title: Detection of equine herpesvirus in horses with idiopathic keratoconjunctivitis and comparison of three sampling techniques.
abstract: OBJECTIVE
  To determine the role of equine herpesvirus (EHV) in idiopathic keratoconjunctivitis in horses and to determine whether sample collection method affects detection of EHV DNA by quantitative polymerase chain reaction (qPCR).
  
  
  METHODS
  Twelve horses with idiopathic keratoconjunctivitis and six horses without signs of ophthalmic disease.
  
  
  METHODS
  Conjunctival swabs, corneal scrapings, and conjunctival biopsies were collected from 18 horses: 12 clinical cases with idiopathic keratoconjunctivitis and six euthanized controls. In horses with both eyes involved, the samples were taken from the eye judged to be more severely affected. Samples were tested with qPCR for EHV-1, EHV-2, EHV-4, and EHV-5 DNA. Quantity of EHV DNA and viral replicative activity were compared between the two populations and among the different sampling techniques; relative sensitivities of the sampling techniques were determined.
  
  
  RESULTS
  Prevalence of EHV DNA as assessed by qPCR did not differ significantly between control horses and those with idiopathic keratoconjunctivitis. Sampling by conjunctival swab was more likely to yield viral DNA as assessed by qPCR than was conjunctival biopsy. EHV-1 and EHV-4 DNA were not detected in either normal or IKC-affected horses; EHV-2 DNA was detected in two of 12 affected horses but not in normal horses. EHV-5 DNA was commonly found in ophthalmically normal horses and horses with idiopathic keratoconjunctivitis.
  
  
  CONCLUSIONS
  Because EHV-5 DNA was commonly found in control horses and in horses with idiopathic keratoconjunctivitis, qPCR was not useful for the etiological diagnosis of equine keratoconjunctivitis. Conjunctival swabs were significantly better at obtaining viral DNA samples than conjunctival biopsy in horses in which EHV-5 DNA was found.
authors.affiliation: Department of Surgical and Radiological Sciences, University of California, One Shields Avenue, Davis, CA, 95616, USA.
authors.forename: Steven R
authors.initials: SR
authors.lastname: Hollingsworth
authors.affiliation: Department of Medicine and Epidemiology, University of California, One Shields Avenue, Davis, CA, 95616, USA.
authors.forename: Nicola
authors.initials: N
authors.lastname: Pusterla
authors.affiliation: Department of Population Health and Reproduction, University of California, One Shields Avenue, Davis, CA, 95616, USA.
authors.forename: Philip H
authors.initials: PH
authors.lastname: Kass
authors.affiliation: Department of Surgical and Radiological Sciences, University of California, One Shields Avenue, Davis, CA, 95616, USA.
authors.forename: Kathryn L
authors.initials: KL
authors.lastname: Good
authors.affiliation: Department of Medicine and Epidemiology, University of California, One Shields Avenue, Davis, CA, 95616, USA.
authors.forename: Stephanie A
authors.initials: SA
authors.lastname: Brault
authors.affiliation: Department of Surgical and Radiological Sciences, University of California, One Shields Avenue, Davis, CA, 95616, USA.
authors.forename: David J
authors.initials: DJ
authors.lastname: Maggs
mesh_terms: D000818:Animals; D005260:Female; D006566:Herpesviridae Infections / Q000175:diagnosis / Q000662:veterinary* / Q000821:virology; D004861:Herpesvirus 1, Equid; D004858:Herpesvirus 3, Equid; D023141:Herpesvirus 4, Equid; D006734:Horse Diseases / Q000175:diagnosis* / Q000821:virology; D006736:Horses; D007639:Keratoconjunctivitis, Infectious / Q000175:diagnosis* / Q000821:virology; D008297:Male; D060888:Real-Time Polymerase Chain Reaction / Q000662:veterinary; D018144:Rhadinovirus; D013048:Specimen Handling / Q000662:veterinary; D018140:Varicellovirus; D019562:Viral Load / Q000662:veterinary
keywords: EHV; conjunctival biopsy; conjunctival swab; corneal scraping; infectious keratitis; qPCR