I can't think why they'd be nervous but maybe the weather was making them so. We've sprayed all the tails with a mixture of baby oil, cayenne pepper and black pepper because the bitter apple didn't work but I was just out a little while ago and my mare's tail is shorter than it was.
The foal we had that did it, ate his mothers whole tail in 1 night. That's what bothered me, all that at one time.
We had just brought the mare and foal home, just bought the foal actually. The guy was nice enough to let us take the mare till the foal calmed down. We had them in a stall, and he wasn't use to that. We figured that was why he did it.
He never showed any sign that eating it bothered him. I checked his poop for a few days, nver saw any sign of it.
The funny thing is, the mare's tail looked like it had been precision cut with a pair of sissors, straight across right at tail bone level.
Becky