Spatial relationships among the cellular tapetum, visual streak and rod density in dogs.

The dog visual system is well suited to dim light conditions due to rod-dominated retina and the reflective tapetum. The topographical distributions of rods and thickness of the tapetum of the dog were quantified in retinal whole mounts stained with thionine, and spatial relationships among the tapetum, rod density and visual streak of high ganglion cell density were elucidated. The relationship between the retina and tapetum was analyzed in parasagittal sections stained with thionine or hematoxylin-eosin.

Macroscopic and histological variations in the cellular tapetum in dogs.

We aimed to document macroscopic variations in the cellular tapetum in the dog, to provide a histologic description of the macroscopic results and to evaluate the correlation between the macroscopic appearance and aging. Fifty three dogs including 5 beagles, 1 Chihuahua and 47 mixed breeds of each gender were used. For a macroscopic study, the fresh tapetal fundi were photographed using digital camera.