My dogs get the lepto, I have two small dogs, one being only 4 pounds and they all have been fine. No reaction. I have lepto in my area, I live on farm land out in the middle of no where where wild animals frequent my area often, rabbits run my property like its thier own personal play ground. I know that the shot only covers a few of the many variety's of the virus but if I can stop my dogs from getting sick from just one of the virus's then Im going too. Its like the annual flu shot that goes around for humans.. some are against it, some are for it.. I am choosing to do what I feel is right for my pets and family. Only you can make that choice..
.. do all the reasearch you can, call different vets to see what they say and go from there.