Excessive Thirst in Dogs: Common Causes & When to See the Vet

Diabetes mellitus causes high blood sugar that's either due to insulin deficiency or insulin resistance. Excess sugar in the blood is excreted by the kidneys into the urine and drags water along with it. In this case, excessive urination can cause excessive thirst in dogs. Diabetes mellitus is treated by modifying the dog's meals and administering insulin.

Dogs with kidney problems may not be able to concentrate their urine. They pee more and, in order to avoid dehydration, they have to drink more. Kidney disease is treated by modifying the dog's food and addressing any underlying causes of kidney failure, such as kidney infections or stones.

Cushing's syndrome is caused when the adrenal gland secretes excessive amounts of cortisol, either due to a tumor in the pituitary gland or an adrenal tumor. Excessive cortisol increases thirst, which then increases urination. Depending on the location of the tumor, Cushing's syndrome is treated with medication or surgery.

Any dog who has diarrhea or vomiting loses body fluids. In order to avoid dehydration, dogs who've recently suffered from diarrhea and/or vomiting may drink more than normal.

Pyometra is the medical term for an infected uterus. This condition only occurs in female dogs who have not been spayed. Pyometra is a life-threatening condition and requires prompt surgical treatment, antibiotics and rehydration with intravenous fluid therapy.

If you notice your dog drinking a lot more water than usual, then make an appointment with your vet as soon as possible. It may be helpful if you bring in a urine sample and come prepared to answer your vet's questions, such as what type of food you've been feeding your dog, if there have been any changes in your dog's appetite or habits, any travel history and a record of your dog's vaccination and preventive care history. You may also want to write down any questions you have for your vet so you don't forget anything.

Your vet will conduct a complete physical exam on your dog and will likely recommend several laboratory tests — be sure to follow all recommendations. The most common labs ordered include a complete blood count, a blood serum chemistry, urine specific gravity and a urinalysis. These tests are important to narrow down the possible causes. They will give your vet information on how your dog's liver and kidneys are functioning, if there are any signs of infection such as elevated white blood cells, and can help rule out conditions like diabetes mellitus and Cushing's syndrome. Urine specific gravity tests how concentrated your dog's urine is and can help diagnose kidney disease and dehydration. A urinalysis can determine whether there's sugar or bacteria in the urine, among other things. Depending on the results of these tests, your vet may be able to diagnose the problem, or additional testing may be required.

If your dog is drinking lots of water all of a sudden and urinating more often, do not withhold water from your dog. If you do, you may put your dog at risk for life-threatening dehydration. According to the American Kennel Club, signs of dehydration include seeking water, excessive tiredness, dry or tacky gums, loss of skin elasticity and mucousy saliva. Instead, allow your dog to drink, and call your vet. With the help of your vet, you'll be able to determine whether your dog's drinking habit is indicative of a larger problem or harmless. Hydrate to be great, but if your dog is overdoing it, get your vet involved.