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. Animals studied Sixty-eight domestic goats (89 eyes). Procedures 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, marrowlike 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.

Ocular microscopy of Bradypus variegatus

“…The ciliary body of adult individuals of these species is formed by stratified epithelium in two layers, the innermost non-pigmented and the outermost pigmented, which is continuous with the retinal pigment epithelium (Slatter, 2005), and which is similar to the characteristics observed in the present species. In this same ocular structure, prolongation of the ciliary processes towards the central region and extensive opening of the corneoscleral trabeculate were also observed in domestic species, such as dogs and cats (Leite et al, 2013), in birds such as the striped owl (R. clamator) (Jezler et al, 2010) and goats (Tusler et al, 2017).…”

“…In this same ocular structure, prolongation of the ciliary processes towards the central region and extensive opening of the corneoscleral trabeculate were also observed in domestic species, such as dogs and cats (Leite et al., 2013), in birds such as the striped owl ( R . clamator ) (Jezler et al., 2010) and goats (Tusler et al., 2017).…”

Skeletons of the Eye: An Evolutionary and Developmental Perspective

“…Both the sesamoid bones and the os opticus elements might be mistaken for the scleral ossicles in fossil specimens. A recent study has documented ossicles and cartilages within the sclera of goats (Tusler et al ), however these are situated at the back of the eyeball, in close proximity to the optic nerve. These bones are likely not homologous to the scleral ossicles that comprise the scleral ossicle ring observed in other sarcopterygians.…”

“… iCan form cartilage nodules in disease; can form cartilage and bone around optic nerve in goats (Tusler et al ).…”

CT appearance and measurements of the normal thyroid gland in goats

“…Similar studies were performed on the caprine abdominal cavity, where the tomographic anatomy, organ dimensions, volume and densities were presented [ 4 ]. The CT characterization of the head, mammary gland, orbital cavity and eyes were also described [ 5 – 8 ]. In single case reports, CT was helpful in diagnosing diseases such as leukoencephalomyelitis, a giant cell tumor of the mandible, a brain abscess and sinusitis [ 9 – 12 ].…”