losthwy- the lyme disease vaccine is one that we dont use ALOT in our clinic, but we do occasionally. we have not had any problems with it, as far as I know. typically, vaccines against bacteria caused diseases are not as efective as those against viruses. (Lyme disease is caused by the bacteria borelia burgdorferi). Furthermore, a vaccine does not prevent infection, it primes the immune system so that when your dog becomes infected, it can fight off disese easier and the symptoms will be diminished or non-existent. That being said, any vaccine, as long as it is safe, is a cheap insurance policy for your dog. if your dog is exposed to a lot of ticks, I would vaccinate him. use something like frontline or advantix collar to prevent tick infestation also. hope this helps.