How to Tell If Your Dog's Increased Thirst Is a Sign of Cushing's Disease

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-08-14

Key Takeaways

• Increased thirst (polydipsia) in dogs is a significant clinical sign that warrants veterinary evaluation, as it can indicate serious underlying conditions such as Cushing's disease, diabetes mellitus, or chronic kidney disease.
• Emergency veterinary care is indicated for dogs exhibiting polydipsia concurrently with vomiting, collapse, severe weakness, pale mucous membranes, rapid breathing at rest, or seizures, as these signs suggest life-threatening conditions.
• A comprehensive diagnostic approach by a veterinarian typically involves detailed history taking, a thorough physical examination, urinalysis to assess urine concentration and detect abnormalities like glucosuria, and blood tests (e.g., complete blood count, chemistry panel) to evaluate organ function and hormone levels.
• Specific diagnostic tests for Cushing's disease, such as the low-dose dexamethasone suppression test or ACTH stimulation test, are crucial for confirming hyperadrenocorticism by measuring the body's cortisol response to hormonal stimulation.
• Management of increased thirst depends on the etiology; Cushing's disease requires lifelong medication to control cortisol levels, diabetes mellitus necessitates insulin therapy and dietary management, and chronic kidney disease is managed with supportive care, specialized diets, and medications to slow progression.
• Owners should meticulously track water intake, urination frequency, and other clinical signs (appetite, weight, coat condition) to provide veterinarians with critical data for accurate diagnosis and effective treatment planning, while avoiding home remedies or water restriction without professional guidance.

If your dog is suddenly drinking far more water than usual, you are right to pay attention. Increased thirst, called polydipsia, is often one of the first clues that something has changed in your dog's body. Cushing's disease is one possible cause, but it is not the only one. Diabetes and kidney disease can also make a dog drink excessively, and so can simple things like hot weather or a change in diet.

Here is what you need to know first: increased thirst alone is rarely an emergency. However, if your dog is also vomiting, lethargic, or unable to keep water down, that changes the picture. In that case, call your veterinarian immediately or go to an emergency clinic. Otherwise, your next step is to gather clear information about your dog's drinking habits and book a veterinary appointment. Do not try to limit your dog's water, even if the drinking seems extreme. Dehydration can happen quickly and is more dangerous than the underlying cause.

Is This an Emergency?

Use this table to decide how quickly your dog needs care. Watch your dog closely and trust your instincts. If you are unsure, call your veterinarian.

{
 "type": "triage",
 "title": "Urgency triage by severity of signs",
 "tiers": [
  {
   "tier": "danger",
   "label": "Go to emergency vet now",
   "signs": [
    "Drinking water but vomiting it back up, unable to keep any water down, collapse, weakness, pale gums, rapid breathing at rest, or seizures"
   ],
   "action": [
    "Do not wait",
    "These signs can indicate a life-threatening problem such as kidney failure, diabetes complications, or poisoning",
    "Seek in-person emergency care immediately"
   ]
  },
  {
   "tier": "warn",
   "label": "Book a same-day appointment",
   "signs": [
    "Drinking noticeably more water for 24 to 48 hours, urinating more often, accidents in the house, increased appetite, weight loss despite eating well, or a dull coat"
   ],
   "action": [
    "Call your regular veterinarian today",
    "These signs point to conditions like diabetes or kidney disease that need prompt testing and treatment"
   ]
  },
  {
   "tier": "safe",
   "label": "Watch at home for a defined period",
   "signs": [
    "Mild increase in thirst for one to two days, linked to hot weather, more exercise, or a recent change to dry food"
   ],
   "action": [
    "Track how much water your dog drinks each day",
    "If the increased thirst continues beyond two days, or if any other signs appear, book a veterinary appointment"
   ]
  }
 ]
}

What Is Cushing's Disease?

Cushing's disease, also called hyperadrenocorticism, happens when your dog's body produces too much cortisol. Cortisol is a natural hormone that helps regulate stress, weight, and immune function. When levels stay too high for too long, it affects nearly every organ system.

The most common form of Cushing's disease develops from a small, usually benign tumor on the pituitary gland at the base of the brain. This tumor signals the adrenal glands to overproduce cortisol. A less common form comes from a tumor on the adrenal gland itself. Cushing's disease is most often seen in middle-aged and older dogs, and certain breeds such as poodles, dachshunds, and terriers are more prone to it.

Increased thirst is a classic sign, but it rarely appears alone. Dogs with Cushing's disease also tend to urinate more, eat more, and lose muscle mass. Their skin becomes thin, they may develop bald patches, and their belly can look potbellied or swollen. If you see several of these signs together, Cushing's disease becomes a stronger possibility.

Other Causes of Increased Thirst

Cushing's disease is not the most common reason a dog drinks more water. Diabetes mellitus, often just called diabetes, is a frequent cause. In diabetes, the body cannot use sugar properly, so excess sugar spills into the urine. That sugar pulls water with it, making the dog urinate a lot and then drink to catch up. Dogs with diabetes often lose weight despite a ravenous appetite.

