title: Gross, histologic, and computed tomographic characterization of nonpathological intrascleral cartilage and bone in the domestic goat (Capra aegagrus hircus).
abstract: OBJECTIVE
  To characterize grossly, histologically, and via computed tomography (CT) the appearance of intrascleral cartilage, bone, or both in domestic goats with otherwise normal eyes and to correlate this with age, sex, and breed.
  
  
  METHODS
  Sixty-eight domestic goats (89 eyes).
  
  
  METHODS
  Forty-nine formalin-fixed globes from 38 goats underwent high-resolution CT, and gross and light microscopic examination. An additional 40 eyes from 30 goats underwent light microscopy only. Age, breed, and sex of affected goats were retrieved from medical records.
  
  
  RESULTS
  Considering all methods of evaluation collectively, cartilage was detected in 42% of eyes (44% of goats) and bone in 11% of eyes (12% of goats); bone was never seen without cartilage. Goats in which bone, cartilage, or both were detected ranged from 0.25 to 13 (median = 3.5) years of age, represented 11 of 12 breeds of the study population, and had a male:female ratio of 11:19. Bone was detected in the eyes of significantly more males (n = 8) than females (n = 2). No sex predilection was noted for cartilage alone. Histology revealed intrascleral chondrocyte-like cells, hyaline cartilage, and islands of lamellar bone. Some regions of bone had central, adipose-rich, marrow-like cavities. CT localized mineralized tissue as adjacent to or partially surrounding the optic nerve head.
  
  
  CONCLUSIONS
  This is the first report of intrascleral bone or cartilage in a normal goat and of intrascleral bone in an otherwise normal mammal. The high prevalence of intrascleral cartilage and bone in this study suggests that this finding is normal and likely represents an adaptation in goats.
authors.affiliation: Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California, Davis, CA, 95616, USA.
authors.forename: Charlotte A
authors.initials: CA
authors.lastname: Tusler
authors.affiliation: Department of Surgical & Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA, 95616, USA.
authors.forename: Kathryn L
authors.initials: KL
authors.lastname: Good
authors.affiliation: Department of Surgical & Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA, 95616, USA.
authors.forename: David J
authors.initials: DJ
authors.lastname: Maggs
authors.affiliation: Department of Surgical & Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA, 95616, USA.
authors.forename: Allison L
authors.initials: AL
authors.lastname: Zwingenberger
authors.affiliation: Department of Pathology, Microbiology & Immunology, School of Veterinary Medicine, University of California, Davis, CA, 95616, USA.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Reilly
mesh_terms: D000367:Age Factors; D000818:Animals; D001842:Bone and Bones / Q000033:anatomy & histology*; D002356:Cartilage / Q000033:anatomy & histology*; D005260:Female; D006041:Goats / Q000033:anatomy & histology*; D008297:Male; D008853:Microscopy / Q000662:veterinary; D012590:Sclera / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D012737:Sex Factors; D013045:Species Specificity; D014057:Tomography, X-Ray Computed / Q000662:veterinary
keywords: anatomy; caprine; chondrogenesis; os opticus; osseous metaplasia; osteogenesis