Hi this is something that I have had discussions with with colleagues.   You get your dog eye tested last year all clear. Have a litter of pups. 18 months later re do eye test and fails eye test   A breed that had HC problems   Does that mean that litter of pups you bred last year are high risk of developing catarracts.  Both grandparents on both sides were clear.  So there was nothing to believe the bitch would fail a test later on   Would contatctin puppy owners be something you would then do   Or could this just be an unfortunate occurrence. 
Thoughts and opinions would be welcome

I don't know what your breed is, but for mine there's no DNA test for HC and the mode of inheritance is unknown. It can "appear" to occur out of the blue. I know of a dog whose parents both failed their eye tests after he was born. He was eye tested up to being just over 6 yrs of age and was clear of HC. (His only tested sibling was clear at their one and only eye test.) He sired 352 puppies from 43 litters. Out of the progeny that had eye tests, only one failed on HC.

For ISDS working sheepdogs/border collies there is no DNA test as yet for PRA. It is known that this IS genetic & not "spontaneous" as cataracts can be in some breeds so if a dog/bitch fails the eye test at any time in it's life for PRA no further puppies will be registered from that dog/bitch.

Is it actually HC that has been found ? If so it is important that puppy owners are made aware & that their dogs are tested on a yearly basis even if they are not being bred from as it is important from the dog's welfare. I would expect that no further litters would be bred from the affected dog & it's parents records noted(I personally would DNA profile the affected dog & parents(because you always known the dam, but need to have the sire verified)to ensure that it's patents are proven.

The ISDS through insisting on eye testing before breeding & refusing to register offspring of failed dogs have reduced CEA/PRA from around 20% of the breed being affected to less that 0.01% with the availability of CEA DNA testing the occurrence of CEA has reduced even further

> You get your dog eye tested last year all clear. Have a litter of pups. 18 months later re do eye test and fails eye test   A breed that had HC problems   Does that mean that litter of pups you bred last year are high risk of developing catarracts.  Both grandparents on both sides were clear.  So there was nothing to believe the bitch would fail a test later on

Unfortunately this is how it goes when there is no DNA test and the eye condition is not Congenital.

We had this same problem with PRA and Glaucoma, both late onset, several had had a litter and then before a second failed at about 4 for PRA, and with Glaucoma 6+.

Fortunately both now have a DNA test and found to be Autosomal recessive, though with the Glaucoma some with two copies of the rogue gene stay symptomless.

So Yes I would write to puppy owners telling them that the Dam is affected, and that all pups at the very least would be carriers, and depending on the sires status could potentially be affected, and should not be bred from.  The Dam should obviously not be bred from again.

> For ISDS working sheepdogs/border collies there is no DNA test as yet for PRA.

Was I mistaken in thinking that they had prcd-PRA for which there is a DNA test?  Or do they also have another form of PRA for which no test is available?  I thought there already was more than one PRA DNA test in Border Collies?

There is no DNA test for CPRA in ISDS WSD/BC, the 1 available DNA test(PRA-PRCD)doesn't detect the CPRA mutation

I did think the breed has more than one form of the disease.

CPRA is the type of eye condition known to exist in Border Collies. I think you may be confused by Rough & Smooth Collies being called Collies in research & they do have a DNA test-rcd2-PRA.

There are no tests anywhere for CPRA in Border Collies

43 litters, that narrows the gene pool.