Hi John,
I don't know if you've read any of my previous posts,and I am certainly no expert on the subject,but my eastern boxie is a worm junkie!I was a little concerned,as well as you,about feeding too many,but in the wild if they found an abundance of worms,I don't see them stoping at just one!The funniest thing I have ever seen is watching his head whoop around when he sees
that movement out of the corner of his eye,and the chase is on!
Talk about fast,I bet he could out run my dog if he wanted to!
Another thing I try(as gross as it is)is mixing up his food for the day,cutting the worm into segments(the sections squirm around for a while)and putting them in with his food.He will unknowingly eat the nutritious things he is picky about while eating the worm!Also I have a liquid vitamin supplement I got from my vet that is high in vitamin A (for about eight bucks) that I either drop in his mouth,or put in a chunk of bannana to make sure he is getting everything he needs.
Hope this helps!
Angie