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.

CEA

CEA is an inherited eye disease common to the Collie breeds including the Rough Collie. In most cases the disease in inherited in a very mild form, so mild in fact that it cannot be detected by clinical examination, and in this mild form it is not believed to affect vision at all. CEA is not progressive, generally speaking what we see in an 8 week old puppy will not worsen with age, except in rare cases where large coloboma are present that can later cause retinal detachment.  In 75% of cases where CEA is diagnosed, the degree of the disease is ‘mild’ and the dog will lead a normal life. A percentage of those diagnosed as ‘affected’ will have one or more small coloboma, tiny holes or dents in or near the optic disc. Provided the coloboma is small, sight will not be affected to any huge degree and once again the dog will lead a normal life.

We need to remember that dogs evolved to hunt prey at dawn and are not nearly as dependent on vision as are humans. Both scent and hearing are equally involved and it  can be said that a dog is only 33% dependent on sight.   

Generally speaking therefore a small coloboma will not greatly detract from the dog’s overall quality of life.  However in a very small percentage of cases that are diagnosed with CEA, a large coloboma and or haemorrhage is present, and in these instances it can lead to detached retina. If the dog has a detached retina this will cause blindness in the affected eye.  Occasionally a puppy is born with severe impairment of vision in both eyes and it is possible to produce an entire litter thus affected, for this reason all puppies should be eye tested between the age of 6-8 weeks.

http://www.laboklin.de/index.php?link=labogen/pages/html/en/geneticdiseases/dog/dog_cea_collie.htm

Many puppies diagnosed age 6-12 weeks as ‘mildly affected’ will appear to be completely free of CEA if tested when older.  This phenomenon is known as CEA ‘go-normal’ although it must be remembered that from a genetic viewpoint, such dogs ARE affected.

For many years breeders have tried to eliminate CEA or at least reduce the incidence and severity. However all efforts have failed and the occurrence and severity of CEA are much the same now as they were when the condition was first diagnosed in the breed. This has confused those breeders with an understanding of basic genetics. CEA is inherited as an autosomal recessive trait. Both parents must carry at least one copy of the defective gene for the offspring to be affected. If those collies diagnosed CEA clear under clinical examination at 6-8 weeks are actually ‘clear’ the following should be applicable.

First of all I shall be referring to CEA non carriers as +/+, CEA clear/carrier as +/-, and affected as -/-

We need to remember that ‘mildly affected’ shares exactly the same gene responsible for producing ‘severely affected’ puppies although it is believed a dog inherits certain 'modifier' genes seperately which do affect the severity of the diseases. Even so, CEA is one gene that displays itself with varying severity in individual puppies and coloboma are part and parcel of the SAME gene.

+/+ mated with +/+ will produce 100% +/+ puppies.

+/+ mated with +/- will produce 50% +/+ puppies and 50% +/- puppies

+/+ mated with -/- will produce 100% +/- puppies.

+/- mated with +/- will produce 25% +/+ puppies, 25% -/- puppies, 50% +/- puppies.

-/- mated with -/- will produce 100% -/- puppies.

The question for those breeders genuinely interested has been...why have no CEA non carriers been found amongst the UK Collie population?, if the puppies clinically diagnosed as clear are truly either +/+ or +/- it would be genetically impossible NOT to produce a percentage of non carriers. So we must ask ourselves...where are these non carrier Collies? Surely they can’t ALL be hidden from the breeding gene pool and in pet homes!

In recent years a new form of diagnosis has been developed, the canine genome has been mapped and a DNA marker found for CEA. At long last an answer to our question is being revealed. Several UK bred Collies living both here in the UK and also on the European continent have now been DNA tested.
 

To my present knowledge every UK bred Collie tested by DNA analysis has been diagnosed as ‘affected’ and not a single collie has been diagnosed +/- or +/+. The Collies used in these tests had all been diagnosed at 6-8 weeks by clinical analysis as CLEAR....but in reality they are AFFECTED. This fully explains why breeders have been unable to make drastic improvements in this area in the UK, and it is extremely possible we have NO ‘true’ clear eye gene in the UK Rough Collie population. Clinical examination has proven to be untrustworthy, although severity of the condition can be discovered by this method.
 

Indeed, world wide it is believed that as few as 5% of Rough Collies are CEA non carrier (+/+) with perhaps 15% worldwide being clear/carrier (+/-) and as I have already said, No true clears have yet to be discovered in the UK...that is until now!  We recently imported two CEA non carrier (+/+) dogs from Canada and are integrating them into the gene pool here at Wicani, every puppy sired by these boys is +/- (by DNA) making collie history here in the UK, as these are the only UK bred puppies presently known to carry the TRUE clear eye gene!  A third non carrier Collie has been imported to the Strobroy kennel in Scotland.

We plan to import several more Collies to further enhance our gene pool, increasing genetic diversity whilst introducing a true DNA marked CEA free gene. I feel humbled and honoured to be in a position whereby I am able help the breed in this way.

