TERMINOLOGY
updated 8th October 2017
For the purpose of this site, below is a brief explanation of the meanings of terms in these databases.
- Gonioscopy = A technique used to evaluate the iridocorneal angle, which will determine the etiology of a glaucoma or a predisposition for glaucoma.
- Goniodysgenesis = refers to abnormal and incomplete development of the
intraocular fluid egrss channels inside the eye. This condition is common in dogs with primary glaucoma
(basset hounds and many other breeds). Normal
intraocular fluid (aqueous humor) is produced inside the eye by the ciliary
body (faucet) and then flows around the lens, through the pupil and into the
drainage angle (drain) in the front of the eye. The pectinate ligaments are
small channels that form tunnels for fluid to drain from the eye. If an
animal has goniodysgenesis, the flow holes are compromised and the animal
may have an increased glaucoma risk.
- Affected = A dog listed on this site as "Affected" means that the dog has undergone a gonioscopy test by a recognised opthalmic specialist and has some abnormality to exclude the dog from being given a "normal or unaffected" physical status for it's eyes. In the UK, as of July 2017, the BVA had commenced a pilot scheme which will be reviewed in November 2017 by th BVA.
A dog that is listed as "Affected" does not necessarily mean that the dog has, or will develop Glaucoma. At present, there is no worldwide standardisation of wording given on eye examination sheets so the usage of the words "affected" or "unaffected" are those adopted in the UK. In other countries, words as "clear" or "normal" may be preferred. To save confusion over the phenotype or genotype of any given dog, the word "clear" is not used in these databases. Should a DNA test become available to clarify a dog's genotype, the word clear will be used in that context.
It should be remembered that at present we only have the possibility of defining whether a dog is normal or not by a physical eye examination and this in no way declares the genetic status of dog, or it's chance of passing on the condition to it's offspring.
- Grades in the UK from July 2017
- Normal Grade O - Highly ulikely to develop primary glaucoma
- Unaffected - Simply means that the dog has passed a physical eye test with no obvious abnormalities. It does not necessarily mean that the dog is genetically clear.
- Affected Grade 1 (in UK) - Mildly affected - unlikely to develop primary glaucoma
- Affected Grade 2 (in UK) - Moderately affected - low risk of developing primary glaucoma
- Affected Grade 3 (in UK) - Severely affected - highest risk of developing prinary glaucoma
- Gonioscopy testing. There is a detailed pamphlet on this and other eye diseases on the British Veterinary Association website, which can be downloaded from the link below. The BVA recommends that a gonioscopy test is best performed from 6 months at the earliest, depending on eye development. Some vets will test at 3 months, but any younger is not normally advised. BVA pamplet link
Clinically affected cannot be an accurate description unless the gonioscopic findings are entirely normal.
The UK Kennel Club will continue to record under the old scheme - and the result grades will be collected, recorded and collated by the BVA.
Further information can be found on the Pastoral Breeds Health Foundation website.
Testing Clarification
Primary closed angle glaucoma (PCAG)/primary angle closure glaucoma (PAGC) is significantly
associated with defective development of the drainage angle which is termed goniodysgenesis
(gonio = angle, dysgenesis = defective development), also known as Pectinate Ligament Dysplasia
(PLD) or Pectinate Ligament Abnormality (PLA).
Goniodysgenesis is inherited in several breeds and is tested for using a technique called
gonioscopy. It was originally believed that the degree of goniodysgenesis did not progress after
birth and so a ‘oneoff’ test before breeding was advised for dogs of certified breeds. However,
recent research has provided evidence of progression of goniodysgenesis with age in several
breeds, namely the Flat Coated Retriever, Welsh Springer Spaniel, Dandie Dinmont Terrier,
Basset Hound and Leonberger. In consequence, the advice on gonioscopy has been updated for
all breeds in which gonioscopy is performed.
It is advised that for Schedule A breeds gonioscopy should be carried out every 3 years, unless
any evidence to the contrary emerges. The first test can be performed in dogs from 6 months of
age onwards and current advice is that gonioscopy is performed at approximately 1, 4 and
7-8 years of age. Repeat testing should provide much needed longitudinal information about the
risk of developing glaucoma in later life and, in conjunction with Breed Clubs, will enable breed-specific recommendations to be developed.