Have your dogs been vaccinated for rabies? If not, then yes, they could and I would take the dead possum to your vet to be tested. If yes, I would still call the vet because I don't know if they would need any type of booster shot or if the vaccine is good enough.
What time of day did they kill the possum? If it was during the day no matter what put the carcass in a bag and take it and the dogs in. If it was killed at night I would see if you do need a booster or like above if the vaccine is good enough.