Trouble is Garbo antiseptic wipes etc, the germs they kill they are none lethal to our dogs anyway....waste of time.....most germs/bacteria do us and our furry friends no harm we've built up a tolerance, makes me laugh when I sometimes see adverts that say kills 99% of germs, it's the 1% it doesn't kill that is dangerous

unless you have a weak immune system, which for many reasons can be so, but on the whole our dogs are safe, unless something like parvo is present.
Still nothing wrong in washing your dogs feet in warm water on return if you are worried, our vets scrub down their tables after each patient, and generally only unnocculated puppies are at risk if put on the floor, but even then it is a low risk, the worst you'll find I guess could be some pee on the floor etc, but no worse than walking in grass, infact if we could see all the germs and bacteria on grass and pavements we'd probably never wish to go out, most sick dogs at the vet don't have anything catching by walking where they have been and then licking feet.
By all means, nothing wrong in what you are doing, you're just being protective, your dogs won't mind

just........ it's probably a waste of time your worrying about it. x