Why is my dog drinking so much water?

Owners may become aware that their dog or cat has suddenly begun to consume more water than usual. This may be the clue to a number of disorders, some only transitory, others of a more serious, chronic nature.

They may notice that the dog’s bowl is constantly empty or the dog may be observed licking at taps or lapping at every puddle while on a walk. Cats may be observed licking the bathroom tiles or hopping into the bath or sink.


A change of feeding may alter the dog’s drinking pattern. A change to dry feeding requires the absorption of far more water from the bowel. Some foods contain much more salt than others and stimulate an increased thirst. A temporary attack of diarrhea will be associated with an increased water intake.

Some medications cause the animal to drink more than usual. Corticosteroids, used to treat skin conditions or arthritis, have a marked effect when given in fairly high doses at the commencement of treatment.

Animals with an inflamed throat or with tonsillitis will lap small quantities of water frequently while refusing solid food. Dogs with long-standing constipation seem only interested in drinking copious amounts of water.

The two most serious diseases to be considered when the animal has a history of excessive thirst over a long period are diabetes and nephritis.


Diabetes is a disorder of the carbohydrate metabolism of the dog caused by a deficiency of the hormone insulin.

Insulin is secreted by specialized cells in the pancreas. The function of insulin in the body is to convert excess glucose to carbohydrate which is stored in the liver for the future needs of the animal.

In the diabetic dog or cat the daily energy requirements must be gained from the immediate intake of sugars.  Any energy requirement not able to be met from the daily food supply must be supplied by the breakdown of fats.

This process is not as efficient as the normal breaking down of stored carbohydrates and over a long time not only does the animal lose weight despite an increased appetite, but the waste products of fat breakdown can cause certain toxic effects in the animal’s body.

Free glucose is excreted by the animal’s kidney cells and this requires much greater amounts of fluid.


Nephritis is a disease of the cells of the kidney that eventually leads to an impairment in their function.

Kidney cells remove the waste products of metabolism and excrete them via the urine. Any impairment in their function is usually detected by the presence of protein in the urine. As more kidney cells are affected the animal compensates for this lack of efficiency by drinking more water in order to flush the impurities with an increased flow of fluid.

Eventually an animal with nephritis will lose weight, but unlike the diabetic animal whose appetite is excessive, it gradually demands less and less food.

It is important to seek veterinary advice where there is a noticeable increase in water intake over a protracted period. Both nephritis and diabetes can be controlled if treatment and dietary changes are begun before the disease process has progressed too far.

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