Section: Information In-depth
Veterinary care often includes diagnostic tests to confirm the present of PRD and to exclude other diseases. Tests may include:
A complete medical and ophthalmic history. Information of particular importance includes any known information regarding retinal diseases in related animals; the duration and pattern of onset (sudden or slowly progressive) of vision loss; any physical abnormalities accompanying the vision loss; and any medications currently given to the pet. A thorough physical examination is performed to determine whether abnormalities are confined only to the eye or involve other organs in the body.
A complete ophthalmic examination is indicated and involves all of the following tests. Your veterinarian may refer your dog to a veterinary ophthalmologist for completion of some of these tests:
– Tests to evaluate vision, such as observing the dog navigate 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, the iris and lens, the vitreous and the retina.
If your veterinarian is concerned that some disease other than PRA is the source of the dog's blindness, then medical tests to rule out other causes may include the following:
– A complete blood count (CBC) and serum blood tests
– Blood tests for the tick borne diseases (Lyme disease, ehrlichiosis, etc.), fungal diseases and toxoplasmosis
– A measurement of systemic arterial blood pressure to rule out high blood pressure
– Possibly immune tests
– Possibly chest and abdominal X-rays
– Ultrasonography of the structures behind the eye
– CT scan or MRI of the brain and vision pathways leading to the brain
– Cerebral spinal fluid tap to evaluate the fluid around the brain
An electroretinogram may be indicated if the retina appears to be the source of the blindness based upon the physical and eye examination findings. This test is essential for confirming the diagnosis of PRD, and to rule out SARD and hemeralopia.
If the dog is purebred and belongs to one of the breeds for which genetic testing has been developed, the PRA can be confirmed with a blood test. Genetic testing is performed by Optigen, LLC of Ithaca. NY.
Related Articles
