After the recent silver lab thread, I contacted the folks at dog-dna.com about whether or not they could identify Weimeraner genes in silver labs.
This is their response...
I just got through talking to Kathy at our lab. We identify breed specific genes within a dog, but not color genes. If a Lab has Weimeraner in its heritage, we should pick that up with our test.
I hope this answers your question. Please let us know if we can be of further assistance.
Mixed Breed Dog DNA Testing