What should we do? We were going to bring her home tomorrow but now we don’t know if it is safe.
Any time a new animal is introduced to a house there is the risk of disease transmission. I recommend that you quarantine the new puppy for several days (preferably two weeks) before you introduce her to your current pets.
However, I also recommend that you not lose much sleep over this matter. The diseases that a healthy unvaccinated puppy can spread to vaccinated adults are not likely to be serious.
If your dog is fully vaccinated then he or she should not be at risk of contracting life-threatening diseases such as parvovirus or distemper. However, minor respiratory infections, fleas, ringworm, and intestinal worms all may be spread to the adult.
The situation for the cats is even better. Most diseases are species-specific. This means that most dog diseases don’t spread to cats, and vice-versa. There are a few exceptions (ringworm and flea infestation come to mind), but it is very unlikely that your cats will come to serious harm when the new puppy is introduced.
Although most canine respiratory infections aren’t contagious to cats, remember that a new puppy in the house will stress the feline family members. Stress can predispose them to opportunistic problems, including species-specific feline respiratory infections. Quarantining the puppy and introducing her slowly will reduce the stress of the process.
The individual I worry about most in your house is the new puppy. Your pets aren’t likely to spread disease to her, but she is at serious risk of parvovirus and distemper (which can be spread by animals outside the house) since she’s not vaccinated. She also probably has worms. I recommend that you get her to the vet for shots, deworming, heartworm prevention, and flea preventatives as soon as possible.