Dear Christopher Cat: I found a kitten I’ve named Maynard who is sneezing and has pus coming from his eyes and nose. My friend said Maynard has an upper respiratory infection caused by a virus, and that lysine will kill the virus. What do you think of lysine?
Christopher Responds: The clinical signs you describe are common with an upper respiratory infection, but I’m only a cat who hasn’t met Maynard, not a veterinarian who has actually examined him, so I can’t make the diagnosis. If your friend isn’t a vet either, I suggest you make an appointment with a veterinarian who can diagnose Maynard’s problem and make treatment recommendations.
Some upper respiratory infections in cats are caused by the feline herpes virus, and initial studies suggested that lysine might be an effective, safe therapy.
However, subsequent, more rigorous research has shown this not to be the case, and lysine is no longer recommended for treatment of upper respiratory infections caused by feline herpes or other viruses.
Multiple, comprehensive studies have shown that lysine fails to prevent cats from becoming infected with the herpes virus, suppress clinical signs of the illness or shorten the duration of the disease. Limited evidence suggests lysine may even worsen clinical signs.
To get Maynard on the road to recovery, make an appointment with a veterinarian as soon as possible.