Page 80 - Aussie Magazine - 2024 Issue 3
P. 80
Informative
It is even more
imperative in Europe Example I
that the Mc allele is
understood completely
as many registries and Even if every Mc dog was removed from the breeding
clubs do not allow the population there would never be an end to the eradication.
breeding or registering Mosaicism is always happening. There is no way to stop
of litters from a Merle the natural shortening of any poly-A tail. With 18% of
x Merle cross. This still Merle dogs being mosaics and 55% of those dog having a
includes Mc x M and shortened Mc allele there is just no way to “get rid of” it.
even Mc x Mc. Imagine
the irreversible damage The following EXAMPLE shows a blacktri dam Figgy who is
that could be done to phenotypically solid and producing offspring with “white body
a closed gene pool by splashes” when bred to an m/M - m/266 sire Royce. Testing
restricting the breeding confirmed that Figgy is not m/m but has a non-expressing
of Mc dogs? A gene pool Mc+ 240 bp allele. The combination of her Mc+ and the sire’s
will get smaller when M allele has resulted in 240/266 in the offspring Pirate which
the number of gene has deleted to pigment to white. Pirate is bilaterally deaf and
variants decrease and unilaterally vision impaired due to this Merle combination. This
are lost due to dogs not is the very important reason that the length for the Mc allele
reproducing and passing was set at 230 bp.
their genetics on to
future descendants.
It is a travesty to remove
a dog from a breeding
program based solely
on a result of Mc and
totally unnecessary!
The base pairs for the
Mc allele were set I sincerely hope that all this information will give breeders
at 230 bp in order to confidence when they receive an Mc 200 - 230 bp result back on a
guarantee it will breed phenotypically solid dog, knowing this dog can safely be bred to a
the same as Non-Merle, visible Merle. But I think we need to address one more important
that no pigment will be fact before moving on. Mc Does Not Lengthen to M.
deleted to white when
bred to M. I know that In the past this type of information was based solely on phenotype
“guarantee” is a strong and the outdated method of testing, which could not provide
word here and not accurate base pair numbers and most importantly could not provide
scientific in the least. any possible mosaic results. In the example given of Astrid’s mosaic
However in this case it results there is a minor M allele present that was inherited from
is a word I am confident her dam. Astrid will breed as a Merle. But what if she had been
using. The limit that was tested using the old method? The result would have been Mc/Mc,
placed on the Mc allele there would have been no M allele included in her results. Since she
could likely have been expresses a Minimal Merle pattern and can produce Merle offspring,
slightly higher, maybe an assumption would be made that Mc can produce limited Merle
even to 234 bp but I areas on the body and will somehow lengthen to M and produce
have seen examples of Merle offspring. Any dog tested as Mc and producing Merle
235 bp x M starting to patterned offspring must have an M allele present.
delete pigment.
80 | A Worldwide Magazine for the Aussie • Issue 3/2024
