I always wondered about that, too, Marjorie. Unless the non-shedding wool-type coat is completely dominant over a hair-type coat that sheds, then why do people expect that absolutely anything mixed with a poodle or bichon won't shed?
Actually, this is somewhat known - enough to be discussed on genetics lists.
Undercoat is dominant to non-undercoat. As Poodles nor Cavaliers have an undercoat, then the mix (if purebred dogs are used) will not have one either.
The bearded gene (I think the symbol is "Wh") IS predictable, and dominant, when it is interacting with a breed that is set at long coat (fluffy) - "l/l" on the locus that determines coat length.
Cavaliers and Poodles are both breeds set at "l/l" on that locus.
If a breeder is using a pure Poodle, and a pure Cavalier, then the first generation pups will all be l/l and Wh/wh on the two loci that determine whether a dog has a bearded face and continuously growing fur/hair.
It would make sense that the
l/l,WH/wh dogs (Cavalier x Poodle mixes) would lose fur/hair more easily than dogs that are
l/l,Wh/Wh (which Poodles are), but they will all have bearded faces, continuously growing coats, and need clipping. There is an allele for curly coat as well, and a mix, would only get one of curly allele at that locus, making the coat wavy, but not curly. (Every dog has two alleles at each gene locus. It inherits a single allele from each parent).
Now, when Poodles are mixed with smooth-coated dogs (L/l) and undercoated dogs, the interaction between the alleles at the four gene loci (undercoat, coat length, curly/straight, bearded) becomes unpredictable - which is why those that mix labs and poodles, or chihuahuas and poodles, etc. etc. end up inconsistent coats on their pups; some with tufts of fur in places and not in others, and some with more "fluffy" or long fur than others.
Just had to share, cuz I LOVE this type of genetics stuff.
What else I'd like to mention is that I share Tania's concern. The small Poodle breeds deal with SM and MVD, patella and eye problems as well.
Oreo
For others interested, this is a good read on the topic:
Coat Variation in the Domestic Dog Is Governed by Variants in Three Genes
http://www.sciencemag.org/cgi/content/abstract/326/5949/150