My Dog is Always Thirsty

Maintaining hydration is an important aspect of your dog's instinct to survive and stay healthy. Since water accounts for more than 60 percent of a dog's body weight, and because breathing, salivating, defecating, and urinating are all responsible for significant losses of water from a dog's body, it stands to reason that dogs need to take in a good amount of fluid each day from what they eat and drink. This is accomplished by a number of intricate feedback mechanisms that directly control a dog's urinary output and thirst center. Most average-sized dogs (around twenty-five pounds) will consume at least sixteen ounces of fluid in a day, either directly or as part of their food. Warmer weather and increased exercise, however, will put greater demands on them and require greater fluid intake.

A little extra drinking and peeing is usually not much to be concerned about. If you are noticing steep increases in these two important functions, however, it is probably worth paying closer attention.

What to Look For

Start by measuring the amount of water your dog is actually drinking in a twenty-four hour period. An average healthy dog drinks about 1/2 to 1 ounce of water per pound of body weight per day.

The amount of water your dog is drinking is an important piece of information to share with your veterinarian and can help avoid unnecessary testing. Keep in mind that dogs are very sloppy, inefficient drinkers. They lap their water instead of drinking the way we do, so take this fact and the amount of water that ends up on the floor near your dog's bowl into account.

What to Do

Ask yourself the following questions to determine what to do next:

• Have you recently changed anything in your dog's diet? Foods and treats that are rich in certain ingredients (such as sodium) will tend to increase your dog's thirst.
• Is your dog taking any medication? Some medications can increase a dog's thirst, particularly steroids and those directed at cardiac disease and seizure control.
• Does your dog have a fever? Like people, dogs become thirsty when they have elevated body temperatures. While the use of a rectal thermometer is the most accurate way to measure, you can get a pretty good idea of whether or not your dog has a fever simply by feeling her ears and groin. Dogs with high fevers tend to radiate heat from these areas.
• Does your dog have an infection? Bacterial and viral infections are often the cause of fever in dogs, resulting in an increased thirst. Other feedback mechanisms related to infection may stimulate a dog's thirst as well, explaining why infected dogs often have an insatiable desire to drink.
• Is your dog dehydrated?Dehydration is probably the most obvious reason why a dog would be drinking excessively, but noticeable dehydration suggests that some outside influence, such as illness or restricted access to water, has prevented the dog from keeping up with her needs.
• To check for noticeable dehydration, grasp a handful of skin at the scruff of your dog's neck. Lift it up as far as it will stretch, then release it. A well-hydrated dog's skin will snap briskly back into place, while that of a dehydrated dog will return slowly to its original position, forming a “tent” in the process.
• If this test seems inconclusive, try lifting your dog's lip to inspect her gums. (See “My Dog Is Drooling Excessively” for instructions on how to do this.) Wet, slippery, reflective gums are healthy. Dull, sticky gums confirm dehydration.
• Is your dog acting sick? Dogs that drink excessive quantities of water without an obvious explanation should always be examined for underlying illness. Usually those dogs happen to be urinating large quantities too, since the urinary tract and the thirst center are closely associated. Don't be fooled into thinking that this is a simple explanation. Without testing, it will remain unclear whether the drinking is causing the peeing or vice versa! Blood tests can identify diseases, including diabetes and Cushing's disease, which might be responsible for increases in thirst.

When to Get the Vet

If your dog is dehydrated despite drinking excessively, she should be seen immediately by her veterinarian to determine why she is not meeting her body's hydration needs.