Eyes

 

The BVA / KC Scheme offers breeders the chance of eye testing annually to screen for inherited eye disease. By doing so, breeders can help eliminate or reduce the frequency of eye diseases being passed on to puppies. Leonbergers are currently on the Schedule 3 List of breeds under investigation. All breeding dogs should be screen annually for signs of inherited cataracts. This will help reduce the occurrence of this hereditary eye disease and help eliminate it from the breeding population. Inherited eye diseases are in the main passed on by BOTH parents so breeding from 2 clear parents is important.The following is an article about this condition, written by Professor Peter Bedford, chair of the BVA/KC eye panel:

 

Glaucoma Research

Evidence has recently emerged suggesting that Leonbergers may be prone to occasionally having narrowed drainage channels in the back of the eye, which can make them slightly more susceptible to developing glaucoma. It is not yet known how widespread this is in the breed. There is a simple procedure to check the width and angle of these drainage canals in the eyes, called a gonioscopy test, which is quick, painless and non-invasive. It can be carried out by any qualified veterinary ophthalmologist, but the results can only be lodged for research purposes if the test is conducted by a member of the British Veterinary Association’s eye panel. The LCGB is working closely with the BVA and researchers at the Cambridge University Veterinary School to gather evidence on the prevalence of this condition in our breed. We urge all owners, especially if they intend to breed their Leos, to ask their BVA panellist to add the gonioscopy test when they next take their dogs in f or their cataract certificates.

 

A list of all BVA eye panellists can be found here:http://www.bva.co.uk/public/documents/EP_list_Jan_2012.pdf

 

Please send a copy of your gonioscopy results to John Beel BVSc CertVOphthal MRCVS john.beel@medivet.co.uk

 

 

Hereditary Cataracts in Leonbergers

 

 

So what is a cataract when the term is applied to the eye? Well you must think of the eye as a camera, a biological camera if you like, and just like a camera the eye contains a film or digital memory stick known as the retina. The retina turns light into a nerve message which is transmitted to the brain and it is in the brain that the message is turned into what we call sight. The retina lines the back of the eye and for it to be exposed to light the front wall of the eye is transparent. This transparent tissue is known as the cornea and once the light has passed through the cornea it then passes through another transparent structure, the lens. Just as the lens in a camera helps focus the light onto the film/memory stick, this lens helps focus light onto the retina.

 

A cataract is any opacity of the lens – it can be of any size from pinhead to total lens involvement. It may affect one or both eyes and there are many causes of cataract development. For example an internal inflammation of the eye may result in cataract formation and it is the ophthalmologist's job to define the cause. Sadly there are currently some 21 breeds of dog in the UK in which the cataract seen may be inherited, usually as a recessive trait, and one of those breeds is the Leonberger.

 

Now, I've said there can be many causes for cataract formation, so how do we know your breed has this disease? I've also said that it is the job of the ophthalmologist to define the cause on the basis of his clinical examination – so what is he looking for? Well, primarily it's the pattern of the cataract inside the lens which dictates the diagnosis, but the ophthalmologist also checks the rest of the eye for any other feature which may indicate any other possible cause. The age at which the cataract makes it's appearance is also significant and in the Leonberger the disease is seen mainly in the young adult. However, it may occur as early as 6 months of age or as late as 8 years of age. It is not sex-linked but currently there is insufficient data to be certain of the mode of inheritance. However, it is very similar to the cataract seen in the Labrador and this we believe to be a recessive trait.

 

So let's have a look at your breed. The cataract is seen primarily as a posterior polar, subcapsular opacity, usually in both eyes. That means that occasionally only one lens may be affected. It is also possible that the appearance of the cataract may differ between the two eyes of the same dog in terms of extent and density, but this is the exception rather than the rule. Usually the cataract is confined to the back half of the lens, but occasionally the whole lens can become involved. So it's the characteristic appearance that makes diagnosis relatively straightforward. What the ophthalmologist sees is a typically triangular shaped whitish/greyish patch at the back of the lens (i.e. posterior), in a central position (i.e. polar) and within the substance of the lens, not on its external surface or capsule (i.e. subcapsular). However, the mildest example can be a small accumulation of whitish specks flecks in the same region of the lens. Sometimes the classical triangular patch is more round or stellate in shape, and there can be opaque extensions into the lens material around this patch. Actual small fluid filled spaces (vacuoles) may also be seen i.e. round the patch.

