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Effect of valacyclovir on EHV‐5 viral kinetics in horses with equine multinodular pulmonary fibrosis

Author:
Easton‐Jones, Charlotte A., Madigan, John E., Barnum, Samantha, Maxwell, Lara K., Taylor, Sandra D., Arnesen, Terry, Pusterla, Nicola
Source:
Journal of veterinary internal medicine 2018 v.32 no.5 pp. 1763-1767
ISSN:
0891-6640
Subject:
blood, etiology, fibrosis, genes, glycoproteins, horses, lungs, nose, oral administration, prospective studies, quantitative polymerase chain reaction, secretion, viral load
Abstract:
BACKGROUND: Equine herpesvirus‐5 is commonly isolated from the lungs of horses with EMPF, suggesting an etiological link. Valacyclovir is used empirically to treat EMPF; however, no data is available concerning its impact on EHV‐5 viral kinetics. OBJECTIVES: To determine the effect of oral administration of valacyclovir on EHV‐5 viral load measured by qPCR in blood, nasal secretions (NS) and BALF in horses with EMPF. ANIMALS: Six horses diagnosed with EMPF. METHODS: A prospective clinical trial was performed. Horses received 10 days of PO administered valacyclovir (loading dose 30 mg/kg, maintenance dose 20 mg/kg). Blood, NS, and BALF were collected for EHV‐5 viral kinetics analyses during treatment. Blood and NS were collected every other day. BALF was collected on day 0 and day 10. RESULTS: There was no statistical difference in median EHV‐5 viral load between day 0 and day 10 for all samples tested. In blood median EHV‐5 viral load was 7676 (range 575‐39 781) on day 0 and 6822 (range 1136‐18 635) glycoprotein B (gB) gene copies per million cells on day 10. For NS median EHV‐5 viral load was 2.944 × 10⁶ (range 184 691‐3.394 × 10⁹) on day 0 and 8.803 × 10⁶ (range 251 186‐9.868 × 10⁸) gB gene copies per million cells on day 10. For BALF median EHV‐5 viral load was 59,842 (range 61‐315 655) on day 0 and 185 083 (range 3562‐542 417) gB gene copies per million cells on day 10. CONCLUSIONS AND CLINICAL IMPORTANCE: Valacyclovir might not be an effective short‐term antiviral treatment but efficacy in treatment of EMPF is unknown.
Agid:
6163953