Trixter ate his psyllium

This morning, we withheld Trixter's food until he ate his psyllium.  It took about 4 hours before he ate it.  After he finished it, he got his food.  He is like a little child that doesn't like his peas.
     We had called the vets yesterday, twice looking for ideas on how to get him to eat his psyllium.  He throws his food onto the dirt before he will eat it and we think he has been eating sand and dirt along with it.