Pet Columns, Office of Public Engagement, College of Veterinary Medicine at the University of Illinois at Urbana-Champaign

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Pets More Susceptible to Side Effects of NSAIDs


Pet Column for the week of November 2, 2009

Related information:

Related site - American Veterinary Medical Association

Office of Public Engagement
2001 S. Lincoln Ave.
Urbana, Illinois 61802
Phone: 217/333-2907
Ashley Mitek
Information Specialist

Source - Stuart Clark-Price, DVM, MS, DACVIM, DACVA
It is now widely accepted in human medicine that one of the largest causes of liver failure (and also liver transplant surgery) in the United States is due to the overuse of a particular type of non-steroidal anti-inflammatory drug (NSAID) named acetaminophen. This stunning research finding was first published in the December 2005 issue of the journal Hepatology. Nearly every person in the country has used one type of NSAID or another, whether that be ibuprofen, naproxen, or aspirin. When taken correctly, these drugs have very few side effects.

However, "the use of NSAIDS is one of the most controversial topics in veterinary medicine," says Dr. Stuart Clark-Price, a veterinary anesthesiologist and internal medicine specialist at the University of Illinois Veterinary Teaching Hospital in Urbana. As many pill-popping humans can attest, these drugs have great anti-inflammatory, anti-fever, and pain relief properties because they inhibit certain enzymes in the body. If these drugs have such great properties, then why is their use so controversial in animals, one may ask?

"Cats and dogs are much more susceptible than people to the adverse effect of NSAIDs," explains Dr. Clark-Price. In short, dogs and cats are not simply smaller versions of people. They lack certain enzymes that we have, and also may process these drugs differently. In short, the use of NSAIDS in dogs and cats comes with a smaller safety margin. Because of this, it is critical that veterinary patients be accurately dosed and routinely monitored for side effects.

Despite of the increased risk, NSAIDS are frequently used in veterinary patients with minimal adverse effects. For example, in a routine spay or castration in a healthy dog or cat over the age of the age of 6 weeks, NSAIDS are a good choice for pain relief. Because there will be mild to moderate inflammation in these instances, which is exactly what these drugs work to prevent, "NSAIDS are probably better for consistent pain control in cases of inflammation than even opioids," notes Dr. Clark-Price.

Another reason dogs are prescribed NSAIDs is due to chronic arthritis. For example, an older Labrador that has a hard time getting up in the morning due to joint pain may be given a certain NSAID daily. But careful monitoring is critical in these patients. The most common complication is gastro-intestinal tract ulceration. This can be a minor problem, but it can also progress to life threatening perforations.

Other problems that can develop are kidney and liver dysfunction, or blood abnormalities such as the decreased ability to clot. Because liver and kidney disease are potential side effects of NSAIDs, it is important that a dog starting on a course of these drugs have its blood tested frequently to determine if kidney and liver function are starting to decrease. If so, it is imperative that NSAID use be terminated.

Symptoms owners should watch for while their pet is on NSAIDS include:

  • Decreased appetite
  • Lethargy or other changes in behavior
  • Vomiting or diarrhea
  • Yellowing of the skin, whites of the eye, or gums
  • Skin redness or scabs


For more information on the risks of NSAID use in pets please talk to your local veterinarian.

Please do not give any NSAIDs to your pet without first contacting your veterinarian. For example, one acetaminophen (Tylenol) pill may kill a cat.