You're on your own with this as far as I know. I never, ever allow my girls to swim until milk is drying up after the litter is 6 weeks. I know they want to swim but with light chemicals or salt pools or a pond with bacterias, it's a big chance.
Several repro vets have highly recommended against it. I listen and I use common sense along with my club friends.
As someone mentioned the cervix is still open also.
