Lucky is a neutered male Border Collie abandoned by some
distant neighbors when they left town five weeks ago. He is
my dog now, and gets along fine with my other six dogs. He
plays with some of them, and with all of the kids who
occasionally come over.

I estimate that Lucky is 20 percent overweight.

Even though we have had mild days here for the last 3 weeks,
Lucky seems to spend 3 to 5 times as much time at the water
buckets as any of my other dogs, and their weights range from
zero percent to 15 percent overweight.

Since Lucky has been with me he has received two (monthly)
doses of Heartguard. He has had no other drugs. His first vet
visit will be this Friday.

Does anyone know what diseases can cause this level of
excessive drinking ?