My Dog is Drinking a Lot of Water (Polydipsia)
The simplest reason that people or animals drink is because they are thirsty. Their body is becoming low on water and they must drink to make up the losses. Since dogs don’t sweat, except from their nose and foot pads, they eliminate body heat by panting. When they pant a lot, they lose water through evaporation. This water loss is physiologic and can be readily replenished by drinking.
Excess water intake that goes beyond a normal amount, or that occurs without cause, may be a sign of disease. In a variety of conditions the body is not able to control water loss even at normal temperatures. This water loss must be replenished and so dogs drink a lot to find a balance.
How much water intake is normal in a healthy dog?
Generally, water intake will vary a little with diet. If dogs are fed wet food, they may drink less, while dogs that are fed dry food or salty treats must make up water intake and seem to drink more than expected. However, this water intake is still physiologically normal.
A good general guideline is that a healthy dog should drink between 20-70ml/kg per day1. Being aware of your dog’s water intake is important because drinking too little water can lead to dehydration while drinking too much water can be an indication of organ disease. If your dog is drinking more, he’ll probably also be peeing more (another sign of a potential problem). In fact, increased intake is often a response to excess fluid loss in urine.
If your dog is drinking excessively (polydipsia) it is possibly because he is losing excess amounts of water for any of a number of reasons. While a number of diseases result in excess water intake and urine output, the most common of these diseases include kidney failure, diabetes mellitus and Cushing’s disease.
An uncommon cause of dogs drinking more is called psychogenic polydipsia. It is a behavioral condition with a physical manifestation of excess thirst. Primary polydipsia is used to describe excessive water drinking that is not due to illness or psychosis: bored puppies or water loving breeds may tank up on water occasionally or consistently. Sorting these out can be a real challenge for your veterinarian.
Some medications, such as cortical steroids often have increased water intake as a side effect.