my chihuahas behaviors

Question
Ok. We'v had our chihuaha for about a year now and we got him when he was still a puppy. One of my concerns is training. We've worked on only 3 commands. Come, Lay down and sit. Problem is no matter how much we say it the same he doesnt always respond and often after saying the command he'll look away or just stare the one thing we got down was were to potty at but we cant leave him out when we are not home because then he'll go in the house. When we take him to the park, he follows anyone that passes and when we call him he keeps running(because we cant get him to walk on a leash either). This is really difficult for us. We know he can, because he has before but we don't know what more to do.  Also he doesn't bark hardly ever(which is ok) and Im concerned about the amount that he poops and wanting to know should i be and if so what do you suggest we do about it all. He's a very friendly dog we would just like for him to be consistent. Please Help!!!!

Answer
Hello. Leash your chihuahua at all times you would be suprised how quite a tiny dog gets hiden by passers by behind legs and whatnot also larger dog may think its a rat and kill it...no pun intended but some dogs hate small moving critters. Put his harrness on for walks not a collar and attach the leash let him walk around your home and yard supervised with this attached he will bite/paw at it but thats ok, he will get used to it(I dont reccomend leaving a harrness on like you would a collar)  pick up the leash and let him come to the end of it he will pull to try get away this is normal just call him to you and walk him around the yard not the other way around. After a f ew attemsp and a few dyas he should accept this fairly well. I cna not help with commands i can offer insight on how to train the dog via things I've read but my own dogs are not well command trained.