Why might my pet be drinking more?
Water balance is tightly controlled by the body through regulation of water intake and water loss in urine. In health, lack of water intake or excessive water loss means the pituitary gland in the brain releases ‘anti-diuretic hormone’ or ADH. ADH tells the kidneys to conserve water and make concentrated urine. In these circumstances, the thirst centre in the brain is also stimulated and this stimulates drinking.
Increased drinking can occur either because the concentrating mechanisms of the kidney fail, because the kidneys do not respond to ADH, because ADH is not produced or released, or because there is an excessive stimulus to drinking (primary polydipsia).
Loss of concentrating mechanisms in the kidney and/or failure of response to ADH can occur through kidney damage, high blood calcium, liver failure, kidney infection, diabetes mellitus (sugar diabetes), pyometra (womb infection), overactive adrenal glands, over active thyroid glands and certain intoxications.
Failure of release or production of ADH (central diabetes insipidus) can occur because of brain damage through trauma, infection or cancer. Some animals are born with a defect in ADH production and release.
Causes of primary polydipsia in dogs and cats are obscure, although we have recognised this in association with gastrointestinal disease and urinary tract disease.