Progressive Retinal Atrophy cord 1 [PRA cord1]

The trials for this condition in dachshunds started in the mid 90's here in the UK and mini longhaired breeders sent blood samples to the AHT,many of those early dogs had passed away by the time the testing was rolled out for general use February 15th 2005 using 3 cheek swabs which you send back to AHT, lists of the results are available for anyone to view on the KC website,you don't have the option to keep your dogs results a secret. After 5 yrs the KC decided no mini long pups could be registered if the parents PRA cord1 status was not known or could result in affected pups, they felt there had been enough time to build up a gene pool of unaffected pups but there were still the occassional affected result on pups born well after 2005 so hence this important decision,unfortunately there are puppy farmers/BYB's who don't register their dogs and therefore there will be pups born with this condition but not from ethical breeders. The AHT continue to follow up on affected dogs with eye testing to see when the disease first appears,it was initially thought to be early in all cases but since it shows that even in litter mates the onset of symptoms and signs vary,a late onset affected parent may produce an early onset offspring these variation is thought to be due to another gene they haven't found yet causing some sort of modification, if we only produce unaffected pups then these genes won't be a concern to us.


This article I first copied and posted in 2007 and have edited it to include findings since then as and when they have arisen.

Here is the info from the website of the Animal Health Trust here in the UK, they went on to working with labs in other countries to allow them to do their own testing instead of sending samples to the UK.


Progressive Retinal Atrophy Cord1 in Minature Long-haired,Smooth-Haired and now Wire Haired Dachshund

Progressive Retinal Atrophy (PRA) is a term for retinal degenerations occuring in many breeds of dog. Many forms of PRA exist, each form being confined to one or a few breeds only. The disease results in a degeneration of the light-sensitive membrane at the back of the eye - the retina - resulting in loss of vision, and often leading to blindness.

The disease is caused by a change to a gene involved in sight. This change, or mutation, occurred spontaneously, but once in the population has been inherited from generation to generation like any other gene. The mutation upsets the delicate processes involved in vision and causes the long-term degeneration seen.

There is currently no treatment for the disease. Breeding stock are regularly checked by eye examination, although this can only pick up affected dogs after symptoms have developed and will never detect the symptomless carriers.

Research at the Animal Health Trust has identified a genetic change underlying pra in Miniature Long-haired Dachshunds. The mutation has been designated cord1 and is a cone-rod degeneration affecting both these types of cells which are crucial to vision in the retina. This mutation has now also been identified in Miniature Smoothhaired and now Wirehaired too and DNA testing is now available to these 2 breeds.

This form of PRA has been documented in scientific literature and was believed to have an age of onset of around 2 years. However, our research has shown that some dogs with the cord1 mutation are not diagnosed until much later in life, sometimes as late as 10 years of age, and the average age of diagnosis of the Miniature Long-haired Dachshunds in our study was 4.98 years. It is possible that the factors causing this variation could delay the onset of obvious clinical signs beyond the lifespan of the dog, so owners may never see behavioural changes and never recognise that their dog has a problem. However, the dog will still be genetically-affected by the disease and have two copies of the cord1 mutation. Genetically-affected dogs will always pass a copy of the cord1 mutation on to all their offspring, unlike carriers who pass the disease gene to only half their offspring. Undiagnosed genetically-affected dogs are therefore a particular danger for the breed and it is likely that the very high frequency of the cord1 mutation in Miniature Long-haired Dachshunds sent in for DNA testing has arisen because of the use of undiagnosed genetically-affected dogs in breeding programmes. These ‘late onset’ pups may develop PRA earlier in life than their parents. We are currently investigating the variation in age of onset, which could be genetic or environmental in origin. Until this research is completed, the factors determining the age at which breeders will begin to see signs of the disease will remain unknown.

Clearly, no blame can be attached to breeders who have unwittingly bred from undiagnosed genetically-affected dogs in the past. However, the DNA test now provides the means to avoid breeding further affected animals, and to eventually eradicate PRA caused by the cord1 mutation from miniature dachshunds.

The test is available now and information on submitting samples is given below.

Breeders will be sent results identifying their dog as belonging to one of three categories:

This dog is CLEAR of the cord1 mutation:

This dog has 2 copies of the normal gene and will neither develop PRA caused by the cord1 mutation, nor pass this mutation to its offspring. This mutation has been shown to be sufficient to cause PRA in the lines originating from UK breeding stock used in our research. However, other factors may delay the effects of the cord1 mutation in some dogs.

