Eye Disease in Collies

"Your Collie's Eyes"

(Cross-section of the Canine Eye)

Like people, Dogs are subject to a large number of inherited eye diseases, two of which can affect a Collie's eyes, CEA and PRA, should be of concern to all breeders.

COLLIE EYE ANOMALY

This is the most common of the Collie eye diseases, but it should be noted that Collies share this disease with several other breeds. Researchers first noted this problem nearly fifty years ago. It was later found to exist in most Collies and in most Collie families. This so-called syndrome, meaning a group of conditions which appear in conjunction with each other, is present prior to birth. Collie Eye Anomaly can be easily checked when the puppies are 5-6 weeks old, by a qualified Board Certified Ophthalmologist. It is something that your average Veterinarian is not qualified to diagnose. The eyes must be dilated prior to the examination, so the interior of the eye can be examined with an Ophthalmoloscope.

A dog is either given a "Normal" or "Affected" rating. If given "affected" the type of abnormality is noted. It used to be popular to use a Grading System and still is being used in certain parts of the country. Currently there is no universal, standardized grading system.

Normal: A "Normal" eye rating is of course the best grading there is. (There are also "Go Normals", which are so mildly affected at a young age, that later, the pale areas disappear, leading to what is termed a "Go Normal". Keep in mind that these are still in fact affected with CEA). There are variations even in "Normal" eyes. These correspond somewhat to a dog's coat color. Thus it is often difficult to judge the pigment in a Blue Merle's eyes as it is diluted along with his coat color.

Choroidal Hypoplasia, Chorioretinal Change:These refer to abnormalities in the coloring or pigmentation of the choroid or central layer of the eye's lining. This is the most common abnormality found in Collie eyes. Often referred to as mild CRC, Grade I or Grade II, it is the least harmful and least severe form of CEA. Most dogs with this eye grade function normally with no ill-effects or loss of vision.

Staphyloma, Coloboma, Ectasia: While not completely synonymous, these terms all refer to a cupping or bulging in the eyeball usually in the area of the optic disc.

Vascular Disease, Tortuous Blood Vessels:Defects in the vessels of the eye which are responsible for its blood supply or "nourishment." These may be malformed, undersized, or even lacking.

Retinal Detachment: Loosening or separation of the inmost, or retina, layer from the wall of the eye. This may involve a tiny area or the entire retina. It can be either one or both eyes. The complete detachment of the retina results in blindness in that eye.

There is a new Genetic Test for Collie Eye Anomaly / Choroidal Hypoplasia. Please visit the OPTIGEN website for details

Can the Collie's eyes become worse? Might he later go blind? The basic answer is "No" as CEA is present prior to birth. However, a dog born with a severe Staphyloma or with Vascular Disease may later suffer loss of sight if a detachment or severe hemorrhage occurs. The majority of dogs that are slightly affected, will have perfectly adequate eye vision throughout their life. (Even a dog with one blind eye will adapt perfectly well in his surroundings.)

What have breeders done to improve Collie eyes? When the eye problem was discovered more than 50 years ago, it was estimated that 90% of the Collie population was afflicted with some form of eye disease. Because CEA has involved such a large percentage of the breed, eradication has been slow . Over the years, with selective breeding and eye checking of breeding stock, the numbers of affected Collies has greatly reduced. ALL reputable breeders eye check not only their breeding stock, but all puppies that are offered for sale.

How is CEA inherited? Most of the specialists agree that Choroidal Hypoplasia is carried as a simple recessive. For a dog to show symptoms, both parents, even if they show no signs themselves, must carry a gene for the condition. Evidence exists that some other parts of the syndrome are inherited differently. Staphyloma, for instance, rarely occurs except in the presence of Choroidal Hypoplasia. Dogs recommended for breeding will vary according to the standard set by the individual doctor. The ideal, of course, is to eliminate all but the clear, non-carriers, from the breed. Please note: Even among the dogs that examine "normal", most are carriers of the gene. They have a "hidden" or recessive gene for the condition and will transmit the gene to half its offspring.

