After sexual maturity is there any preference or rejection of litter
mates? ie. do dogs, or other amimals mate with siblings?

Hello barryba~

I know from personal observation that cats will mate with
siblings?-and even with parents. (See also ?Neuter or not to Neuter??
at PetJam: http://www.petjam.com/pages/pr_health_pj_health_cats_48.html
) Dogs, too, will sometimes mate with close relations. (See ?Puppy
from Sibling Parents,? at Pet People?s Place:
http://www.petpeoplesplace.com/Advice/dogs/breeding/21.htm )

In fact, it seems that almost all animals will inbreed, depending upon
their circumstances, even when not encouraged to do so by humans. This
includes cheetahs and other big cats,  (See ?Inbreeding? at The Free
Dictionary: http://encyclopedia.thefreedictionary.com/inbreeding ),
reptiles of many types, rabbits, fish, wolves (See ?Is Incest Common
In Gray Wolf Packs?? at Northern Prairie Wildlife Research Center:
http://www.npwrc.usgs.gov/resource/2000/wfincst/discuss.htm ),
rodents, horses, pandas (See ?Pros and Cons of Inbreeding? at Messy
Beast: http://www.messybeast.com/inbreed.htm ) and some birds. This is
not to say that inbreeding is common in nature. Even among the animals
mentioned, inbreeding is generally rare.

In many cases, inbreeding causes the animal no harm; in fact, many
animal breeders purposefully inbreed in order to combine the ?finest?
characteristics among their animals. Yet prolonged inbreeding can
cause health problems. The worst traits pass on just as easily as the
good traits; in addition, the immune system and fertility decrease
with constant inbreeding. In short, the genes are weakened the more
inbreeding takes place. To learn more about how inbreeding affects an
animal?s genes, see ?Inbreeding and its Genetic Effects? and
?Inbreeding Effects on the Immune System? at YSU:
http://cc.ysu.edu/~helorime/inbred.html

Regards,
Kriswrite

RESEARCH STRATEGY:
Dogs mate siblings
://www.google.com/search?hl=en&ie=ISO-8859-1&q=dogs+mate+siblings

animals mate siblings
://www.google.com/search?hl=en&lr=&ie=ISO-8859-1&q=animals+mate+siblings&btnG=Search

Inbreeding
://www.google.com/search?hl=en&ie=UTF-8&q=inbreeding&spell=1

inbreeding nature animals
://www.google.com/search?hl=en&lr=&ie=ISO-8859-1&q=inbreeding+nature+animals

breeding nature animals
://www.google.com/search?hl=en&lr=&ie=ISO-8859-1&q=breeding+nature+animals&btnG=Search

breeding siblings
://www.google.com/search?hl=en&lr=&ie=ISO-8859-1&q=breeding+siblings

animal breeding incest
://www.google.com/search?hl=en&lr=&ie=ISO-8859-1&q=animal+breeding+incest

I used to raise mice as pets. When given the choice, my mice generally
preferred to mate with close relatives such as their siblings and
their parents, rather than with mice from outside sources. I do not
know whether this is true of all mice, but in my limited experience,
it seemed that inbreeding was the norm.

Natural inbreeding usually occurs when there's not much else in the
way of choices. Therefore, animal populations that are small and cut
off from others of their species tend to inbreed. This may explain
your mice, Pinkfreud, and also explains why animals like pandas and
cheetahs tend to inbreed.

Kriswrite