Editor’s note: The publication on the net of  part 4 of the British Dog World series on the bob-tailed Boxers, without the detailed background on the earlier work on Dr. Cattanach’s experiment contained in Parts 1- 3 of the Dog World story, clearly shocked many people used to the association of pedigree with purebred. For this reason I have collected here in BU Bruce Cattanach’s subsequent posts to the Showboxer-L (an e-mail list for serious boxer breeders/exhibitors), which show the whole picture more clearly. If you haven’t read the beginning of the story in the October BU and Part II in the December issue, you might want to start reading there first. Dr. Cattanach has granted BU permission to reproduce the following posts from the Showboxer-L.

THE BOBTAIL STORY, Part III:
Post-Publication Notes on Bob-tail Boxers
by Dr. Bruce M. Cattanach

MRC Mammalian Genetics Unit
Harwell, Didcot, Oxon OX11 0RD, UK
email: b.cattanach@har.mrc.ac.uk
Tel: 01235 834393 Fax: 01235 835691

Post #3

All the concerns about Corgi genes and possible (virtually impossible) throwbacks are purely hypothetical and have no real merit. There are no real risks from the cross itself. The real issue, the potentially real risk, relates to the bobtail gene itself. Is this just an everyday gene or is it associated with ill effects?

The basis for thinking there might be ill effects stems from work on tail mutations in the mouse. Many of these, and I have personally worked on quite a number, may cause spinal effects in carrier animals. Manx cats with abnormal short tails also show such defects. But what about the dog? The literature is very poor, very old, and not very convincing. Some tail effects do seem to have ill effects and others not. The key question for me concerns the Corgi bobtail gene.

I am advised that sample dogs have been studied at the Norwegian veterinary school in Oslo and no ill effects have been found. The animal with the single dose of the gene would therefore appear to be normal, but I will be writing to the vets concerned for precise details.

The next problem is the consequence from bob x bob matings. What happens to double dose animals? Again the Norwegians have come up with an answer, if only a partial one. The data belong to someone else so I cannot quote them but the bottom line is that there is good evidence that the litter size from bob x bob matings is no lower than from bob x normal matings, and again no abnormal pups.

The absence of any detectable loss suggests that the homozygous double bob animal is born, is not abnormal, and is not distinguishable from the heterozygous single bob dog. It suggests this, but does not prove. What one needs is direct evidence on the homozygous double bob animals. On the basis of the 1 : 2 : 1 Mendelian ratio, one-third of the bobs should have the double dose and such animals should produce only bob progeny in matings with long tailed (docked) dogs. This evidence has not as yet been obtained. It might seem that the matings are not being done in a systematic way that would give the answers but rather there is just an accumulation of data from standard show breeding practices. In Britain, a problem has been that all the bob as well as the normal tailed dogs are docked and no record is kept of which are bobs and which are normal. Whatever, an associated abnormality has not been found and this too has been my experience.

There is another explanation for the normal sized litters from bob x bob matings, however. Embryo and fetal loss is normal; only a proportion of fertilized eggs result in puppies. It is therefore possible that the double dose animal might die very early in development and this loss might replace the normal wastage. The expected 25% loss might therefore be reduced to more or less balance out the final litter size at birth. Were this true, there would be a 2 : 1 ratio of   bob : normal, not 3 : 1. On the basis of the current Norwegian data, obtained from about 40 litters, there is a reasonable fit to both possibilities. We therefore don't yet have the answer, but at worst it may be that bobs might not breed true; they might always produce some long tailed pups. For me this would be disappointing but as a worst scenario might still be better than acceptance of long tailed boxers.

From the above, I hope it clear that there is still a long way to go with this project; thoughts on distribution into the general Boxer breeding program are still pipedreams.

In my next and necessarily last message of this type, I will outline future plans.

