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Encyclopedia > Progressive retinal atrophy

Progressive retinal atrophy (PRA) is a genetic disease of the retina that occurs bilaterally and is seen in certain breeds of dogs. It causes progressive vision loss culminating in blindness. PRA is actually a group of retinal degenerations with different causes. Nearly all are hereditary. There is no treatment. Genetics (from the Greek genno γεννώ= give birth) is the science of genes, heredity, and the variation of organisms. ... Human eye cross-sectional view. ... Trinomial name Canis lupus familiaris (Linnaeus, 1758) The dog is a canine mammal of the Order Carnivora. ...

Contents


Diagnosis

Progressive vision loss in any dog in the absence of glaucoma or cataracts can be an indication of PRA. It usually starts with decreased vision at night, or nyctalopia. Other symptoms include dilated pupils and decreased pupillary light reflex. Fundoscopy to examine the retina will show shrinking of the blood vessels, a darkened optic disc, and increased reflection from the tapetum due to thinning of the retina. Secondary cataract formation in the posterior portion of the lens can occur late in the disease. In these cases diagnosis of PRA may require electroretinography (ERG). For the band with this name, see Cataract (band). ... Nyctalopia (Greek for night blindness) is a condition making it difficult or impossible to see in the dark. ... The human eye The pupil is the central transparent area (showing as black). ... The optic disc or optic nerve head is the point in the eye where the optic nerve fibres enters the retina; it is not sensitive to light. ... tapetum lucidum in a calf eye, with the retina hanging down The tapetum lucidum (Latin: bright carpet) is a reflecting layer immediately behind, and sometimes within, the retina of the eye of many vertebrates (though not humans); it serves to reflect light back to the retina, increasing the quantity of... Light from a single point of a distant object and light from a single point of a near object being brought to a focus by changing the curvature of the lens. ... Electroretinography, is used to measure the electrical responses of various cell types in the retina, including the light-sensitive cells (rods and cones) and the ganglion cells. ...


Types of PRA

Generalized PRA is the most common type and causes atrophy of all the neural retinal structures. Central progressive retinal atrophy (CPRA) is a different disease from PRA involving the retinal pigment epithelium (RPE), and is also known as retinal pigment epithelial dystrophy (RPED). Atrophy is the partial or complete wasting away of a part of the body. ...


Generalized PRA can be divided into either dysplastic disease, where the cells develop abnormally, and degenerative, where the cells develop normally but then undergo a damaging change. PRA can be further divided into affecting either rod or cone cells. Rod cells detect shape and motion, and function in dim light. Cone cells detect color and definition, and function in bright light. Cells in culture, stained for keratin (red) and DNA (green) The cell is the structural and functional unit of all living organisms, and are sometimes called the building blocks of life. ... Normalised absoption spectra of human rod (R) and cone (S,M,L) cells. ... Normalised absorption spectra of human cone (S,M,L) and rod (R) cells Cone cells, or cones, are cells in the retina of the eye which only function in relatively bright light. ...


Generalized PRA

Commonly affected breeds:

  • Akita - Symptoms at one to three years old and blindness at three to five years old.
  • Miniature longhaired Dachshund - Symptoms at six months old.
  • Papillon - Slowly progressive with blindness at seven to eight years old.
  • Tibetan Spaniel - Symptoms at three to five years old.
  • Tibetan Terrier - Symptoms at less than one year old, often blind by two years old, and cataract formation by four years old.
  • Samoyed - Symptoms by three to five years old.

Akita (秋田, autumn ricefield) is a Japanese surname and the name of serveral places. ... The Dachshund is a short-legged, elongated dog breed of the hound family. ... Country of origin France Classification and Breed Standards The Papillon is a small dog with large, luxurious ears that earned it its name, the French word for butterfly. ... Breed standards (external links) FCI, AKC, ANKC, CKC KC(UK), NZKC, UKC Tibetan Spaniels are a breed of small, highly intelligent dogs originating in the Himalayan mountains of Tibet. ... Country of origin Tibet Classification and breed standards The Tibetan Terrier is not a member of the terrier group, the name being given to it by European travelers to Tibet who were reminded of terriers from back home when they first encountered the breed. ... Common nicknames Country of origin Russia Classification and breed standards The Samoyed dog takes its name from an obsolete term for the Nenets people of Siberia. ...

Rod-cone dysplasia type 1

  • Irish Setter - Rod cell response is nearly absent. Night blindness by six to eight weeks old, often blind by one year old.

Country of origin Ireland Classification and breed standards The Irish Setter, also known as the Red Setter, is a breed of gundog. ...

