If a bitch was not cerf'd until she was over a year old and passed, later was bred and a puppy od said litter has retinal folds, how does one go about finding out who the carrier was? I am trying to figure this out and so far my research has not helped in any way. Please help with any ideas.

I don't know that there are any absolutes. Try to breed her to a different line the next time and ask whether folds have been produced by the next stud dog you use. You could also look into getting a second opinion. Are there many folds? are they typical?

folds can also happen if the bitch had a fever during the pregnancy.

Vet said it was a very mild case in both eyes but if the puppy was going into my breeding program I should not do it and place her. It certainly took me by surprise that the pup had RD. He said her sight was not affected and if I had waited until she was a year she would have passed her CERF. That is generally why as careful as we are we definitely need to make sure every puppy is CERF'd at 7-16 weeks. It breaks my heart, she is a lovely bitch but my love of the breed tells me it is the right thing to do in placing her. There are so many unknowns in this breeding game.

sorry to hear about your RD puppy. RD should be discovered when the puppy went to it's first cerf exam though.

5 yrs ago, we took one of our "Keepers" to her first Cerf when she was a Yr old and found out she has RD. The dr said if we had brought her in when she was a puppy, the RD would have been detected. True RD is different than a little fold here and there, now those will disappear by the time the puppy is older. R you sure your puppy had RD or could it be small fold in each eye ?

The Cerf dr at the time didn't know with 100 % accuracy that RD is produced by 2 parents having recessives or if it only takes 1 parent. Both the sire and dam that produced my RD baby were both cleared and up to date on their Cerfs so it had to be a recessive at play.

This is what the veterinary ophthalmiologist told me about RD:
Retinal folds, geographic lesions and total retinal dysplasia are all part of the same genetic disease complex and have the same mode of inheritance (recessive). Minor "puppy" folds that fade with time and leave the dog supposedly normal are still categorised as RD because the dog will always be genetically affected with RD. Therefore retinal folds can never be thought to be a minor problem. If bred to other high risk pedigrees for RD they can go on to produce total retinal dysplasia (blindness). So, folds seem to be a NO BREED situation even if they disappear with age.

Exactly what he said to me as well. He also said if two dogs were bred with even minor cases of RD (ie: folds) they could produce dwarfs with serious issues as well. As I stated earlier this is so important to get PUPPIES checked... I still am curious as to where/how one can find out who the carrier is.

My understanding of Retinal Dysplasia is that it's dominant with incomplete penetrance, not a recessive gene. So only one parent needs to have the gene and pass it on for RD to show up. When 2 parents with the gene are bred together you have a 25% chance of producing puppies with skeletal dysplasia - the 2-copy dwarfism and blindness associated with the single copy RD gene.

I will say I produced a puppy with retinal folds from a bitch who had cleared twice as a puppy (and since as well). My ACVO was convinced she was clear as the sire of the affected puppy hadn't been checked as a puppy himself, though he'd been used fairly often and the stud owner hadn't heard of any other problems. I subsequently bred the bitch to a totally different line and all 7 puppies cleared no problems, and the bitch I kept from the second litter produced clear puppies as well.

And I bought a bitch that was tested at 8 weeks (she was clear, rest of litter not tested - 12 years ago). She was bred to outside dog - folds. I kept a girl with no folds. Test bred to dog who had had countless litters tested with no folds ever - folds.

Turns out sire of this girl subsequently produced TWO dwarves.

Anyhow, bred the "clear" bitch and produced folds. Kept a clear girl and bred her - folds.

Sometimes the gene takes a different route. Murphy's Law says it will take the route I want to go.

Well - that's just a great example of the dominant with incomplete penetrance of the gene. Your first girl obviously had the gene, but expressed it so little (no obvious folds) that she clears CERF - but she passed it on. Same thing with her daughter.

I dug out an article from JAVMA - in 1988 - titled "Inheritance of associated ocular and skeletal dysplasia in Labrador Retrievers". Here's part of the summary:

"Analysis of the distribution of lesions in pups indicated that the syndrome is caused by one abnormal gene, which has recessive effects on the skeleton and incompletely dominant effects on the eye."

What is the percentage of effected offspring when one of the parents have RD?

That would very much depend on whether the other parent is clear, affected or a carrier.

When the other other parent is clear yes!

Well, obviously if one parent carries one copy of the gene, they have a 50/50 chance of passing it on to any offspring, though with the incomplete penetrance, you might be keeping a puppy that carries the gene, but doesn't express it (like the person a few messages back who kept a clear daughter that still produced folds).

In 2002, Pam Davol wrote several posts about RD which I have saved. According to Pam, there are two forms, the European form which is simple recessive, and the American which is dominant and which causes dwarfism. If you would like a copy of the exchange, let me know.

Barbara

"Both the sire and dam that produced my RD baby were both cleared and up to date on their Cerfs so it had to be a recessive at play"

Joy were the sire and dam's eyes cleared at 7 weeks?

My ACVO says check the whole litter as pups....no pup from the litter should have folds if you want to keep ANY to breed.

Well I think just because one parent has the RD does not mean it is straight 50/50, that seams to easy I would like data to back that up.

Barb - I also kept a copy of two different threads explaining the difference between the two types and their inheritance. Pam was certainly a gem to have on any board!

In many countries, small early folds are not considered a real threat in our breed and cases of geographical or total RD are few and far between. To my knowledge, these were not linked to dwarfism (as in the American form of RD). Of course, with today's ease of AI, there are few existing frontiers and the two forms may already be meeting in several bloodlines.

I spoke with DR. Aguirre at an eye clinic in January 2007.
He said the blood test for RD should be available within a year.
Why don't you contact him at Univ of Penn if you want the latest correct info.