If your dog seems excessively thirsty lately, you should be concerned. Increased thirst—medically known as polydipsia—can indicate urinary tract problems, liver or kidney failure and other health problems. While you should definitely check with your vet about your dog's excessive water drinking, don't panic. If the new thirst coincides with a switch in dog food, that may account for the change.
If you've switched your dog from wet canned food to dry kibble, it may prompt a noticeable increase in her water consumption. Canned dog food has an average water content of 75 percent. That provides a good deal of fluids over the course of the day, especially relative to a young or small dog's needs. In contrast, dry dog food typically contains only 6 to 10 percent moisture. The change to dry food may have left a considerable deficit in your pet's water intake that she's now accounting for by hitting the water bowl more often or for longer drinks.
We know salt makes us humans thirsty, but it has the same effect on your dog. And just like processed people foods, processed pet foods are often high in sodium, especially considering that AAFCO (Association of American Feed Control Officials) guidelines don't set a maximum recommended sodium content for dogs. High sodium intake can drive your dog right to the water dish. Compare the sodium content of your new food to that of the food you were using previously. If there's a big discrepancy, this is probably your explanation. Remember, though, that if you're comparing a canned food to a dry food, you must account for the fact that mineral content is expressed on a "dry matter" basis; for canned food that's only 25 percent dry matter, multiply the sodium content by four to determine how salty it really is.
Food Allergies and Intolerances
Dogs can be allergic or have sensitivities to different types of meat and fish, wheat, soy, dairy, egg, filler or preservative ingredients and other stuff in their food. Allergies and intolerances cause a variety of symptoms, which can include unpleasant sensations in the mouth and throat, stomachaches, diarrhea, vomiting and others. Your dog has no way to tell you her throat feels funny, nor does she have much recourse other than to try drinking it away. Diarrhea and vomiting can deplete your dog's fluids, making her excessively thirsty. If you suspect an allergy or intolerance, your vet can design an exclusion diet to figure things out.
Switching dog food may have caused your pet's excessive water drinking for other reasons. Other ingredients, such as sugar and certain spices, can trigger thirst the same way salt does. If your dog doesn't like the new food, she may not be eating enough and be attempting to suppress her hunger by drinking more. But again, a number of health problems can also trigger excessive thirst in your dog, so it's best to talk things over with your vet, who will probably want you to come in for a complete history, a physical examination and possibly some tests. Prepare for the visit by keeping track of how much your dog drinks, when she drinks, how much and how often she's urinating, whether she's showing appetite changes, whether she's exhibiting behavioral changes and anything else that seems concerning.