eating and behavior problems

Question
Sorry, this may be long. Have 1 1/2 male wheaten terrier (had since 8 weeks) who from beginning was very picky eater because of me, i know. first time he didn't eat food, I put stuff in it to make appealing, which was worst thing I could do. He is currently on prescription diet from vet for skin allergies (venison and potato), but previously have changed his food many times, gradually, trying differnt ones to see if he would like one and also tried the leaving down for 15 mins and picking up rule, with no treats at all, and went about 3 days without hardly eating, maybe 1/2 cup in all. Then I gave in and added stuff again, and he gobbled it up and then after 2 days got tired of that and now not eating again. So need help with what to do about that problem. And other problem is he's aggressive toward other dogs at the park when he's got a toy or even if they come up to him to sniff him and he doesn't want to be bothered. He doesn't bite, but does that vicious warning growl toward them and not really sure what the right thing to do is when this happens.  
If you have any advice on both of these problems, I would really appreciate it.
thank you very much

Answer
Hi Donna,

If you had a child who wanted nothing to eat but candy bars for every meal, would you allow it? Adopting a "tough love" attitude for your dog is no different. He is totally dependent on you to provide healthful food, and giving into to his  child-like whims isn't helping him.

You should return to the regimen of setting down his food for 15 minutes, etc. and stick to it. It's nothing short than a battle of wills, since you've trained your dog to be this way.  If you stick to your guns, your dog WILL eat the food you provide.

Don't stand around during your dog's mealtime and try to coax him into eating. Set down the food, leave the room, and return in 15 minutes, with no cajoling or commentary on your part. Next mealtime it's the same deal.

If your dog is aggressive in the park, he should either be on his leash at all times, or he should be wearing a wire basket style muzzle. This style of muzzle is a very humane, a dog is able to drink water while it's being worn.

It's natural dogs not to want other dogs near their toys. Your dog is displaying dominate behavior by protecting what is his, rather than giving up the toy (dogs rarely share!). Enrolling in an obedience class can help, as your dog will learn that he really isn't "top dog", you are! Classes are run by experienced people who can observe your dog if he gets aggressive with other dogs in the class, and show you how to train your dog out of it. Learning from a live person is much more effective than reading about how to do it.

Best of luck,

Patti