HomeNewsDec 14, Progressive Retinal Atrophy in Dogs (PRA): Causes, Symptoms, Care

    Dec 14, Progressive Retinal Atrophy in Dogs (PRA): Causes, Symptoms, Care

    Progressive Retinal Atrophy by Janice Jones |Updated 12-14-2022

    Retinal Atrophy (PRA) occurs in many dog breeds and is a non-painful
    disease of the retina in the eye that leads to blindness.  

    PRA is not
    one disease, but a group of them that include dysplastic (abnormal
    development), dystrophic (loss of cells) or degenerative disease
    of the retinal cells.

    Progressive Retinal Atrophy in Small Breed DogsProgressive Retinal Atrophy has been identified as having occurred in the Tibetan Terrier among other small dog breeds.

    The Retina of the Eye

    A quick anatomy lesson…

    Progressive Retinal Atrophy: Eye AnatomyNotice Where the Retina of the Eye is located at the back of the eye structure.

    Before we
    can understand how all this happens, we need to do a mini review of the retina’s
    function.  The retina is located at the back of the eye where it
    receives light coming through.  

    the digital age, experts described the retina as the film in the camera.   A chemical reaction occurs there that causes a
    nerve impulse.  That impulse passes
    through to the optic nerve where it goes to the brain.  Vision takes place in the brain.

    As you can
    see, the eye is just an organ that collects light and focuses the light rays
    onto the retina.  Without the work of the
    retina, light cannot be converted to real vision.

    The retina
    contains two types of cells, the rods,
    and the cones.  Rods are involved in the
    black and white or night vision.  Cones
    are involved in day vision or color. 

    Progressive Retinal Atrophy affects
    either the rods alone or both together.  As the rods
    begin to die, the dog’s vision diminishes first in dim light (aka night
    blindness or poor vision in the dark). 

    As the disease progresses, cones die off resulting in all the areas
    becoming affected until the dog is blind.

    In PRA, the
    cells are programmed to die because it
    is an inherited disorder.  For most dog breeds
    and mixes, the mode of transmission from parent to a child requires recessive genes.  
    Most forms of PRA involve an autosomal recessive trait.

    Progressive Retinal Atrophy Takes Many Forms

    As mentioned above, PRA is not one single disease but includes many each of which affects the retina in different ways and is inherited in dissimilar ways.


    The most common
    type is Generalized Progressive Retinal Atrophy and it causes
    atrophy or death to all rods and cones. 
    Generalized PRA can be dysplastic where the rods and cones develop in an
    abnormal way.  In the degenerative form of Generalized PRA, the rods
    and cones develop normally but then change and die. 

    PRA can affect breeds such as the Akita, the miniature long haired Dachshund, Papillon, Tibetan Spaniel, Tibetan Terrier and Samoyed. 


    Another form of PRA, Rod Cone Dysplasia is caused by a defect in the gene for cGMP-
    phosphodiesterase.  It is considered an
    early onset type and has been identified
    in Irish Setter, Collie, Sloughi and Cardigan
    Welsh Corgi. 

    The average age of onset and how fast the disease
    progresses varies from one breed to the next. 
    The median age of onset is about
    six to eight years. 

    Progressive Rod-Cone Degeration (PRCD)

    This type of progressive retinal atrophy involves rods and
    cones that initially develop normally but then the rods degenerate
    followed by the cone cells. 

    This is a disease with normal rod and cone
    cell development but late onset degeneration of the rod cells that
    to the cone cells. It is inherited as an
    autosomal recessive trait and there is a
    DNA test for this type of PRA available for
    some breeds.

    affected include the English and American Cocker Spaniel, Chinese Crested, Labrador
    Retriever, Portuguese Water Dog, Chesapeake Bay Retriever, Australian Cattle
    Dog, American Eskimo Dog,  Entlebucher Mountain Dog, Finnish Lapphund,
    Golden Retriever, Lapponian Herder, Miniature and Toy Poodle, Swedish Lapphund,
    the Nova Scotia Duck Tolling Retriever.

    Photoreceptor Dysplasia

    PRA is caused by abnormal development of both the rods and cones cells resulting in night blindness initially and the progressing onto blindness during the day. 