I am in no way criticising my fellow breeders that have made different decisions and prioritised differently in their breeding programs, and as I have already said, a collie affected with CEA seldom shows signs of impaired vision and many will appear to be clear of this condition in clinical examination. Another point worth remembering is that the Breed has lived with CEA since its beginnings, however, on a personal note I wish to begin the eradication of any defective gene wherever possible, and if I can prevent the birth of one blind puppy, I feel my task will have proven itself worthwhile.  

For those interested I use in my home pages the following terminology:

NORMAL EYED NON CARRIER (+/+) A Collie that is not carrying the gene for CEA and cannot pass an affected gene to their offspring

(also referred to as N/E N/C)
 

NORMAL EYED (+/-) A Collie with the true clear eye gene but carrying an ‘affected’ gene. This Collie can pass to its offspring either a true clear gene or an affected gene. (also referred to as N/E)
 

CLINICALLY CLEAR (-/-) A Collie that has been diagnosed ‘clear’ by clinical examination, but if DNA tested would prove to be ‘affected’ this Collie can only pass an affected gene to its offspring, even though he/she ‘appears’ to be clear themselves and even if the offspring ‘appear’ to be clear by clinical examination.(also referred to as C/free)
 

AFFECTED (-/-) A Collie who appears ‘affected’ (whether mild or severe) on clinical examination.

REMEMBER, the only TRUE way to check a Collies eye status is by DNA analysis.  

Contribuition:

Angela Harvey. (Wicani Collies)

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 already a genetic test for PRA, please consult OPTIGEN website for more details!

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.

For more info: ..\Collie Eye Anomaly.doc

OFA stands for Orthopedic Foundation for Animals. It is a "not for profit organization", with the purpose to "provide a standardized evaluation for hip dysplasia and to serve as a data base for control of hip dysplasia through selective breeding." In order to receive an OFA number, a dog has to be at least 24 months or older on the day of his X-rays. Younger dogs can be x-rayed and evaluated but cannot receive an OFA number. Many breeders do this as a potential early screening. Because of the difficult positioning of the rear legs, (they must be extended and pulled parallel), most dogs require sedation or anesthetic. Film identification is extremely important. Permanent film identification in the film emulsion is required for all radiographs. Upon completion of X-rays, the owner fills out an OFA application. The radiograph, signed application and fee are then submitted to OFA. OFA also recommends that a copy of a dog's AKC registration be enclosed.

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.

Guidelines for Breeding dogs who are Carrier or At Risk for DM- DEGERERATIVE MIELOPATHY

Owners with dogs testing as Carriers (DM/N), or At-Risk (DM/DM) are strongly encouraged to share these results with their attending veterinarian and seek genetic counseling when making breeding decisions. 

The “DM” (mutated) allele appears to be very common in some breeds. In these breeds, an overly aggressive breeding program to eliminate dogs testing DM/DM or DM/N might be devastating to the breed as a whole because it would eliminate a large fraction of the high quality dogs that would otherwise contribute desirable qualities to the breed. Nonetheless, DM should be taken seriously. It is a fatal disease with devastating consequences for the dog, and can be a trying experience for the owners that care for them. A realistic approach when considering which dogs to select for breeding would be to treat the test results as one would treat any other undesirable trait or fault. Dogs testing At-Risk (DM/DM) should be considered to have a more serious fault than those testing as Carriers (DM/N). Incorporating this information into their selection criteria, breeders can then proceed as conscientious breeders have always done: make their breeding selections based on all the dog’s strengths and all the dog’s faults. Using this approach and factoring the DM test results into the breeding decisions should reduce the prevalence of DM in the subsequent generations while continuing to maintain and improve upon positive, sought after traits.

We recommend that breeders take into consideration the DM test results as they plan their breeding programs; however, they should not over-emphasize the test results. Instead, the test result should be one factor among many in a balanced breeding program.

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

• Promote appreciation and knowledge of dogs in general and Collies in particular.
• To further understanding of the diseases, defects, injuries, and other ailments that afflict dogs in general & Collies in particular.
• To sponsor medical research on health problems, genetics, breeding and history.

Research

• Establish a national data base of resource materials about Collies.
• To sponsor medical research on health problems, genetics, breeding and history.

Publish and Distribute Educational Materials on

• Care
• Treatment
• Breeding
• Development
• Training

In order to meet these objectives, every year the Foundation awards financial Grants to selected individuals and organizations. Periodic reports of these research projects, are published in the newsletter.. In its ongoing pursuit of providing the Collie fancy with important educational and research tools, the Foundation has sponsored book projects, such as "The Collective Writings of Bobbee Roos." We also sponsored the two book by Kristina Marshall, "His Dogs" and "The Lost Stories of Albert Payson Terhune." Other health and educational materials are also occasionally made available to the Foundation membership. Our most recent project is a comprehensive Health Survey, which hopefully will give us an understanding of the current status of the breed's health. This will provide an ongoing aid in determining our Collie health priorities when seeking Grant funding.