Most of the information generated on this subject presently has been
on
Border Collies, which have a very different herding style from Catahoulas.
For lack of other breeds being researched, this is presently the best we
have
to go on. For further information I suggest starting with the links on
the Canine
Genetics Sites page, part of the Border Collie website.
In correspondence with C. Denise Wall, PhD., she indicated that the
herding
instinct appears to be inherited as a dominant trait. For sake of example,
let's
make H a gene for herding instinct, and h for no herding instince. Thus,
your
dog that has herding instinct could be Hh. Bred to a bitch with herding
instinct
that is also Hh, 25% of the pups will be HH and display herding instinct,
50%
will be Hh and will also display herding instinct, while 25% will be hh
and not
have herding instinct. Breeding your Hh dog to a hh bitch will produce
50%
Hh pups displaying herding instinct, while 50% of them are hh and will
not
have herding instinct.
I'm sure it is obvious by this point that if herding instinct is not
selectively bred
for, it can be lost entirely as we have already seen in other breeds.
All breeds have preferred color patterns, but there can be hidden pitfalls
and
sometimes disastrous consequences in breeding for special colors. Two of
the
genes affecting canine coat color which also produce blue eyes in canines
are
the piebald gene (as seen in Dalmatians, among others) and the merle
gene
(also seen in Australian Shepherds, Collies, Danes, Shetland Sheepdogs,
and
more) which is responsible for the famous Leopard color of the Catahoula.
To date, all research in this area has been done on other breeds, but
it must
be assumed for the genetic safety of the Catahoula that Catahoulas are
subject
to the same genetic defects displayed in other breeds in which the merle
gene
is an allowed registerable coat pattern. Certainly not all blue-eyed dogs
are
deaf or have vision impairents. However, there does seem to be a link with
blue eyes/merle coat color and certain inherited defects or diseases
across several
breeds.
By far the most helpful site on eye problems was the Canine Opthalmology
Center page, Eyevet. Here
is what Dr. Michael Zigler had to say:
"I personally have only examined two Catahoulas. From talking with
a few
opthalmologists in the US, it seems that the Catahoulas have ocular problems
very similar to the 'Multiple Ocular Anomalies' syndrome in the Australian
Shepherd where there may be lack of pigment in the iris and the retina
(this
is called "sub-albinism") and associated deformations of the
iris such as an
abnormal size or shape or location of the pupil, iris coloboma, persistent
pupillary membranes, cataracts, optic disc coloboma, and possibly retinal
abnormalities."
"There are not enough statistics to make a breeding recommendation,
but as a general rule, dogs with inherited abnormalities of the eye which
are
visually threatening, should not be propagated. Certainly, I would recommend
that all Catahoulas be examined by an opthalmologist in an effort to gather
more data."
Colobomas are described as "outpouches of the sclera", which
are associated
with Collie eye syndrome. Persistent pupillary membranes are strings of
iris
tissue that can connect iris to iris (which is not too serious), but also
can connect iris to cornea or iris to lens. The latter are thought to be
a cause of cataracts.
The Internet and World Wide Web have opened up vast resources to us
all,
providing a way to gather the latest information on any subject without
leaving
the comfort of home. Here are more links to genetic information for the
serious
dog breeder:
Elementary Merle
Genetics For Newcomers is an excellent basic explanation
of the workings of the merle gene. If you'd like to get really deep
into color
breeding, Canine
Coat Color is a very thorough discussion on canine coat
color genetics, including merle. The article Congenital
Deafness In Dogs And
Cats discusses the link between color and genetic defects. Genetics
Of Deafness In Dogs is another excellent source of valuable information
for any dog breeder, whether your object is raising an occasional litter
from the family pet, or several litters per year for personal use or resale.
Biographical yarn for the curious: Megan Capon is employed as technical
support for Comtronic Systems in Cle Elum, Washington, and has a BS in
Environmental Science. She is also "stuck in an apartment", and
while
waiting for an available rental house with room for a puppy she researches
the subjects of her desires.
