FAQ

Q

Do we have any idea of the percentage of Cotons that are carriers?

A

We don’t have an overall estimate of prevalence of the NCA mutation in Cotons as a whole – we have only tested those dogs that owners have opted to test. As of June, 2011, we have tested a total of 294 Cotons for this mutation: 223 have tested NORMAL, 49 have tested CARRIER, and 22 have tested AFFECTED.

Q

If I have a carrier, how far back do I have to look in a pedigree to find its origin?

A

Unless we had DNA to test from each individual in the pedigree, we cannot determine exactly where the mutation originated. Even if we were able to pinpoint an individual dog where it began, that dog would have to have one normal copy of the gene too, or else it would have died young and not reproduced – which means some of its offspring inherited a normal copy of the gene, and some inherited the mutated copy of the gene. There would be no point in eliminating those descendants that inherited the normal copy of the gene, so there really is no use pointing to one individual and laying blame there. It must have been a reasonably good dog, or it would not have been bred, and the mutation would not have been passed on.

Q

How many generations can this mutation skip before showing up in a litter?

A

If a carrier is bred to a normal dog, there could be many generations of carrier offspring with no affected dogs, so nobody would know it’s there without a DNA test. With each generation, it’s a flip of the coin if the carrier parent passes the normal copy of the gene, or the diseased/mutated copy of the gene to each pup.  Even breeding carrier to carrier, a breeder could get lucky and have only normal and carrier pups. We expect to see about 25% normal, 50% carrier, and 25% affected pups from a carrier-to-carrier mating, but that’s the ratio over large numbers of trials (or pups) – say 100+. In the few pups you see in a litter, it’s possible to get any extreme and all variations between the extremes. For instance, in a litter of two pups, you could get 2 normals, or 2 carriers, or 1 normal and 1 carrier, or 1 normal & 1 affected, or 1 carrier & 1 affected, or 2 affecteds – there’s no way to predict, we only have the expected ratios that play out when you look at 100 or more examples of that breeding.

Q

I was told that there has never been any Bandera’s Syndrome in my dogs’ bloodlines. Can I be sure?

A

It’s very possible that there could have been carriers bred to normal mates for many generations, so the disease was never seen. It’s also possible there were affected pups that were dismissed as not viable and euthanized, and nobody knew what was wrong with them. And remember, it’s also possible that at some point there was a carrier-to-carrier breeding and the breeder got lucky with no affected pups born, so they didn’t know. Without a DNA test, you cannot tell a normal from a carrier, and until someone breeds a carrier to a carrier and gets unlucky, nobody would know the mutation is lurking there.  It is very important to remember that this DNA test is a tool, and the results should be one part of many traits that are considered when making good breeding choices. It’s an important factor because the disease has a terrible impact when an affected pup is produced, but it is not the only factor. You are breeding a whole dog – not a test result.  By using the test wisely, there is no need to produce an affected pup. Carrier individuals CAN be bred to retain all their good qualities; if bred to a mate that DNA tested NORMAL, the pups will all be either normal or carrier. There is no way to produce an affected pup if one parent is normal.

Outstanding carriers SHOULD be used – they’re outstanding in all other traits, and if bred to a normal, with a little luck the pup that inherits those good traits may inherit the normal copy of the NCA gene – so you’ve kept the good, and eliminated the “bad” copy of the NCA gene. If the best puppy happens to be a carrier, that dog can be bred to a mate tested that tested normal, with no risk of disease, but still keeping the good traits.

Q

Is there a difference between “Bandera’s Sydrome” and  Neonatal Cerebellar Ataxia?

A

Neonatal Cerebellar Ataxia (NCA) is the general name for a type of balance/coordination problem seen in newborns and young pups.  “Bandera’s Neonatal Ataxia” (BNAt) was the name given for specific NCA seen in one of the first pups that was diagnosed and defined with this disease.  While they are describing the same disease, Bandera’s Syndrome is specific just to Cotons.  We have never seen a report of this exact same ataxia in any other breed.

Answers provided by Liz Hansen
Animal Molecular Genetics Laboratory, University of Missouri College of Veterinary Medicine