As said previous it is totally up to you and depending on your situation. But here are the complete facts of Lepto and how they can get it.
It is considered a pretty serious disease because it is one of the few that can be tranmitted to us. (humans). It is a bacterial infection that attacks the kidneys and can leave permanent damage...... Signs of lepto can range from mild to severe and include: depression, weakness, abdominal pain, sudden unset of ulcers on the tongue or in the mouth, jaundice in the whites of the eyes, diarrhea often bloody and vomitting. It is slow to recover and can cause death as soon as 5-10 days after signs are noticed, if they make it through there can be damage to the liver and kidneys.
How do dogs get it?
Lepto is passed through contaminated urine. Animals that can carry Lepto are raccoons, rats, mice, pigs, sheeps, goats, deer and cattle. Once the animal who is infected urinates.....it can enter into puddles, ponds or other water sources. Dogs generally pick it up by swimming in contaminated water, walking through it, drinking it or eating grass that has been urnited on.
However with all that said, lepto is a fairly rare diease and if your dog is mainly an inside pet chances are that they won't come in contact with it.....The exception would be dogs that while outside go swimming in ponds or rivers, that are out in wooded areas or that you live in areas with more wildlife.
This is a vaccination that some dogs will have reactions to, some say that the reaction is to the bacteria itself while others say that it is to the agent added it the bacteria. Either way, your vet can add medication to the vaccine ahead of time to reduce or prevent a reaction if your dog is prone to reactions to vaccinations and you prefer to have the vaccination given. The best thing to do is look at your individual situation and then talk to your vet to find out the number of cases they have seen in your area.