A friend of my co-worker's cat die from heart attack while it was traced by a dog brought into her house by a friend! You got to make sure the dog you bring in doesn't trace your cat, also some cats don't like other animals or kids around,each cat has it's own character!
To pet a cat is totally different from to pet a dog. A cat and a dog to pet together from their very young age works a lot better/easier. But every cat/dog works differently with other cat/dog and there is no rule to trace ga bor, only if you put them together and test it out (with certain risk). Not just adopt a new member only because of feeling mercy, it might not be the best for the cat/dog.
Do more research and get yourself well prepared first, and see if you can put them together for some time see if they can really get along without any problem before you decide to adopt the cat in a long run la.