Q. We have a 4-year-old German Shepherd who has started drinking water in excess lately. He will drink and drink, then drink more. Sometimes he drinks so fast that he throws up. Should we be worried?
A. Excessive water intake is always a cause for concern in dogs. The big question is: Is your dog sick, or is this a behavioral issue? Some dogs just start drinking water because they enjoy it, which can lead to a kidney condition known as medullary washout, which causes them to keep drinking lots of water. Over time, their water intake will normalize.
The main causes of increased water intake that are tied to underlying disease are diabetes, kidney failure, and Cushing’s disease. It is relatively easy to rule out each of these with some simple blood and urine tests.
Diabetes is the easiest to diagnose: A urine test strip will show high levels of glucose in the urine. When diabetes was first discovered in humans, medical students would taste urine to see if it had a sweet taste. A very basic test, but not currently recommended. Diabetes is also accompanied by weight loss, and high glucose levels in the bloodstream. The glucose tends to pull additional water into the bloodstream, and out through the kidneys, leading to increased water intake to replace losses.
Renal failure occurs when the kidneys lose their water concentrating ability, and excess water is lost through the urine, leading to increased water intake. Often, there is exposure to some kind of toxin (such as antifreeze) which leads to the kidney damage. Sometimes it occurs for no apparent reason, but usually in older dogs.
Cushing’s disease is a hormonal disease that occurs when the adrenal gland produces too much cortisol. This, in turn, leads to excessive loss of water into the urine and increased water intake.
You should arrange to get a physical exam and at least a few basic screening tests for your German Shepherd to rule out medical causes. Hopefully, he is just enjoying drinking water.