Yes, domestic cats can overdose on veterinary and human medications for a number of reasons. Accidental ingestion of veterinary bills and pills for humans are a common cause of poisoning in companion animals including cats. This may happen when a veterinary medical product is flavoured to encourage a cat to ingest it causing the drug to be eagerly consumed if it is left lying around for whatever reason. We know how curious domestic cats are and if there are one or two pills on the floor they might decide to investigate, sniff them and then consume them.
Perhaps the reason why many veterinary drugs are not flavoured is to prevent accidental ingestion of drugs which are toxic if taken in sufficient quantities.
Another reason why a domestic cat might overdose on medications is because their owner bought the medications online without veterinary approval to treat a variety of symptoms. Sometimes people believe that when a medicine works for them it will work for their cat. This, however, isn’t true. Cats can be very sensitive to many medications. Human dosages of over-the-counter drugs are often highly toxic to cats. Some human drugs are toxic to cats in any amount.
For example, painkillers such as Advil (ibuprofen) and Tylenol (in America) are very toxic to cats (NSAID). Tylenol is paracetamol which is known as acetaminophen in the USA. It is also known as Panadol.
Domestic cats don’t have the enzymes to detoxify and eliminate these medications. They lack the liver enzyme glucuronyl transferase. It is an enzyme which breaks down drugs so they can be metabolised. Without the enzyme there will be an accumulation of dangerous substances in a cat after the drugs be metabolised. These substances cause abdominal pain, weakness, vomiting and salivation.
The type of human drugs that can cause poisoning in cats might include: antidepressants, vitamins, blood pressure pills, heart pills, diet pills, sleeping pills, nonsteroidal pain relievers, antihistamines and antidepressants.
If you think that your cat has been poisoned by human or veterinary drugs then you should contact your veterinarian immediately. My reference book tells me that you should immediately induce vomiting and coat the bowel to prevent poison absorption.
I am reluctant to describe this process but I will touch on it for the sake of completeness. My reference books states that you induce vomiting by giving your cat hydrogen peroxide at a 3% solution. If it doesn’t work you can repeat every 10 minutes up to 3 times. If possible, you should get your cat to walk or gently shake him in your arms after administering hydrogen peroxide. This may stimulate vomiting. Once he has vomited you give him activated charcoal which binds the poison that remains in his stomach to prevent absorption. The recommendation is five-gram compressed activated charcoal tablets which should be in an emergency medical kit on standby at all times.
The dosage is one tablet per 10 lbs (4.5 kg) of body weight. Liquid versions are harder to administer according to my reference book. An alternative is to coat the intestines with milk and egg whites using 1/4 cup of egg whites and 1/4 cup of milk. You mix it up and give the cat about 2 teaspoons by mouth. You can administer it by using a plastic syringe to inject the liquid into the cat’s cheek. You might add it to food. Other than that, you should take your cat a veterinarian for possible hospitalisation and intravenous fluid support.
Ref source: Cat Owner’s Home Veterinary Handbook, 3rd edition at pages 30-31 and 29.
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