Ophthalmological findings in Merle dachshunds
Dausch, D.; Wegner, W.; Michaelis, M.; Reetz, I.
Deutsche Tierärztliche Wochenschrift 84(12): 468-475
1977
ISSN/ISBN: 0341-6593 PMID: 340189 Document Number: 123925
Studies were carried out with 44 Dachshunds reared and kept under identical conditions. Eleven extreme dapples with a cutaneous depigmentation greater than 50% (homozygous merle, MM) showed severe defects in various forms; microphthalmia and microcornea, microcoria and corectopia, cataracts and colobomas, rudimentary lenses and ectasia. In heterozygous merles (Mm) with percentage of white coat colour less than 50%, iris bicolor and heterochromia irides, lack of the tapetum lucidum, depigmented retina, anomalies of the pupil and ectasia of episcleral blood vessels were found, as well as in MM dogs, but not in all. It is concluded that these are effects of the incompletely dominant merle gene which is used to produce a harlequin dappling in many breeds of dogs. Homozygous well pigmented controls (mm) showed none of these anomalies except for ectasia of episcleral vessels in a few dogs.