Thanks to you Margaret, Jane and others who replied to my question. At least now I know what it is and what to avoid. Penny >>> margaret lauterbach <mlaute@micron.net> 01/14 11:37 AM >>> At 07:33 AM 1/14/99 -0400, you wrote: >Hi Rosemary - Sorry to hear about your dogs. I have no idea how to prevent it, but would like to know what giardia is/does to animals/people? > >Penny in fridgid Nova Scotia - -20C and with the windchill its -40C - coldest yet this winter It causes violent diarrhea and vomiting, Penny. Some become dangerously dehydrated from the loss of liquids. People are advised not to drink out of any river or stream. When I was a child, a thousand years ago, I was always told it was safe to drink out of a free-flowing mountain stream. Not any more. Margaret L