Our 5 month old puppy has had giardia for the past two weeks. Really awful smelly runs, small bit of vomiting but very lethargic and off his food for most of the holidays. Not able to walk much as too weak and the smell from poo stuck to his fur, then brought into the house has been dreadful.
Anyway it was treated by 3 day course of anti-biotic after a stool sample confirmed what it was. A newly qualified vet treated him. Two days after finishing meds he is back with smelly runs again and I've just spoken to another vet who said it often takes a week of the antibiotics to treat in puppies. Their immune systems are not up to fighting it themselves and the 3 day course is rarely enough to work in puppies.
I thought I'd mention incase any other puppies get it - worth asking for a longer course than might be offered. The second vet said it was through her many years of experience seeing this in puppies that if she's treating it she goes straight for a full week. The first vet we saw was lovely but newly qualified so going by the book.