One breeder did say that in her experience, it is possible that a rabbit that seemed to have matching claws as a junior will, at maturity, have mismatched claws. Because blue tort and liliac tort are dilute colors and quite light to begin with, it can be difficult to tell if the claws match. Add wool to the paws, and it can be even more difficult to discern. Perhaps only after a rabbit is mature is it relatively easy to see the contrast between the pigmented claws and the ones that lack color. Another possible reason for a rabbit that previously had matching claws to turn up with an unpigmented claw is injury; if a claw is pulled out, it might grow back in without pigment.
I have not been able to find any reputable source that supports the claim that tortoiseshell is heat sensitive. Only “ch” (himi/pointed white) is heat sensitive. This article on the National Center for Biotechnology Information website explains the action of the ch gene: “Gene interaction in coat color of mammals”.
Tortoiseshell has the “C” gene. It is the dominant gene, and “C” signifies “color.” C is completely dominant and is not influenced by whatever recessive allele might accompany it. Here are the genetic codes for tortoiseshells:
aa / B_ / C_ / D_ / ee (“black” tort)
aa / bb / C_ / D_ / ee (chocolate tort)
aa / B_ / C_ / dd / ee (blue tort)
aa / bb / C_ / dd / ee (lilac tort)
For more information about Angora color genetics, see Marna Davis’ excellent resource at Class Act Angoras
Insofar as the actual temperature sensitive color, pointed white, is concerned, you may be interested in this blog post that Betty Chu wrote about why she abandoned the color in her breeding program.
See more information. (Added June 27, 2014.)
 Blue tort kit |
 Chocolate tort kit |
 4 month old “black” tort |
 Margaret Bartold’s “Carmella.” |