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Progressive Retinal Atrophy

 

Unfortunately around 25 years or so ago it was discovered the Glen of Imaal Terrier suffers from an hereditary eye disease called Progressive Retinal Atrophy. The breed worldwide pulled together to combat this & the two research projects,  Optigen in the United States and Bochum in Germany, arrived at the self same discovery within weeks of each other!

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DEFINITION OF PRA

~ Progressive a slowly developing disease process ~ the affected dog will gradually lose its sight and will usually adjust to its handicap

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Generalised progressive retinal atrophy (GPRA or PRA) was first recognised in the Glen of Imaal Terrier in the mid 1990’s.  This condition causes gradual loss of vision.  To develop PRA, an affected Glen has to have inherited two copies of the disease gene … one from each parent.  Up until recently, the only way to diagnose PRA in the Glen was by eye testing.  Glen PRA is late onset, with some affected Glens not showing any clinical signs of disease (by eye examination) until seven years old and older … in many cases after breeding duties were completed.  This made it almost impossible to “breed out” PRA from the Glen gene pool.

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In 2010, the gene that causes Glen PRA was identified.  The Glen is the only breed with this particular variant of PRA … cone-rod dystrophy 3 (crd3).  The development of a DNA test means that we need never again breed a Glen that is at risk of developing crd3; and we can work towards eliminating crd3 from our gene pool.  As long as breeders have at least one DNA-tested or hereditary Clear parent in a pairing, the puppies will not develop crd3.

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 At least one of a breeding pair must DNA tested Clear for crd3 or be Hereditary Clear (where both parents are known to be Clear):

 

  • Clear x Clear (safe) mating
    All puppies will be Hereditary Clear and do not need to be DNA tested

  • Clear x Carrier (safe) mating
    Puppies will be either Clear or Carrier status
    These Glens are not at risk of developing crd3 but must be DNA tested if they are to be bred from

  • Clear x Affected (safe) mating
    All puppies will be Carrier status
    These Glens should only be mated to a Clear individual

  • It is not necessary for all Glens to be DNA tested for GPRA-crd3 but any Glen that is to be used for breeding must be DNA tested, (unless it is already known to be Hereditary Clear).

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How Do I Arrange A crd3 Test For My Glen?

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  • ALL Glen owners are encouraged to have their dogs eye tested at regular intervals throughout their lives:

 

Professor Bedford, a veterinary eye specialist and patron of the Glen of Imaal Terrier Association (UK) writes on GOITA’s Glen Health page, “As a breed you have already developed the discipline of eye examination and you should continue to be certain that another problem does not become entrenched within the breed …… Eye examination is essential to ensure that our delightful breed remains free from other potential ocular [eye] disease.”

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  • Both parents to have an up-to-date eye test certificate at time of mating i.e. within the twelve months prior to mating

  • Ideally, breeding stock to have regular eye tests, if practicable, throughout their lives – at least every 24 months until the age of 10 years

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Eye test results can be found for individual Glens via the Kennel Club’s Health Test Results Finder

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Glen DNA results for crd3 are listed on the Kennel Club website

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