Cat · Felis catus · typical adult weight 2.50–7.00 kg
L-Lysine is dosed at 250–500 mg/cat PO q12-24h in cats, per Rees TM, Lubinski JL. Oral supplementation with L-lysine did not prevent upper respiratory infection in a shelter population of cats. J Feline Med Surg. 2008;10(5):510-513. doi:10.1016/j.jfms.2008.03.004; Maggs DJ. Antiviral Therapy for Feline Herpesvirus Infections. Veterinary Clinics of North America-Small Animal Practice. 2010;40(6):1055-+. doi:10.1016/j.cvsm.2010.07.010 — Verified against Plumb's Veterinary Drug Handbook, 10th Ed, p.815 (2026-08-01).. L-Lysine is used in cats for Feline herpesvirus-1 (FHV-1) management. Routes documented in cats: PO. A typical adult cat weighs 2.50–7.00 kg. ExoticRx lists 1 cited dose rule for L-Lysine in cats, drawn from published veterinary references. Verify against current literature before clinical use.
US trade names: Enisyl-F, Viralys
| Route | Dose | Frequency | Duration | Indication | Evidence | Source |
|---|---|---|---|---|---|---|
| PO | 250–500 mg/cat | q12-24h | Long-term supplementation | Feline herpesvirus-1 (FHV-1) management | Weak | Rees TM, Lubinski JL. Oral supplementation with L-lysine did not prevent upper respiratory infection in a shelter population of cats. J Feline Med Surg. 2008;10(5):510-513. doi:10.1016/j.jfms.2008.03.004; Maggs DJ. Antiviral Therapy for Feline Herpesvirus Infections. Veterinary Clinics of North America-Small Animal Practice. 2010;40(6):1055-+. doi:10.1016/j.cvsm.2010.07.010 — Verified against Plumb's Veterinary Drug Handbook, 10th Ed, p.815 (2026-08-01). |
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Competes with arginine for absorption and incorporation. Theoretically suppresses herpesvirus replication by reducing arginine availability needed for viral protein synthesis.
Efficacy debated in recent studies. Generally very safe. May cause GI upset at high doses. Commonly used for FHV-1 in cats despite limited evidence.
Species-specific contraindications and adverse-reaction reports for cats may differ from canine / feline reference data — consult the primary citations listed with each rule.
L-Lysine dose range in cats, with cited source references: PO 250–500 mg/cat q12-24h. Reference ranges from cited sources — verify against current literature before clinical use.
Documented routes for L-Lysine in cats: PO.
Cited course lengths for L-Lysine in cats include: Long-term supplementation. Duration depends on the indication — match it to the specific dose rule in the table above.
L-Lysine is indicated in cats for: Feline herpesvirus-1 (FHV-1) management.
These are general warnings for L-Lysine across species; consult the cat dosing table above for species-specific guidance. Efficacy debated in recent studies. Generally very safe. May cause GI upset at high doses. Commonly used for FHV-1 in cats despite limited evidence.
Why a species-specific page? L-Lysine pharmacokinetics differ across species: dose ranges, intervals, and route preferences are not interchangeable. Cross-extrapolation from canine doses is unsafe in cats — the rules above are the citations specific to this species, not generic recommendations.
Sourced from published veterinary references; awaiting credentialed clinical reviewer. See our editorial process. Reference only — not veterinary advice.