CEA & I
By C. A. Sharp
About 15 years ago, while I was a member of the
Australian Shepherd Club of America's genetics committee, we began to get
frequent reports of Collie Eye Anomaly-affected Aussie pups. One breeder
donated an affected pair--a dog and a bitch. She also went public with the
problem and was promptly pilloried.
We
started using our regular column in the club magazine to educate people about
CEA. The disease was not recognized by ACVO as a breed problem. More than a few
examiners were over-looking or mis-diagnosing the
disease in our breed, particularly where the affected dogs had only minor choroidal hypoplasia, a thinning
of the vascular tissue in the back of the eye which is a sign of CEA, along
with optic disc coloboma and retinal dysplasia/detachment.
The
"go normal" phenomenon further complicated the issue. As pigment
fills in in the back of a young puppy's eye, it can obscure
areas of choroidal hypoplasia,
making the defect impossible to detect upon ophthalmic exam. A young pup would
be diagnosed and, on re-exam a few weeks or months later, would show no sign of
disease. Hence "go normal." This unfortunate bit of jargon has
allowed more than one breeder in more than one breed to succumb to a massive
case of what I call Ostrich Syndrome. Such self-deluded individuals would
decide hat affected dogs are "normal" and the disease went away, so
they had no cause for concern. Interestingly, the two donated pups were
"go-normals."
We
were collecting pedigree data, along with CERF exam sheets. What we had
indicated recessive inheritance. We launched a program of test matings. The affected sibs to each other produced all
affected offspring. We bred the male to a daughter of an implicated popular
stud (who, by amazing coincidence, died of something very non-genetic in the
prime of his life just as people were becoming aware
there was a problem in the breed.) The daughter proved a carrier--three out of
seven affected.
One
of the carrier bitch's normal daughters, by a stud proven not to be a carrier,
also proved to be a carrier when bred to the affected stud. Most the offspring
up to this point had choroidal hypoplasia
and a few also had unilateral optic disc colobomas.
One puppy out of the carrier daughter's litter was totally blind due to retinal
detachment.
While
all of this was happening, I ceased to hold any official capacity in the club.
I kept gathering pedigrees and exam sheets. I had nearly 40 pedigrees with
varying degrees of relationships plus the test-mating data. I went in search of
an ACVO vet who might be interested in what I had and was directed to Lionel
Rubin of the
I
worked up genealogy charts for each affected dog's pedigree, cross referenced
to the other pedigrees. Dr. Rubin agreed that the trait appeared to be
recessive. Using my gathered data, he wrote "Collie Eye Anomaly in
Australian Shepherd Dogs" (Prog in
Vet/Comparative Ophth Vol 1
No 2, pp105-108) and gave co-author credit to me and my other former club
committee member.
The
article not only made CEA in Aussies "real" in the world of
veterinary medicine, it provoked a critical editorial in the subsequent issue
of the journal attacking our semantics--the writer thought it should be
"Australian Shepherd Eye Anomaly." Dr. Rubin rebutted with a piece
that, if I remember correctly, was titled "A Rose by Any Other
Name..." The semantic flap soon subsided and the article has since been cited
in numerous other articles and books.
Back
in the trenches the CEA problem persisted. At least two significant sires of
the mid-80s were carriers. The bulk of the affected animals were from show
lines but a couple of pedigrees indicated that working lines were not immune.
At
the time I didn't know if the paucity of data on working lines was because
there actually was less CEA there or because most working breeders had their
own case of Ostrich Syndrome, declaring "I don't have to worry about that
genetics stuff, my dogs WORK." Fortunately for them, time has proved CEA
is a minor problem in working lines. Recently, however, there have been rumors of clandestine Border Collie/Aussie crosses to
produce better trial dogs. It will be interesting if CEA crops up in the
suspect lines.
I
tried to help breeders by setting up a pedigree analyses program based on the
data from the paper plus things that came in subsequently. I continue to
up-date my file as I gain new data. I roughed the program out then ran it by
George Padgett at
I
will not perform a pedigree analysis for someone who does not own a dog (or one
of the dogs in a prospective cross). This is necessary to save myself
unnecessary grief from outraged owners and breeders, as well as potential legal
entanglements. The resulting rating indicates the probability that the
particular pedigree might produce an affected individual and a carrier
individual. That done, I factor in the "suspected carriers," the
parents, offspring and full-sibs of proven carriers and give an additional
rating (Severe, Moderate, Slight or Non-existent). With the rating I send
information on the disease and how to interpret the rating. I also advise the
owners on their options.
While
I was working up the pedigree analysis program, a bunch of northern
These
breeders also took a public stand. As a group, they purchased a full-page ad in
the breed magazine admitting they had produced CEA and listing the names of
their carrier dogs. In a subsequent ad they told about the test-breeding they
had done to clear their related stock. There is safety in numbers. While there
was plenty of quiet grumbling about what they did, no one dared the kind of
frontal assault suffered by the earlier breeder who donated the pups which
formed the axis of our research breedings.
These
good people proved invaluable in another way. When people call me about genetic
problems in their Aussies, I'm "the expert," not a kindred spirit. A
lot of folks I spoke to were suffering varying degrees of emotional distress. I
called upon the breeder group to serve as a support net. Again, they came
through.
CEA
hasn't gone away--I got another pedigree just a couple weeks ago--but there
appears to be a lot less of it out there. I think the knowledge that the
disease is recessive and that one can test-breed to clear suspected carriers
has resulted in more effective management of the disease by breeders, even
though a fair number of them wouldn't ever admit they'd thus managed their way
out of it.
Ah
well. The ultimate result is what's important.
Copyright 1998 C. A. Sharp. All rights
reserved. C.A. Sharp
is editor of the "Double Helix Network News", the quarterly
newsletter for those interested in genetics and hereditary disease in the
Australian Shepherd.
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