Dangers of Human Pain Medications for Dogs and Cats

Laurie Anne Walden, DVM

Photo by Hal Gatewood on Unsplash

Over-the-counter (nonprescription) pain medications can cause serious problems for dogs and cats. Because these medications don’t need a prescription and are used for children as well as adults, some pet owners mistakenly believe that they’re safe for animals too. But dogs and cats don’t process these drugs the same way as humans.
 
If your pet has signs of pain, call your veterinarian instead of giving your pet something from your medicine cabinet. Prescription pain medications developed specifically for dogs and cats are safer and more effective for them than over-the-counter human medications. In any case, animals that have a level of pain high enough to be obvious to a human need to see a veterinarian.
 
Nonsteroidal Anti-Inflammatory Drugs (Aspirin, Ibuprofen, Naproxen)
The most common human nonsteroidal anti-inflammatory drugs (NSAIDs) available without a prescription are aspirin, ibuprofen, and naproxen. Some brand names are Advil, Aleve, Ascriptin, Bayer, Bufferin, Ecotrin, Midol, and Motrin.
 
In animals, NSAIDs can cause these problems:

• Vomiting
• Diarrhea
• Decreased appetite
• Lethargy
• Stomach ulcers
• Kidney damage
• Liver damage
• Seizures

 
NSAIDs reduce inflammation by blocking the activity of cyclooxygenase (COX) enzymes, which are responsible for prostaglandin production. Prostaglandins are hormone-like substances with many functions; they’re involved in the inflammatory response and also protect the stomach lining and maintain blood flow to the kidneys.
 
Because NSAIDs decrease prostaglandin levels, these medications decrease inflammation and pain. However, the lower prostaglandin levels can also cause serious adverse effects like stomach ulcers and kidney damage. Some newer NSAIDs target specific COX enzymes and prostaglandins that are less likely to affect the stomach and kidneys.
 
Several NSAIDs have been approved for use in dogs, and a few are available for cats. Examples are carprofen, grapiprant, deracoxib, and robenacoxib. These species-specific drugs are available only by prescription from a veterinarian and are less likely than human NSAIDs to cause adverse effects in dogs and cats. Animals receiving prescription NSAIDs need regular examinations and bloodwork to monitor kidney and liver function.
 
Acetaminophen
Brands containing acetaminophen include Tylenol, Panadol, Excedrin, and Midol. Some pain relievers labeled “complete” or “dual action” contain acetaminophen plus aspirin or ibuprofen. Acetaminophen is also called paracetamol.
 
Acetaminophen is highly toxic and often fatal to cats. Acetaminophen is also potentially toxic to dogs, but it can be used in dogs with caution and veterinary oversight.
 
In humans and dogs, acetaminophen is broken down mainly in the liver through a process called glucuronidation. A toxic dose of acetaminophen in a human or a dog damages liver cells and causes liver failure.
 
Cats don’t have the enzymes needed for glucuronidation, so their bodies break down acetaminophen through a different process called sulfation. The sulfation process in cats creates products that react to hemoglobin, the substance within red blood cells that carries oxygen throughout the body.
 
In cats, acetaminophen exposure causes anemia and life-threatening oxygen deficiency. Cats that swallow acetaminophen are less likely than dogs to develop liver failure because they usually die of oxygen deficiency before the liver has a chance to fail.
 
An antidote to acetaminophen (N-acetylcysteine) is available, so dogs and even cats with acetaminophen poisoning can recover if they are treated immediately at an emergency veterinary clinic.
 
For More Information
Get the Facts About Pain Relievers for Pets (US Food and Drug Administration): https://www.fda.gov/animal-veterinary/animal-health-literacy/get-facts-about-pain-relievers-pets
 
Image source: https://unsplash.com/photos/round-white-pills-iPl3q-gEGzY

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