Understanding Polydipsia (Excessive Thirst) in Dogs

Before we begin, we know that “polydipsia” sounds fancy and scary. This article will explain what “polydipsia” is, how it appears in dogs, the potential reasons for polydipsia and what you can do about it.

What is polydipsia?

“Polydipsia” is a Greek word that means “excessively thirsty”. Excessive thirst is not a diagnosis; it is a clinical sign observed in humans and animals. Therefore, although this article focuses on dogs, please note that polydipsia does not just happen to dogs!

You may then wonder if excessive thirst always indicates a medical problem, as it is common for humans and pets to drink lots of water on a hot day!

Defining Polydipsia in Dogs

Polydipsia in dogs is defined as a “fluid intake of more than 100ml/kg/day”. It is a given that the amount of fluids drunk will fluctuate from day to day, and differ amongst individuals. Thus, the fluid intake of more than 100ml/kg/day has to be consistently observed in a dog over several days.

You can check for polydipsia by measuring the volume of water you place into your dog’s water bowl, measuring the volume of water left in the bowl after 24 hours, and working out the difference. You should also keep track of the number of times you refill the dog’s water bowl over the day. In severe cases, dog owners have noticed their dogs drinking more often than usual, even if these owners were not keeping an active lookout.

Many polydipsic animals will drink fluids from places outside of their water bowl (e.g. dripping taps, drain water, other pets’ water bowls). Do look out for this in your pet.

Polydipsic pets also urinate a lot - this is called “polyuria”. As polyuria always accompanies polydipsia, vets normally lump them together and refer to the clinical sign as “PU/PD” (which stands for polyuria/polydipsia).

What should I do if I suspect polydipsia/polyuria in my dog?

Consult a veterinarian for advice. It is not advisable to try and diagnose the cause(s) of polyuria/polydipsia in your dog.

What causes polydipsia in dogs?

There are many causes of polydipsia in dogs, which can be grouped into several categories:

1) Medications

Certain medications (e.g. Prednisolone, Frusemide) will make dogs pee more. Thus, these dogs will drink more to compensate for the increased water loss. Having said that, check with your vet before you stop any medications. These medications would have been prescribed for good reasons, and it’s always good to clarify matters with your vet. Besides, it can be dangerous to stop some medications (.e.g Prednisolone) abruptly.

2) Infections

Bacterial infections (e.g. urinary tract infections) or viral infections (e.g. leptospirosis) can cause polydipsia in dogs. Other signs of a urinary tract infection include (but are not limited to) bloody urine, more frequent urination, straining to urinate and so on. Other signs of leptospirosis include (but are not limited to) vomiting, diarrhea, less activity, yellow gums and eyes, and so on. Consult a veterinarian if you notice any of these symptoms in your dog.

Antibiotics (e.g. Vedamox) are prescribed for bacterial urinary tract infections. Leptospirosis is a serious condition that requires intensive management, including antibiotics like Doxycycline

3) Endocrine/Metabolic/Organ Issues

Conditions such as kidney disease, diabetes, Cushing’s disease and liver failure can lead to polydipsia. These conditions have many overlapping symptoms (e.g. PU/PD, lethargy, vomiting/diarrhea, reduced appetite) and only a vet can rule in/rule out root causes by taking a history, doing a physical exam and conducting diagnostics like blood tests. Also, only a vet can prescribe treatments/management plans for these conditions. Therefore, if you notice any of these signs in your pet, please consult a vet! Do note that the list of conditions mentioned above are not the only endocrine/metabolic/organ function issues that can cause polyuria/polydipsia. There are other conditions like Fanconi’s syndrome (rare), renal gluycosuria (rare) and many more.

Generally speaking, kidney issues in dogs are managed with prescription diets and fluid therapy. Your vet may prescribe medications for renal complications (e.g. benazepril for hypertension). You can also consider kidney supplements such as Renacor and Azodyl. Diabetic dogs are generally managed with insulin injections. Diet also plays a huge role in management of diabetes, so do consult your vet regarding the best diet for your diabetic dog. Cushing’s disease is managed with medications like Trilostane (e.g. the Vetoryl brand). Management of liver disease is multimodal, with many liver supplements (e.g. MaxxiSame, Livermarin for you to ask your vet about.

4) Diabetes insipidus (central/nephrogenic)

When other causes have been ruled out, your vet may check for diabetes insipidus. The ADH hormone controls urine’s water content. Kidney-associated ‘nephrogenic’ diabetes insipidus (NDH) happens when ADH in the body is adequate, but the ADH has limited or no effect on the kidneys. Central Diabetes Insipidus (CDI) occurs when there is no ADH production, or abnormally low ADH production by the brain. In both CDI and NDI, the kidneys cannot reabsorb enough water into the bloodstream. This results in excessively dilute urine (polyuria) and low blood volume, triggering affected dogs to drink more (polydipsia).

Potential causes for CDI include brain masses (e.g. cysts, tumors), brain trauma, birth
defects in the brain etc. Possible reasons for ADI include bad drug reactions,birth defects in
the kidneys and so on. Diabetes insipidus can even occur for unknown reasons! Signs of diabetes insipidus include PU/PD, sunken eyes, sticky gums . Uncontrolled DI can lead to life-threatening complications (e.g. comas, seizures) that require emergency treatment. Consult a vet asap if your dog experiences any of these signs.

What can I do about polydipsia in my dog?

As mentioned several times in this article, please consult your vet if you notice polydipsia in your dog. In the meantime, provide your dog with free access to clean water and let your dog drink as much clean water as possible. It is dangerous to limit water intake in dogs, even if you think they’re drinking truckloads of water.

We hope that this article has given you a better understanding of polydipsia in dogs. Please consult your vet if you need any further advice!