Polyuria

Polyuria describes an abnormally high urine production in dogs – usually over 50 ml per kilogram of body weight daily. A 20-kilo dog thus produces more than a litre of urine a day.

The symptom rarely occurs alone. You will probably notice the more frequent urination first – or that your house-trained dog suddenly leaves urine in the flat. Behind this could be harmless causes, but also serious illnesses.

Which diseases cause polyuria?

Diabetes mellitus tops the list. The high blood sugar “draws” water into the urine – the body tries to get rid of the excess sugar. Affected dogs therefore drink extremely much.

Cushing’s syndrome is accompanied by excessive cortisol production. The stress hormone disrupts the water balance. Dogs with Cushing’s often develop a pendulous abdomen and pant more.

Kidney insufficiency makes itself noticeable through diluted urine. The damaged kidneys can no longer concentrate the urine – large amounts of watery urine are the result.

Diabetes insipidus is rare, but dramatic. Here, the hormone vasopressin is missing, or the kidneys do not react to it. Affected dogs can drink 10 to 15 litres daily.

Bladder inflammations cause frequent but usually low-volume urination. True polyuria is not present here – nevertheless, owners often confuse the symptoms.

Which medications trigger polyuria?

Cortisone preparations mimic Cushing’s syndrome. After just a few days of treatment, dogs drink and urinate more. After discontinuation, this usually normalises again.

Diuretics (water pills) deliberately promote urine production. In heart patients, this is desirable – but can lead to dehydration.

Antiepileptics such as phenobarbital burden the liver. A damaged liver no longer filters toxins reliably – the body tries to excrete them via the urine.

When does polyuria become dangerous?

Go to the vet immediately if your dog drinks more within 24 hours than its body weight in millilitres. A 25-kilo dog thus over 2.5 litres.

Warning signs are: apathy despite thirst, pale gums, vomiting or a skin fold that only slowly returns to its original position. This indicates dangerous dehydration.

It becomes particularly critical with puppies and seniors. Their water balance gets out of control faster than in healthy adult dogs.

How do you measure the drinking amount correctly?

In the morning, fill a measured amount of water into the bowl. In the evening, measure the remainder – the difference shows the drinking amount. In multi-dog households, observe each dog individually.

Healthy dogs drink 20 to 70 ml per kilogram of body weight daily. A 15-kilo dog should thus drink a maximum of about a litre.

From 100 ml per kilo, one speaks of polydipsia – excessive drinking. This automatically leads to polyuria.

What awaits you at the vet?

The urine examination comes first. Diluted urine with a specific gravity below 1.020 confirms polyuria. Sugar in the urine points to diabetes.

The blood count reveals kidney problems, blood sugar and liver enzymes. If Cushing’s is suspected, hormone tests such as the ACTH stimulation test follow.

Imaging comes into play with unclear findings. Ultrasound shows kidney changes, X-rays can reveal bladder stones.

How is polyuria treated?

Treatment depends on the underlying disease. Diabetes requires insulin and diet food. Cushing’s patients receive trilostan or Vetoryl.

In cases of renal insufficiency, special kidney diet food with reduced phosphorus content supports kidney function. Bladder inflammation subsides in many cases after a one-week course of antibiotics.

Drug-induced polyuria disappears after discontinuation – if medically possible. With life-saving medications, the increased water intake must be accepted.