what causes dogs to be so thirsty
Quick Answer. Dogs can exhibit signs of excessive water drinking for a variety of reasons, including life-threatening dehydration, illness, side effects to medication, diet and physical activity, according to WebMD. If a dog is dehydrated, it may also have a dry tongue and gums, be lethargic and exhibit thick ropelike saliva. Illnesses such as liver disease, diabetes, Cushing's disease, diarrhea, fever and infection can also cause dehydration.