Effect of oral administration of L-lysine on conjunctivitis caused by feline herpesvirus in cats

Abstract

Oral administration of 500 mg of lysine to cats was well tolerated and resulted in less severe manifestations of conjunctivitis caused by FHV-1, compared with cats that received placebo. Oral administration of lysine may be helpful in early treatment for FHV-1 infection by lessening the severity of disease.

Corneal ulceration associated with naturally occurring canine herpesvirus-1 infection in two adult dogs

“…[62][63][64] One dog also received L-lysine, which has been found to reduce the in vitro replication of FHV-1 and HSV, decrease viral shedding in cats following experimentally induced reactivation of latent FHV-1 infections, reduce the severity of conjunctivitis in cats after primary FHV-1 infection, accelerate recovery from natural HSV infection in humans, and suppress natural HSV infection recurrence in humans. [65][66][67][68][69] In one of the dogs reported here, healing of the corneal ulcers was observed after topical administration of idoxuridine and discontinuation of topically administered dexamethasone. Flurbiprofen was also administered topically in this dog.…”

Feline herpesvirus

“…Treatment with L-lysine therefore decreases viral proteosynthesis and has been shown to have some inhibitory effect against both human herpesvirus and FeHV-1 infection. Oral supplementation with L-lysine reduces the severity of experimentally-induced FeHV-1 conjunctivitis when administered prior to primary infection [127] and the number of shedding episodes associated with reactivation of latent infection induced by re-housing [80]. It may therefore be of use early in acute disease or as a means of reducing the severity of disease and virus shed at times of stress: suggested dosage regimens are described elsewhere [82,128].…”

“…The effect of L-lysine on FeHV-1 replication has recently been explored both in vitro and in experimental cat studies [79,80,127]. L-lysine is an antagonist of arginine, which has been shown to be essential for human herpes simplex virus and FeHV-1 replication [80].…”

Opinion of the Scientific Panel on Additives and Products or Substances used in Animal Feed on the safety and efficacy of L-lysine sulphate (Vitalys®Liquid and Dry) for all animal species

“…increase of around 0.5 -0.6 % of dietary lys) seem to reduce severity of conjunctivitis caused by feline herpes virus type 1 (FHV-1) and virus shedding (Maggs et al, 2000(Maggs et al, , 2003Stiles et al, 2002). It is assumed that arginine has a growth promoting effect on FHV-1 and herpes simplex which will be diminished by excess dietary lysine due to the interaction between Arg and Lys (Tankersley, 1964;Maggs et al, 2000), however without affecting the plasma arginine concentrations (Stiles et al, 2002;Maggs et al, 2003;Fascetti et al, 2004). Therefore, the effective Lys dosage and even very high dietary Lys concentrations (up to 8.6 %) have obviously no adverse effects on arginine metabolism and on health of cats (Maggs et al, 2003;Fascetti et al, 2004).…”

“…(Flodin, 1997) In the cat, high doses of L-lysine (0.4 -0.5 g additional L-Lys per day; i.e. increase of around 0.5 -0.6 % of dietary lys) seem to reduce severity of conjunctivitis caused by feline herpes virus type 1 (FHV-1) and virus shedding (Maggs et al, 2000(Maggs et al, , 2003Stiles et al, 2002). It is assumed that arginine has a growth promoting effect on FHV-1 and herpes simplex which will be diminished by excess dietary lysine due to the interaction between Arg and Lys (Tankersley, 1964;Maggs et al, 2000), however without affecting the plasma arginine concentrations (Stiles et al, 2002;Maggs et al, 2003;Fascetti et al, 2004).…”