Eyes Conditions Overview
DRAFT
General
Healthy eyes are like having car headlights, and eyelids work like the windscreen wipers. With each blink the eyelids gently glide over the cornea, replacing the natural layer of lubrication. The eyelashes function as a barrier, preventing debris and sweat from touching and irritating the eye.
This is a brief overview of eye conditions for pet owners. If you want more information about each condition including my own research notes, informal statistics etc you'll find these under the menu on the right.
American College of Veterinary Ophthalmologists (ACVO) "Blue Book"
The ACVO maintain information and guidelines regarding ocular disorders of concern in dogs. Based on scientific literature, it is ever changing as more precise technologies evolve, and scientific research expands our knowledge.
The statistics for each breed for the most recent year and from the previous 5 years, are reviewed and recommendations regarding the ocular disorders and the breeding advice are compiled. The section for Cocker Spaniels is included below under General Articles and is worth taking time to read. However It's 2020 data is included within this page.
The ACVO Genetics Committee was formed in response to requests from The Orthopaedic Foundation for Animals (OFA), Canine Eye Registration Foundation (CERF), other breed registry groups, breed clubs, and practicing veterinarians, and is engaged in an ongoing effort to update information on ocular disorders proven or suspected to be hereditary in purebred dogs.
There is a section specific to each breed. The "Blue Book" is a compendium of ocular disorders and breeding recommendations are "interim guidelines" as they are reviewed regularly and revised whenever additional information becomes available.
The condition descriptions in "quoted italics" below Ref: ©2022 Orthopedic Foundation for Animals and American College of Veterinary Ophthalmologists. ENGLISH COCKER SPANIEL PAGE 404-406 (under fair use for education & research)
An eye condition where the lens becomes partial or complete opaque (generally whitish) It is the result of pathologic changes in lens protein composition or
disruption of lens fibre arrangement.
Cataracts are the most common cause of blindness in dogs, it is progressive.
Distichiasis and Ectopic Cilla are abnormal eyelashes in dogs. They are small hairs, that usually require high magnification to be seen, that grow along the eyelid in the wrong direction.
Distichiasis refers to the hairs are growing downward.
Ectopic cilia refers to the hairs that grow from under the eyelid in toward the eye.
Ectropion & Entropion
Ectropion: rolling-out of the eyelid margin.
Entropion: “rolling-in” of the eyelid margin.
Both are conformational defects which may cause ocular problems.
Most likely familial and influenced by several genes (polygenic), defining the skin and other structures which
make up the eyelids, the amount and weight of skin covering the head and face, the orbital contents
and the conformation of the skull.
Keratoconjunctivitis sicca (KCS)
Also called dry eye. Tear production is considerably reduced. There is a quick simple test for this condition - the Schirmer Tear Test, a non-toxic filter paper strip is placed in the lower eyelid and the amount of moisture on it is measured.
Glaucoma
Primary glaucoma is an inherited condition caused by a build-up of pressure in the eye. This increased pressure occurs because the eye is not able to properly drain away enough of the fluid made inside.
Primary glaucoma can be divided into two types:
Primary open angle glaucoma (POAG)
Primary angle closure/ closed angle glaucoma (PCAG)
Gonioscopy is a type of eye exam that looks for signs that a dog is affected by this painful and blinding disease. How much the eye is affected is recorded as a grade, which can be used to make health focused breeding decisions, that reduce the risk of producing puppies that grow up to be affected by primary glaucoma.
Gonio (goniodysgenesis: A developmental abnormality of the drainage angle can in some cases result in decreased outflow during times of inflammation. This can cause closed-angle glaucoma in English Cocker Spaniels.
Goniodysgenesis is considered to be one of several factors in the development of glaucoma, and only a very small part of gonio affected cockers will develop glaucoma.
The BVA/KC/ISDS Eye Scheme is trialling a pilot gonioscopy grading scheme. This may help scientific researches further understand the disease better. And help breeders make health focused breeding decisions that reduce the risk of producing puppies that grow up to be affected by primary glaucoma.
The mode of inheritance is still unknown.
