Newly adopted 4 year old Shih Tzu

Question
About a month ago I paid a re-homing fee and took home a 4 year old Shih Tzu from a family that allowed it to run loose on 5 acres of mud and swore he hated toys which I have found to be untrue.  They also gave me about 2 cups of a dry dog food called Nutro Max Mini Chunks which they said he loved.  I went out and bought another bag, but have discovered the dog hates it unless I mix in canned dog food with it.  I used to own a black lab/wolf mix (18 years til he passed on) and I never gave him canned food as I was told it wasn't good for the dogs teeth.  I don't want to ruin Lucky's (his name) teeth by continuing to mix the wet and dry, but was told if I switch him to another dry dog food, not only could it give him the runs, but that because he is 4 years old, he might not eat it either especially if the families who owned him before me fed him table scraps and canned food.  What should I do?  Any ideas?
I've noticed that he also likes to try and chase cars (even with the leash on), so any ideas there would be helpful also.  Thanks for your time and God Bless.

Answer
Well, it is hard to teach an Older dog new tricks... The chase cars thing will take some time to break.  He has been given free roam of 5 acres and it will be hard to train him  on a Leash.  
It can be done.... go to the Library and get a few books on Leash training.
You can also go to Amazon.com and see what they have for dog training tips.
We have some behavior experts here that may be able to help you two.

Ok, about the food situation.  How about you mix the Nutro Max with some Wellness Dog food canned/ or Innova Evo canned food.
A few tablespoons of Wet dog food each feeding is not a problem for his teeth.  It is fine and he will enjoy the brands I mentioned.

Sorry about the loss of your 18 yrs old canine pal.....


Good luck with this new kid!

Marie Peppers LPN MA