untrained rural blue heeler

Question
We live way out in the country, and a couple years ago inherited a 5 or 6 year old (we're not sure) blue heeler from a neighbor who passed away. He's never had a bath, been to the vet, worn a collar and leash, or been in a car.  This is of course not good, but my main question is how to introduce a new dog into our home.  I'm disabled and would really love a smaller dog, say,a toy fox terrier, which are supposed to be good service dogs (fetching things for me, etc. would be great), but I'm afraid of a bad situation developing between the two dogs, one of them having to go, maybe, so I need advice on how to introduce a new puppy.  The blue heeler is very smart, learns things quickly and is generally obedient.  

Any help on this would be highly appreciated.  Thank you.

Answer
Hi Zoe;
I would send the Blue Heeler for service dog training. He has natural nurturing built into his blood, and would make an excellant one.
If all you need is for a dog to fetch things for you, etc, he could just be taken through obedience training, then teaching hi to fetch things would be very easy.
Petsmart and Petco have weekend classes in basic obedience.
Do you have someone who could take him and handle him through the classes?
If you got a fox terrier, that would have to be trained too.
I introduce them slowly. It would be better if they could meet and get aquainted before the puppy comes into your home, then short visits from the puppy.
Have you had experience with the dog not accepting other dogs?
If you have nt seen any aggression to other dogs, there may not be any.
You could check with the trainer at those stores, or at Man's Best Friend, and ask what they recommend.
If the puppy is already there, and the dog is not accepting it, and you are not attatched to the Bue Heeler, maybe it would be best to call the animal rescue groups in your area to get them to find an good home for him.
Charlotte