Dave,
One of my passions in my younger years was running hounds. English redticks was our preferred breed and typically it was a 3 or 4 night a week habit. Probably a 1/4 of that time was in lower northern Michigan and I can't ever remember the dogs getting sick much.

We also competition hunted (My dog was Grand Night Champion and one of the best friends I've ever had)..........I can never remember anybody talking about giardia nor was there ever any precautions taken. Not saying it can't happen.........

What I did have problems with was porcupines. Now that was a big mess. The quills are very hard to get out.......infections are usually standard procedure. Very tough situation. The worst thing was Duffy hated them with such a passion he couldn't resist killing one if he came across them.....fortunately it only happened a few times but It stopped me from going into porky country much...... 

Not sure what kind of dog you have and if he/she would take hold of one but it is something to think about. On the other hand I can't ever remember seeing any porkys out and about much in Canoe country but they gotta be there.