This dog is a CARRIER of the cord1 mutation

This dog has one copy of the normal gene and one copy of the cord1 mutation. It will not develop PRA but will, if bred from, pass on the cord1 mutation to 50% of its offspring, on average. This mutation has been shown to be sufficient to cause PRA in the lines originating from UK breeding stock used in our research. However, other factors may delay the effects of the cord1 mutation in some dogs.

This dog has TWO COPIES of the cord1 mutation

This dog has 2 copies of the cord1 mutation. This mutation has been shown to be sufficient to cause PRA in the lines originating from UK breeding stock used in our research. There may however be additional genes in the population which can delay the effects of the cord1 mutation in some dogs

Because of the very high frequency of the cord1 mutation, we would advise breeders to take a gradual approach to eliminating the mutation from their stock to avoid restricting the gene pool available. Both carriers and affected dogs can be used to breed - but only when crossed with DNA tested clear dogs. For carrier x clear crosses, half the offspring (on average) will be clear and half will be carriers. Litters from these crosses should be DNA tested to distinguish clears from carriers. Genetically-affected x clear crosses will only produce carriers; there is therefore no need to DNA test these litters.

There may be other forms of PRA in the miniature dachshund population that are caused by a different mutation to cord1. The current DNA test is specific for the cord1 mutation and will not therefore detect dogs affected by alternative forms of PRA. During the course of our research we did see some evidence of another, late-onset form of the disease, in a restricted number of lines.


SORRY it's so long but well worth reading to prevent this awful disease in the pups being bred.

I know from reading threads on forums that there are folk in other parts of the world who don't believe in this test, but each time someone raises something about false negatives[these are double checked] etc.I contact AHT and ask for their comments and receive back info I have then posted on the forums. Many of those breeders who participated in those early trials got devastating news back on their dogs,they knew this could happen but still agreed to take part, some threw in the towel and stopped breeding dachsies,others had to start from scratch with help from friends with better results,getting a clear dog from a breeder was very hard for a while but with those with clear studs allowing them to be used on outside bitches things got better. I have even read on forums that only creams are affected and them being exported/imported is what sent it everywhere,that isn't true,in the early lists of results the colour of the dog was mentioned and it was any colour/pattern available here in the UK

Even if breeders were only to test their males and only use Clear/Normal on untested breed quality females they would not get affected pups,the worst they would get would be carriers and possibly clears,if then show/breed quality pups were tested you could go on from there with the clear ones or keep a carrier you know will always need to be mated to a clear stud.

Unlike many faults in dogs this can be successfully eradicated in in a couple of generations with the right planning. I have been lucky that my 2 females were tested clear before I got them,Rhuari was born before the testing was rolled out for general use so I had to get him tested myself and he too came back clear and the pups I produced are hereditary clear because I used a clear outside stud.

So those of you breeding blindly[no pun intended] please give it some more thought.

Thank you, some very pertinent information on this disease. Ruth

Thanks Ruth, it has been read 17 times but you are the first to comment.

Thanks for the info, Rhona.
There is so much conflicting information flying around out there in the US
that it is hard to decide what to go with. I guess your side of the pond
developed the test and have proven it over there.
I did order my kits and have them here. It is just a matter of deciding if
any dogs I have is worthy of keeping in my program and testing them.
When I have a few extra dollars laying around, I will probably do my
2 males (litter mates) just out of curiousity to see how the whole
testing bit works. I do read everything that is posted and try to learn
as much as possible. Since I can't remember it all, I have started to print
off articles and have a notebook started of things I like to refer back to.
I almost wish our AKC would require testing of what they feel is the
most important for each breed, then there wouldn't be any question
about it......test or don't register with them.
Although I have seen some that are tested, that are not a good
example of the breed. PRA status us not (how to put it) a go ahead
to breed just because they are clear.

Anyhow, thanks for the information. I am hoping everyone posts their
favorite links to testing sites or genetic information so we can all learn more.

Thanks for your comments and taking time to read it all.

I agree that testing clear doesn't mean they should be bred from,I got Rhuari evaluated by more than one show/breeder before getting him tested as I wouldn't waste £70 if he wasn't good enough to be bred from.

I also tell those who need to test a litter to only do the pups who are of show/breed quality to save on the costs.

What is happening now that various tests are available,hip scoring etc.that puppy buyers are taking breeders to court who have not done these tests and the pup later develops the problem and the courts are finding in favour of the puppy buyer, these days folk sue for the smallest of reasons and this is now one of the more serious reasons they do it.

Good Luck Cindy with your results.