Acetaminophen is a common, non-aspirin pain reliever found in many home remedies, particularly all Tylenol products. Acetaminophen is very toxic to cats and can be toxic to dogs as well. Normal adult acetaminophen tablets contain 325 mg. The toxic dose for cats is 10 mg/kg (so the average 8 pound or 4 kg cat would be toxic tat 40 mg or 1/10th of a tablet!. In dogs, the toxic dose is 150 mg/kg of body weight, so a single tablet is unlikely to be dangerous to any dog above 10 pounds. However, sometimes dogs will eat many tablets at one time, which can be toxic depending on the weight of the pet.

Principle of Toxicity:

Acetaminophen interferes with the metabolism of a chemical called glutathione. Glutathione is important in protecting the liver and red blood cells from damage caused by oxidative stress. As a result, the hemoglobin in the red cells may become non functional (met-hemoglobin) and unable to carry oxygen properly. This form of hemoglobin causes the pets mucus membranes to turn a muddy brown color. In addition, damaged red blood cells are destroyed by the body leading to severe anemia. Moreover, acetaminophen can cause liver damage and liver failure.

Clinical Symptoms

Swelling of the face and feet, excessive salivation, muddy brown colored mucus membranes, bluish color to tongue, icterus (yellow tinge to mucus membranes and whites of eyes), hyperventilation and vomiting.

Diagnosis

The diagnosis of Acetaminophen toxicity is based on known ingestion of the drug, or a combination of the clinical symptoms and results of blood tests, which may include:

  • Anemia
  • Heinz body formation in the red blood cells
  • Increased liver enzymes
  • Characteristic brown color of blood.

Treatment

Treatment includes purging the drug from the system (if known ingestion has occurred) by inducing vomiting and/or gastric lavage. Administering activated charcoal in the stomach to help absorb the drug before it is absorbed.

A number of drugs can help counteract the effects of this drug including:

  • Anemia
  • Heinz body formation in the red blood cells
  • Increased liver enzymes
  • Characteristic brown color of blood.

General supportive care, including intravenous fluids, oxygen support, blood transfusions etc.

Prognosis

The prognosis in this intoxication is linked to the size and species of animal (smaller animals and cats have worse prognosis), the amount of drug ingested and the amount of time passing before diagnosis. This drug can be fatal, especially to cats. So, early detection and aggressive treatment is critical. With early detection and treatment, many of these pets can be saved. If you think your pet has eaten even the smallest amount of acetaminophen, call our veterinary hospital at 909-980-3575, or take your pet to a veterinary emergency hospital if it is after hours.