2 dogs, same symptons

Question
2 dogs, both exhibiting loss of appetite, increased water intake, 'accidents' in the house.  #1:  13yo, 45 lbs, Sheltie/Shep mix.  #2: 7yo, 58lbs, Bl lab/something mix.  #2 is on amoxi. since Saturday (she exhibited signs first).  One now has blood in stool (not sure whom).
Have tried switching to lamb and rice blend, sprinkling with rice and a little chicken.  Have read enough tonight to be scared out of my gord, but again, 2 dogs exhibiting the symptons.  Can you help?

Answer
You need to have blood work done on both dogs.  The blood in the stool could be due to an intestinal parasite such as Giardia or Coccidia.  You should feed strictly a bland diet of chicken and rice with plain yogurt--no regular dog food.  The loss of appetite and increased water intake could be a sign of kidney/liver disease or something like leptospirosis, which only blood work will reveal.  Diabetes can also cause increased thist, but that is not contagious.