Rod-cone dysplasia type 2

  • Collie - Rod cell response is nearly absent. Night blindness by six weeks old, blind by one to two years old.

A Rough Collie Collie refers to a breed of herding dog originating primarily in Scotland. ...

Rod dysplasia

  • Norwegian Elkhound - Rod cell response is nearly absent. Night blindeness by six months old, blind by three to five years old. This has been bred out of this dog.

Country of origin Norway Classification and breed standards Notes The FCI divides this into two breeds, Black and Grey. ...

Early retinal degeneration

  • Norwegian Elkhound - Night blindness by six weeks old, blind by twelve to eighteen months old.

Country of origin Norway Classification and breed standards Notes The FCI divides this into two breeds, Black and Grey. ...

Photoreceptor dysplasia

This is caused by an abnormal development of both rod and cone cells. Dogs are initially night blind and then progress to day blindness.

The Miniature Schnauzer is a breed of small dog of the Schnauzer type that originated in Germany in the mid-to-late 19th century. ... Belgian Shepherd Dog (also know as the Belgian Sheepdog or Chien de Berger Belge) can refer to any of four breeds of dog: the Groenendael, the Laekenois, the Tervueren, or the Malinois. ...

Cone degeneration

  • Alaskan Malamute - Temporary loss of vision in daylight at eight to ten weeks old. There is a purely rod cell retina by four years old.

The Alaskan Malamute is a large northern dog breed originally developed for use as a sleddog. ...

Progressive rod-cone degeneration (PRCD)

This is a disease that starts in the rod cells and progresses to the cones.

The Poodle is a breed of dog; specifically, it is a gun dog noted for its ability in the water and bird hunting skills. ... Common nicknames Country of origin United Kingdom Classification and breed standards The English Cocker Spaniel is a breed of dog. ... The American Cocker Spaniel evolved in the United States from spaniels imported from Great Britain. ... The Labrador Retriever (Labrador or Lab for short), is one of several kinds of retriever, and are the most popular breeds of dog (by registered ownership) in both the United States and the United Kingdom. ... Common nicknames Portie, PWD Country of origin Portugal Classification and breed standards Portuguese Water Dogs are a breed of dog, bred by the Portuguese to be companions at sea. ...

Hereditary retinal degeneration

A working dog breed that originated in eastern Siberia, the Siberian Husky is a medium-sized dog, 35 to 60 pounds (16 to 27 kg) in weight, 20 to 23. ... The X chromosome is one of the two sex chromosomes in mammals (the other is the Y chromosome). ...

Central progressive retinal atrophy (CPRA)

CPRA is also known as retinal pigment epithelial dystrophy (RPED). It is characterized by accumulation of pigment spots in the retina surrounded by retinal atrophy. It is an inherited condition. CPRA occurs in older dogs. Peripheral vision is retained for a long time. Vision is better in low light and better for moving or distant objects. Not all affected dogs go blind. Secondary cataracts are common.


Commonly affected breeds

The Labrador Retriever (Labrador or Lab for short), is one of several kinds of retriever, and are the most popular breeds of dog (by registered ownership) in both the United States and the United Kingdom. ... The Golden Retriever is a relatively modern and very popular breed of dog. ... A Border Collie is a hard-working herding breed of dog that originated in the border country of England and Scotland. ... A Rough Collie Collie refers to a breed of herding dog originating primarily in Scotland. ... Common nickname Country of origin Scotland Classification and breed standards The Shetland Sheepdog (or Sheltie) is a breed of dog, originally bred to be small sheep dogs ideally suited for the terrain of the Shetland Islands. ... Common nicknames Country of origin United Kingdom Classification and breed standards The English Cocker Spaniel is a breed of dog. ... The English Springer Spaniel is a gun dog breed of dog used for flushing and retrieving game. ... The Chesapeake Bay Retriever is a breed of dog that was developed along the Chesapeake Bay to hunt waterfowl under adverse weather and water conditions, often having to break ice during the course of many strenuous multiple retrieves. ... The Briard is a large breed of dog, one of many herding breeds. ...

Hereditary retinal dysplasia

There is another retinal disease in Briards known as hereditary retinal dysplasia. These dogs are night blind from birth, and day vision varies. Puppies affected often have nystagmus. It is also known as lipid retinopathy. Look up Nystagmus in Wiktionary, the free dictionary Nystagmus is rapid involuntary rhythmic eye movement, with the eyes moving quickly in one direction (quick phase), and then slowly in the other (slow phase). ...


See also

References

  • Gelatt, Kirk N. (ed.)(1999). Veterinary Ophthalmology (3rd ed.). Lippincott, Williams & Wilkins. ISBN 0-683-30076-8

 
 

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