OVERVIEW OF HEREDITARY (INHERITED) EYE DISEASE

The eye diseases listed below are considered to be inherited in the English Springer Spaniel. They are known to exist, although they are not widespread.  However, it is important to be aware of them and to use common sense and caution, whether breeding English Springers or looking for one to own.

The ESS Breed Clubs advise all ESS owners and breeders to make use of the KC/BVA/ISDS Eye Scheme www.thekennelclub.org.uk/item/310 for annual clinical examination of all ESS breeding stock until at least the age of 8 years.  Breeders are also encouraged to use the DNA test for the PRA Cord 1 mutation (see below).

TEST RESULTS:

To find test results for individual dogs, click on KC Health Test Results Finder

To find a list of PRA Cord1 DNA test results, click on List of PRA Cord1 DNA test results


PROGRESSIVE RETINAL ATROPHY (PRA):

Progressive Retinal Atrophy is a collective term used to describe a group of eye diseases in which the retina (which lies at the back of the eye) degenerates and is eventually destroyed.  The cells of the retina receive light stimuli from the external environment and transmit the information to the brain, where it is interpreted to become vision.  In progressive retinal atrophy (PRA), degeneration of the retinal cells causes impaired vision, eventually resulting in total blindness. The retina has 9 inner layers, the outermost of which consists of the photoreceptor (light sensitive) cells - the rods and cones.  RODS are responsible for vision in dim light (night vision) and CONES are responsible for vision in bright light (daytime and colour vision). The outer layer of the retina is the retinal pigmented epithelium (RPE). In dogs, the retina is not mature until 6 or 7 weeks of age.

The term "progressive retinal atrophy" covers several types of inherited degeneration (deterioration) of the retina. Sub-classifications of PRA (see below) are based on the age at which dogs show signs of the disease and the type of retinal cells which are affected.

Sub classifications of PRA:

  • Generalised (GPRA) (Progressive rod-cone degeneration): Primarily affects the photoreceptor (light sensitive) cells. Both eyes are similarly affected (bi-lateral) and dogs eventually become totally blind. It is regarded, in the English Springer Spaniel, as being a late onset (4 - 5 years) condition, but it can appear as early as 2 years of age.

In 2007, researchers announced that a gene mutation (known as the Cord1 mutation) had been identified as a major risk factor for the development of one specific form of PRA in English Springer Spaniels.   A DNA test for this mutation has been developed and is now available in both the USA and UK.  Following the introduction in 2008 of a KC Breed Scheme for the PRA Cord 1 mutation, ESS owners and breeders are encouraged to use the DNA test available.  Other forms of PRA that may also exist in the Breed have not yet been genetically identified and can only therefore be detected by clinical eye testing.

As it would appear that there are other mutations in the English Springer Spaniel that are causing PRA (other than Cord 1), it is vital that blood samples/cheek swabs from any ESS that are clinically diagnosed as affected (but are not genetically affected for the Cord 1 mutation) are submitted to the Animal Health Trust to assist in further studies of canine PRA.

Please click on PRA Cord 1 mutation for more detailed information on this major risk factor for the Breed.

To use the PRA Cord1 DNA test and obtain testing forms please click on http://www.aht.org.uk/genetics_tests.html

  • Centralised (CPRA) (Retinal Pigment Epithelial Dystrophy - RPED): The abnormality is in the retinal pigmented epithelium (RPE). The photoreceptor cells will also degenerate eventually. The rate of vision loss is much slower than with generalised PRA, and not all dogs become totally blind. Detectable between the ages of 12 - 18 months by clinical eye examination.

GPRA and CPRA are listed for English Springer Spaniels under Schedule A of the official KC/BVA/ISDS Eye Scheme.  Results of clinical eye tests carried out under the Scheme for these conditions are recorded on each dog's KC registration record and published by the KC in the Breed Records Supplement and on their website.

Results of DNA tests for the PRA Cord1 mutation are recorded on each dog's registration record and published by the KC under the official KC/AHT/ESS Breed Scheme.


