Why is my dogs hair patchy?

Well it could be so many different things. Ringworm could still be possible sometimes it is not seen with the naked eye, the vet will use an ultraviolet light to see if it is ringworm. It could also be diet issues. Pruina is a good food that has also been reccomended by my vet. Fleas also will cause scabbing and hairloss. Just keep a close eye on it. If it continues to get worse and is losing hair fast, call the vet as soon as possible, most places will work with you if you have good standing. I hope this helps.