I am so sorry to hear that your dog has lyme disease
Here are some links with infor about causes, treatment, and prevention:

Canine Lyme Disease
Lyme Disease in Dogs



Also, don't hesitate to ask your vet all the questions you need to better understand the prognosis, treatment, and prevention. I use Advantage KillTix topical treatment to keep ticks off my dog and also have my vet give him a Lyme Disease vaccine.

Best of luck to you and your pooch. He will be on my mind.