HEREDITARY CATARACT

For many years our breed was on Schedule B of the BVA/KC/ISDS eye testing scheme as there was concern that it could be affected by late onset hereditary cataract. Last year the Border Terrier was removed from the list due to the low number of affected dogs which had been found.

This might sound like a positive move but in reality so few dogs were actually screened that it probably did not give a true representation of the possible incidence of this condition within the breed.

Hereditary cataracts are known to be present in many breeds and although there is some difference in the appearance of the cataract and the means of  inheritance between breeds they can be broadly divided into two categories; juvenile where the changes can be seen within the first few months of life and late onset where changes aren't usually present until between 3 and 7 years of age. Juvenile cataracts will usually be present and of similar size in both eyes and will often lead to significant sight loss or total blindness by 2 to 3 years of age if left untreated. Late onset hereditary cataracts may be unilateral or bilateral, vary in shape and in the speed at which they progress often taking quite a few years before they significantly interfere with vision. By the time they become apparent affected animals may well already have been bred from.  

The concept of a condition which develops from possibly as young as 3 years of age being referred to as late onset may seem a little odd but it helps to distinguish these hereditary cataracts from the "senile" ones which are age related and likely to occur in animals older than 10.

In a number of breeds eye screening is regularly performed on all potential breeding stock. Routine eye screening has not been carried out by the vast majority of Border breeders in the UK as we have been working on the assumption that we do not have a significant problem.

However, in some areas of the world such as North America and Scandinavia eye exams are more commonly undertaken and cataracts are the commonest defect being recorded, albeit at fairly low levels. Both juvenile and late onset cataracts have been recorded and it would seem naive to think that the condition isn't present in dogs in the UK.

Previous requests for reports of confirmed cases have had a disappointing response but a couple of related dogs have recently been diagnosed with late onset cataract and their breeder has kindly put that information in the public domain. This does not mean that we currently have a major problem but it does raise the question as to whether we should perhaps be more proactive with regards to having routine eye screening carried out.

As it can be difficult to differentiate between cataracts which are hereditary and those which have other origins e.g. eye injury or systemic diseases such as diabetes, eye testing is normally carried out by certified ophthalmologists, a list of whom can be found on the BVA (British Veterinary Association) website at: 
https://www.bva.co.uk/canine-health-schemes/eye-scheme/find-an-eye-panellist/?fbclid=IwAR3sxTeROM9yRTHlcPbvZUQ9kUW7W6x8yBoBIPCp9QfBb2MxJY-kppdCnO8

The Breed Health Group is keen to monitor this condition and we would appreciate our standard questionnaires being completed for any dogs diagnosed with cataracts particularly those confirmed by an eye panellist. Whether the diagnosis has been made by a panellist or a first opinion vet please include the dog's age at the time of diagnosis along with details of the person carrying out the diagnosis.  Any additional information would also be welcome. It would also be appreciated if owners could fill in this form for all dogs which have had a clear eye exam. To complete the survey please go to: click here for online survey   or here for download 
 
A good response will help us to formulate future plans for dealing with the condition which may include organising testing sessions at Breed Club Shows when this becomes possible and trying to explore the genetic factors involved.

Remember, the only way breed health can progress is by the sharing of information. Anyone can be unlucky enough to breed a dog affected by a hereditary problem but being open about it may help to prevent issues becoming more widespread.
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