The reason for your dog drinking a lot will depend upon its cause. For example:
Kidney Disease or Kidney Failure
In kidney (also called renal) disease, the kidneys don’t work correctly which leads to their being unable to filter toxins out of the bloodstream as they would typically. This condition will lead to the water balance in your dog’s body being off, causing him to drink more.
In kidney (also called renal) failure, where the kidneys will no longer function, the condition can come on quickly or over a long period of time and may bring other complications with it. The acute form of the condition is usually the result of injury or your dog ingesting a toxic substance. Chronic kidney failure is more likely to occur in older dogs. Your dog’s kidneys will eliminate metabolic waste and create urine to flush the waste out. The blood that flows through your dog’s kidneys is filtered and there is a certain amount needed in the blood and an amount to be gotten rid of.
When the kidneys are not working, the waste will build up, leading to an increase in thirst.
Treatment needs to be administered right away; typical early signs are an increase in thirst and increased urination. Your dog will drink excessive amounts of water because as the condition gets worse, his kidneys will not process toxins efficiently and more water will be needed to do the job. Despite the increase in urination, toxins won’t be eliminated as well as they had prior to the kidney disease.
Your dog may be susceptible to kidney disease as a result of underlying health issues or injury, among other reasons.
Diabetes Mellitus
Also known as “sugar diabetes” the condition occurs when your dog’s body is struggling to connect his glucose and insulin, which are necessary for your dog’s health. When they are not working properly, diabetes is developed; the cause is your dog’s pancreas not producing insulin as it typically would. Without insulin, your dog’s body will not obtain the glucose his body requires.
Cushing’s Disease
Clinically defined as hyperadrenocorticism, Cushing’s disease is when your dog’s endocrine glands don’t keep the necessary balance of cortisol in his body. The origin of the condition is an unusual growth of tissue or trauma in either the pituitary or adrenal glands. In Cushing’s disease, the hormone cortisol will be over produced. Usually the hormone is in your dog’s system in low levels and will elevate during stress. Its role is to help suppress inflammatory signaling and increase your dog’s blood sugar.
Psychogenic Polydipsia
While not common in dogs, psychogenic polydipsia is a behavioral condition where excess thirst will physically manifest itself.
In Reaction to Medication
Some medication will note an increase in thirst as a side effect.