HGG Community Forums

According to the chart : SB1 with W1 is a moderate risk of Lethal White. I think the "excessive" White on the mares lower strand, coupled with the "Light", may have also help trigger it.

I mean, no W1 combo is “safe” so it’s a possibility it’s just that

It could be that the foal inherited both splash genes, an extensive white factor, and also possibly W20, which made the total white expression way too high to produce a viable foal. White factor does increase the lethality of crosses, and W20 boosts white expression. I think breeding W1 with splash also increases the risk of lethality. Similar to W1 with Sabino genes.

W1 doesn't have any "safe" combinations. https://www.huntandjump.com/faq.php#870

It's important to remember that low risk is not equal to no risk. I also breed splashes and sabino (on HJ2) and I periodically lose one to white factor overload. Not often - maybe one every other season, or even less, which means I'm breeding hundreds of low risk foals.

It never happening before reflects the low likelihood. It will probably be another long period before you lose another.