You are incorrect about lepto. It is carried by deer, raccoons, rabbits, cattle, foxes. If your dogs run in the field, drink out of streams or ponds. they are susceptible to Lepto.
MWK
It is mostly transmitted by rodents' urine when they feed on the animals food.
Both are correct. I've read about the city dwellers having issues and certainly, the wildlife carries it. Stagnant ponds are a big risk in W. WA esp. I've been told by my W. WA friends that "Lepto is our (C.Wa) parvo". It's not that they have a lot of rats but they do have a LOT of raccoons, etc. carrying it. I do as MWK does and vaccinate in the early spring annually since my dogs are in the water, and esp the younger ones, are running hunt tests, etc in W. WA where it's prevalent.