Boston Terrier Cataract Test Advice

[Jane V]

I wonder if any of you can help with some advice.
My beloved pet Boston died a few weeks ago aged 11.5 from complications with her heart. In the last two years of her life she also became almost completely blind from a worsening cataract condition.

I really want to get another Boston puppy but I want to do all I can to try to mitigate the known cataract problem in the breed. I have seen a puppy from a reputable Kennel Club breeder and both the Sire and the Dam have had the hereditary HC-HSF4 DNA test and passed.

The problem I have is that the Sire has had 4 additional BVA/KC/ISDA eye examination screenings, the first 3 were clear but the fourth at aged 8 in February this year shows that he is HC "affected".

So now I am completely confused and not sure what this means and if I should find another puppy instead.

Any advice or help would be amazing...the puppy is gorgeous and I have fallen in love but want to do the right thing.

 

[leashedForLife]

.

I am completely at a loss -
how in heaven’s name could both sire & dam test clear before the mating, IOW neither was even a carrier, yet these many years later, the sire is not merely a carrier of hereditary cataracts, but has been genetically transformed, & is now AFFECTED by hereditary cataracts?!?

Is this a dominant trait in Bostons, meaning only one parent needs to carry one gene, for both that parent AND the approx 50% of their progeny who get that one gene, to be affected?

I thot it was recessive, meaning both parents must carry one gene for cataracts, in order for any pup of their breeding to be affected? —- which is easily avoided: breed carrier to clear, & test those pups b4 any consideration of using any of them as a potential dam or sire.

Are U sure that the sire’s cataracts are the HEREDITARY form?
Cataracts do arise for many other reasons... aging eyes are prone to them, past trauma can predispose a damaged eye, IIRC glaucoma can also damage the lens of the eye.

How could he test clear previously, & now - assuming I read the OP correctly, & also presuming that such genetic cataracts are indeed recessive — he has TWO copies of the heritable-cataracts gene, not one?
Did the lab switch the original DNA sample for a different dog’s tissue?
Did the breeder test the sire’s brother, he tested clear, & they assumed the other male “must be” clear, too?

This doesn’t make sense - so far as I know, it’s impossible for any animal who tested CLEAR for a genetic disorder that is inherited thru simple recessive traits, to later develop that disorder unless that individual is a chimera, & the affected body part is chimeric tissue.
That would be incredibly, unbelievably rare, & such a case would become a famous dissertation in genetics!

Help, anyone??

- terry

.

 

[excuseme]

Optigen, DNA testing for heriditary cataracts.

https://www.optigen.com/opt9_hsf4_inheritedcataracts.html

Have you checked on the Kennel club health testing results to see if the two dogs do actually have clear certificates, or are carriers or affected. Were you actually shown the certificates?

 

[Jane V]

Hi Terry

Thanks for your reply.

All I have to go on is the official entry on the KC website.

I can confirm that both sire and dam and at least 3 generations on the sires side are clear for HC-HSF4.

The only other entry on the sires KC website following the BVA/ KC examination is “affected HC” what is clear os that the sire does not carry the HSF gene for early onset cataracts but has developed late onset mild cataracts at 8.

So what I THINK a this means is that the puppy will not fall victim to early onset. What I don’t understand is what “affected HC” really means.

If you’re confused imagine how I am feeling !

 

[leashedForLife]

QUOTE, "Jane V:

... I have seen a puppy (bred by) a reputable Kennel Club breeder, & both Sire and Dam had the hereditary HC-HSF4 DNA test, & passed.

... the Sire has had 4 additional BVA/KC/ISDA eye examination screenings, the 1st 3 were clear, but the 4th test, aged 8 in Feb of this year, shows he is “HC affected”.

... I am completely confused and not sure what this means -
... should I find another puppy? ...
__________________________________________
.


I, too, am completely confused. Gives us something in common!


As I said above, to the best of my knowledge, it is impossible for the same dog to test genetically CLEAR at 2-YO, & then 6 years later, test as “affected”.
Either the lab switched tissue samples, or the original test was fraudulent.


It sounds more as tho the sire was being physically examined annually for cataracts, & although he tested CLEAR for the hereditary form, way back when, he has begun to develop cataracts at 8-YO. What he is developing are age-related cataracts, I think - not “hereditary”.


After all, U would not test a dog - nor a horse, human, or any other organism - annually for a hereditary issue; U test them ONCE, & it’s done, U have the answer per that specific gene, are they clear, carrier, or affected?
The answer will not change from year to year - their germ plasm would only be altered by a spontaneous mutation, radioactivity, or other bizarre, unlikely events.


If U have a Siberian with blue eyes, & mate that dog to a Sibe with bicolor eyes, U might get bicolor or blue eyes in the resulting litter, & some pups might also be brown-eyed.
If U mated a brown eyed Sibe to another brown eyed Sibe, & both had one blue eyed parent, there would be a 1 in 4 chance of each of their pups being blue eyed, because each of those brown eyed dogs was a carrier for blue eyes, with a gene from a blue eyed parent.

But if U mate 2 brown eyed Sibes, who were born of 4 brown eyed parents, all descended from brown eyed grandparents, there is NO WAY that any pups in that coming litter will be blue eyed.
Blue eyes do not result from age or environmental insult - they are inherited from parents or grandparents, & they are a known simple recessive trait.

Cataracts can be caused by age, trauma, disease, chronic exposure (repeated snow blindness, maybe? - or intense repeat UV exposure in the Southern Hemisphere, due to the damaged ozone layer?), etc.

I think his DNA is fine - I think he’s simply older, & like thinning skin & thinning hair coat, cataracts can arise with age, in any dog.
If I loved the pup, i’d buy her or him, & not worry about senior issues ahead of the need to plan for them (ex., reduce calories for the older dog) or prevent them (ex., avoid joint deterioration by keeping my dog fit, lean, & active).


- terry

.

 

[Jane V]

Hi Terry

I think you have reached the same conclusion that I have.

Both dogs were tested clear for the HSF which is a big tick and therefore it is almost impossible that the puppy will generate early onset cataracts,

Subsequently for some unknown reason the sire developed cataracts which are most probably not hereditary as it was an eye exam and NOT a DNA test. But the HC affected eye exam comment has completely thrown me.

Net net I think it boils down to how much I love the puppy ...and cataracts seems to be a complete lottery.