 

These cataracts are seen quite readily once the pupil has been dilated (the pupil is the hole in the iris behind which the lens is found). Any cataract is spotted using an ophthalmoscope and its detail is further described using an instrument called a slit lamp. Often a cataract may be seen with the naked eye as it stands out against the background of the coloured part of the retina. The use of the “drops” (a drug which is short acting and harmless) is an essential part of the examination procedure, the drug taking 20 minutes to dilate the pupil fully. Already there are DNA based tests for inherited cataract in other breeds and I expect a test will appear for your breed in the not too distant future. In the meantime it is most essential that you continue testing your stock through the BVA/KC/ISDS scheme – this scheme is based on annual clinical examination and from the affected results you can work out where the carriers are in the pedigree. A one-off DNA test will be really useful when it arrives, but for the moment you must rely on the ophthalmologist and his ophthalmoscope.Peter G C Bedford

 

 

Leonberger Club of GB Update on Glaucoma & Testing in the UK for the Leonberger

 

Further information on glaucoma developments.In order to clarify current developments regarding glaucoma cases in Leonbergers, the LCGB health committee would like to draw attention to the following items:

This statement has been provided to the LCGB by Dr. David Williams, veterinary ophthalmologist at Cambridge University Vet School.

 

“Over the last year several ophthalmologists, both in the UK and abroad, have encountered Leonbergers with glaucoma. This may have many causes, but one is an inherited abnormality in the drainage pathway of aqueous fluid from the eye. Several Leonbergers have been noted to have this abnormality, known as goniodysgenesis (from gonio = angle: the space between the iris and cornea through which the aqueous fluid drains form the eye and dysgenesis: abnormal development).

 

We need information on which animals have this goniodysgenesis in order to assess the inheritance pattern of the condition. The angle can only be assessed with a specific examination (gonioscopy). Putting the breed onto Schedule B of the BVA/KC eye scheme would highlight the concern regarding this condition, encouraging gonioscopy at eye scheme panel examination and allow evaluation of the inheritance pattern for the condition, which is as yet unclear.

 

The breed is not on schedule B as yet, as this requires a defined collaboration between ophthalmologists, owners and breeders. We look forward to such an investigation of this concerning condition.”Ian Mason, chairman of the BVA eye panel, has kindly provided some initial answers for our membership regarding glaucoma in Leonbergers and its implications.

 

1- What, briefly, are the causes of glaucoma and is it always inherited?Glaucoma can be described and diagnosed as either primary (inherited) or secondary. Primary glaucoma development is linked to the presence of the abnormality goniodysgenesis, where the aqueous fluid drainage system from the eye is impaired due to this change. Secondary abnormality arises as a result of other disease processes in the eye e.g .infection, inflammation or tumour.

2- If there is an increase in glaucoma cases in our Leonbergers, will there be a single clear and objective method of screening widely available to help guide future breeding practices?Gonioscopy is currently the technique of choice for examination of the drainage angle of the eye and assessing any degree of abnormality and thus predisposition to glaucoma development.

3- Will one screening test be sufficient, or is it possible thatabnormalities of the drainage pathways can or will alter over time and need further assessment?This is not clear in the Leonberger at present but the general feeling has been that in those breeds where goniodysgenesis is a problem one examination in a lifetime has been the correct procedure. We are currently carrying out follow up examinations in 2 breeds to check on that point.

4- If, for example, there have been reported 7 cases in seven unrelated dogs, does this in fact mean we have 7 affected breeding lines?Firstly one needs to establish whether all cases are primary glaucoma linked to goniodysgenesis. Secondly some degree of pedigree analysis would be required before drawing that type of conclusion.

 

Mr. Mason will be among the speakers at our 2012 health seminar, details of which will be published as soon as they are finalised. (Eye testing for both glaucoma and hereditary cataracts should also be available at that seminar).We will also be reporting back from the BVA eye panel’s April 2012 meeting as soon as the details regarding our breed are made available to us.And finally, John Beel, veterinary consultant to the LCGB health subcommittee, attended the November 2011 meeting of the British Association of Veterinary Ophthalmologists where incidents of glaucoma were discussed. He is currently compiling further data on the frequency of cases being diagnosed nationally in Leonbergers. Seeking this information from veterinary ophthalmologists directly will be complimentary to the efforts of Dr. David Williams.

 

Please submit details of Gonioscopy test results to John Beel at john.beel@medivet.co.uk.The LCGB will continue to pursue this matter in collaboration with relevant qualified experts, and will only report information once its accuracy has been firmly established.

 

Here is a link to the list of certified BVA ophthalmology panellists and dates etc:

 

 

Ectropion: Outward Folding of the Eyelids in Dogs

 

Entropion - Inward Folding Eyelids in Dogs

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