Chronic kidney disease is another major cause. As kidneys lose their ability to concentrate urine, the dog produces large volumes of dilute urine and drinks more to compensate. Kidney disease is common in older dogs and can be detected with simple blood and urine tests. The International Renal Interest Society staging guidelines describe how veterinarians stage kidney disease and monitor it over time.

Other possibilities include urinary tract infections, liver disease, and certain medications like steroids. Even a simple change in diet, especially switching from wet to dry food, can make a dog drink more. The MSD Veterinary Manual Pet Owner Version explains that increased thirst has many causes, and sorting them out requires a veterinary examination.

How Your Veterinarian Will Figure It Out

Your veterinarian will start by asking detailed questions about your dog's water intake, urination frequency, appetite, and energy level. Be ready to say how many times your dog drinks in an hour and whether you have noticed accidents in the house. If you can, measure the water you put in the bowl each day and estimate how much is left.

The next step is usually a urinalysis. This simple test checks for sugar, protein, and infection. It also measures how well your dog's kidneys are concentrating urine. If the urine is very dilute, that points toward kidney disease or Cushing's disease. If sugar is present, diabetes is likely.

Blood tests follow if the urine test is not conclusive. A complete blood count and chemistry panel can reveal liver enzyme changes, high cortisol levels, or other abnormalities. For Cushing's disease specifically, your veterinarian may recommend a low-dose dexamethasone suppression test or an ACTH stimulation test. These tests measure how your dog's body responds to hormones and can confirm the diagnosis. The American Animal Hospital Association senior care guidelines recommend regular blood and urine testing for older dogs, which can catch these conditions earlier.

What Happens Next

If your dog is diagnosed with Cushing's disease, treatment focuses on controlling cortisol levels instead of curing the disease. Most dogs take medication for life, and the dose must be carefully adjusted based on repeat blood tests. Your veterinarian will determine the exact dose for your dog, and that dose will likely change over time. Never adjust or give medication without your veterinarian's guidance, because the wrong dose can cause serious side effects.

If the cause is diabetes, treatment involves insulin injections and a consistent diet. Kidney disease is managed with special diets, fluids, and medications to slow progression. Each condition has a different outlook, but early diagnosis gives your dog the best chance at a good quality of life. The American Veterinary Medical Association pet owner resources emphasize that regular veterinary visits are the best way to catch chronic diseases before they cause serious harm.

For now, do not panic. Increased thirst is a signal, not a verdict. Write down what you observe, keep your dog's water bowl full, and call your veterinarian to schedule an appointment. With proper testing, you will know what you are dealing with, and you can take the next step from there.

What You Can Do at Home Right Now

If your dog is drinking more than usual, do not restrict their water. A dog with increased thirst needs access to fresh water at all times. Restricting water can lead to dehydration, especially if the underlying cause is kidney disease or diabetes. Let your dog drink as much as they want until you have spoken with a veterinarian.

You can safely do three things at home today. First, measure how much water your dog actually drinks. Second, track urination frequency and any accidents in the house. Third, write down any other changes you have noticed in appetite, energy, coat condition, or body shape. This information is gold for your veterinarian.

Do not give your dog any medication, supplement, or herbal remedy for thirst or Cushing's disease. Over-the-counter products are not tested for this condition and can cause harm. Prescription treatments for Cushing's disease require a diagnosis and careful dosing by a veterinarian. Giving the wrong drug or dose can be dangerous.

Do not change your dog's diet without veterinary advice. Some conditions that cause thirst, like diabetes or kidney disease, respond to specific dietary changes. Guessing can delay proper treatment.

What to Measure and Write Down

Before you call or visit a veterinarian, gather these details. You do not need to be perfect, just consistent.

Water intake tracking sheet

To measure, use a measuring cup each morning. Fill the bowl with a known amount. At the same time the next day, pour the leftover water into the measuring cup and subtract. A dog who drinks more than about 1.5 to 2 cups of water per 10 pounds of body weight per day is drinking excessively. But do not panic if your dog is above that line. Some active dogs, dogs on dry food, or dogs in hot weather drink more.

Also track these signs:

• How many times per day your dog urinates. Most adult dogs urinate 3 to 5 times daily.
• Whether your dog wakes you at night to go out.
• Whether your dog has accidents in the house despite being house trained.
• How much your dog eats at each meal. Cushing's disease often increases appetite.
• Whether your dog pants more than usual or at rest.
• Whether your dog's belly looks round or pot-bellied.
• Whether your dog is losing hair, especially on the flanks or tail.
• Whether your dog seems tired or less willing to exercise.
• Whether your dog's skin bruises easily or is slow to heal.

Take a short video of your dog panting, walking, or drinking if you can. Video can help a veterinarian see subtle changes in body condition or breathing.

