Eye Diseases which are
NOT APROVED for Breeding
Unless suspected otherwise, eye diseases must be considered heritable.
Keratoconjunctivitis sicca (KCS) – Breeding is not recommended for any animal demonstrating keratitis consistent with KCS. The prudent approach is to assume KCS to be hereditary except in cases suspected to be non-genetic in origin.
Cataract – Breeding is not recommended for any animal demonstrating partial or complete opacity of the lens or its capsule unless the examiner has also checked the space for “significance of above cataract unknown” or unless specified otherwise for the particular breed.
Lens luxation or subluxation
Persistent hyperplastic primary vitreous (PHPV)
Retinal dysplasia – geographic or detached forms
Optic nerve coloboma
Optic nerve hypoplasia
Progressive Retinal Atrophy (PRA) – Breeding is not advised for any animal demonstrating bilaterally symmetric retinal degeneration (considered to be PRA unless proven otherwise).
What is CAER?
CAER is the Companion Animal Eye Registry of the Orthopedic Foundation of Animals (OFA).
Why do breeding dogs need a full eye exam each year?
The CAER exam is much like your own eye check-up. The pupils are dilated and the opthamologist looks into the internal structure of the eye. The opthamologist is looking for abnormalities that may predict future vision problems, especially those which are believed to be heritable. Some diseases are noted as Breeder Option, meaning that under certain conditions, breeding may not be a problem (breeding to an unaffected dog for instance). In other diseases, breeding is NOT APPROVED due to the high likelihood of passing blindness causing disease to offspring.
The annual eye exams will catch the early indication of cataracts (clouding of the lens), problems with the placement of the lens (subluxation), the optic nerve and the retina. Results of the exams are stored in a database by OFA and can be reviewed for any dog. Here are the links for Nelson and Nakita.
At Bar TT Ranch Entlebuchers, we adhere to the annual eye exam and include optional tests for glaucoma called Initial Opening Pressure (IOP) and Gonioscopy (a measurement of drainage angles). In the OFA database, this is noted as "NORMAL w/GONIOSCOPY".
We don't have DNA tests that will tell us which dogs may have future problems, other than PRA-prcd, Unfortunately, it's not easy to see, in terms of behaviour, at the early stages of most eye disease. Many of the conditions we screen for can cause premature vision loss which can unfortunately be passed onto the offspring. Although blind dogs manage very well in a familiar environment, it obviously limits their activities.
By completing the CAER eye exam annually, and always before breeding, we ensure that our dogs had healthy eyes at the time of breeding. In other words, we didn't knowingly nor irresponsibly produce dogs that will go blind through these known causes.
Some problems don't appear for several years, so the system is not fool-proof, but it is the best we can do at this time.
How do we know so much about canine eye disease?
Dogs are affected by many of the same diseases as humans and represent a readily available model for studying disease. Since the identification of the dog genome, significant research has been done which can be transferred from dogs to humans. Because of our genetic similarities, dogs are becoming very well studied and understood in the medical genetics fields.