
I'm a bit confused.
An established FB breeder ? Do you mean someone who advertises their dogs on FB for sale ?
Has your dog had a parental DNA test done ? The only way to know who is the sire & dam of a puppy is for all three to have DNA profiling done & the results compared. It can be done as soon as pups are weaned. Results do not take 4/5 months to be returned.
The
CMO DNA test is available from Laboklin or AnimalLabs Your vet can take the sample, but not do the DNA test
Has you puppy shown any of the symptoms ?
CMO is an autosomal dominant with incomplete penetrance mode of inheritance(ie a dog may only have 1 copy of the gene to be affected)& your puppy may or may not inherit the mutation from it's sire, it depends on whether the sire has 1 or 2 copies of the mutation