THE NAME OF THE GAME IS GENETICS
by Megan Capon
We can all point to many multi-purpose working breeds that have had a
meteoric rise in popularity, only to lose the positive traits which the dogs
were originally noted for. We have also seen those breeds deteriorate
genetically to the point that inherited diseases are rampant. The Catahoula
is a treasure well worth keeping, and as such I have done a little research
into the heritability of the herding instinct and genetic disorders associated
with blue eyes and the merle coat color pattern. Here is a brief overview
of what I've found, as well as links to places on the web where anyone
can do more of their own research.
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
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
"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
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
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.