Amitriptyline for Cats with Aggression toward Other Cats in the Household

Since he's been medicated, we're the best of friends.
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If your house has become a feline war zone and there's one particular instigator, amitriptyline might restore peace and relative tranquility. However, along with medication, your cat requires behavioral modification. Even the kitty victim might require another type of medication as well as behavioral therapy.


Marketed under the brand name Elavil, amitriptyline is a tricyclic antidepressant developed for people. In pets it also works as an antihistamine, painkiller and anti-inflammatory, making it a very useful medication. Although it's not approved for use in animals by the US Food and Drug Administration, your vet is permitted to prescribe it for "off-label" use. Don't let the name "antidepressant" fool you: these types of drugs can also reduce aggressive behavior.


Life is hell for cats dominated and abused by their feline housemates. While some cats exhibit play aggression, getting a bit too rough with their kitty friends, dominance aggression is the primary reason you need to protect victim cats. While amitriptyline might help the aggressor, it's also necessary to aid the abused kitty. Nebraska-based All Feline Hospital recommends treating the victim cat with antianxiety medication, which makes her less afraid to stand up to the bully. As with all sorts of bullies, a victim who stands up for himself isn't as attractive to a tormentor. AFH also suggests letting the dominant cat outside to burn off excess energy, if that is safe and feasible. Very often, bringing a new cat home starts the aggressive behavior in the prior resident. Eventually these cats might work it out. If you observe pre-aggressive behavior, such as growling or flat ears, remove the aggressor cat before a fight starts. Since male cats are more likely to become aggressive than females, preventing aggression is another good reason to neuter your cat. (Not that you needed one, right?)

Veterinary Evaluation

Amitriptyline has an unpleasant flavor, but the pharmacy may be able to mask the taste of the drug in a liquid or paste, or you may receive a transdermal gel you'll apply to the inside of your cat's ear. Once your cat receives amitriptyline, you'll bring him to the vet regularly for a few months for evaluation. Keep a detailed record of your cat's behavior toward his victim, so you and your vet can see whether the aggressive behavior is changing and if there are specific triggers that set off your cat. The vet might also change the amount of medication your cat takes. Your cat requires regular blood work to ensure his organs aren't affected by the drug.

Side Effects and Contraindictions

As with any medication, amitriptyline can cause side effects. These might be relatively mild, such as drowsiness, or more serious and uncomfortable conditions such as problems urinating, vomiting and diarrhea or constipation. In rare cases, cats become disoriented or even more aggressive. It can also cause heart rhythm abnormalities and bone-marrow suppression. Your vet may want to give your cat an EKG to make sure his heart is healthy before prescribing amitriptyline.

Don't give amitriptyline to pregnant or nursing cats. Cats with diabetes or epilepsy or those suffering from kidney, liver, eye or heart ailments should not take the drug.

Other Uses

If your dominant cat also sprays urine around the house, amitriptyline might solve two problems at once. Your dominant cat could be spraying to identify his "turf" to his victims. It's also prescribed for cats exhibiting excessive grooming behavior, which results in so much licking that bald spots and lesions develop.

Always check with your veterinarian before changing your pet’s diet, medication, or physical activity routines. This information is not a substitute for a vet’s opinion.

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