GONIODYSGENESIS/PRIMARY GLAUCOMA
:  

Primary Glaucoma in English Springer Spaniels is an inherited condition, also known as Angle Closure Glaucoma.  It usually begins in one eye, but almost always eventually involves both eyes, leading to complete blindness. Abnormal drainage of the eye's aqueous fluid leads to the pressure inside the eye rising to double or treble its normal value.  The increased pressure destroys cells within the retina, and this can happen so quickly that often treatment is too late to restore eyesight.  It is characterised by sudden onset blindness and pain, and such is the damage that removal of the eye may prove necessary in many instances.  The onset of Glaucoma is a medical emergency.

A condition called Goniodysgenesis, in which dogs are born with a narrowing of the iridocorneal angle (the angle at which the iris and cornea join), is known to be a major risk factor for the development of Primary Glaucoma.  Veterinary Ophthalmologists use an eye test called gonioscopy to identify those dogs that may be predisposed to the development of Primary Glaucoma.  This test involves placing a special contact lens directly onto the surface of the eye which allows examination of the drainage angle.  Gonioscopy is a one-off test, and screening can be carried out on dogs from the age of 4 months onwards.  

Goniodysgenesis/Primary Glaucoma is listed for English Springer Spaniels under Schedule A of the official KC/BVA/ISDS Eye Scheme.  Results of gonioscopy eye tests carried out under the Scheme are recorded on each dog's KC registration record and published by the KC in the Breed Records Supplement and on their website.

For more information about Glaucoma, click on Goniodysgenesis/Primary Glaucoma

MULTI FOCAL RETINAL DYSPLASIA (MRD):  
 
Retinal dysplasia is an eye disease affecting the retina and is usually non progressive. As well as a genetic defect, it can be caused by a viral infection, drugs, or Vitamin A deficiency.  It is characterised by folds or rosettes (round clumps) of the retinal tissue.  Retinal dysplasia can be focal, multifocal or geographic, or accompanied by retinal detachment (causing blindness).  Focal and multifocial RDs appear as streaks and dots in the central retina, whereas geographic RDs appear as an irregular or horseshoe shaped area of mixed hyper (too much) or hypo (too little) reflectivity in the central retina.  Cataracts or glaucoma can also occur secondary to retinal dysplasia.  MRD can be identified by clinical eye examination from 6 weeks of age.

MRD is listed for English Springer Spaniels under Schedule A of the official KC/BVA/ISDS Eye Scheme.  Results of clinical eye tests carried out under the Scheme are published by the KC in the Breed Records Supplement and on their website.  However, it should be noted that, at the present time, MRD results are NOT recorded on registration records. 

ENTROPION:

The inward rolling of the eyelid, most commonly the lower lid. This irritates the surface of the eye (the cornea) and may ultimately cause visual impairment. Generally both eyes are affected.

It is a common hereditary disorder in dogs and in some instances the selection of exaggerated facial features with prominent eyes and/or heavy facial folds, has created or worsened this problem - although thankfully this is not the case in the English Springer Spaniel.

The problem is usually evident before the dog is a year of age and can occasionally be seen in puppies as young as 6 weeks of age. The dog may be sensitive to light and rub at its eyes. Chronic irritation caused by the turned in eyelid may cause corneal ulceration and scarring which is painful and, if not corrected, can impair vision.

Entropion may be corrected surgically, but if possible (provided the dog is not in great discomfort) this procedure should be delayed until the dog is an adult, since the involved facial structures are still growing and changing - and in some instances the condition has been seen to have corrected itself by that stage.

Most vets support the belief of waiting until the dog is older before attempting surgery to correct entropion, as it is preferable to the risk of causing ectropion (a defect of conformation in which there is a sagging or rolling out of the eyelids, resulting in abnormal exposure of the eye) which can also lead to irritation and infection.

Breeders are advised to avoid using ESS affected with this condition in their breeding programmes.



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