Originally Posted by TudorRose
8 months is right around when his last set of baby teeth come in so he's teething. The grain he is probably getting it too hard for his gums to handle. You don't say what you're feeding grain wise but you might consider soaking it in some water so it forms a mush. However thinks still in their husks like oats will still be pretty tough so you might to consider switching him onto something different at least temporarily.
Just to make sure you caught this..if you do swich the grain do if slowly, like add a little of the new stuff 4 the first week, then a little more on the 2 week and so on and so on...it's very hard on horses digestives system and is not good......^^^i agree with everting turdor rose said