You should seek the advice of your veterinarian if your pet is ill as only he or she can correctly advise on the diagnosis and recommend the treatment that is most appropriate for your pet.

Paracetamol poisoning is seen from time to time in both cats and dogs. Treatment with acetylcysteine or ascorbic acid (cats) is recommended

Poisoning with paracetamol is not uncommon because owners frequently administer drugs that they have available for themselves to their pets. An article on this has been broadcast on Provet - under the Petfacts section for pet owners.

Cats are more susceptible to paracetamol poisoning - which occurs at concentrations of only 45mg/kg body weight - because they :

• have a deficiency of liver enzymes to combine the drug with glucuronide
• feline haemoglobin is susceptible to oxidative damage and readily forms methaemoglobin  

In dogs much higher doses (250mg/kg body weight) are needed to induce toxicity - which results in liver and kidney failure.

Recommended treatment for paracetamol poisoning involves :

• Intravenous fluid administration
• Induce vomiting if presented early
• Gastric lavage
• Acetylcysteine :
  • Dogs - give intravenously at a dose rate of 140mg/kg as soon as possible, then give 70mg/kg after 30 minutes, and after 1 hour
  • Cats - give 140 mg/kg body weight intravenously initially, then 70mg/kg by mouth 4 times daily for 5 days.
• Ascorbic acid - in cats - give by intravenous injection 30mg/kg body weight every 6 hours to reduce methaemoglobinaemia as well as acetylcysteine

Even though paracetamol (acetaminophen) is not licensed for use in dogs it is being used increasingly off-label by the veterinary profession,. This is a matter of concern because efficacy and safety have not been demonstrated . In one study hepatotoxicity was present even at accepted "therapeutic" doses. 

Updated October 2013