Aspirin or Acetylsalicylic Acid Poisoning in the Cat

Filed Under: Cats

Is your cat feeling a little under the weather? Think you might help him out by giving him half of an aspirin. Don’t! Aspirin may be toxic to your pet, especially your feline friends.

Although aspirin is one of the most extensively used and most easily available over-the- counter, or OTC, drugs available and has been used since the time of the ancient Greeks and Romans, it is not without its toxic effects. Cats are particularly sensitive to various drugs including aspirin due to a lack of certain enzymes, glucuronyl transferases, manufactured in the liver which are responsible for the conjugation and excretion of aspirin and certain other drugs. The lack of this enzyme prolongs the effectiveness of various drugs. Kittens or cats with renal or hepatic disease are particularly susceptible to the effects of the medication.

Aspirin, or acetylsalicylic acid, is available in a 5-grain size, of which there are 60 mg to a grain, or 300 mg of the drug found in just one regular strength tablet. A baby aspirin contains 81 mg of acetylsalicylic acid per tablet. Cats have been severely poisoned by as little as 30 mg/kg or 15 mg per pound of body weight.

Aspirin does have a therapeutic use in the cat for thromoboembolic disease (formation of blood clots that are attached to a vessel or occlude a blood vessel) associated with cardiomyopathy. For the prevention and dissolution of blood clots associated with hypertrophic cardiomyopathy, aspirin has been given at a 25 mg/kg dose every three days in cats.

Clinical signs of poisoning most commonly appear as vomiting from gastric ulceration accompanied by clinical signs of hemorrhage, especially in vomit or discharge from the rectum. In addition, these cats may be lethargic, anorexic (lack of an appetite), anemic, and weak. These pets are often toxic and painful as exhibited by tachypnea (rapid shallow breathing) and panting. Small superficial hemorrhages called petechia often occur on the skin and mucous membranes. There may be an acetone odor to the breath. Aspirin toxicosis commonly results in a drug-induced hepatitis which is seen clinically by icterus and jaundice. A rare complication, hyperthermia (elevated temperature) may occur and is associated with a poor prognosis. In the later stages muscular weakness will be followed by ataxia, seizures, coma, and death of the affected individual.

Gastric lavage may be helpful for up to 12 hours following exposure to aspirin since the aspirin itself often inhibits gastric emptying thereby keeping the aspirin in the stomach area. With enteric-coated aspirin tablets the absorption of the salicylates is prolonged thereby assisting in its removal.

Treatment consists of the use of an emetic to induce vomiting and gastric lavage with potassium permanganate diluted 1:5000 or activated charcoal to prevent absorption. The resulting acidosis may be treated orally with sodium bicarbonate. Valium or diazepam may be necessary for the control of seizures. Gastric protectants such as sucralfate may be useful in the treatment of gastric ulceration. Fluid therapy and possible peritoneal dialysis may become necessary in severe cases.


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.

Norsworthy, Gary, Ed. The Feline Patient. Blackwell Publishing 3rd Edition. 2006. P. 23.

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