Amino Acid Lysine for Cats

Cats need lysine from proteins in their diets.
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If your kitty is sneezing and sniffling, she may be suffering from a kitty cold due to the feline herpesvirus. To keep this virus in check, your vet may recommend that you add some extra lysine to your furry friend's food, which helps to fight the virus causing her discomfort.

What is Lysine?

Lysine, also referred to as L-lysine, is a type of amino acid found in animal-based protein sources like meats, poultry, eggs, yogurt, fish and cheese. It's also found in vegetable-based protein sources like beans or wheat, although in lower amounts than in animal-based ones. Amino acids are the building blocks of proteins and some are required for a kitty to survive. Lysine is considered an essential amino acid for kitties, meaning that it must be included in their diet because their bodies can't produce it naturally. This essential amino acid is one of the 11 needed by our feline friends, according to the American Society for the Prevention of Cruelty to Animals.


To ensure that your kitty receives enough protein and lysine in her diet, choose foods that adhere to the profiles established by the Association of American Feed Control Officials. You'll see this on the label of the food along with the phrase "complete and balanced," according to the U.S. Food and Drug Administration. These foods contain at least the minimum amount of lysine required to maintain your kitty's health, namely 1.2 percent in kittens and 0.83 percent of the food's content in adults. Foods that don't adhere to the AAFCO feeding profiles may not contain enough lysine to keep your furry buddy healthy, so consult with your vet regarding her diet if you are concerned.


While healthy kitties eating a balanced diet shouldn't require additional supplementation with lysine, those with the feline herpesvirus type one may benefit from it. Feline herpesvirus causes upper respiratory infections and conjunctivitis in a kitty, typically resulting in a sneezing, sniffling feline with runny eyes. To help reduce these symptoms, mix 500 mg of lysine powder in your furry buddy's food each day during her outbreak, recommends the Cat Doctor & Friends. This speeds healing of the virus and lessens the symptoms, which can occur during periods of stress in a kitty that has been exposed to the virus at any point during her life.


According to Holisticat, 500 mg of lysine daily is a safe amount to give your kitty for a week during a feline herpesvirus outbreak and up to 250 mg daily for a longer period to keep your kitty virus-free. However, in kitties with the feline herpesvirus, those given 400 mg of lysine for one month experienced no ill effects, according to a study published in the January 2003 issue of the "American Journal of Veterinary Research." These kitties did experience less symptoms of the virus, including signs of conjunctivitis. Because lysine can compete with arginine, another amino acid in your kitty's body, it's best to consult with your vet regarding dosage and length of treatment using lysine.

Considerations and Safety

Before administering this amino acid to your kitty, bring her to the vet for an exam. Your feline friend might be suffering from a bacterial, rather than viral infection, which requires an antibiotic to treat, or even an allergy mimicking the symptoms of an upper respiratory infection. While lysine won't hurt these conditions, it's won't help them either. When purchasing lysine for your furry friend, look for formulations such as gels, pastes and powders formulated specifically for pets. Such formulations won't contain any additives or preservatives like propylene glycol, which may be harmful for felines and may be included in the human versions, recommends VetInfo.

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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