Hi  i have been reading your disscusion from yesterday eve and this morning and have a question of my own regarding genetics. my bitch is black by a yellow dog who is from predominantly yellow background. Her mother is a black but by a yellow dog. her mother also black by yellow but that mother black by choc (are you following this?!) if i mated her with a black dog carrying chocolate would i get any chocs? the same dog was used to good effect (5 CC 2 BOB) on the 3rd dams litter sister producing chocolate. would the addition of the yellows decrease the chance of chocolate? my aim is for all three colours. yes my bitch is hip and eye tested and has been shown with success to champ level. hope that this makes sense as it is hard to describe a pedigree. my e-mail is jamie.went@tesco.net  please help with any info and/or theories.

Hi Jamie

If I have followed you correctly :-)  your bitch has a chocolate in the 4th generation.  This gives her a 12.5% chance of carrying it. She is definitely a carrier of yellow, her genotype is  - B Ee

If she doesn't carry choc, she won't produce it to any dog but if she does you will get black:choc at a 50:50 rate mated to the black dog carrying choc.

Yes, the occurrence of yellow does reduce the rate of chocs (and blacks) produced as this overrides these two colours even though it is a recessive but only at the rate of 25% if both parents are carriers.

You will have a chance of all three colours if you bitch does carry choc and the sire carries yellow.

Julie

Hi Jamie,

Here you have a useful link to an illustrated guide for a coat colour interitance chart:
http://www.vetgen.com/color.html