Progressive retinal atrophy - (PRA)


R e t i n a   s e e n   i n   a n   o p h t a l m o s c o p e
Normal eye with many blood vessels
Central part with the sight nerve  
Periferal part with well
developed blood vessels
PRA eye with very few blood vessels
Central part with thin blood vessels
Periferal part without blood
vessels and increased reflexion


During the last few years there has been an eye disease discovered in many breeds. It is nothing new, the first case of PRA was observed in England almost hundred years ago. We have tried to believe it could not affect our lovely Lhasa Apsos. To be realistic, though, why could it not happen to our breed when all the other Tibetan breeds are affected with PRA ?

The first case was confirmed in Sweden in the beginning of 1996. Since then, we have had a total of 57 cases of PRA confirmed: 6 in Sweden, 21 in Norway, 3 in Denmark, 2 in Australia, 3 in the Netherlands, 1 in Germany and 20 cases in England. There are now (September 2011) hundreds of Lhasa Apsos tested for this disease and 57 are proven affected with PRA. Because this is a recessive gene, it means that as many as 570 may be dogs carrying the defective gene! (The predicted carrier rate is about 10 times as high as the affected rate).

There are also 6 Lhasa Apsos not counted in the above statistics. They are eye tested a couple of times by one eye specialist as affected and also tested by another specialist as unaffected! Before listing these four dogs we need a safe identification (microchip/tattoo)

PROGRESSIVE RETINAL ATROPHY (PRA) is the medical name of the disease. It means that the thin light sensing layer, the retina, in the back of the eye slowly will die out. The dog has full sight at birth and then slowly begins to lose cells of the retina. The unfortunate thing about PRA is that it may not show up until the dog is around two and a half to eight years of age. It always will end up in blindness.

The first signs can be seen when the dog doesn't want to go out at night or when the dog is afraid of going into a dark room. The dog has lost the night vision. When PRA progresses the dog can go upstairs but seldom downstairs, it will jump up in the sofa or the bed and must be helped down. When it has come this far it is important not to move any objects in the dog's surroundings. The dog can still perceive moving objects but will not see stationary things.

You can often see a green or orange shine reflecting out of the dogs eyes. This is due to incoming light reflecting off the retina. Normally we don't see this except in very dim light, because in most situations the pupil is constricted. In PRA, the pupil will often be widely dilated - the eye's vain attempt to let in more light. Some dogs can be aggressive when loosing sight but most of them will still be social. Even if your Lhasa Apso has been blind it can live a normal life if you don't move the dog from its normal surroundings. When loosing one sense the remaining senses will be developed and more used.

This disease don´t follow what we call common sense because the dogs develop their other senses to a level we never can imagine and we are completely fooled into thinking a PRA dog still has a very good sight.

The first case of PRA in Sweden was discovered when the owner took the dog to the vet because they thought he had pain in the back when he refused to go downstairs. The vet thought the dogs eyes seemed to be a little bit strange so he was referred to an eye specialist the same day. The dog was completely blind from PRA at 5 and a half years of age. The owners of the dog told his breeder about the diagnosis, but they were told to be quiet and not to discuss this with anybody. Two months later the owners couldn´t keep this secret any longer and later on this dog's parents were tested. The sire was also affected with PRA but he could still see a little at seven years. His owner says he can move freely in the forest and also see very small spiders moving on the wall ?? We met the father a year before he was tested and we thought he behaved himself a little bit peculiarly.

Another dog, went to the vet for an eye infection and she was also sent to an eye specialist. She was also completely blind with PRA at nine years of age. All the other cases were discovered through deliberate testing. In every case, the breeders were shocked because they hadn´t noticed anything unusual about their dogs. They went to the ophthalmologist believing their dogs could see very well, and totally convinced that their dogs would be tested clear. Some of these other cases were also totally blind!.

An eye specialist veterinarian can see if there is any PRA in the eyes of your Lhasa Apso. Only dogs having PRA will test positive. They have gotten a defective gene from both their parents. If your dog is tested clear from the disease it can still be a carrier of the defective gene and this gene has come from one of the parents.

If you plan to breed, it is necessary to test the stud dog every year and the bitch each time before breeding them. The only thing we can do to date is to examine our Lhasa Apsos and not to use proven carriers of PRA in our breeding. In a couple of years we hope there will be a gene test available where we also can identify the carriers. While we are waiting for this method, every Lhasa Apso breeder and owner should examine for PRA and report the test result to their local Lhasa Apso Club and of course to the breeder of the tested dog. Breeders all over the world are working together to accumulate information about PRA, because they need to know the dimensions of the PRA problem in their respective breeding populations, and we need to encourage the research toward a DNA test for the disease.



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