Lysine for FHV? Researchers Say Don’t Bother
Niedziela, Ken. Veterinary Practice News, January 13, 2016.
Excerpt: Two virologists are urging veterinarians to immediately stop lysine supplementation in cats suffering from feline herpesvirus-1 because they say the therapy is ineffective.
How I Treat the Chronic Feline Snuffler
Scherk, Margie, DVM. World Small Animal Veterinary Association World Congress Proceedings. 2008
Excerpt: L-lysine helps to reduce the frequency of herpesviral recrudescence by competing with arginine, preventing viral replication. The dose is 250 (kittens)–500 (adults) mg PO q12h long term.
Lysine Supplementation Is Not Effective for the Prevention or Treatment of Feline Herpesvirus 1 Infection in Cats: A Systematic Review
Bol, Sebastian, and Evelien M Bunnik. BMC veterinary research. U.S. National Library of Medicine, November 16, 2015.
Excerpt: There is evidence at multiple levels that lysine supplementation is not effective for the prevention or treatment of feline herpesvirus 1 infection in cats. Lysine does not have any antiviral properties, but is believed to act by lowering arginine levels. However, lysine does not antagonize arginine in cats, and evidence that low intracellular arginine concentrations would inhibit viral replication is lacking. Furthermore, lowering arginine levels is highly undesirable since cats cannot synthesize this amino acid themselves. Arginine deficiency will result in hyperammonemia, which may be fatal. In vitro studies with feline herpesvirus 1 showed that lysine has no effect on the replication kinetics of the virus. Finally, and most importantly, several clinical studies with cats have shown that lysine is not effective for the prevention or the treatment of feline herpesvirus 1 infection, and some even reported increased infection frequency and disease severity in cats receiving lysine supplementation.