Two other conditions not part of the CEA, which can occur, should be noted:

Hypoplasia of the Optic Nerve: An undersized nerve which is noted where it enters the eyeball. In extreme cases, this can cause blindness.

Corneal Dystrophy:This condition comes on when the dog is mature, often during stress. Opaque spots appear centrally on the surface of the cornea. (It is often confused by the layman with cataracts which occur in the lense.)

In the beginning there was a lack of veterinarians trained to examine eyes. Then in 1972, the American Veterinary Medical Association formed the American College of Veterinary Ophthalmologists (ACVO), thus providing specialists in the animal eye field. The Collie Club of America encourages its members to have all their puppies checked as young as possible by a member of the ACVO. Where there is none in the area, the alternative is to sell a dog contingent on a later check. No dog should be used for breeding until examined and found to be above the examiner's standard.

PROGRESSIVE RETINAL ATROPHY

The other Collie eye problem that can occur in rare instances is Progressive Retinal Atrophy (PRA). Since the name is just what it implies, it can be a progressive disease, that may not appear until later in life. This is a completely different and unrelated disease to CEA. As the name indicates, PRA is a progressive disease which refers to retinal degeneration. It can result in complete blindness in one or both eyes. However, Collies seem to be blessed with the fact that PRA seems to have an early onset. Fortunately, this is an eye disease that has largely been eradicated thanks to breeders efforts of test breeding potential carriers. Since PRA is a simple recessive gene, it is much easier to test for than CEA. Also, thanks to funding of certain grants by the Collie Health Foundation, research is being done to locate the genetic markers for this disease, which will further reduce the occurrence. Currently there is no genetic test for PRA, but rumor is that researchers are very close to finding a DNA marker.

PRA has proven to be a simple recessive in all the breeds studied. Again, this means that even though the condition is not present at birth, both parents must be carriers. If one parent has PRA, half the puppies may develop PRA, but all will be carriers for the disease. Early signs of the problem may be noticed by the owner as "night blindness." The dog has trouble seeing in dim light and will bump things. An expert may detect early signs in the eye at six months or younger.

THE IVERMECTIN STORY

There is a genetic syndrome in collies that can be deadly if not addressed. Some of our collies do not have the proper transport system in the brain to move chemicals back and forth between the brain tissue and the blood that supports the brain tissue. These collies are very susceptible to certain toxic drugs that enter the brain and cannot get back out. The dogs that do not have a proper transport system can become intoxicated, seizure and possibly die when exposed to certain drugs.

Among the drugs that can affect our collies are ivermectin and ivermectin sister drugs (the active ingredient in certain heartworm preventatives and ear medications), Imodium (an anti-diarrheal medication), and a number of the drugs used for chemotherapy. Exposure to these drugs in a large number of our collies can be fatal.

When dealing with the genetic makeup of our breed, APPROXIMATELY 35% OF OUR COLLIES ARE AFFECTED and will become intoxicated when exposed to those drugs listed above.

APPROXIMATELY 45% OF ARE COLLIES ARE CARRIERS OF THE AFFECTED GENES. These collies may or may not react to those drugs listed above. If they react it is usually not as severe a reaction as the affected collies. However, when two carriers are bred they can produce affected, affected carriers and unaffected non carriers.

APPROXIMATELY 20% OF ARE COLLIES ARE NOT AFFECTED AND NOT CARRIERS.

There is now a genetic test available to determine if your collie is affected, a carrier, or not affected. It is a simple cheek swab.

WHAT HEARTWORM PREVENTION TO USE

FOR YEARS THERE WAS ONLY ONE TYPE OF HEARTWOM PREVENTATIVE TO USE. THAT WAS THE DAILY PILL THAT CONTAINED THE ACTIVE INGREDIENT, DIETHLYCARBAMAZINE (DEC). THIS PILL WAS CHANGED FROM A NOT SO EXCITING TABLET TO A CHEWABLE DAILY TREAT UNDER MANY BRAND NAMES, THE MOST POPULAR BEING, FILARIBITS.

