As in the number of mammals, the most prominent feature of the ganglio
n-cell layer in the retina of the German shepherd dog is the sharp inc
rease in the density of ganglion cells in the central area. There is a
n area of maximum density and also a 'cat-like' visual streak, located
dorsal to the optic disc. The isodensity lines of ganglion-cell distr
ibution is roughly concentric. Their values vary from 530-13 000 cells
/mm(2) in the central area, with the cells densely packed, to 1000 cel
ls/mm(2) or less in the periphery, where the cells are sparsely distri
buted. There were some individual differences amongst the animals stud
ied, although all of them were pure-bred dogs. This suggests that the
configuration of the retina in the canine species is not only dependen
t on the breed itself but also on some other parameters such as phylog
enetic heritage, environment, aptitude, lifestyle, or even training.