Dog Health 15.03.2021

PRA (Progessive Retinal Atrophy) in dogs - what you need to know about it

Sissi by Sissi, Sissi has been a blogger since 2014, got on the dog in 2018. Since then, she struts her 10000 steps through the world every day with Loki. The Beagdor (Labrador-Beagle mix) is a therapy dog for children and also accompanies her to schools. Secretly she fancies a French Bulldog as a second dog.

Progressive Retinal Atrophy

Progressive Retinal Atrophy is the most common inherited retinal disease in several breeds of dogs. Poodles, Labrador Retrievers, Golden Retrievers, Portuguese Water Dogs, Spaniels, Maltese, Rottweilers and Yorkshire Terriers are particularly affected. The progressive processes lead to blindness in your dog.

shutterstock.com / FamVeld

Basics and causes of PRA in dogs

PRA is inherited in an autosomal recessive manner. Female and male dogs are equally affected. Affected by progressive retinal atrophy is the layer deep inside the eye, the retina. This layer contains the rods and cones (sensory cells) that are responsible for light-dark and color vision. At the beginning of the disease, the rods slowly die off. The vision in the dark is completely lost. As PRA progresses, there is also degeneration of the cones. Your dogs can no longer see even in normal daylight. Eventually, blindness occurs in both eyes.

Some dogs carry the defective gene in their genetic material and pass it on to their offspring. However, they themselves do not become ill.

Symptoms and diagnosis

  • Fear at dusk
  • Uncertainty
  • wide and round pupils
  • the tapetum lucidum glows more intensely, the eyes appear yellow-green in the dark
  • blood vessels of the ocular fundus recede
  • Lens opacity: the lens is white and opaque
  • During the eye examination the pupils do not react to the incident light
  • pale, grey papilla (entry point of the optic nerve)

The diagnosis is made by a veterinarian during an eye examination. If the retina can no longer be assessed due to the opacity of the lens, an electroretinography (ERG) must be performed. The sensory cells on the retina are stimulated by light signals. The electrical signal emitted by the retina can be measured with a computer program. ERG can also be used for early diagnosis of PRA in dogs in which the retina does not yet show changes.

In some breeds of dogs, the gene responsible for progressive retinal atrophy can be detected with a blood test and genetic testing. The genetic test can also be used to assess whether the dog will later develop retinal degeneration.

  1. Eye examination

  2. Electroretinogram

  3. Blood test to determine the defective gene

Therapy and prevention

Since inherited retinal disease is a non-curable eye disease, only the symptoms can be treated. Your dogs have to put up with the loss of vision. However, orientation in the environment can easily be done by the sense of smell and hearing. Surgical removal of the clouded lens will not be successful because the problem of impaired vision is caused by the retina's failure to transmit signals. Since the eye disease is not painful, your dog's quality of life is hardly affected. Vitamin supplements can slow the progression of retinal degeneration.

The eye disease can progress at different rates. In some dogs, blindness occurs as early as the second year of life, while other dogs do not show the first symptoms until they are six to seven years old.

Since there is no therapy available for the inherited retinal disease, affected dogs must be excluded from breeding. In some dog breeds, the genetic test is part of the ERVIP examinations (checking for the presence of hereditary diseases) before being allowed to breed.

In the affected dog breeds, an eye examination should be performed once a year by a veterinarian. During the examination, the intraocular pressure must also be measured. A cloudy lens can cause painful glaucoma with an increase in eye pressure.

Precaution to prevent PRA:

  • regular examination of the eyes
  • Vitamin preparations
  • Exclusion of affected dogs from breeding
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