You might want to check out a rescue group. Rescue groups have dedicated foster parents for the dogs.

You can ask the fosters about the nature of the dog and if the rescue group is reputable, the fosters will give you an honest assessment of the dog.

It is also in their best interest to tell you honestly and to best of their ability to say what the dog is really like. They want to match the dog to a right family so the dog isn't returned.

As suggested, figure out what are you looking for in his/her personality? Once you figure that out, and know what kind of dog you want, check with rescue groups. They should help you match the right dog for you. You do have the last say in which dog you get.

yes we used to foster dogs too and not just cats.

One more thing, since you have senior cats, you do need to check to see if the dog has lived with a cat. or is okay with a cat. Jack Russel are too hyper for a cat so not recommended. Goldens we have fostered have never given any grief to our cats. We are biased obviously toward golden retrievers.

Wish you lots of patience in finding a right dog. It is worth to be patient to find the perfect one. And you will find him.

best wishes,