A cataract is defined as any opacity of the lens or its capsule. Cataract formation may be:-
- Congenital, due to in utero insult.
- Traumatic, as a result of blunt or penetrating injury to the eye.
- Metabolic, as a consequence of, for example, diabetes mellitus.
- Toxic, caused by some drugs.
- Nutritional, produced by inappropriate diseases, such as uveitis and neoplasia.
- A complication of other primary ocular diseases, such as uveitis and neoplasia.
A number of cataracts have been demonstrated to be inherited and it is these that the Eye Scheme reviews. The age of onset, appearance and progression of the cataracts that are certified under the Scheme are usually quite specific within the affected breeds, thus enabling inherited cataracts to be distinguished from cataracts from other causes.
The BVA/KC/International Sheepdog Society (ISDS) Eye Scheme offers breeders the possibility of eye testing to screen for inherited eye disease. By screening breeding stock for these diseases, breeders can use the information to eliminate or reduce the frequency of eye disease being passed on to puppies. Although any breed can be examined for eye disease, currently only the results of those breeds that appear on Schedule A of the Eye Scheme are sent to the Kennel Club for inclusion on computer records and printing in the Breed Records Supplement. The Old English Sheepdog are included on Schedule A for hereditary cataracts. In general, the best age for eye testing is before a dog has reached one year old and thereafter on an annual basis
The eye scheme currently relates to conditions involving the eye itself and not those involving the tear ducts, the eyelids or other surrounding structures. Hereditary eye conditions of the lens, retina and other internal structures are listed, whilst eyelid conditions such as entropion are not. These latter conditions are of importance, but because of their extremely complex nature and the paucity of scientific evidence relating to their degree of heredity, they are not included in the Scheme at present.
Schedule A lists the known inherited eye diseases in the breeds where it is considered that there is enough scientific information to show that the condition is inherited in that breed and often what the mode of inheritance is. For the breeds in Schedule A (including the Old English Sheepdog), a certificate is issued with results of "affected" or "unaffected" and these results are recorded and published by the Kennel Club. Schedule B lists those breeds in which the conditions are, at this stage, only suspected of being hereditary and therefore are "under investigation". The Old English Sheepdog are on Schedule B at present for Multi-ocular defects and congenital hereditary cataracts.
There is a list available from either the British Veterinary Association, http://bva.co.uk or The Kennel Club, www.thekennelclub.org.uk of appointed eye panellists who can issue certificates under the scheme and owners can make an appointment with one of the panellists directly or through their own veterinary surgeon. Often Breed Clubs will arrange for a BVA panellist to attend their shows. This allows many dogs to be examined on one occasion and may save time and money.
Owners of Kennel Club registered dogs must have the relevant documents with them at the time of testing to qualify for an eye test under the scheme. Wherever possible, any previous eye certificates issued for the dog should also be provided. The panellist will examine the dog, issue an eye certificate and inform the owner of the result at the time of examination. A copy of the certificate will be sent to the BVA and to the owners veterinary surgeon.
There is a time limit of 30 days and a set procedure for appealing against the result of an eye examination under the scheme.