Breeding Advice for Eye Diseases

By Jan Sommons

This article summarizes information from Ocular Disorders Presumed To Be Inherited in Purebred Dogs (Blue Book) which is published by the Genetics Committee of the American College of Veterinary Ophthalmologists (ACVO). The text in quotation marks is taken directly from the publication.

“The Companion Animal Eye Registry (CAER) is a joint effort between the Orthopedic Foundation For Animals (OFA) and ACVO. The addition of eye examination results to the OFA database makes the OFA the most complete source of canine health screening results in the world, allowing responsible breeders to make more informed breeding decisions in an effort to reduce the incidence of inherited disease.

Due to the potential for disease to arise from inherited genetic defects at any age the Genetics Committee recommends annual eye exams.

A disorder is suspected to be inherited when:

  • The frequency is greater than in other breeds
  • The frequency increases in a given breed as a whole
  • The frequency is greater in related dogs within a breed
  • It has a characteristic appearance and location
  • It has a characteristic age of onset and course of progression (predictable stages of development and time for each stage to develop)
  • It looks identical to an entity which had been proven to be inherited in another breed

  • The breeding advice given is determined by the significance of the condition to vision and/or very strong evidence of heritability.

    Two categories of advice regarding breeding have been established:

    NO: Substantial evidence exists to support the heritability of their entity AND/OR the entity represents a potential compromise of vision or other ocular function.

    BREEDER OPTION: Entity is suspected to be inherited but does not represent potential compromise of vision or any ocular function.

    When the breeding advice is “NO” even a minor clinical form of this entity would make this animal unsuitable for breeding. When the advice is “BREEDER OPTION” caution is advised.

    Below are the conditions that Shih Tzu are screened for during a CAER eye exam.

    Keratoconjunctivitis sicca NO*
    Glaucoma NO*
    Entropion Breeder Option
    Distichiasis Breeder Option
    Ectopic cilia Breeder Option
    Corneal dystrophy-epithelial/stromal Breeder Option
    Exposure keratitis Breeder Option
    Persistent pupillary membranes - iris to iris Breeder Option
    Cataract NO*
    Vitreous degeneration - anterior chamber Breeder Option
    Retinal detachment NO*
    Retinal atrophy - generalized NO
    Optic nerve hypoplasia NO
    Retinal degeneration NO

    * Note: The prudent approach of these disorders is to assume they are hereditary except in cases specifically known to be associated with trauma, other causes of ocular inflammation, specific metabolic diseases, or nutritional deficiencies.

    It is up to the conscientious breeder to use this information along with other criteria in selecting which animals to breed. To assist this determination, current certification is recommended. Animals currently free of heritable eye disease will be issued a certificate on receipt of the examination/application by OFA. To avoid confusion between a normal animal (no evidence of heritable eye disorders) and one that may have a minor fault coming under the advice of Breeder Option, the Breeder Option category will be printed on the certificate. This is intended to stimulate conversation as to the specific nature of the Breeder Option condition found in that particular animal, allowing breeders using a dog in a breeding program to make an informed decision.

    The ACVO does not serve as a registry organization, however OFA does follow the guidelines set forth by the ACVO Genetics Committee in the Blue Book.”

    The ophthalmologist who does the eye exam is a good resource for advice on breeding dogs who have a breeder option designation. As an example the ophthalmologist who examines my dogs recommends breeding a dog with a “Breeder Option” condition to a dog who has been examined and determined to be clear of that condition. She also recommends not doubling up on a dog in your pedigree if that dog has been diagnosed with a “NO” condition later in life. This is one reason why annual eye exams are so important to a breeding program.