I'd just use it through the worst of the season then. Long term isn't good for the immune system even at low levels - but oddly the dose for the antibiotic treatment is quite high, like half of the pieces in a large garlic each day for a large dog. I've seen it work wonders as an antibiotic when used that way and there used to be scientific articles on the subject online which sadly have disappeared years ago. One of which even discussed a study which found it could be used with traditional antibiotics. I'm not sure why all positive mention of garlic and dogs seem to have gone away :( . Like anything else there are benefits and drawbacks, but I've never had a problem with its use.

!PIZZA !ALIVE !LOL