I am no vet but living in the tropics has taught me many things. There are different strains of this but it can be transmitted from dog to human via the sand fly if I am not mistaken. Take a look on the internet, Wikipedia for example. Why would you risk your life and that of your community for a dog?
I personally don't like to see dogs elevated to the current positions they hold in some homes. They are almost treated as children.
I have had dogs as pets as well but why spend the money treating an ill animal.
I am sorry your dog is becoming ill, but I feel that all too often a vet doesn't always do what is best for you and your pet but what is best for his pocket.
As I said, I am in the tropics where diseases can spread quickly. I am sure you understand what I am saying with regards to your dog.