BCCA Specialty Eye Clinic,
By Thomas Miller, DVM, MS, DAVCO
Beardie Bulletin, November 1996
[I was pleased to meet and with Dr.
Tom Miller at the Specialty in Orlando. Dr. Miller received his veterinary degree from University of Guelpb in Ontario, Canada and additional
training to achieve ophthalmology certification from the University of Florida in
Gainesville. He practices veterinary ophthalmology in Largo, Florida. This was the first
Specialty (Ed note: correction - this was the second specialty) at which CERF screening
was offered-thanks to the Bearded Collie Club of Central Florida. I suggested that Dr.
Miller write an educational article for us about the most frequent eye problems in
Beardies (per CERF research reports) and the one that was found to be most prevalent at
the screening clinic. I encourage everyone to read thoughtfully what follows in the
interest of prompting the best possible health for our beloved Beardies. Elsa Sell, BCCA
I would like to thank the BCCA for the
opportunity to administer an eye clinic at your National Specialty in Orlando. I enjoyed
the show and its activities and meeting some of your members and their dogs. The
predominant eye problem in the breed and at the clinic % was cataracts, so I have prepared
a section on lens anatomy and terminology used to describe these abnormalities to
accompany a description of the problem.
Anatomy of the Lens
Cataracts are opacities within the lens of the eye. Cataracts are classified
by the age of onset, location within the lens, or cause. The lens is shaped like a
magnifying glass or an M&M (i.e., both sides are convex). The lens is encased in a
cellophane-like capsule which covers it like the coating of an M&M. The lens itself is
made up of tiny lens fibers, which are arranged in layers, like an onion or tree rings.
Like a tree, new fibers grow around the outside portion of the lens. The fibers you are
born with (the center of the lens) is termed the nucleus. The new fibers that are produced
after birth (the outer layers) are termed the cortex. Each individual fiber reaches only
halfway around the lens. The fibers are highly organized, so that the end-to-end junctions
of the fibers are aligned with each other. This creates a "suture line", which
is visible on the slit-lamp examination. The suture pattern typically is Y-shaped, upright
in the front and inverted in the back, hence the term.
With aging the new lens fibers growing
around the outside of the lens tend to compress the central nucleus, creating a
"hardening" called nuclear sclerosis. This process is responsible for the blue
hazing that is seen in the pupil of all dogs as they reach 8-10 years of age. This haze is
different from cataract formation, except with extreme old age.
Causes of Cataracts
Cataracts can be caused by
trauma, metabolic disease (such as diabetes), nutritional imbalance, or they can be
inherited. The vast majority of cataracts encountered are inherited. The exact mode of inheritance is unknown. Traumatic cataracts
generally have an accompanying history of injury and other eye abnormalities that go along
with trauma. Metabolic diseases may be ruled out by blood testing. Nutritional cataracts
are most often seen in dogs raised on milk replacer, or in pups from large litters who
have received bottle supplementation. These cataracts have a typical pattern. They form
early in life and usually do not progress after the pup is weaned to solid food. Cataracts
of a nutritional cause are like the rings of a tree which can indicate year(s) of drought.
An opaque cortex is formed around the nucleus and a normal clear cortex forms over the
underlying opaque cortical region. This creates a ring-cataract around the nucleus. This
appearance is distinct from inherited cataracts.
Anatomic Location and Size of
On the CERF form, cataracts are separated into those that occur in the
anterior cortex (those occurring in front of the nucleus), the posterior cortex (the
cortex behind the nucleus), the equatorial cortex (around the lens periphery), or within
the nucleus itself. Cataracts that involve the suture lines are separated into anterior or
posterior suture line cataracts. All cataracts are further described by size. Punctate
indicates small, focal cataracts. Intermediate describes those involving a larger area of
the lens than punctate. Diffuse cataracts refer to those involving an entire area.
Generalized cataracts involve all areas of the lens.
Therefore, most cataracts are described by
both size and location. It is possible to have more than one type of cataract in a lens.
An example would be a punctate anterior cortex cataract and an intermediate posterior
cortex cataract. It is also very important to understand that a cataract can change over
time; an example, would be progression from a punctate cataract to an intermediate and
eventually a diffuse or generalized one.
The typical inherited cataract of the Beardie is a punctate to intermediate,
anterior cortex cataract. These account for nearly two-thirds of the cataracts in Beardies
reported to CERF over the last five years. This type of cataract was seen in 7/40 (17.5%)
of the Beardies at the 1996 specialty clinic. Punctate to intermediate, posterior suture
line cataracts were seen in 8/40 (20%) at the clinic. Although the cataracts of this
second type were very small in several of the dogs and may turn out to be nonprogressive
in some cases, the findings are worrisome. The worry is because of the fact that some were
already intermediate in nature, indicating that progression can occur. Also, the number
seen suggests this type of cataract is common within the breed. The majority of dogs with
cataracts of either type were in the 2-5 year age range.
What is the Bottom Line?
The dogs examined at the clinic came from all geographic areas of the USA and
Canada, thus representing a cross-section of many breeding programs from all areas. In
theory, dogs at a National Specialty represent the best breeding stock available. Fifteen
of 40 (37.5%) dogs failed to obtain CERF certification due to cataracts. This is an
amazing failure rate for a breed that "doesn't have eye problems." CERF
statistics indicate the average failure rate is in the range of 5%.
What Do You Do About It?
You can stick your head in the sand and muddle along, maintaining the old
belief that Beardies don't have eye problems. This seems to have been the approach of many
breeders in the past, as CERF statistics show only a small fraction of dogs (an estimated
2%) are ever examined.
You may wish to have a second opinion by
another board certified veterinary ophthalmologist if your dog was found to have a
cataract at the Specialty clinic.
Check all breeding stock for eye
Check all dogs from litters in which
cataracts have been diagnosed, even pets and those already neutered or spayed.
Dogs should be reexamined until they are
at least 5 or 6 to identify those who develop cataracts during the high risk 2-5 year
period. Early examination at 1 or 2 years of age is useful to rule out retinal folds,
early onset progressive retinal atrophy (PRA), and some other problems. However, cataracts
can and do develop beyond 1-2 years.
Affected dogs should be removed from your
breeding program and they should continue to have eye examinations yearly to document the
progress (or not) of the cataract(s).
Your health committee and board need to
vigorously pursue development of an open registry for listing dogs who are affected with
cataracts so as to document classification, track progression, and hopefully identify the
mode of genetic inheritance.
Owners of a dog with cataract(s) should
notify the dog's breeder.
Breeders need to become advocates for the
open registry process.