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visual pathways may not compromise welfare of Siamese cats kept as pets
because they adapt well to their miswired visual systems ( Guillery, 1974 ).
However, visual tests that were more demanding than shape discrimination
revealed that albinos have subtle visual perception deficiencies. Sheridan
(1965) found that black and white hooded rats with pigmented eyes per-
formed better than albinos on a visual discrimination task with one eye
covered. Compared to the albinos, the hooded rats performed the task bet-
ter when they had to switch eyes. This principle is also vividly shown in
mice. Guillery et al. (1971) found that flecked mice with variegated areas
of both pigmented and depigmented areas of skin and fur have normal
visual pathways to the brain, even though they are roughly 50% albino.
The white areas of skin and hair are albino and the dark areas are pigmen-
ted. The welfare of laboratory albino rats is not compromised because they
eat, drink, and mate normally. However, abnormalities of the visual system
and auditory systems may cause functional problems and could possibly
confound the results of research on vision or hearing. Albino rats have
more unmyelinated nerve fibers in the optic system compared to hooded
rats ( Lund, 1973 ). In albinos, the visual cortex is also thinner ( Lund, 1973 ).
This is a further indication of a correlation between nervous system abnor-
malities and depigmentation.
Highly depigmented or albino animals are rare in nature. When they do
occur, the animals generally have difficulty surviving in the wild. One brief
reference in Science by Minckler and Pease (1938) refers to a colony of
albino rats living under feral conditions. These rats inhabited an area at a
local dump in Montana. The exact source of these animals is unknown, but
it was presumed that students from the local university released them.
Abundant food, water, shelter, and a lack of predators created a sheltered
environment suitable for an albino colony to survive. However, white cats
depend on humans to maintain them. Even dark-eyed white cats do not sur-
vive under feral conditions. Furthermore, many animals with genetically
based behavioral problems are often highly depigmented. For example,
Viennese white rabbits are known to have seizures ( Hohenboken and
Nellhaus, 1970 ). In the paper on nervous pointer dogs by Dykman et al.
(1969) , both authors noticed that five nervous pointer dogs in the photo-
graphs were almost all white. These dogs had greater areas of white fur than
typical pointers. It would be interesting to measure the amount of depigmented
areas on the bodies of both normal and nervous pointers and then compare
these to Dykman et al.'s (1969) continuum of nervous traits.
The first author has observed possible signs of over-selection for depig-
mentation in high-producing, commercially bred hybrid pigs. The nervous,
excitable pigs discussed earlier are usually very lean and are white or mostly
white. The relationship between depigmentation, albino genes, spotting
genes, and nervous system problems is documented extensively in mammals
( Arman, 2007; Silversides and Smyth, 1986 ). The link in poultry is much
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