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Afriend ofminejust had a litter ofeight<br />
from two merles. None ofthe puppies are<br />
double merle. How is this possible?<br />
It's possible. You can have all merle or all<br />
non-merle pups in a cross with one merle<br />
parent, too—or all or none of any other<br />
color you might reasonably expect to see.<br />
It'sjustthe luck ofthe genetic draw for that<br />
particular litter. If all merle pups from a<br />
merle-merle litter are normally marked and<br />
have normal hearing and eyes, most likely<br />
they are all normal merles. It's unusual, but<br />
it can happen.<br />
One thing to be aware of, though; If<br />
either or both parents have minimal white<br />
markings, it is possible for a homozygous<br />
merle pup to have what appears to be<br />
normal coloration.. These pups can usually<br />
hear, but will have eye defects typical of a<br />
homozygous merle.<br />
Is there any generation where you canfeel<br />
safeifaffected!carrierdogs arepresentin<br />
a pedigree?<br />
It depends on what the condition is.<br />
Obviously, producing a missing tooth is not<br />
in the same league as producing epilepsy.<br />
I look back five generations. If there<br />
has been no connection (affected, parent or<br />
grandparent ofan affected) to the unwanted<br />
trait in that amount oftime, odds are it isn't<br />
there. However, since it is impossible to<br />
know about every dog affected with any<br />
given problem, what you think is a "clean"<br />
pedigree may not be. If there is background<br />
at all, you know there is at least a little risk<br />
that your dog is carrying genes for that<br />
unwanted trait.<br />
A caveat: There is no such thing as<br />
genetically clean dog or line. All of them<br />
have genes for something you don't want.<br />
It's the breeder's task to become aware<br />
as she can of the risks and do everything<br />
reasonably possible to avoid producing<br />
pups that have these things. It's really<br />
no different than what you do about<br />
conformation or working traits you don't<br />
want. If you know you might produce it,<br />
you try to avoidputtingmates togetherwho<br />
will.<br />
76 AUSSIETIMES I <strong>July</strong>-<strong>Aug</strong>ust <strong>2005</strong><br />
Send your questions to:<br />
C.A. Sharp<br />
730 E. Weldon Ave. • Fresno, CA<br />
93704-6135<br />
Fax: (559) 485-2136<br />
e-mail; ca@ashai.ora<br />
If you do your homework and make<br />
health issues a priority, you will reduce the<br />
frequency of these problems in your line.<br />
But every once in a while something will<br />
go wrong. The issue isn't that it happens,<br />
because it will. It's what you do about it<br />
when it does.<br />
I discoveredthatmy bitch as slippedhocks.<br />
I told my vet about it and he doesn't know<br />
what I'm talking about. How can I make<br />
sure shegetspropertreatment? Whatdoes<br />
this meanfor my breedingprogram?<br />
Your vet hasn't heard about it because it is<br />
not a medical condition. You will not find<br />
"slipped hocks" in any veterinary reference.<br />
It is not a disease, so there is no treatment.<br />
Nor is there any proof that it is correlated<br />
with any disease or any tendency to<br />
structural breakdown. At most, you might<br />
call it a conformation fault but even that<br />
is arguable.<br />
The"test" for slipped hocks is to stack<br />
the dog and putgentle forward pressure on<br />
the hock. If it pops forward, it is said to be<br />
"slipped." This probably indicates a minor<br />
laxity in the connective tissue—something<br />
that exercise would likely overcome. Ifyou<br />
put enough pressure, most dogs' hocks are<br />
apt to pop fortvard.<br />
If your bitch shows no gait faults<br />
related to her hocks, I seriously doubt<br />
there is anything wrong with her at all. If<br />
"slipped hocks" truly were a common or<br />
significant problem, there would be much<br />
more information available from qualified<br />
sources. Not only is there no mention in the<br />
veterinary literature, none of the renowned<br />
experts on locomotion, Curtis Brown,<br />
Rachael Page Elliot, or Quinten LaHam,<br />
make mention of it in their writings.<br />
I think eliminating an animal from your<br />
breeding program on the basis of"slipped<br />
hocks" would be extremely shortsighted.<br />
Does my dog need to be affected to donate<br />
his DNA to research?<br />
That would depend on the needs of<br />
the particular study. Some may want<br />
samples only from affected dogs, but<br />
most are looking for family groups. What<br />
constitutes "family" will be defined for a<br />
particular study by the researchers. Some<br />
will want only the affected dog's parents,<br />
offspring, and full siblings. Others may<br />
include half-siblings, grandparents, or<br />
other closer relatives. Read the particulars<br />
ofthe study you are interested in, or contact<br />
them to ask.<br />
What is a tapetum? I was told my blue<br />
merle boy doesn't have one in his left eye<br />
andI'm worried.<br />
The tapetum is a layer of reflective pigment<br />
in the back of the eye. It enables dogs and<br />
other animals to see well in very low<br />
light. People, by comparison, don't have<br />
a tapetum and therefore do not see well in<br />
low light.<br />
The irregular pigmentation that causes<br />
the merle color can affect any pigmented<br />
area in the body, so it is possible that a<br />
merle dog might not have a tapetum.<br />
The tapetum in most merles will be<br />
irregularly pigmented and is described as<br />
being "tigroid" in appearance.<br />
As long as all else is normal, your dog<br />
should be fine, though he may not see as<br />
well in the dark as other dogs<br />
I just learned that a dog ofmy breeding<br />
started having seizures at six-and-a-half<br />
years ofage. All the vets' work-up points<br />
to epilepsy, but isn't that starting rather<br />
late? Is it possible the owners missed<br />
earlier seizures?<br />
Actually, epilepsy can start at virtually<br />
any age, though it's unusual that late. It<br />
is possible that prior seizures might have<br />
been missed, even for several years. Not all<br />
seizures are grand mal. Focal seizures are
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