    Breeds affected include the Miniature Schnauzer and Belgian Shepherd Dog. In the latter, puppies can be blinded by the age of 8 weeks.


    It is not
    uncommon to have cataracts form as the retina degenerates.  This may be the first signs of the disease
    observed by the dog’s owner. 

    once cataracts have developed, it is more difficult for the veterinarian to visualize
    the retina and diagnose progressive retinal atrophy.

    Cataracts are removable
    through surgery, but even then, their removal will
    not bring back vision if the dog also has PRA

    How is PRA Diagnosed?

    In the early
    stages, people may not be aware of the problem. 
    The progression can be akin to the dimming
    switch.  As the lights are slowly dimmed in the room, your eyes adjust
    and may not notice it until total darkness occurs.  Think about the experience in a movie

    Dogs rely
    more on other senses such as smell and hearing and may use those even more so
    as their vision dims. 

    Most dogs
    that are diagnosed with Progressive Retinal Atrophy have been afflicted for quite awhile.  Sometimes they are diagnosed during their
    yearly check up.  A general vet may
    notice some changes in the eye while observing with an ophthalmoscope.  They will then
    make a referral to a veterinary ophthalmologist.     

    The only way
    to diagnose PRA is through eye exams done by a veterinarian. Your general vet will likely refer you to a specialized
    veterinary ophthalmologist. 

    The eye
    specialist will use an electroretinogram
    to measure the retina’s ability to respond to light. The exam involves
    placing an electrode on the dog’s cornea and two electrodes are placed under
    the skin around the eye. 

    The ERG is
    similar to an electrocardiogram because they both measure electrical impulses.  Just as the ECG creates a characteristic wave
    pattern as it measures the heart, the ERG
    creates a pattern that can even diagnose dogs before they have full-blown
    clinical signs.

    Some dogs
    may need full anesthesia while others just need sedation.  There is a little risk to the procedure
    including an infection or corneal ulceration.


    PRA affects
    both eyes and will eventually end in
    blindness.  There is no way to reverse or
    treat the degeneration that causes blindness. 

    While there is no cure, there are now tests that can be performed on
    breeding animals that will help breeders make informed decisions on
    which dogs to mate to help prevent PRA from being transferred to the

    Prevention of Progressive Retinal Atrophy

    The only way
    to avoid the problems lies in the hands
    of breeders. 

    Eye Exams

    Dogs that
    are intended for breeding can be examined
    by a veterinary ophthalmologist and the
    results sent to the Orthopedic Foundation of America (OFA) formally the Canine
    Eye Registry Foundation (CERF). 

    exams can be done once a year and dogs that are found to have PRA should not be bred. 
    Unfortunately, in some breeds, the age of onset of PRA is six to eight
    years of age. 

    Many breeding dogs are
    either being retired or have already been retired by this age, so they very
    well may have passed on the disease to their offspring before the onset of the
    disease in themselves.

    DNA or Genetic Testing

    A rcd4 mutation that
    causes late onset (10 years old and older) has been
    identified in Setters (Gordon, Irish,
    and English), Australian Cattle Dogs, Polish Lowland Sheepdogs, Small
    Munsterlanders, and Tibetan Terriers. Tests results will show whether the dog is clear,
    a carrier, or is affected. 

    Another type of PRA, prcdPRA (prcd”
    stands for “progressive rod-cone degeneration) has a genetic test offered by

    Breeds where this test is available include: American Eskimo, Australian Stumpy Tail Cattle Dog, Australian Cattle Dog, Chinese Crested, Entlebucher Mountain Dog, Finnish Lapphund, Golden Retriever, Lapponian Herder, Miniature and Toy Poodle, Nova Scotia Duck Tolling Retriever, Swedish Lapphund.

    Blindness in Dogs

    While blindness
    may seem very scary to people, dogs adjust very well to their gradual loss of
    vision.  There is no pain, and they begin to use their other senses
    to get the same information that they used to when they had sight.  As long as their environment remains
    unchanged, they get along fine.

    As owners, we want the best for our pets.  There have been many advancements in genetic research, and one would expect this trend to

    While there is no cure for Progressive Retinal Atrophy
    at this time, there is hope that
    eventually the problem will resolve
    itself through excellent breeding practices. 
    At the same time, PRA is not life threatening,
    and many blind dogs live long happy lives. 

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