[Jacob-list] Re: mismatched bite

[ranchrat at telusplanet.net]

Fred Horak wrote:

> The problem of jaw misalignment seems to be a recessive. There was a study 
> done on some commercial breeds that concluded that jaw deformities were 
> associated with level of inbreeding. 

Heel low:

I am certainly not qualified to respond at Fred Horak’s level, but when I 
produced a (very low inbreeding coefficient match) puppy with a lower jaw that 
never grew to meet the upper jaw, I was advised that the lower jaw bone is the 
slowest bone to develop (in ACDogs it may take 4 years) and to not give up hope 
that the jaws would eventually line up properly.  I had a friend post my query 
about “Parrot mouths” to a canine geneticist’s list and the consensus there was 
that the upper jaw is inherited separately than the lower jaw.  So it is not 
necessarily a bad fault that is inherited, but more an inheritance of the 
incorrect “matched set” of jaws; one parent’s upper jaw (larger) and the other 
parent’s lower jaw (smaller) are inherited by the progeny resulting in a 
mismatched set of jaws.  Under or overshot jaws are a disqualification in the 
ACD standard and the breed is predisposed to this fault
.probably because we do 
have such a variance in the size of muzzles in the gene pool; some breeders 
preferring huge blocky heads, while others target more Kelpie like refined 
profiles. 

In Jacobs mismatched bites would not be as detrimental or detectable with them 
having their teeth align up with a larger dental pad
presuming this allows for 
a greater degree of misalignment correction.  In dogs that are suppose to have 
a scissors bite, we were dealing with lower & upper canines not meeting.  Some 
suggested surgery (removal, bracing, etc.), but the dental vet we consulted 
decided to allow the animal to mature prior to considering these extreme 
measures unless of course the animal was unable to eat or was in discomfort.  

The geneticists were undecided whether they would use such an animal in a 
breeding program
I guess the question was whether you use a normal sized 
muzzled animal or try for either extreme, big muzzle or little and hope you get 
a matched set in the offspring.

Hope some of these experiences help!

Doggone,

Tara 
-- 
    ____(\                Tara Lee Higgins                  /)____ 
   (_____~>        Rat Ranch - An ACD is for LIFE          <~_____) 
  ( ``  ``          ranchrat at telusplanet.net                ``  `` ) 
   \                       Alberta Canada                         / 
    )  http://www.telusplanet.net/public/ranchrat/index.html     (