IN THE EIGHTIES MONTHLY HEARTWORM PILLS HIT THE MARKET. THE FIRST WAS HEARTGUARD. THIS CONTAINED THE ACTIVE INGREDIENT, IVERMECTIN. THE NEXT TO HIT THE SHELVES WAS INTERCEPTOR, AGAIN A MONTHLY PILL, THE ACTIVE INGREDIENT BEING MILBEMYCIN. THEN CAME REVOLUTION. THIS WAS A MONTHLY TOPICAL PREPARATION THAT CONTAINED SELAMECTIN. THIS WAS APPLIED IN A LIQUID FORM BETWEEN THE SHOULDER BLADES. TO MAKE HEARTWORM PREVENTION EVEN EASIER THAN ONCE A MONTH THREAPY, FORT DODGE PUT OUT PROHEART 6. THIS WAS AN INJECTION THAT WAS GIVEN EVERY 6 MONTHS TO PREVENT HEARTWORM INFECTION.

UP UNTIL LATELY, DOGS THAT COULD NOT TOLERATE THE MONTHLY OR SEMIANNUALLY HEARTWORM PREVENTION, COULD ALWAYS OPT FOR THE DAILY FILARIBITS. NOW FILARIBITS ARE OFF THE MARKET. AT PRESENT THERE IS NO REPLACEMENT FOR FILARIBITS.

I HAVE CHANGED ALL MY DAILY DOGS TO INTERCEPTOR SINCE THE NUMBER OF COLLIES REACTING TO THIS LONG TERM PREVENTATIVE IS LESS THAN WITH ANY OTHER PREPARATION.

Here are some links to websites giving more information on Ivermectin sensitivity in Collies:

"Prevalence of the mutant MDR1 allele associated with ivermectin sensitivity in Collies." Dr. Katrina Mealey of Washington State University. Email Dr. Mealey at kmealey@vetmed.wsu.edu

Multidrug Sensitivity in the Collie (includes Ivermectin and others)

Ivermectin Toxicity in Collies

Once the x-rays are received by OFA the process first begins by screening the X-rays for correct positioning and technique. If acceptable, the X-rays are then evaluated by (3) board certified Veterinary radiologists and a consensus of their opinions is taken. "The hips are evaluated for subluxation, shallow acetabulum (socket), femoral head/neck remodeling, acetabular rim/edge changes and degenerative joint diseases."

THE GRADING CATEGORIES ARE:
Excellent, good and fair....all considered Normal and will receive OFA numbers.
Borderline......Recommend a recheck in 6-8 months.
Mild, Moderate and severe...Dysplastic.

As with CERF, in order for the OFA number to be on the dog's AKC registration form, as of July 1, 1996, a dog must be either tattooed or micro-chipped at the time the X-rays are taken. This identification should be noted on the X-rays. OFA sends a quarterly report of OFA numbers to AKC.

The OFA number is similar to the CERF number, in that each element has a precise meaning. Using the number... CO-1620E24M-T as an example..CO is the breed identifier (in this case for Collie); 1620 is the ascending numerical order of normal individuals assigned a breed registry number; E stands for Excellent; 24 is the age in months when the x-rays were taken; M is for the sex of the dog and T stands for tattoo. An OFA number is good for the entire lifetime of the dog, but OFA reserves the right to correct or revoke any number.

Of added interest, OFA is branching out into other areas of health, with the recent addition of a Canine Thyroid Registry and a registry for Congenital Heart Disease as of January1, 1996.

Further information on OFA may be obtained by writing or calling: OFA at 2300 E. Nifong Blvd, Columbia MO 65201-0418, telephone 1-573-442-0418; Also information may be obtained from The American Kennel Club, at 1-919-233-9767. Here is a link to the OFA website:

Written by Gayle Kaye - from the April 1998 CCA Bulletin.

CANINE CYCLIC NEUTROPENIA

There's a new genetic DNA test for "Grey Collie Syndrome" or as it's officially known......Canine Cyclic Neutropenia.

