of not clotting for the side effects of medication. Image Credit: Elayne Massaini, Shutterstock Pregnant female dogs are at an even higher risk of aspirin toxicity as it can lead to high concentrations building up in fetuses leading to death and bleeding for the mother. A single dose of aspirin or repeated dosing can both be toxic to dogs, so since it’s so dangerous compared to other pain medications and isn’t better at controlling pain than the others, aspirin is not safe to give to dogs. One of aspirin’s lingering uses was as an anticoagulant or medication that prevents clotting. Even that has been replaced by a more effective, safer medication, leaving little use for aspirin in dogs. Signs of Aspirin Toxicity Vomiting, especially with blood Diarrhea Any stool with a black, tarry appearance or blood Lethargy Pale or yellow gums Abdominal pain Rapid breathing Seizures Poor clotting Weakness Hyperthermia Increased drinking and/or urinating Sudden collapse If your dog is showing any of these signs, we recommend speaking with a vet.