You never know...they could develop allergies to most anything. But I'd really suspect something else...maybe something in the air. Winston will run and hide when I grab the hairspray can.
Best thing to do, is hold back on the cheerios and see if it gets better. If it does...BINGO...avoid them!!!
__________________ As Ever, Kathy 
Intruducing Bentley  Winston and Spencer: RIP My Sweet Angels |