T Editors note: Heres
the latest on the Steynmere bobtail boxers from their breeder, Dr. Bruce Cattanach. For
details on the beginnings of the bobtails, see the Oct. & Dec. 98 and the Feb.
99 issues of BU.
To Slide Show
by Dr. Bruce
Cattanach, Steynmere Boxers, UK
Exciting things are happening in the
bobtail Boxer project. Perhaps the least of these, which is still of note, is that we have
moved through another generation. The first litter of the fifth generation Boxer backcross
from the original Boxer x bobtail Corgi cross was born two weeks ago. There were eight
pups, four bobs and four normal tails. Unfortunately, despite the bitch having an easy
whelping of 10 pups in her previous litter, this time she needed a caesarian after taking
two hours between the first two pups and then coming to a dead stop. One normal tailed pup
and another with a bobtail were lost.
The bobtail parent of the cross was the big
solid red dog I have been showing of late, Steynmere Hot Shot, and the dam was an older
bitch of mine, Vonadel Twist And Shout of Steynmere, who was shown quite successfully as a
youngster. The bitch is flashily marked, but no whites were expected or obtained in the
litter, the dog being solid. There were three flashy and five solids (plains).
Unfortunately, in the sense of looking for something to show in the continuing anti-solid
climate, the two that were lost were flashy. So, the present score is two solid bob dogs
and one bobtail bitch, and one flashy normal tailed bitch plus two other solids. Overall,
a little bit disappointing as I needed bobtail bitches and the one bitch produced is not
the best quality. Nevertheless, all look typically Boxer. One bobtail dog may be of some
show potential and there are a couple with the normal tail type that look interesting.
Actually the appearance of anything of show interest at all is quite intriguing as the
bitch used does not have the best of heads. This was supposed to be a
"production" litter rather than one for show quality. Show quality breeding may
come later in the year with a couple of fourth generation bitches when, hopefully, I will
have the option of a range of top stud dogs to use.
The most exciting news involves the
scientific aspects of the study and comes in two parts. The first part concerns the
bobtail gene itself. Colleagues in London whose interest is primarily in the genetics of
human facial features have been eager to check out their candidate human "face"
genes in an animal model. The Boxer and Corgi cross and backcrosses provided ideal
material, the head types being so different, and the DNA for such a study was already
there. But they had by chance also isolated another unknown DNA sequence. On checking the
world gene database they found that this sequence had homology/similarity with a known
mouse tail gene. They therefore offered to see if, by any remote chance, this gene might
be responsible for the dog bobtail. Amazingly, given that there are many tail genes known
in the mouse, it was. What a story: a human DNA sequence, a mouse tail gene, and now
the same in the dog. Perhaps this illustrates why people like me are employed by Medical
Research Council to work on mouse genetics.
From here on the study becomes
"deep." The group has sequenced almost the whole way through the gene -
identifying the order of the base pairs - and have found one base pair change that may
constitute the mutation that causes the tail effect. Consistent with all of this has been
the finding that throughout my four generations of crossing all the bobtail dogs were
shown to have this variant form of the gene and all of the normal tailed dogs had the
normal form. What is called functional analysis is now being performed, investigating the
RNA and how it is expressed. And the two dead pups from the last litter, which have been
held in a minus 80 degree freezer for the last two weeks, were taken up to the London
group a few days ago for investigation. Studies on them may show if the gene brings about
its effect in the dog in the same way as it does in the mouse, by affecting the
inter-vertebral discs. This work and the findings made so far are considered so
exciting that a publication is being rushed out. If the expression results can be obtained
in time, a paper will be submitted for publication in one of the top international
for a "fun" dog breeding study.
The second part of this scientific
investigation is of more immediate application and brings in the Norwegian Kennel Club
with their two vets and their geneticist. They have been interested in the Corgi tail gene
for some time. The vets have been searching for any associated ill effects, without
success. The geneticist had planned to find the position of the gene on the dog gene map,
but the new work in the UK has rather scooped this. Thus, because we now know what gene
is involved and where it is located in the mouse gene map, we should be able to predict
where it lies in the dog map. And the news of the moment is that the dog gene has just
been located - in the appropriate position! Once again, this again shows the lack of
boundaries in genetics.
But there is another critical question to
be answered, and with the new results, this answer can be easily obtained. The question
concerns the double-dose bobtail, the homozygote. And the question can be phrased in three
ways. What happens when bobtail dogs are crossed together? What happens to the homozygote?
Will the condition breed true?
To get the answers, bobtail
intercrosses have to be done and a statistically defined numbers of the bobtail progeny
have to be investigated. This would have been too demanding in terms of time, effort, and
facilities for me to do alone, and it would even have been tough for a group of breeders,
since every bobtail would have had to be test-mated. But now things are different. The
Norwegian Corgi breeders have already done needed bobtail x bobtail matings. They have all
the bobtail pups needed. And now, with the gene identified, test-matings are no longer
required. Blood samples from the requisite number of dogs will be all that is needed to
ascertain the presence or absence of homozygous double-dose bobtails.
The Norwegian-UK collaboration has
started, and in a few weeks we will have the answers. But what then? If the homozygote is
found and is normal in all respects other than the tail, the gene could validly, and
without any perception of health risk, be available within the Boxer world and indeed, by
the route of crossbreedinging, also to other customarily docked breeds. But, now knowing
the mouse gene involved, I have to confess to pessimism. Maybe the Norwegians are
convinced from the normal litter sizes and absence of abnormal pups in bobtail x bobtail
matings that the homozygote will be produced and indistinguishable from heterozygous
single-dose bobtail dogs, but the odds are that homozgous bobtail dogs will not be found.
If correct, it would then have to be concluded that the homozygotes die early in
development and include or replace the usual resorbtion losses that occur during
pregnancy. They would then never be detected. The only observable consequence would then
be that the bobtail condition would not breed true. Long tailed pups would be detected.
The only observable consequence would then be that the bobtail condition would not breed
true. Long tailed pups would always be produced in bobtail lines, just as whites are in
current show lines. The frequency of longtailed pups would also be similar to that of
whites in flashy show stock.
Would this scenario be an acceptable
alternative to long tails in the event of an international ban on docking? I have some
doubts about this, but perhaps I am jumping the gun. Let's get the answers first. I do
hope that the Norwegians are right and that I will be proved wrong. The next bobtail
report will be the critical one.