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Journal of veterinary internal medicine2018; 32(5); 1763-1767; doi: 10.1111/jvim.15230

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

Abstract: 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. Objective: 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. Methods: 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 × 10 (range 184 691-3.394 × 10 ) on day 0 and 8.803 × 10 (range 251 186-9.868 × 10 ) 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: Valacyclovir might not be an effective short-term antiviral treatment but efficacy in treatment of EMPF is unknown.
© 2018 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.
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Publication Date: 2018-09-17 PubMed ID: 30221792PubMed Central: PMC6189341DOI: 10.1111/jvim.15230Google Scholar: Lookup
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  • Clinical Trial
  • Veterinary
  • Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research evaluates the impact of the antiviral medication, Valacyclovir, on the viral load of Equine herpesvirus-5 (EHV-5) in horses diagnosed with equine multinodular pulmonary fibrosis (EMPF). The study found no significant difference in viral load before and after treatment suggesting that Valacyclovir may not be effective for short-term antiviral treatment of EMPF.

Research Objective

  • The main goal of the research was to determine the effect of the oral administration of Valacyclovir on EHV-5 viral load in horses diagnosed with EMPF. The sample included six horses and the viral load was measured using quantitative Polymerase Chain Reaction (qPCR) analysis in blood, nasal secretions (NS), and Bronchoalveolar lavage fluid (BALF).

Methods

  • A prospective clinical trial was conducted where the six diagnosed horses were given an oral loading dose of 30 mg/kg of Valacyclovir, followed by a maintenance dose of 20 mg/kg for 10 days.
  • Blood and NS samples were collected every other day, while BALF was collected on the first (day 0) and last (day 10) days of the experiment.
  • The viral load, in terms of glycoprotein B gene copies per million cells, was then analysed in these samples.

Results

  • The study found no statistically significant difference in the median EHV-5 viral load between day 0 and day 10 for all samples tested.
  • The viral load in the blood was 7676 on day 0 and decreased slightly to 6822 on day 10.
  • In NS, the viral load was around 2.944 x 10 on day 0 and increased considerably to 8.803 x 10 by day 10.
  • For BALF, the median viral load significantly increased from 59,842 on day 0 to 185,083 on day 10.

Conclusion

  • The research concluded that the administration of Valacyclovir appears to have negligible effects on short-term EHV-5 viral kinetics in horses with EMPF. There was no significant reduction in viral load in the tested samples, with some even showing considerable increase.
  • While Valacyclovir is commonly used to treat EMPF based on perceived associations between the disease and EHV-5, its efficacy for this particular purpose remains uncertain. More research is required to evaluate the drug’s long-term effects and potential utility in treating EMPF.

Cite This Article

APA
Easton-Jones CA, Madigan JE, Barnum S, Maxwell LK, Taylor SD, Arnesen T, Pusterla N. (2018). Effect of valacyclovir on EHV-5 viral kinetics in horses with equine multinodular pulmonary fibrosis. J Vet Intern Med, 32(5), 1763-1767. https://doi.org/10.1111/jvim.15230

Publication

Journal of veterinary internal medicine
ISSN: 1939-1676
NlmUniqueID: 8708660
Country: United States
Language: English
Volume: 32
Issue: 5
Pages: 1763-1767

Researcher Affiliations

Easton-Jones, Charlotte A
  • Willian R Pritchard Veterinary Medical Teaching Hospital, University of California Davis, California.
Madigan, John E
  • Department of Medicine and Epidemiology, University of California, Davis, California.
Barnum, Samantha
  • Department of Medicine and Epidemiology, University of California, Davis, California.
Maxwell, Lara K
  • Department of Physiological Sciences, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, Oklahoma.
Taylor, Sandra D
  • Department of Veterinary Clinical Sciences, Purdue University, West Lafayette, Indiana, IN.
Arnesen, Terry
  • Stillwater Equine Veterinary Clinic, Stillwater, Minnesota.
Pusterla, Nicola
  • Department of Medicine and Epidemiology, University of California, Davis, California.

MeSH Terms

  • Animals
  • Antiviral Agents / administration & dosage
  • Antiviral Agents / therapeutic use
  • Bronchoalveolar Lavage Fluid
  • DNA, Viral
  • Dose-Response Relationship, Drug
  • Female
  • Gammaherpesvirinae
  • Herpesviridae Infections / drug therapy
  • Herpesviridae Infections / veterinary
  • Herpesviridae Infections / virology
  • Horse Diseases / drug therapy
  • Horses
  • Male
  • Pulmonary Fibrosis / pathology
  • Pulmonary Fibrosis / veterinary
  • Pulmonary Fibrosis / virology
  • Valacyclovir / administration & dosage
  • Valacyclovir / therapeutic use
  • Virus Replication / drug effects

Grant Funding

  • University of California, Davis Center for Equine Health with funds provided by the State of California satellite wagering fund and contributions by private donors.

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Citations

This article has been cited 2 times.
  1. Hardefeldt L, Thomas K, Page S, Norris J, Browning G, El Hage C, Stewart A, Gilkerson J, Muscatello G, Verwilghen D, van Galen G, Bauquier J, Cuming R, Reynolds B, Whittaker C, Wilkes E, Clulow J, Burden C, Begg L. Antimicrobial prescribing guidelines for horses in Australia. Aust Vet J 2025 Dec;103(12):781-889.
    doi: 10.1111/avj.70003pubmed: 40903020google scholar: lookup
  2. Craven A, Todd-Donato A, Stokol T, Liepman R, Glasberg I, Wilkins P, Luethy D, Wong D, Schoster A, van den Brom-Spierenburg AJ, Tomlinson JE. Clinical findings and outcome predictors for multinodular pulmonary fibrosis in horses: 46 cases (2009-2019). J Vet Intern Med 2024 May-Jun;38(3):1842-1857.
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