title: Corneal dystrophy in Friesian horses may represent a variant of pellucid marginal degeneration.
abstract: OBJECTIVE
  To describe the clinical presentation, treatment, and outcome of a corneal dystrophy in Friesian horses and to analyze affected horses' pedigrees to investigate its heritability.
  
  
  METHODS
  Nine Friesians with bilateral disease were identified.
  
  
  METHODS
  Retrospective medical record review was used to identify Friesian horses exhibiting bilateral symmetric corneal lesions. Variables identified from medical records included patient sex and age at diagnosis; location, depth and size of corneal lesions; medical and surgical therapy instituted; and visual outcome. A four-generation pedigree for each included horse was used to construct a combined pedigree.
  
  
  RESULTS
  The nine included horses had an average age at diagnosis of the first eye of 10.7 years, with males (8/9) significantly more frequently affected than females (1/9), P = 0.012. Lesions were inferior and averaged 5 mm in diameter. Depth ranged from superficial facets to perforations, which developed in nine of 18 eyes. Eight of nine perforations were surgically repaired, with seven of eight repaired eyes visual at last follow-up. All nine eyes that had not perforated remained visual. All affected horses shared a common ancestor within six generations.
  
  
  CONCLUSIONS
  This form of corneal dystrophy in Friesian horses, characterized by bilateral symmetric stromal loss, appears to be progressive but responds well to surgical repair, occurs more frequently in males, may have a genetic component in Friesian horses, and may be a variant of pellucid marginal degeneration.
authors.affiliation: New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, 382 West Street Road, Kennett Square, PA, 19348, USA.
authors.forename: Mary
authors.initials: M
authors.lastname: Lassaline-Utter
authors.forename: Anne J
authors.initials: AJ
authors.lastname: Gemensky-Metzler
authors.forename: Nicole M
authors.initials: NM
authors.lastname: Scherrer
authors.forename: Riccardo
authors.initials: R
authors.lastname: Stoppini
authors.forename: Claire A
authors.initials: CA
authors.lastname: Latimer
authors.forename: Nicole E
authors.initials: NE
authors.lastname: MacLaren
authors.forename: Kathern E
authors.initials: KE
authors.lastname: Myrna
mesh_terms: D000818:Animals; D003315:Cornea / Q000473:pathology; D003317:Corneal Dystrophies, Hereditary / Q000175:diagnosis / Q000473:pathology / Q000601:surgery / Q000662:veterinary*; D005260:Female; D006734:Horse Diseases / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology / Q000601:surgery; D006736:Horses; D008297:Male; D010375:Pedigree
keywords: Friesian; cornea; dystrophy; pellucid marginal degeneration; ulcer