"Glaucoma is characterized by an elevation of intraocular pressure (IOP) which, when sustained, causes intraocular damage resulting in blindness. The elevated intraocular pressure occurs because the fluid cannot leave through the iridocorneal angle. Diagnosis and classification of glaucoma requires measurement of the IOP (tonometry) and examination of the iridocorneal angle (gonioscopy). Neither of these tests is part of a routine screening examn. Glaucoma in the English Cocker Spaniel is recognized in England. The frequency and significance of this disease in the breed in the United States is not known, but is probably low."
*** NB Looking at internet research available I note that the American Cocker Spaniel has the highest incidence of Glaucoma. If looking at research articles ensure the 2 breeds are identified separately.
Persistent pupillary membranes (PPMs)
Persistent pupillary membrane (PPM): Blood vessel remnants of the embryological
vascular network (pupillary membrane) in the central anterior part of the lens fail to regress which
normally occurs during the first 4 to 5 weeks of life.
"Persistent blood vessel remnants in the anterior chamber of the eye which fail to regress normally by 3 months of age. These strands may bridge from iris to iris, iris to cornea, iris to lens, or form sheets of tissue in the anterior chamber. The last three forms pose the greatest threat to vision and when severe, vision impairment or blindness may occur. In the English Cocker Spaniel, this is a particularly serious problem as the majority of PPMs identified on routine screening examination bridge from the iris to the cornea and are associated with corneal opacities which may result in vision impairment. Lens pigment foci/no strands is considered an insignificant finding and therefore is not noted on the certificate."
In the 1993-2017 data IRIS TO
CORNEA followed by IRIS TO IRIS had the highest incidence, However in the 2018-2022 data this changed and LENS
PIGMENT FOCI/ NO STRANDS followed by IRIS TO IRIS.... A change from the most concerning type to the least.
PRA has multiple variants which effect different breeds. Research to date shows that Cocker Spaniels are effected by the inherited prcd variant, it is commonly abbreviated as PRA- prcd or PRCD. This form of late-onset progressive retinal atrophy affects the photoreceptor cells in the eye involved in both night and day vision.
There is no treatment for PRA or PRCD at this time. So its important that you purchase your cocker spaniel puppy from a reputable breeder undertaking DNA health testing, and breeding to ensure any progeny is not affected by this condition.
Retinal dysplasia (RD)
Abnormal development of the retina present at birth and recognized to have three forms:
Folds: linear, triangular, curved or curvilinear foci of retinal folding that may be single or multiple.
Geographic: any irregularly shaped area of abnormal retinal development, representing changes not accountable by simple folding.
Detachment: either of the above described forms of retinal dysplasia associated with separation (detachment) of the retina.
"Linear, triangular, curved or curvilinear foci of retinal folding that may be single or multiple. When seen in puppies, this condition may partially or completely resolve with maturity. Its significance to vision is unknown.
There are a considerable number of canine eye diseases and one of the best sources of information is the American College of Veterinary Ophthalmologists (ACVO) Blue Book.
DNA Testing is not done at your local vets.
Responsible breeders are screening their breeding dogs for inherited eye diseases. An ophthalmic examination and certification provide breeders with vital information to improve future eye health.
minimum Health testing: Eyes General
There is currently no mandated minimum health testing requirements for Cocker Spaniels in NZ. I would like to see this change and include my thoughts on the who, what & how...
Testing: Clinical Eye Test
Cert by: GP Vet or Ophthalmologist.
Frequency: Bi-annually
Cavet: Ophthalmologist certification is mandatory if a condition is suspected/diagnosed.
Many eye other conditions can be diagnosed by regular GP Vets, and we should allow certification from them.
Our dogs should be seen annually for a welfare check up and vaccination boosters so the frequency requirement is easily achievable, with only a small increase in cost.
However they should be a cavet: A vet that identifies any issue should not certify that dog, but it must be referred to a Veterinary Ophthalmologist for a Specialist consultation and certification.
This would resolve the ongoing issue of accessibility to Specialist Veterinary Ophthalmologists in NZ.
It makes testing and certification more practical and therefore achievable, but continues to ensure that issues would be evaluated by Ophthalmologists.
* I believe CHWC are not including Eye Certs in LRL submissions, until this can be resolved.
Reliable genetic testing for determining breeding strategies is important so the gene diversity is retained and a depressed gene pool does not create other problems within the breed
Cocker Spaniels that don't carry the mutation have no risk of having affected pups. Past successful breeding strategies have breed clear to carrier/affected slowly reducing the incident of the disease.
***Much of the research data comes from Agria Insurance Data