New Genetic Info for Appy enthusiasts

[zacharyfarms]

Today there was a press release by the Appaloosa Project concerning a study that was done

2005-2006 on appaloosa horses with night blindness and published in the "Veterinary Ophthalmology" . You can go to the link below and click on

CSNB Night Blindness on the side navigation bar. " CSNB stands for “congenital stationary night blindness”. More commonly referred to as night blindness, CSNB is the name given to any disease that is typified by:

a) impaired/absent night vision

b) present at birth

c) inherited

d) non-progressive "

It appears from the study that all appaloosa horses that are homozygous for the Lp gene (fewspots, near fewspots, snowcaps of all levels and homozygous for characteristics only) are night blind. These horses are night blind from birth and can only see when light becomes at a level where you can read a book. Very intersting study..especially to me who owns a snowcap stallion. And the link gives you care information as well. Now I need to put up my dusk to dawn lights in my stallion's paddock. Appaloosa Project

 

[Debby - LB]

Wow Judy thank you, I'm going to read.

 

[speckles]

Thanks heaps Judy. I have a large appy mare, approx. 14.3hh, who does suffer from nightblindness. I have been aware of the study and have been awaiting the results. I am not sure exactly what colour she is officially now. Have just done her adult registration here in New Zealand. Her colour has changed since I got her 18 months ago. She is now three years of age. I am breeding from her this season to an appy stallion, and can't wait to see the results!

Going to go and look at the project results now.

Once again, Many thanks.

Sandra

 

[Tony]

Thanks so much for the information.

 

[HGFarm]

I find that interesting since I have had snowcaps and a few spot, and known others- and they dont have any trouble getting around in the dark!!

Will have to read that when I get time this weekend.

THANKS for posting that!!! Always love to hear new info!!!

 

[Lisa-Ruff N Tuff Minis]

Interesting... I have a few spot who circles all night long in a small stall, large pen makes no differene all night long a tiny little circle made her lame actually not to mention a hard keeper. But during the day never - not one circle... maybe this explains it a bit

 

[zacharyfarms]

Interesting... I have a few spot who circles all night long in a small stall, large pen makes no differene all night long a tiny little circle made her lame actually not to mention a hard keeper. But during the day never - not one circle... maybe this explains it a bit

Hi Lisa, this sounds like a classic reaction to the night blindness. What is interesting to read is about the breeding of a CSNB afflicted broodmare. The foals tend to realize the mares can't see them at night and play games with them..

hiding etc. The homozygous for Lp fewspots, snowcaps etc. are born like this so never no any difference than total darkness at night, they never dark adapt like we or other normal sighted animals do. I never had any idea that Tex was night blind until the study began and still he has adapted so well. He does live with another stallion and does seem much much happier when they are together. He never starts any quarrels with any of the other stallions. I think he knows he needs their protection at night.

 

[rabbitsfizz]

I have been aware of this problem, without proof, for some time but I have also noticed that there is no "blind/ not blind" answer to the problem, either.

The animals affected are affected to different degrees- also their ability to cope with the problem obviously affects whether it is noticed of not.

We had a few spot colt that had real problems, blind as a bat in weak light and night time, so could not be kept outside, and then again a snowcap stallion who managed and still manages just fine, even though he can obviously see little at night- he is fine in weak light, and OK at night in familiar surroundings- as said I think the degree of "blindness" caused varies hugely.

 

[zacharyfarms]

This is what they found in the study..this is quoted from the FAQ's of the study

"7.Do all Appaloosas diagnosed with CSNB have the same degree of vision at night?

As far as we can tell through our ERG studies, all horses affected with CSNB have similar impairment of night vision. Our ERG recordings in affected horses tested were nearly identical.

Normal night vision vs CSNB affected

8. At what level of lighting do horses diagnosed with CSNB experience a change in vision?

As soon as light levels drop below what you can comfortably read a book by. The change for the horse is dramatic. Below this level, a darkened room that still has enough light for you to see in and avoid all objects easily is totally black to an Appaloosa with CSNB. Likewise, outside on a moonlit night, where you can see trees, rocks and ground texture, an Appaloosa with CSNB sees nothing. The world is completely black, unless it looks straight at the moon or some other light source that is bright enough to appear as a light spot in its field of vision.

I think that the level of coping with the affliction varies with the appaloosa with CSNB is what you see to make you think their are different levels of blindness. Degrees of night blindness in other animals including man does vary, however.