A GENETIC TEST FOR COLLIE EYE ANOMALY
Information Sheet – revised February 2006

New Rules Apply
The Society has introduced new rules from February 2006 that apply to the testing of dogs before pup registration. These all relate to Collie Eye Anomaly (CEA), a hereditary disease that affects the dog’s vision. The potential for improved control of the disease through better breeding information will benefit the Border Collie. We have tried to make the rule changes as simple as possible, but it does all take some explaining. In the following paragraphs we will try and answer most of the questions that should arise. A copy of the rules is available from the ISDS.

In Essence…..
There is now a genetic (DNA) test available that uses a sample of the dog’s blood. As explained in the March/April 2005 edition of ISN, the Society would like to help breeders reduce, and even eradicate, the incidence of the disease for the breed’s health. A veterinary eye examination of an individual dog will never tell you whether it carries the potential for the disease whereas the DNA blood test will.

Is it compulsory?
No, you have a large degree of choice. All the current eye examination (ophthalmic) rules remain and breeders can carry on with these. The DNA test is quite expensive, but many will want to make use of the new rules since it will let them breed pups of a known CEA condition. However, if Carrier or Affected dogs are confirmed then there will be compulsion to continue testing. Also, if progeny are found to be affected by CEA in future, the Society will require a DNA test of parents before further pups can be registered.

Are the new rules right and fair for everyone?
In looking at the amount of genetic testing required, a balance was struck between setting rules for the best breeding practice and helping members accept new ideas and options. The cost implications of compulsion were also taken into account, since this might lead to a disinclination for registration and thus complete loss of control. The new rules have received the support of experts at the British Veterinary Association and the Society has been commended for taking very constructive steps.

Why compulsory microchipping of parents?
The DNA test laboratory result can only properly be applied to a dog that was fully identified at blood sampling. The Society’s view is that microchipping is good for proper dog identification and thus improved breeding and health controls. Thus, the Society has made it a requirement that dog identification is by microchip only for all dog identification under the DNA CEA scheme. Tattooing may be seen by some as a useful form of identification but it is not a substitute for a microchip.

Are you saying it is OK to breed from Carrier dogs?
Definitely yes, but only under controlled conditions. Following discussion with the experts in genetics, it was recognised that controlled breeding from CEA Carrier dogs could be of benefit to the genetic strength of the breed while ultimately permitting eradication of the atypical CEA gene. Most all animal geneticists will point out that it is very bad for a breed’s health to ‘ban’ a single gene characteristic as this can easily lead to unforeseen consequences. Normally, the Society will not accept pup registration where one of the parents is an Affected but, if the dog is of exceptional merit, there can be an appeal to the Stud Book committtee for specific permission.

Why the insistence on microchipping pups before registration?
Once breeding takes place between known DNA status parents then the progeny have to be registered according to new rules; if their identity is confirmed by microchip then any purchasers can be more assured of their eye condition. It is to raise the standards and assurance of identity.
Why do you still require an ophthalmic examination if a DNA test has been done?
The veterinary examination is looking for conditions other than CEA. For example PRA in older dogs, and various other conditions that your vet might talk to you about.

Remind me what Normal, Carrier and Affected means.
CEA disease in an Affected dog is brought about when two particular genes (one from each parent) come together. The mechanism of transmission is known as autosomal recessive inheritance, or more simply a 'recessive gene'. There are three possible conditions:
• A dog with a pair of 'normal' genes is known as a Normal or Clear dog.
• A dog with one 'normal' and one 'atypical' gene will never show an eye defect and is known as a Carrier dog.
• A dog with a pair of 'atypical' genes will probably show the eye defect and is known as an Affected dog.

The complication comes in predicting the offspring when the three conditions are interbred. The following diagram explains the average outcomes.

Note that we are avoiding the use of words like defective or bad for the atypical gene. It is important to understand that a Carrier dog is perfectly healthy and happy; indeed many of our top champions and stud dogs may be Carriers and there is nothing wrong with that. What we should avoid is breeding two Carriers because that will produce a proportion of Affected pups. As long as one of the parents is known to be Normal (i.e. Clear) none of the pups produced will be Affected.

How do I get a test done?
The DNA test for CEA is only available from an American organisation known as Optigen, and at a cost of around £90.00, plus any veterinary sampling fee and postage. At the moment, members who want a DNA CEA test must look on the Optigen web site www.optigen.com and download an application form. Having obtained an application form they should speak to their local veterinary surgery (any) on what to do next. The ISDS Office cannot advise you on what you should do. However, there are some additional requirements that must be followed: It is very important 1) that the dog is micro-chipped; 2) that the microchip number, ISDS Dog Name and Number are all written on the Optigen Request Form; 3) that you ask the veterinary surgery to sign and stamp with the veterinary surgery name, and; 4) you take a copy of the form that will later be sent to the ISDS.

When you receive the result from Optigen (which can be by certificate or email copy) you must staple that to the Optigen Request Form and send both to the ISDS. If the chip number, veterinary stamp or Request Form copy are missing then we WILL NOT accept the result. All this is because the ISDS wish be be assured of the dog identity on the DNA CEA result sheet.

The test result will state with a high degree of confidence whether the dog is DNA CEA Normal, DNA CEA Carrier or DNA CEA Affected, and the latter may arise whether or not an ophthalmic examination can detect any eye abnormality. The Society will accept a DNA CEA result as overriding any ophthalmic result.

Will the ISDS publish results?
The ISDS will not seek to publish DNA CEA results. Although this may be helpful to some people seeking a mating partner for their dog, the emphasis for seeking matches should be on other characteristics. Within a short time, it should be common knowledge within an area if a good dog or bitch is DNA normal. Breeders can advertise the fact in the magazine if they so wish. The ISDS will not try to organise collective blood sampling sessions but will assist in the free advertising of any sessions organised by any local group.

Do you think many people will take up the DNA testing?
Initially, those with very good dogs, but which have been identified as Carriers, will probably seek to have pups registered after DNA testing. Others will be keen to demonstrate that their pups are all of a known, CEA Normal status and advertise this fact when they are sold. Within a few years, there will be a population of ISDS registered dogs in which all parents and progeny are of known DNA status. From a genetic control viewpoint, it is best always to breed from dogs of a known CEA status. However, note that the rules do allow for progeny from DNA Normal parents to be bred with partners with just ophthalmic test passes and breed by those rules. This is a concession to allow members time to accommodate the new ideas, to not unfairly restrict those with limited finance and to ensure vitality in the gene pool.

Are these new rules really going to help?
It depends on how many people use DNA testing. There is the question of cost but there is not much we can do to reduce that. Certainly, members have been asking the Society to respond to the availability of the test as soon as possible and this is what has been done. The difficulty until now is that the ophthalmic test system is probably just holding the CEA Carrier incidence in the ISDS dog population at around 25% - it would possibly have stayed at that figure for ever. But now, the DNA test system undoubtedly gives any breeder the opportunity to eradicate the CEA gene from their bloodstock and without sacrificing the good line characteristics. The Society has therefore given everyone the opportunity to take advantage of the new test, and this has to be good for the healthy development of the Border Collie.