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Progressive Retinal Degeneration (PRD) or atrophy (PRA) is where the cells of the retina begin to decline in function, thereby leading to impaired vision or even blindness, states PetMD.com.
Petplace.com says, “When the photoreceptor cells deteriorate, vision is lost because the animal has no way to generate an image from the light reaching the retinal.”
“Many dogs are not seen until the late stages of disease and have advanced changes in their retinas because they compensate very well as their vision slowly deteriorates. Sometimes the blindness can appear to be sudden in onset, even though it has been developing for months, because the dog may show almost no clinical signs until the last bit of vision has been lost.”
According to PetMD.com, “Progressive retinal atrophy is a group of diseases that worsens over time, and is seen especially in Collies, Irish Setters, Miniature Poodles, Cocker Spaniels, Briards Labrador Retrievers, and Mastiffs. It is linked to the X chromosome in Samoyeds and Siberian Huskies.”
What Causes Progressive Retinal Degeneration?
PetMD.com lists several issues that can lead to PRD:
Genetic – Hereditary degeneration is common. This is characterized by the formation and development of a faulty group of cells, which gradually worsen in function over life.
Degenerative – Long-term glaucoma, scarring inflammation or separation of the retina due to trauma, abnormal structure, abnormal structure at birth or abnormal development of the retina with age.
Metabolic – Insufficient or excess amounts of certain enzymes.
Cancer – Cancer from other parts of the body that has spread to the retina.
Nutritional – Deficiency of Vitamin A or E.
Infectious/Immune – Infections of the retina or infections that spread from other parts of the body.
Idiopathic (Unknown Cause) – Unexpected blindness due to sudden acquired retinal degeneration syndrome (SARDS).
Toxic - Adverse reactions to specific drugs.
According to petMD.com, these are the symptoms you should be on the alert for if you suspect your dog has PRD:
Night blindness that progresses to blindness in light as well
Inability to see clearly in bright light
In some conditions, only central vision may be lost; your dog may still retain peripheral vision
The pupil (opening of the eye) has abnormal reactions to light
The retinal structure appears abnormal when a doctor examines it with an ophthalmoscope; a cataract may be observed
The liver may also be affected; obesity may be observed
Unpredicted blindness may be due to sudden acquired retinal degeneration syndrome (SARDS)
How is Progressive Retinal Degeneration Diagnosed?
According to petMD.com, “Standard laboratory tests include a blood chemical profile, a complete blood count, an electrolyte panel and a urinalysis, in order to rule out other causes of disease.”
Your vet will also give your dog a physical exam that will include a full ophthalmic exam using a slit lamp microscope, where the retina at the back of the eye will be closely observed for abnormalities and the electrical activity of the retina will also be measured.
Here are the other methods that your vet will use to determine if your pooch has PRD, according to petplace.com:
Tests to evaluate vision, such as observing the dog as he navigates an obstacle course in both bright and dim light, and certain neurologic reflex testing
Pupillary light reflex testing
A Schirmer tear test and fluorescein staining of the cornea
Tonometry to measure the pressure within the eye
Specialized examination of the front chamber of the eye, iris and lens, vitreous and retina.
Petplace.com states, “PRD can sometimes be confirmed at the time of retinal examination because it causes characteristic changes in the appearance of the retina. Early stages of the disease can be more difficult to diagnose, and in that instance the disease can be detected through an electroretinogram to evaluate the function of the photoreceptor cells when they are stimulated with flashes of light.”
How is Progressive Retinal Degeneration Treated?
PetMD.com states, “Since diet can cause retinal degeneration, providing your dog with a balanced (omnivorous), low-fat diet may improve or mitigate the degeneration which has already occurred. Surgery is not indicated if your dog’s eyes are blind and non-painful. There are currently no medications available that can reverse retinal degeneration.”
Petplace.com points out that “early diagnosis of PRD using electroretinography or genetic testing is important in kennels to eliminate individuals from the breeding pool that are either clinically affected or represent genetic carriers of the disease.”
How is Progressive Retinal Degeneration Prevented?
Petplace.com states that there is no preventative care that is available because PRD is genetic and therefore affected animals should not be used for breeding.
“Genetic testing is available for about 15 breeds of dogs affected with PRD. Testing performed on a blood sample can identify which dogs are affected and which are carriers of the disease. This information can then be used by breeders to decide which dogs may or may not be used for breeding.”
“In addition, dogs can be examined on a yearly basis by a veterinary ophthalmologist and certified to be clinically free of the disease. The certification is valid for a period of one year from the time of examination.”
Find A Vet HOW TO articles are intended for informational purposes only. You should always consult with your veterinarian about any health issues affecting your dog.