HGG Community Forums

1st question: frame has gotten a complete overhaul for image generation to make it much more realistic in the last month or so. Foals and older horses whose images were generated under the old version of frame may look slightly or extremely different if you refresh their images now. Higher white factor and more patterned genes will result in a horse that is much more white now.

2nd question: basically horses aren’t supposed to have any white markings on them. The more white they have, the more broken genes are somewhere in their personal set of chromosomes. And of course, most gene breakages have effects beyond just color or appearance. For instance, homozygous Frame horses in real life are born with incomplete digestive tracts—I think I remember that their intestines don’t link up with the rectum, so they eat but they can’t poop. Obviously, that’s a problem. It’s more complicated than just two blind pouches because that could potentially be surgically fixed...but I think that is one of the more obvious problems if you know what to look for.

Another relatively obvious issue you might see in real life is horses (and dogs) with a ton of white on their heads and blue eyes often have hearing issues up to the point of complete deafness. There are some good papers out there that talk about why these animals are deaf (something about pigmentation affecting the little “hairs” in your ears that pick up vibration and relay that to your brain so you “hear”).

Basically, on horses the more white markings they have, the more “broken” they are. Appy seems to be the exception to this and you can put Appy with lots of extensive white genes without a problem (in game...not sure how true this is in real life as my experience with fancy colors in real life is minimal), but splash, frame and the Kit White genes all seem to be associated with health issues if the white is too extensive.

What Cheers said. Visual white is representative of "broken" genes. It is not limited to horses. Dogs, cats, even people have health issues. Mutations on PAX3 and MITF, which is where splash occurs in horses, can cause Waardenburg syndrome in people. Symptoms include exceedingly light eyes or heterchromia, white patches in skin or hair and various levels of deafness, among other things. Mutations on EDNRB, where frame occurs, is responsible for Hirschsprung disease in people. Similar to horses, people affected with have nerves missing from their intestines, as well as other problems with the colon/intestines. Luckily in people it can be surgically corrected.

In both real life and the game, horses that carry frame can be completely solid. It often needs a "boost" from other white patterns. The latest update brought frame more in line to real life. Your pretty boy has splash, W, and frame, and a large white factor so he now has a lot of white :)

@ShelteredShadows the horse you posted was born before the update. The update to frame was rolled out on October 21st. That horse was born October 17th. So it would have been born with the old frame and then when he aged up, the frame updated.

My 2 cents for the second question:
In addition to everything Cheers and RipshinCreekFarm said, from my (somewhat rusty) knowledge of genetics both pigment cells and nerve cells are released during development from the same place, called the neural crest (I've forgotten what exactly the neural crest is but I'm pretty sure it's near the back of the head). They are also released at about the same time - I think the nerve cells are first though. These cells sort of "flow" from the neural crest down the back and sides to the rest of the animal.

Splash markings are a good way to visualize this.

White markings genes don't actually add white, they stop color from existing in the first place. In other words, a horse with markings is more like a horse that's had painter's tape applied before the color, as opposed to one with white painted on after.

Anyway, white markings are caused by genes that stop cells as they spread out from the neural crest (think splash markings again). The more white you see, the more cells have been stopped.

But because nerve cells are released from the same place and only slightly earlier, they can get stopped along with the pigment cells. Obviously it doesn't completely stop nerve cells - if you poke a tobiano's spots it'll still feel it - but in my understanding this is the gist of it.

There is also the fact that if there is less color in an eye then there is less pigment to absorb light. Without pigment to absorb it light spends more time bouncing around in the eye causing damage. But I believe most problems are caused by the cell dispersal issues.

I'm sure others on here can be more specific than I can, please feel free to correct me!