I get a bail of hay delivered to my house as and when needed for my buns and guineapigs, but the bail of hay that i had delivered the other day has lots of thistles in it. I have pricked my finger almost every time I have gone to give my furbies fresh hay, I have taken the spikey bits out when i have found them and threw them away. Are the thistles ok for the bunnies and guineapigs ? will they harm them at all ?