Hi Sprinkler,
So sorry to hear this about your dog. There are many reasons your dog could have what sounds like lesions. One reason could be an allergy to something in the soil. Another could be some type of parasite or mite. Mange even comes to mind if his hair is falling out. You can read this site and do a search as well. Have you taken him to the vet? If not, I would suggest that you take him to a vet as soon as possible. If this has been going on for a year, your dog could become quite ill over time and is definately suffering.
http://www.peteducation.com/article....&articleid=137
Please let me know how he is doing. If you are unable to take him to the vet, please let me know and I'll see if I can get some help for you.
Regards,
Newt
When weeding, the best way to make sure you are removing a weed and not a valuable plant is to pull on it. If it comes out of the ground easily, it is a valuable plant.