title: Clinical course of ophthalmic findings and potential influence factors of herpesvirus infections: 18 month follow-up of a closed herd of lipizzaners.
abstract: BACKGROUND
  To date the influence of herpesviruses on the development of equine ocular diseases has not been clearly determined.
  
  
  OBJECTIVE
  The purpose of this study was to illustrate the course of equine ocular findings over a period of 18 months at 6 month intervals, in correlation with the results of herpesvirus detection.
  
  
  METHODS
  266 Lipizzaners in 3 federal states of Austria underwent complete ophthalmologic examination 4 times. Blood samples, nasal- and conjunctival swabs were obtained at the same time and used for the detection of the equid gammaherpesviruses EHV-2 and EHV-5 using consensus herpesvirus PCR and type-specific qPCRs. Ophthalmic findings and results of herpesvirus PCRs were recorded and statistically analysed using one-way ANOVA, and multiple logistic regression analysis to determine the influence of herpesvirus infections and other contributing factors on the presence of ophthalmic findings.
  
  
  RESULTS
  In the first, second, third and fourth examination period 266, 261, 249 and 230 horses were included, respectively. Ophthalmic findings consistent with herpesvirus infections included conjunctival- and corneal pathologies. Statistical analysis revealed that the probability of positive herpesvirus PCR results decreased with progressing age; however the presence of corneal findings increased over time. At the time of each examination 45.1%, 41.8%, 43.0%, and 57.0% of horses with conjunctival or corneal findings, respectively, were positive for EHV-2 and/or EHV-5. However, 31.6%, 17.6%, 20.1%, and 13.0% of clinically sound horses were positive for these herpesviruses at each examination period, too.
  
  
  CONCLUSIONS
  Based on the results of our study there is a significant influence of young age on EHV-2 and/or EHV-5 infection. Corneal pathologies increased over time and with progressing age. Whether the identified findings were caused by herpesviruses could not be unequivocally determined.
authors.affiliation: Clinic for Surgery, Dentistry and Ophthalmology, Department of Companion Animals and Horses, University of Veterinary Medicine Vienna, Vienna, Austria ; Viral Zoonoses, Emerging and Vector-Borne Infections Group, Institute of Virology, Department of Pathobiology, University of Veterinary Medicine Vienna, Vienna, Austria.
authors.forename: James O
authors.initials: JO
authors.lastname: Rushton
authors.forename: Jolanta
authors.initials: J
authors.lastname: Kolodziejek
authors.forename: Alexander
authors.initials: A
authors.lastname: Tichy
authors.forename: Norbert
authors.initials: N
authors.lastname: Nowotny
authors.forename: Barbara
authors.initials: B
authors.lastname: Nell
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001317:Austria; D001483:Base Sequence; D017931:DNA Primers; D005500:Follow-Up Studies; D006566:Herpesviridae Infections / Q000503:physiopathology / Q000662:veterinary*; D006734:Horse Diseases / Q000503:physiopathology / Q000821:virology*; D006736:Horses; D016849:Keratitis, Herpetic / Q000503:physiopathology / Q000662:veterinary*; D016133:Polymerase Chain Reaction
chemical_list: D017931:DNA Primers