Bruce

Post #4

Please excuse me folks. I had promised to indicate the future plans for the bobtails. However, I have been overwhelmed with work. Although I officially retired at the end of September, my mouse work goes on. I am therefore still "working" so to speak, but now without assistance. And exciting things are happening and this takes my mind completely off dogs.

Never mind, let me try a quick summary of concepts for the future. There are two basic objectives: 1. To display the bobtails and upgrade them to quality show dogs; and 2. to crutinize the single dose animals in detail for ill effects and determine the fate of the double dose types.

Registration has permitted me to take the existing bobtails to shows - principally for demonstration purposes. This I will do this for a short while, but may continue longer with any bobtail that can hold its own at any level. Thereafter I would like to breed some again to show Boxers to turn over a further generation and hopefully get something better for show.

The Corgi search for ill effects in single dose animals has been quite thorough in terms of numbers of dogs but I still have to find out what the vets screened for. Irrespective of the clearly negative findings in Corgis I aim to have specialist vets screen some of my bobtails together with matched normal tailed sibs. This could be expensive so I will be looking for funding from various sources. If any ill effects were found, the project would stop there.

The Corgi data on interbreeding bobtails is also quite substantial even though the fate of the double dose animals has still not been established. I have written to the Norwegian group concerned, suggesting what needs to be done, and I hope they will be able to generate the necessary evidence. I would never be able to match this in terms of numbers of dogs but I would still wish to try some interbreeding with some of my bobtail (or other Corgi derived) dogs, and not only to show that "Corgis" or Corgi-like features don't reappear but also to search for double bobtail dose animals. With only few available animals there will obviously be competition with the show breeding objectives, but still something can and will be done.

Unfortunately, even a small scale interbreeding study with the bobtails will be quite large in normal terms. Thus, we will first have to generate numbers of bobtail progeny from bobtail x bobtail matings and see that none are abnormal.

If abnormal pups are found, end of story! If however, they are all normal, we will have to see if any, when mated to normal tailed dogs, produce only bobtail progeny. Only when, and if, some such dogs are found, can it be concluded that double dose animals are viable and normal. Again, any such dogs would again have to be fully screened by specialist vets.

If we don't find any double dose animals it will have to be concluded that these die well before birth such that they are undetectable. This would mean that bobtail dogs could never breed true; they would always produce a proportion of long tailed pups. This would be disappointing but still possibly a preferred option over having long tailed dogs.

This is obviously a large project, but fortunately, a few other UK Boxer breeders are now interested in helping, so this may all be possible.

There is one other angle I would hope to pursue. This concerns either identification or finding linked markers for the bobtail gene. Either would allow distinction of single dose and double dose animals with a simple blood (DNA) test, avoiding all the lengthy and complicated test matings.

This is very rushed presentation of future plans and is probably incomplete. I hope that I have not made mistakes and that it is generally understandable. I must spend less time on these communications for a while but I will nevertheless endeavor to answer any questions.

Bruce

The following was a post to the Showboxer-L sent by Bruce on December 1, 1998:

A Low and a High with Bob-tails

The Low:
One of the worst things to happen in dogs happened to my bob-tail bitch - the brindle with the longer tail shown in the [British Dog World] article. She and her half- brother managed to escape, got out on the busy road, was hit by a car and killed. The brother was OK. Not nice, and a big loss to the project.

The High:
The brother, the solid red dog in the article, now 6 months old went to his first two shows at the weekend. Each show had a puppy sweepstakes as well the show proper. In the first sweepstakes he managed nothing much, being placed 5 in an entry of 5. Likewise in his puppy class of the show, he was not placed in 10 or so. But in the later solid class he was first among three. So at least he fitted in. The next day he fared better, getting placed 5 among 10 sweepstakes puppies, but showed nothing later with another judge.

Whatever, maybe he is not the greatest show dog, and he was never thought to be one, but he is still seen as a Boxer, and not the worst either. So the point is made. And a bob-tailed Boxer was on display for the first time for all to see.

Don't expect to show him again until maybe next Spring.