A blood disorder that is present at birth, affected puppies are smaller and weaker, with a noticeable pale gray or pinkish/gray or beige color. This blood disorder affects red and white blood cell production approximately every 10 to 12 days. Due to the cyclic nature of the disease, these puppies rarely live beyond a couple of days and when they do survive, they are extremely susceptible to all sorts of infections. With treatment they can be kept alive, but few have lived beyond a couple of years old.

Gray Collies have been documented in many different Collie bloodlines for more than 60 years and coincidentally the disease is also present in humans. Both sire and dam need to be carriers in order for the gene to present itself (autosomal recessive). However, it should be noted that carriers do not manifest the disease.

Please see the HealthGene Corp. website for more information on testing your Collie - http://healthgene.com/canine/C136.asp

WHAT IS EPILEPSY?

Idiopathic epilepsy is a "diagnosis of exclusion" - there is no test at this time that says "yes, this dog has epilepsy". A dog experiencing repeated seizures, with no identifiable underlying cause (tests run to exclude things that can cause a seizure), is diagnoses as an idiopathic epileptic. Most people don't run every test known to veterinary medicine, as that's quite expensive and probably not productive in terms of changing the treatment plan, but there are basic tests that rule out major things. We have info on testing and why to do or not do various tests in the "Basics" section of our website - http://www.canine-epilepsy.net/. Bottom line, a dog experiencing seizures is affected with seizures; repeated seizures over time, the dog is called an epileptic - but could be primary (idiopathic) or secondary epilepsy (caused by something, such as a tumor, etc).

When we see idiopathic epilepsy in dogs in their prime - 1-5yrs - when they should be healthy and have no problems, tests show no underlying cause, it is generally assumed they have inherited "something" that is allowing them to seize. That "something" is what we're trying to find. When we can identify the mutation, or find a marker linked to the disease, then there WILL be a test for inherited epilepsy. We're not there yet though!

Liz Hansen

Animal Molecular Genetics Laboratory University of Missouri - College of Veterinary Medicine

321 Connaway Hall Columbia, MO 65211

573-884-3712

HansenL@missouri.edu

The Collie Health Foundation

www.colliehealth.org

In 1986 the Collie Club Of America established the Collie Club Of America Foundation, Inc. The concept for this organization was conceived by the late R.L. Rickenbaugh, a longtime breeder, along with his wife Hilda, of the Bannerblu Collies. With the Collie Club of America's assistance and cooperation, the reality of the organization was set into motion. The benefits would be two-fold. Not only would it provide tax deductions for potential donors, but it would result in additional income to the club, for some very worthwhile causes. Previously, the Collie Club of America was only able to give limited support for collie medical research and related activities. Health problems, such as Collie Eye Anomaly (CEA), Progressive Retinal Atrophy (PRA), Bloat, Epilepsy, skin problems, Dermatomyositis (DM) and Grey Collie Syndrome, that can affect the collie breed, need significant funding if they are ever to be conquered. Thus, the Foundation was born, with the primary function of addressing the breed's major health problems. Its main purpose is to issue grants to worthwhile organizations for research in breeding, genetics and health issues of all dogs, with the primary emphasis on Veterinary research as it relates directly to the Collie. So far the Foundation has given grants to the following areas of research: Bloat, Grey Collie, Epilepsy, eye diseases (most notably PRA), DM and many other health related problems. The very important message of the Foundation is "funding research" and "education." It is a "not-for-profit" corporation that receives its funds through membership donations, fund raising activities and other contributions such as $1 from every CCA member's dues. The larger the Foundation's membership becomes, the more generous its grants for research can be. In essence, the Foundation has filled a large void, as prior to its establishment, the club's commitment to medical research was very limited. Many other breed clubs, including the American Kennel Club, have followed suit and established their own Health Foundations (AKCCHF), using the CHF as the role model. The Collie Club of America was and is a leader in this area.

Purpose & Goals of the Collie Health Foundation

Education

Research

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