CANINE EYES

It was during the 1940s that Irish Setter breeders first made the discovery that Night Blindness in their breed was an inherited condition, and they were fortunate in that it could be detected at an early age. With the encouragement of the Irish Setter Association’s secretary, Mr W. J. Rasbridge, who was also a member of The Kennel Club, breeders of the day instituted a programme of test mating in an effort to eradicating the condition. The almost total absence of Night Blindness or PRA in today’s Irish Setter is a lasting tribute to the dedication of breeders who were prepared to put the breed’s long term well being ahead of their own short term material gain.

Test mating, the pairing of an affected with an unaffected animal, is both costly and heartbreaking in that whole litters, which could contain a high proportion of affected whelps and no genetically clear offspring, had to be reared until they reached an age where signs of the condition could be detected. That affected animals require culling, a practice that would be frowned upon today, and not all breeds, known to suffer with this debilitating eye condition, show clinical signs at a young age make such drastic action inappropriate for the majority of breeders.

Of the known hereditary eye conditions the Rough Collie is only thought to be susceptible to the three detailed on the Discover Collie Eyes page.

THE WAY FORWARD

Good as these schemes undoubtedly are, and they have allowed breeders to reduce the instance and severity of debilitating eye abnormalities, the future must be in the early detection of those subjects who carry hidden genes for these conditions, and scientific advances in DNA testing have, for a number of years, been seen as the way forward. Progress in this direction is however proving to be much slower than was originally anticipated as the mutations which cause these eye abnormalities tend to be breed specific therefore research has also to be breed specific with each requiring a different DNA test before it is possible to diagnose the genetic status of any animal.

Although slow, and at times deplorably slow for breeders who look forward to a time when they will know with certainty the genetic make up of their kennel, progress has been made. The Kennel Club currently records the results of several breed specific genetic eye tests publishing the results quarterly in its Breed Record Supplement.

COLLIE EYES

Rough Collie enthusiasts have always emphasised the importance of eyes to breed type, the 1898 Breed Standard describing them thus: ‘The EYES are a very important feature and give expression to the dog; they should be of a medium size, set somewhat obliquely, of almond shape and of a brown colour except in the case of “merles”, when the eyes are frequently (one or both) blue and white or china; expression full of intelligence, with a quick alert look when listening.’ while the most recent Standard, revised by the Kennel Club in 2008/2009, reads: ‘Eyes — Very important feature giving sweet expression. Medium size (never very small) set somewhat obliquely, of almond-shape and dark brown colour, except in the case of blue merles when eyes are frequently (one or both, or part of one or both) blue or blue-flecked. Expression full of intelligence, with quick, alert look when listening.’ proving how little the ideal has varied in the intervening years.

“A Window Into Their Soul” may sound a fanciful description for Rough Collies eyes; they should however reflect their personality. Displaying their innate steadfastness and gentle nature with its spark of mischief, together with a desire to please coupled with personal initiative and high intelligence"

Central Progressive Retinal Atrophy or CPRA is in many ways a more insidious condition, which can not be detected until it manifests itself sometime after the first year of life, and frequently not until quite late in life explaining why breeders are urged to submit their breeding stock for regular eye screening. The condition’s development is also somewhat unpredictable often taking many years before serious loss of sight is experienced if ever. It is also considered that improvements in canine nutrition may have been largely responsible for today’s low incidence of the condition as it is known that Vitamin E deficiency can affect the eventual outcome and most modern feeds use Vitamin E as a preservative.

The possibility of a DNA test being discovered remains slim as the actual mode of inheritance is still not fully understood, and with the number of confirmed cases being less than 0•25% of all dogs tested under the BVA/KC Eye Scheme there is little encouragement for further research.

COLLIE EYE ANOMALY

Just as Collie breeders were beginning to congratulate themselves on a reduction in the incidence of PRA, a new and far more far-reaching eye abnormality was diagnosed. Initially discovered shortly after PRA was diagnosed in Rough Collies few were to realise the seriousness or extent of this more wide spread condition for another decade due to the concentration of veterinary and breeders efforts on one known to caused eventual blindness.

Collie Eye Anomaly more usually referred to as CEA is a non-progressive congenital, present at birth, hereditary abnormality of the eye which affects members of the wider Collie family. Originally thought to be a simple recessive its mode of inheritance no longer appears to be quite so simple and it is probable that its more severe expressions involve additional gene mutations that have yet to be identified.

Usually bilateral, affecting both eyes, in its milder forms it is no more than a slight lack of pigment to, or thinning of the optic disc which does not appear to affect the sight in any way. In its more severe forms, which thankfully represent less than 9% of the total Rough Collie population, it can manifest itself as Colobomas of varying sizes and/or partially or wholly detached retina, this latter condition producing blindness.

Being a congenital condition CEA can be detected at an early age, and as there are no known genetically clear Rough Collies in this country, the only method of discovering which if any puppies are clear or only mildly affected by CEA is to have the whole litter eye screened for the condition, by a BVA listed ophthalmologist, at the age of 6 to 7 weeks.

Research, funded by three separate health research foundations interested in Choroidal Hypoplasia [CH] plus the American Border Collie Association, has recently isolated the mutation which causes CH in our own species and CEA in the wider collie family. This in turn has allowed the development of a DNA test for the underlying condition, and although more work is necessary before the two more sever forms, which can cause sight deterioration, can be detected in this way it would appear to be the way forward.