Tylenol, or Acetaminophen, is a harmless drug that we take all the time to make us feel better. You would think that this "harmless" drug is safe for our dogs and cats as well, but think again. 1 extra streangth Tylenol tablet (500 mg) will kill a cat and just 50 mg to 60 mg can posion a cat. Dogs can have as high of a dose as 150 mg before dangerous signs occur. Yes, this drug is fine in people but not in animals and I wrote this article to tell you why. Many times an owner gives an older dog or cat some tylenol to help with arthritis and then thses same animals are presented to an animal clinic with lethargy, open mouth breathing, ect.

In cats Acetaminophen causes cellular destruction, liver damage, and damage to red blood cells which carry oxygen throughout the body. Hemoglobin is the substance in red blood cells that carry oxygen, Acetaminophen changes this hemoglobin to methemoglobin which cannot carry oxygen as good. This drug also causes red blood cell hemolysis (breakdown of red blood cells) and heinz bodies on red blood cells. Heinz bodies usually indicate posion and any animal will die from them. They cause abnormal red blood cells. Cats will also have colocolate colored mucous membranes and dark urine.

Dogs need a higher dose then cats to become posioned. They will present with the same signs as cats along with hepatic necrosis (breakdown, decay of the liver), weight loss, and icterus (jaundice, yellow looking from liver failure). On their hematology observations you will fine heinz bodies and hemolysis of red blood cells.

THE REASON:

Acetaminophen is usually conjugated with glucuronic acid and sulfate so it can be metabolized and eliminated. A small portion of Acetaminophen is changed or metabolized into a toxic metabolite. This toxic metabolite is usually congugated with glutathione to form a nontoxic metabolite in stead. A cat's supply of glutathione is very limited therefore limiting or even prohibiting the change of the toxic metabolite to a nontoxic metabolite. In addition to this, glutathione and sulfate conjugation in the cat is less efficient which causes a higher amount of the toxic metabolite. This toxic metabolite builds up in the liver and causes liver dammage / failure along with hemolysis, heinz bodies, and icterus / jaundice.

TREATMENT:

The only treatment for Acetaminophen posioning is to give the animal drugs that contain glutathione, such as acetylcysteine (Mucomyst).


I would suggest staying away form Tylenol when considering a pain and fever reducer for your pets. Please, if you have any questions email me anytime. I'll be happy to answer all of your questions.