Lepto is easily contracted by your dog doing so much as walking outside in an urban area... if an infected rat pisses somewhere where rainwater carries it, they can pick it up. Like Parvo, often fatal to smaller dogs.

I'm not sure beyond rabies, parvo, and lepto, any more do any good; depends where you live and what threats you face.

Pretty low rabies threat in most areas, but as others stated, if you ever have a bite incident there are a lot of really cruel laws on books for your best friend if they don't have that vax. At least here, you can get a 3y shot (vs 1Y) which is pretty much the same dose, so you do it LESS often...

Just think rationally... two years ago we may have said "why should I feed my dog this Ivermectin de-wormer, those awful pharma scammers..." and now I'm like "sh*t, probably cures cancer as well as deworms..."