If your dog is suddenly drinking and urinating excessively, you might worry about diabetes. But there’s another, less common condition that could be to blame: diabetes insipidus.
Diabetes insipidus (DI) in dogs is a rare disorder that impacts water balance, not blood sugar. This is a key difference between DI and diabetes mellitus, which does affect blood sugar.
DI happens when there’s a problem with antidiuretic hormone (ADH), which regulates how much water the kidneys conserve. There are two main types: central diabetes insipidus (CDI) and nephrogenic diabetes insipidus (NDI).
This article will give you a comprehensive overview of diabetes insipidus in dogs, including what causes it, the symptoms to look for, how it’s diagnosed, and the treatment options available.
Understanding Antidiuretic Hormone (ADH) and Its Function
To understand diabetes insipidus, it’s helpful to understand the role of antidiuretic hormone (ADH) in your dog’s body. ADH, which comes from the pituitary gland, is responsible for maintaining the correct balance of water.
Normally, ADH works on your dog’s kidneys to help them reabsorb water back into the bloodstream. This prevents your dog from losing too much water through urination.
But when ADH is deficient, or when the kidneys aren’t responding to it, the body can’t concentrate urine the way it should. This leads to two classic symptoms: excessive urination (polyuria) and extreme thirst (polydipsia).
When the pituitary gland is damaged or not working correctly, it can lead to a specific type of diabetes insipidus called central diabetes insipidus (CDI), in which your dog’s body simply isn’t producing enough ADH.
Types of Diabetes Insipidus in Dogs
There are two types of diabetes insipidus, and they have different causes:
Central Diabetes Insipidus (CDI)
With central diabetes insipidus (CDI), your dog’s body isn’t producing or releasing enough antidiuretic hormone (ADH). This could be because of a birth defect or because the dog has had a head injury or a tumor.
Nephrogenic Diabetes Insipidus (NDI)
If your dog has nephrogenic diabetes insipidus (NDI), it means their kidneys aren’t responding to ADH the way they should. This can also be due to a congenital problem, but sometimes NDI is caused by kidney disease, an electrolyte imbalance, or a medication your dog is taking.
Both types of diabetes insipidus are relatively rare in dogs.
What causes diabetes insipidus in dogs?
Diabetes insipidus (DI) in dogs comes in two main forms: central diabetes insipidus (CDI) and nephrogenic diabetes insipidus (NDI). They each have different underlying causes.
CDI can be caused by problems with the pituitary gland, such as:
- Pituitary tumors
- Head trauma
- Congenital defects (birth defects)
- Sometimes, the cause is unknown (idiopathic)
NDI is usually related to kidney problems or other health issues, including:
- Kidney disease (acute or chronic renal failure)
- Pyometra (infection of the uterus)
- Hypercalcemia (high calcium levels)
- Hypokalemia (low potassium levels)
- E. coli infections
- Certain medications, like glucocorticoids
Sometimes, even after extensive testing, vets can’t figure out what’s causing a dog’s diabetes insipidus. In these cases, it’s called idiopathic DI.
Recognizing the symptoms of diabetes insipidus
How can you tell if your dog might have diabetes insipidus?
Primary symptoms: increased thirst and urination
The hallmark symptoms of DI are polydipsia, or excessive thirst, and polyuria, or excessive urination. In other words, your dog will be drinking more and, as a result, peeing more.
But how much is too much? As a general guideline, if your dog is drinking more than 90 to 100 milliliters of water per kilogram of body weight per day, or if they’re urinating more than 50 milliliters per kilogram, it’s time to check in with your veterinarian.
Other symptoms to watch for
Along with increased thirst and urination, dogs with DI often have:
- Very dilute urine
- Accidents in the house
- Weight loss
- Lethargy
- Signs of dehydration
- A need to urinate during the night
- Urinary incontinence
Keep an eye on their water bowl
Monitoring how much your dog drinks and how often they need to pee can give you valuable information that you can share with your vet, so you can help them get the care they need.
Diagnosing Diabetes Insipidus in Dogs
If your veterinarian suspects your dog has diabetes insipidus, they’ll likely begin with a few key tests.
Initial Diagnostic Steps: Blood Tests and Urinalysis
The first step usually involves a complete blood count (CBC), a biochemistry profile, and a urinalysis. These tests help to get a general overview of your dog’s health and can rule out other conditions that might be causing similar symptoms.
One of the most important things your vet will look at is urine specific gravity (USG). USG measures the concentration of your dog’s urine. Normal urine concentrations are typically around 1.035 or higher. A USG below 1.012 indicates dilute urine, and anything below 1.008 is highly suggestive of diabetes insipidus.
Your vet may also order a symmetric dimethylarginine (SDMA) test. In one documented case, a dog with DI had an SDMA level of 15ug/dL, while the normal range is 1μg/dL to 14μg/dL.
