Rabies can spread through contact between a wound and the saliva of a rabid dog especially if the wound has been licked. Considering the low level of contact was between a partially healed wound and the abdomen of the dog it is very unlikely to be a source of transmission (rabies is a sensitive virus which doesn't survive for long in the environment). The fact that the dog has been under observation in the past makes it more positive .
Next Steps
Get the dog vaccinated to avoid risk of exposure to rabies while in contact with him in the future,for the good of society and also for your peace of mind.