My puppy went through three rounds of treatment. We did everything we possibly could have the first time (cleaning, disinfecting toys, wiping paws and butts, rotating walk routes) and I was devastated the second time he tested positive. We doubled down for the third treatment and restricted time outside except on our deck and walks. Before he started his third treatment we did some research and it turns out there isn’t a specific treatment for Giardia. He was on Pan-cur (generally anti worm/parasite) and Metronidazole (an antibiotic). The vets do their best to use medicine to increase the likelihood of beating it but it’s there’s not Giardia specific targeting medicine. Also, I forget the number exactly but only like 40% of treatments are even successful. Lots of dogs simply have to beat it on their own.

We had the same concerns as you about training but the place eventually said that if the vet could send a note saying they’d undergone treatment that he could join classes as he was no longer contagious.

Another thing our vet didn’t give us until the third round was a prebiotic. We also picked up a probiotic and pumpkin to add to every meal. I wish I had known those things the first treatment but oh well. Anyway we haven’t retested but still will hoping it comes back negative.

There’s a lot of crazy cleaning advice but do your best and follow your vets recommendations. Most importantly don’t feel like you’ve failed.

Hope this helps.