What this means
This pairing matters because it is an early sign of several quite different internal problems. The kidneys, the pancreas and the hormone-producing glands each govern, in their own way, how much water the body holds on to. When one of those systems stops working as it did, the first thing noticed at home is often an emptying water bowl and a request to go outside during the night.
Measuring helps enormously. For a few days running, put in a known amount of water and see what is left in the evening, discounting what other pets in the house drink. That figure, alongside your dog's weight, tells your vet far more than an impression that "he's drinking more than he used to".
It is worth separating frequent urination from a large volume of urine. If your dog asks out often but passes only a little each time, strains, or there is blood in the urine, that points at the bladder and urinary tract. If the volume really is large and the dog is drinking heavily with it, the cause more often lies deeper, in the kidneys or the hormone balance.
Possible causes
These are things that can cause this sign. It is not a diagnosis, and they are not equally likely for your dog.
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A shift in hormone balance
When sugar handling is disturbed, the body clears the excess through the urine and loses a lot of water with it. A large appetite alongside falling weight often goes with it.
About the condition: Diabetes mellitus -
Declining kidney function
Failing kidneys can no longer hold water back, so the volume of urine rises and the dog drinks more. Appetite and coat may decline, and vomiting can appear.
About the condition: Kidney disease -
Too much hormone from the adrenal glands
An excess causes marked thirst, a bigger appetite, a thinning coat and a rounder belly. The changes usually build gradually over months.
About the condition: Cushing's disease -
Too little hormone from the adrenal glands
The opposite state shows as waves of lethargy, vomiting and a poor appetite, with the dog looking well in between. It can worsen suddenly.
About the condition: Addison's disease -
Bladder inflammation or stones
A urinary tract problem makes a dog ask out repeatedly while passing only small amounts. There may be straining, licking, or blood in the urine.
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Womb and reproductive hormone changes
In an unspayed bitch a few weeks after a season, increased thirst with lethargy can mean infection of the womb. That is an emergency.
About the condition: Pyometra
What else to watch for
These observations help your vet build the picture faster. Note down what you saw and when.
- How much water your dog drinks in a day
- Whether urination is frequent and small, or infrequent and large
- Whether there is blood in the urine, or straining
- Whether your dog asks out at night, or has had accidents indoors
- Whether appetite or weight have changed
- Whether the coat or the shape of the belly have changed
When to book a routine visit
Book a visit if the thirst and urination have risen and stayed that way for several days, even if your dog seems bright in every other way. Measure the daily water intake and bring the figure with you — it is one of the most useful things you can gather at home.
Related conditions
Conditions whose entries mention this sign. The list is somewhere to read on, not a way to reach a diagnosis.
- Diabetes mellitus Hormones and metabolism Diabetes mellitus is a disease in which the body makes too little insulin or can no longer use it properly, so sugar cannot move from the blood into the cells and builds up in the bloodstream. The body's cells go short of energy even though the dog is eating enough, and blood sugar that stays high for a long time can harm various organs, such as the eyes. It is a long-term condition that needs ongoing monitoring together with a vet.
- Kidney disease Kidneys and bladder The kidneys filter the blood, remove waste from the body and help keep the balance of fluids and salts. When they are damaged suddenly, for example by poisoning or infection, or weaken gradually over a longer time, substances they should remove start to build up in the body. Long-term kidney changes can go unnoticed for a long time, because the healthy part of the kidneys takes over the work for a while.
- Cushing's disease Hormones and metabolism Cushing's disease is a condition in which the body makes too much of a stress hormone. This hormone affects many of the body's processes, so an excess gradually changes a dog's appetite, skin, coat and muscles. The changes come on slowly, so they are easy to mistake for simple ageing.
- Bladder stones Kidneys and bladder Bladder stones are hard clumps of minerals that form in the urine and slowly grow inside the bladder. They irritate the bladder wall, causing inflammation and pain, and if one gets stuck in the urethra it can block the urinary tract. A dog that cannot pass urine is in a life-threatening situation and needs a vet immediately.
- Addison's disease Hormones and metabolism Addison's disease is a condition in which the adrenal glands make too little of certain hormones that help the body cope with stress and keep its balance of salts and water. Its signs are vague and can come and go, so it is easy to miss. The condition can, however, suddenly worsen and become life-threatening, and then the dog needs a vet immediately.
- Urinary incontinence Kidneys and bladder Urinary incontinence is a condition in which a dog leaks urine without meaning to, sometimes without even noticing. It can be caused by a weak seal at the bladder outlet, urinary tract infections, stones, inborn defects of the urinary tract, nervous system disorders or other illnesses. It is not the dog's fault, and finding out why it is happening is a job for a vet.
- Leptospirosis Infections Leptospirosis is a bacterial infection that a dog catches from water, damp ground or objects contaminated with the urine of infected animals, especially rodents. The bacteria damage the kidneys and liver, and the illness can quickly become life-threatening, so the dog needs a vet immediately. Leptospirosis also passes to people.
- Pyometra General health Pyometra is a pus-filled infection of the womb that can develop in an unspayed bitch in the weeks after a season. Pus collects in the womb, and substances released by the bacteria harm the whole body. The condition can quickly become life-threatening, so the bitch needs a vet immediately.
Body systems: Hormones and metabolism Kidneys and bladder Infections General health