Foxtail in hay

Ok Fellas, educate me on foxtail in hay. Due to a poor second cutting we had to buy some large squares to make sure we had enough to get through winter. After cutting a bale open I find what looks like foxtail throughout the hay. I am not familiar with foxtail as its either not in our fields thankfully or just not an issue in our area. For your horse customers how big of a deal is this stuff. We have 5 horses and I definitely don't need to be vetting 5 horses due to mouth ulcers from hay.

Foxtail in hay