Modified Water Deprivation Test
A modified water deprivation test is often used to confirm a diagnosis of diabetes insipidus. This test involves carefully restricting your dog’s water intake under close veterinary supervision. The goal is to see if your dog’s body will start conserving water and producing more concentrated urine. If your dog has DI, their urine will likely remain dilute even when water is restricted.
It’s important to note that this test carries risks, including severe dehydration, so it must be performed under the direct supervision of a veterinarian.
Desmopressin Trial
Desmopressin is a synthetic form of vasopressin, the hormone that’s deficient in central diabetes insipidus (CDI). A desmopressin trial can help differentiate between CDI and nephrogenic diabetes insipidus (NDI).
During this test, your dog will be given desmopressin, and their urine production and concentration will be monitored. If your dog responds to desmopressin with decreased urination and increased urine concentration, CDI is likely. If there’s no response, NDI is suspected, meaning the kidneys aren’t responding properly to vasopressin.
Treatment Options for Diabetes Insipidus in Dogs
The way diabetes insipidus is treated depends on whether it’s central diabetes insipidus (CDI) or nephrogenic diabetes insipidus (NDI).
Treatment of Central Diabetes Insipidus (CDI)
The main treatment for CDI is desmopressin, also known as DDAVP. Desmopressin is a synthetic hormone that replaces the vasopressin that’s lacking in dogs with CDI.
Desmopressin comes in a few different forms, including eye drops, tablets, and injections. One dog in the case study was initially given desmopressin tablets and responded well, but eventually developed diarrhea as a side effect.
Like any medication, desmopressin can have side effects. Dosage adjustments may be needed to manage those side effects while still controlling the symptoms of CDI. The dose was adjusted for the dog in the case study, and the dog’s condition improved.
Treatment of Nephrogenic Diabetes Insipidus (NDI)
With NDI, the kidneys aren’t responding properly to vasopressin. So, treatment for NDI focuses on finding and treating whatever’s causing the kidneys to malfunction.
In some cases, thiazide diuretics can help reduce urine volume in dogs with NDI, counterintuitively. A low-sodium diet, along with hydrochlorothiazide and desmopressin, may be recommended for primary NDI.
General Management Strategies
Regardless of the type of diabetes insipidus, it’s critical that dogs with suspected or confirmed diabetes insipidus have unlimited access to fresh water at all times. They’ll be drinking a lot and need to be able to replenish their fluids whenever they need to.
A low-sodium diet can also be helpful for managing NDI, as it can help reduce urine volume.
Living with Diabetes Insipidus: Prognosis and Management
The prognosis for dogs with central diabetes insipidus (CDI) and nephrogenic diabetes insipidus (NDI) hinges on what’s causing the condition and how well they respond to treatment. Generally, the outlook is favorable, assuming the underlying cause is manageable.
Regular vet checkups are crucial. Your veterinarian will want to monitor your dog for any signs of complications and assess kidney function periodically.
Successfully managing diabetes insipidus in dogs requires a team effort, and the owner plays a vital role. It’s essential to closely follow your veterinarian’s instructions regarding medication and other management strategies. Consistent administration of medication, usually desmopressin for CDI, is key to controlling symptoms. Equally important is ensuring your dog has constant access to fresh water and is allowed frequent opportunities to urinate.
Diabetes insipidus vs. other conditions
It’s important to note that there are other conditions that can look a lot like diabetes insipidus, so getting a correct diagnosis is critical.
Diabetes insipidus vs. diabetes mellitus
First, understand that diabetes insipidus is not the same thing as diabetes mellitus (sugar diabetes). Though they share the same name, they affect the body in different ways. With diabetes mellitus, the problem lies in the body’s ability to regulate blood sugar. With diabetes insipidus, the issue is that the body can’t regulate its fluid balance.
Diabetes insipidus and Cushing’s disease
Cushing’s disease, also known as hyperadrenocorticism, can sometimes mimic the symptoms of diabetes insipidus. For this reason, it’s important for your veterinarian to run the appropriate diagnostic tests to differentiate between the two conditions.
Closing Thoughts
Diabetes insipidus (DI) in dogs is a condition where the body doesn’t properly regulate fluid balance, leading to excessive thirst and urination. This happens because of a problem with ADH, a hormone that helps the kidneys conserve water. There are two main types of DI: central DI, where the brain doesn’t produce enough ADH, and nephrogenic DI, where the kidneys don’t respond to ADH.
If you notice your dog is drinking and peeing excessively, it’s important to get them checked by a veterinarian as soon as possible. Early diagnosis and treatment are key to managing DI and improving your dog’s quality of life.
By working closely with your veterinarian, you can develop a management plan that meets your dog’s specific needs. With proper care and monitoring, dogs with DI can live relatively normal, happy lives.