Progressive Retinal Atrophy

I wanted to share my answer to an email I received recently. Here are the question portions of the email, edited and with identifiers removed.

I (am) concerned about the possibility of PRA and called my Vet to see about having my dog tested through Optigen for the gene that causes it.

My Vet said "they can not test my dog as they do not test Icelandic's". Do you know whether somebody can test in the US?

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You ask great questions. I'll try to answer them. If I miss one, let me know, OK?

My dog does NOT have PRA. (PRA stands for Progressive Retinal Atrophy.) She turns six this year and, if she had PRA, the early symptoms should probably have presented by now.

Neither of her parents have PRA either. Her mother is ten years old now; her father nine.

In fact there are no Icelandics that we know of YET that have been diagnosed with PRA.

There is one suspected case of PRA in Iceland. The female dog that has this "suspected"case of PRA has the same father as my dog but not the same mother.

If the suspected case does turn out eventually to actually be PRA, that probably means that dad and mom each carry one recessive gene for PRA that they each gave to that daughter.

My dog's mom most probably does not have the PRA gene.

If my dog's dad does have the gene, then there is a 50% chance of inheriting that ONE gene from dad.

Listen up: -
If he does have the gene, my dog has a 50% chance of inheriting that gene from him. (My dog has 50% chance of getting the normal gene instead.) Your dog has a 25% chance of inheriting that same gene. (Your dog has a 75% chance of getting the normal gene.) Your dog's pups, if there are any, would have a 12.5% chance of inheriting that gene.

That might sound bad. A better way to say the same thing is: Your dog's future pups would have a 87.5% chance of NOT inheriting the PRA gene. Those are really good odds.
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Every dog has on the average 6 - 8 harmful genes that they carry in the hidden or recessive condition. All dogs (and people too) can pass those harmful genes on to their offspring. The bad traits show up only when the offspring inherit one bad gene from dad and one bad gene from mom for the same bad trait.
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* Even if both parents have the same bad gene, because dogs have litters with several puppies, there will be a variety of pups produced in each litter. (Animals that have only one offspring at a time have a disadvantage.)

* One puppy from a litter may actually get two of the same bad genes (one from mom; one from dad). If they get two bad genes, they will actually have the trait. The odds of that happening are 1:4 (25% chance).

* Half of the puppies in that litter will get one bad gene from dad OR one bad gene from mom BUT NOT BOTH; they will NOT have the bad trait. The odds of that happening are 2:4 (50% chance).

* Here's the interesting fact that is usually overlooked by gloomy people. One puppy from that litter will NOT get a bad gene from dad nor a bad gene from mom and will not carry the gene as a hidden recessive nor have that bad trait. The odds of that happening are also 1:4. (25% of the pups will be completely normal.)
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You're right. There is no gene test yet for Icelandic Sheepdogs for the PRA gene (genes actually, there is more than one kind of PRA). Every breed of dogs has PRA. Even wolves have PRA. That helps put things in perspective.

We have our breeding dogs looked at by veterinary ophthalmologists annually. The test is called a CERF test. (Canine Eye Registration Foundation - I think.) The ophthalmologist looks for anything wrong with the eyes but for our dogs there are three things (now) that we have to specifically ask them to look for: 1. distichia (tiny extra eyelash hairs), 2. cataracts (juvenile ones that start while the dog is still young), and now - 3. PRA

So what does the ophthalmologist look for when they are looking for PRA if they do not have the gene test?

They look at the retina on the back of the eye for early signs of retinal atrophy. They look for blood vessels that look unusually thin. That seems to restrict the flow of blood to the retinal cells starving them slowly. They also look along the outer edges of the retina (like a dinner plate) to see if the cells there look healthy and vigorous. If they do not look strong, then that could mean PRA. Because the changes happen slowly, dogs need to be looked at annually.

So, you could schedule your dogs for their first annual CERF test just to ease your minds. They will be fine.

Ask your vet to find you a place where they do CERFs. Usually there are clinics where lots of dogs are tested for a reduced fee. If you make a special appointment, it will cost more. There's no hurry.

A drop of dilating fluid will be placed in their eyes and, when the pupils have dilated, the ophthalmologist will take a good look inside. Let them know the three things that could be there so they will take a more careful look for those three things (1. distichia, 2. juvenile cataracts, 3. PRA) It's a quick easy visit.

Unfortunately there is currently nothing to stop the loss of retinal cells. Perhaps a good diet now helps put off the damage. I have always fed my dogs raw carrots for lunch - to reduce their calories and add bulk. Now that we know this, maybe carrots are also good for healthy eyes, at least my Mother always told me that.

If there is a bright side, it's that the condition is not painful nor life threatening. Yes, eventually the dog does go blind but that may not happen until the dog is old. I know that does not sound good. I think your dog will be just fine.

When I talked with the two ophthalmologists, they both told me that it would be OK to breed my dog again as long as I chose the mate carefully; choosing one that was not a carrier - - even though my dog may not carry the hidden recessive gene - there's no way of knowing because there is currently no test - no genetic test, that is - for Icelandics. Perhaps the mother country of the breed will check into finding one for our dogs.

I hope this helps - - - -