Giardia cysts are present in some water sources in Maine and New Hampshire as well as many other statesand if ingested can lead to an infection of Giardiasis. Once ingested the protozoan makes their way into the intestine and can cause episodes of diarrhea in both humans and dogs. Infections can last 2-6 weeks and will preset different symptoms on an individual basis. Treat all water before you drink it. Keep an eye on dogs after they drink from streams, pools and other mountain water sources. You can pack in all of your drinking water for yourself and your dog, but it is very difficult to prevent them from helping themselves when water is available. If you suspect Giardiasis in your visit your veterinarian there are treatment options available.