Aspirin or Acetylsalicylic Acid Poisoning in the Dog

Filed Under: Dogs, Poisoning

Is your dog having trouble getting around? Do you think your dog may be running an elevated temperature? Think you might help him out by giving him an aspirin? Don’t! Aspirin may be toxic to your pet, especially in high doses.

Aspirin or acetylsalicylic acid has been used as far back as the ancient Greeks and Romans and it is one of the most extensively used and most easily available over-the-counter or OTC drugs available. A normal aspirin contains 5 grains of which there are 60 mg to a grain, or 300 mg to a regular aspirin. Baby aspirin contains 81 mg of acetylsalicylic acid per tablet.

In one study dogs were given aspirin at doses of 25 mg/kg without adverse effects for up to 3 weeks. Conflicting results were obtained in an unrelated study where a slightly larger dose of 37 mg/kg in dogs demonstrated aspirin to cause gastric ulceration and blood in the stool, or melena.

As with other NSAIDs the most commonly seen adverse effects from aspirin are vomiting and hemorrhage, typically secondary to gastric ulceration or erosions. Animals may appear depressed and weak, often becoming unable to stand. Nose bleeds, some of which may be severe, can occur in the dog resulting in various levels of anemia. Puppies or dogs with hepatic or renal disease have a decreased ability to metabolize aspirin and toxic levels are obtained more easily. Aspirin is primarily metabolized in the liver by esterases, which are less efficient in immature animals. Additional minor metabolism of aspirin occurs in the gastrointestinal tract and erythrocytes (red blood cells), also by esterases.

Treatment consists of emesis (induction of vomiting), gastric lavage with potassium permanganate diluted 1:5000, or activated charcoal to inhibit absorption. Gastric lavage may be helpful for up to 12 hours following exposure to aspirin since the medication will inhibit gastric emptying, and with enteric-coated aspirin tablets the absorption of the salicylates is prolonged. In the treatment of gastric ulcers, gastric protectants such as sucralfate are often used in combination with an H2 receptor antagonist such as cimetidine, ranitidine, or famotidine, which are used to suppress the secretion of gastric acid. Fluid therapy or blood replacement may be necessary in severe cases of anemia. Perforated or severe ulcerations may require surgery.

Aspirin may also interact with other medications, most commonly Spironolactone, where it will inhibit its diuretic effects.


Gupta, Ramesh, Ed. Veterinary Toxicology. Elsevier. 2007. Pp. 377-379.

Kirk, Robert, and Stephen Bistner. “Handbook of Veterinary Procedures and Emergency Treatment.” 1981. W.B. Saunders Co. Pp. 157-158.

Ettinger, Stephen, and Edward C. Feldman. Textbook of Veterinary Internal Medicine. Vol. 2. 5th Edition, 2000. Pp. 1165-1168.

Topics: aspirin, poisoning

Symptoms: hemorrhage, ulcers, vomiting

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