Acetaminophen (Tylenol or Paracetamol) Poisoning in Cats

Acetaminophen toxicity is a common condition in cats, as many pet parents give their animals acetaminophen-containing drugs in an effort to manage pain or inflammation at home. Acetaminophen toxicity is an emergency: consumption of as little as a quarter of an acetaminophen tablet has the potential to be deadly, depending on the cat’s body weight. If ingestion is known or suspected, immediate veterinarian attention is crucial in improving the cat’s prognosis.

Symptoms of acetaminophen toxicity vary depending on which tissue is affected. Acetaminophen poisoning may damage red blood cells, the liver, and/or the kidneys.

Acetaminophen toxicity is caused by the ingestion of a toxic dose acetaminophen. Once ingested, acetaminophen enters the animal's system. Cats lack the enzyme to break down acetaminophen appropriately. When the compound reaches the liver, it forms toxic metabolites that damage the cat’s red blood cells and liver.

The potentially lethal dose for cats is 10mg/kg; as little as a quarter of a regular acetaminophen tablet (50 mg) can be deadly for an average-sized cat. There is no safe dose for cats.

Symptoms of acetaminophen toxicity develop between 1 and 4 hours after ingestion.

If ingestion of acetaminophen is witnessed, the diagnosis is self-evident. In some cases, ingestion can occur without a witness.

A cat suspected of having ingested acetaminophen will undergo the following diagnostics:

• Physical examination
• Blood tests
• Urinalysis

If the ingestion is known to have occurred and treatment is sought rapidly, the objective of treating acetaminophen toxicosis is removal of the toxin.

• Induced vomiting: emesis is the most effective way to decontaminate the GI system. **There is no safe way to induce vomiting at home. **
• Gastric lavage: gastric lavage involves rinsing the stomach contents through a tube passed from the mouth into the stomach
• Activated charcoal: activated charcoal can be administered to slow the absorption of acetaminophen. **Activated charcoal must be administered by a veterinarian, as its improper administration can be aspirated into the lungs and cause life-threatening changes in sodium levels. **
• N-acetylcysteine (NAC): administration of NAC reduces the extent of liver damage caused by acetaminophen. NAC binds to the acetaminophen metabolite and helps its elimination. Following decontamination and NAC treatment, monitoring is required for up to 48 hours, including repeated blood work to catch any signs of organ damage quickly.

If ingestion was not witnessed but symptoms lead to suspicion of toxicity, treatment is targeted at reducing organ damage and may include fluid therapy and blood transfusions.

If treatment is sought early, prognosis is good. Cats with severe liver damage have a very poor prognosis, and may have life-long liver function abnormalities. If untreated, acetaminophen toxicity can be fatal.

Acetaminophen toxicity is completely prevented by removing the possibility of ingestion of acetaminophen. Strategies include:

• Diligent storage and disposal of medications
• Always contacting a veterinarian before administering any kind of drug to pets

Acetaminophen toxicity is fairly common in cats because pet parents may give their cats acetaminophen in an effort to treat pain or inflammation at home, not knowing that it is toxic.

• Gastrointestinal decontamination
• N-acetylcysteine