Light microscopy studies of the cornea of Merle dachshunds
Klinckmann, G.; Koniszewski, G.; Wegner, W.
Deutsche Tierärztliche Wochenschrift 94(6): 338-341
1987
ISSN/ISBN: 0341-6593 PMID: 3301289 Document Number: 289528
The width of the corneal epithelium and stroma, and the number of cells comprising the height of the epithelium were measured in 18 adult Dachshunds, of which 9 were homozygous (MM), 6 heterozygous (Mm) and 3 normal (mm) for the merle gene. The corneal epithelium consisted of 8 rows of cells in all three groups, but was significantly thicker in Mm and MM than in normal dogs. It seems that the merle factor is associated with delayed corneal and/or eyeball growth during embryonic development. The diameter of the cornea was significantly smaller in merle than in normal dogs, and the increased thickness of the corneal epithelium results in a greater breaking strength in the cornea. The stroma was thicker in homozygous than in normal dogs, but thinner than normal in heterozygous dogs. It is concluded that merle dogs should be emmetropic (i.e. have perfect vision) as a consequence of the increased corneal refraction and shorter eyeball.