Polyuria and Polydipsia in Dogs

Polyuria and polydipsia are symptoms that usually go hand in hand. It's not a disease in itself, just a sign or expression of one.

Below, we'll look at what these words mean and which conditions or disorders can cause them in dogs. Does it need to be treated? Now we'll find out.

What Are Polyuria and Polydipsia?

Polyuria means an excessive increase in urine production, occurring several times a day. It needs to be distinguished from pollakiuria, which is the need to urinate several times during the day, but with normal or lower-than-normal volumes.

Polydipsia is an excessive increase in water intake, beyond normal amounts, in our pet. This results in the constant sensation of thirst dogs experience. These two conditions also occur (like most) in human medicine.

When water intake increases, blood volume increases and blood osmolality (solutes) decreases. In short, this increases urine volume. Although it may seem contradictory, dehydration can occur even though water intake has increased.

What Conditions Cause Polyuria and Polydipsia?

As explained earlier, both terms are signs or symptoms, not diseases in themselves. In addition, when one occurs, so does the other, since they go hand in hand. That said, whenever they occur, there's an underlying condition they're pointing to. Some of these conditions are:

• Diabetes Mellitus. This is a disease of the endocrine pancreas. It's characterized by a total or partial lack of insulin production and release. This leads to a state of chronic hyperglycemia (insulin is responsible for moving glucose from the blood into cells and making it usable). There's type I: total absence of insulin, and type II: insulin is present but there's resistance to its action.

The increase in glucose in the kidney's filtrate pulls water into the urine, increasing its production. This is why polyuria and polydipsia appear in cases of diabetes mellitus.

• Cushing's syndrome or hyperadrenocorticism. There's adrenal and pituitary hyperadrenocorticism. Basically, this results in an abnormal excess of corticosteroid (cortisol) production in the body, causing various symptoms, notably polydipsia and polyuria. This is because excess cortisol increases glomerular filtration. This occurs in 80-90% of Cushing's syndrome cases, including in cats.
• Pyometra. Pyometra is the name for uterine infection, which occurs in unspayed females (one of the reasons to have this surgery done). It can be closed (contents don't leak out of the vagina) or open (we'll notice discharge). It's usually caused by the bacterium Escherichia coli. One of the many symptoms that can appear is polydipsia and polyuria, possibly triggered by this bacteria traveling up from the reproductive tract to the kidneys.

Treatments for These Conditions

By treating the underlying condition, we'll manage to reduce and eliminate our dog's polyuria and polydipsia. Let's take a detailed look at what these treatments involve.

• Diabetes Mellitus: treating this endocrine pancreas disease aims to control the symptoms caused by glucose deficiency in the cells. This will mainly be done with insulin (regulated by a glucose curve the vet can run over the course of a day). Diet and exercise will help, with a diet rich in fiber and slow-absorbing carbohydrates, and low in fat, being beneficial. Spaying female dogs will be necessary, since this stops the production of hormones like progesterone in their bodies (which induces insulin resistance).
• Cushing's syndrome or hyperadrenocorticism. Main treatment will aim to reduce excessive cortisol synthesis in the blood. This can be achieved with trilostane, a cortisol synthesis inhibitor. Given its high effectiveness and low toxicity, it's the treatment of choice for Cushing's syndrome. It will be given orally for life.
• Pyometra: treatment for this condition is spaying, followed by antibiotics, as well as non-steroidal anti-inflammatories along with cleaning the incision with diluted chlorhexidine or Betadine for a week to ten days. An Elizabethan collar will be necessary to prevent the female from licking the incision and it becoming infected. Giving antibiotics alone without surgery often has a poor prognosis. So it will be highly advisable to spay to prevent this and many other conditions.

Is It Important to Treat Polyuria and Polydipsia?

This is one of the questions we'll ask ourselves and that will linger in our minds if we notice this sign in our dog. At first glance, it might seem like a mild symptom that therefore wouldn't need treatment. This is relative, since our dog will have a constant sensation of thirst (and usually hunger too, known as polyphagia).

So it may not be one of the most serious symptoms out there, but the diseases causing it, such as those mentioned above, certainly are. So it will be necessary to treat it, given the need to treat the underlying disease producing the polydipsia and polyuria. Below, we'll look at the types of treatment for these three conditions that most commonly cause polydipsia and polyuria.