new dog in home

Question
I have acquired an old english sheepdog that i thought would be perfect for us (we are middle aged with heart disease and needed a walking companion as well as a companion for our older (8 year old yorkie/mix) dog.  The dogs are simply not getting along...only when they walk outside together on a leash.  I have read countless books and tried the approaches suggested.  We are in our third day of training....so very new.

The oes dog came from humane society and presented as very congenial and friendly, though he did bite at my jacket when excited.  He vomits his water.  Took him to the vet, he checked out okay, vet suggested getting bigger bowl and placing it at a 24" height from ground.  Still vomits.  Tried adding half ice/water mixture.  Still vomits, not as much.
Should I try to return him to the society or give him a longer time to adjust.  I know it is only three days, but my terrier is 28 pounds and he is 80 pounds.  My terrier is getting more afraid of him each day and he seems to be becoming more aggressive and un predictable.  My husband and I have been home full time (took leaves from work) so that we can properly pay attention to the animals, etc.
No small children in house (ours are older and away at college).  We have a crate and all the right supplies...I am just wondering if perhaps this dog was a serious behavior problem but just presented well due to fear and the newness of it all.  Now that he is in a good home, perhaps he is showing his true colors or he just can't get a long with a terrier.  The only thing the terrier does is growl if he challenges her food.   Any advice you can give would be great.  Thank you very much.

Answer
Sounds like you have a pretty volatile situation. Unless you are willing to put in lots of time and work to retrain this dog, I would suggest trying a different breed. OES's can have lots of behavioral issues and must have tons of exercise as well as stringent obedience training. The fact that his behavior is getting worse leads me to believe that he could harm your smaller dog. Terriers will only tolerate so much abuse and then they will respond in kind. Try getting a more even tempered breed such as a beagle, basset hound, standard poodle, golden retriever, etc. There are many needy dogs out there who would probably work out beautifully for you. Also be sure that any rescue that you c hoose has been thoroughly evaluated. Unfortunately humane society's are not usually great at that, but breed rescues normally do a wonderful job. Humane society's are a necessary thing in our society but are understaffed, underpayed and overcrowded. It's wonderful that you're making the effort to help a homeless dog, but perhaps finding one that will fit in more easily to your home is the best plan
Diane