A new dog

Question
I adopted a dog today from a small animal shelter that will only neuter him, no shots. I have a12 year old dog already that is in perfect health, and I would like to keep it that way. I was wondering, in your experience, is it a good idea to get a parvo test or any other tests for the new dog before bringing him home to my older dog? The new dog is an adult, but was previously a stray, so I don't know what he was exposed to. He has no symptoms of parvo, but I know sometimes symptoms can show up after the dog becomes contagious, and I would hate to get my older dog sick. My older dog is up to date with the required vaccines for dogs in Louisville, Kentucky, which I believe include distemper and rabies vaccines. I have not brought the new dog home yet, he will stay in the shelter until he gets neutered on Friday, and I was thinking about asking the vet to do any needed tests while he is in for his neuter, but I know they will be biased, so I wanted a second opinion of what is really a good idea to do, as I am not made of money! Thank you! Also, I know you may not be able to answer everything, I just want to know a much as I can!

Answer
Parvo tests are generally run on a dog that is sick to determine if what they have is parvo. If he is an adult, chances are he is already immune to parvo, or has been exposed and kicked the disease.  

However, it takes 7-10 days for the virus to show up full blown once a dog is exposed. That is the incubation period and they are contagious for a long time after they get well because the virus can shed and it lasts in the environment for over 6 months. It is a very hardy virus but diluted bleach will kill it.

Can you get them to vaccinate him for you if you buy the vaccination from a vet? That would give him a few days to build up some protection from the virus as well.

If your dog is current on his parvo vaccinations then he will be protected pretty well from the virus. Older dogs and certain breeds are more likely to get sick, but if the new dog appears healthy right now chances are pretty good he is okay.

Getting a new dog is always a risk, but it appears lower with an older dog (the new one) as opposed to a new puppy under 16 weeks old.

Get him vaccinated and early and then everyone should be fine. That is just a guess but it's all you can hope for, right?