What a Veterinary Visit Usually Involves

Your veterinarian will start by asking questions. Expect questions about how long the thirst has been present, how much water your dog drinks, urination habits, appetite, weight change, energy level, and any medications your dog takes. Bring your water tracking sheet and notes.

The physical exam is hands-on. The veterinarian will feel your dog's abdomen, check for a pot-bellied appearance, listen to the heart and lungs, check the skin and coat, and take a temperature. These steps cannot be done remotely.

Blood and urine tests are the standard next step. A urine sample checks for infection, diabetes, and kidney concentration ability. Blood work checks kidney values, liver enzymes, blood sugar, and thyroid levels. For Cushing's disease, specific tests like a low-dose dexamethasone suppression test or an ACTH stimulation test are often needed. These tests measure how the adrenal glands respond to hormones.

The cost of this workup varies widely. A basic blood panel and urinalysis might range from $150 to $400. The specific Cushing's tests add another $200 to $500. Imaging like an ultrasound, if needed, can add $300 to $800. These are rough ranges only. Prices vary by region, clinic type, and your dog's size. Ask your veterinarian for an estimate before testing.

What drives cost up or down? A young dog with a simple urinary tract infection will need less testing than a senior dog with multiple signs. Complicated cases may need repeated bloodwork, an abdominal ultrasound, or referral to a specialist. Pet insurance may cover some of these costs if you have it.

A Symptom Comparison Table

This table helps you see how Cushing's disease compares with other common causes of increased thirst. It is not a diagnosis. Many signs overlap.

If your dog shows weakness, collapse, vomiting, or stops urinating, seek emergency care immediately. These can be signs of a life-threatening problem.

When an Online Vet Can Help, and When It Cannot

Some situations in this article require hands-on care. A dog with vomiting, collapse, difficulty breathing, or straining to urinate without producing urine needs in-person emergency care right now. Do not use a remote consultation for these signs. A dog with a painful or swollen abdomen, or a dog who cannot stand, also needs immediate in-person attention.

A remote consultation is genuinely useful in other situations. If your dog has mild increased thirst and you are unsure whether a visit is needed, an online vet can help you decide. If your dog has a known chronic condition like kidney disease or diabetes and you have a question about a small change, remote advice can be practical. If your dog started a new medication and you wonder whether thirst is a side effect, a remote vet can guide you.

A remote veterinarian can take a detailed history, watch your dog on video, and advise you. In many states they can prescribe medication. But they cannot feel your dog's abdomen, listen to the chest, take a temperature, run bloodwork, or perform imaging. These limitations matter. Prescribing rules differ by state, and a veterinarian may require an in-person examination before prescribing. For a new problem like suspected Cushing's disease, an in-person visit is almost always necessary for diagnosis. Use remote care as a first step, not a substitute for hands-on medicine.

Common Mistakes Owners Make With This Problem

When a dog starts drinking more, owners often fall into one of several traps. Recognizing these can save you time, money, and worry.

Mistake one: waiting to see if it passes. Increased thirst rarely resolves on its own. If your dog has been drinking noticeably more for more than a day or two, the cause will not simply disappear. Early testing gives your veterinarian a clearer picture and can slow the progression of conditions like kidney disease or diabetes.

Mistake two: restricting water to reduce urination. This is dangerous. If your dog is drinking more because of an underlying illness, limiting water can lead to dehydration. Never limit access to fresh water unless your veterinarian specifically instructs you to do so.

Mistake three: assuming it is just old age. Senior dogs do not drink more simply because they are older. The AAHA Senior Care Guidelines emphasize that changes in thirst and urination warrant a health assessment, not a shrug. Age makes disease more likely, not less.

Mistake four: switching foods or supplements on your own. Some owners try low-protein diets or herbal remedies before a diagnosis. This can interfere with test results and delay proper treatment. Let your veterinarian guide any dietary change.

Mistake five: comparing your dog to another dog. Every dog has a normal water intake range. What matters is your dog's own pattern over time. A Labrador and a Chihuahua will differ, but a sudden change in your dog's habits is the signal.

How to Reduce the Chance of It Happening Again

You cannot fully prevent Cushing's disease, diabetes, or kidney disease. These conditions often develop from factors outside your control. What you can do is catch them earlier.

Schedule wellness exams at least once a year, and every six months for dogs over seven years old. The AVMA Pet Owner Resources recommend regular checkups as the foundation of preventive care. Routine blood work can reveal early changes before you notice symptoms at home.

Keep a simple log. Once a month, note how quickly your dog empties a water bowl and how often you refill it. This gives you a baseline. If something changes, you will know within days, not weeks.

Maintain a stable weight. Obesity increases the risk of diabetes and makes other conditions harder to manage. Your veterinarian can help you set a target weight and a feeding plan.

What Recovery and Ongoing Management Usually Look Like

Recovery depends entirely on the underlying cause. There is no single timeline.

For Cushing's disease: Treatment usually involves daily medication that must be adjusted over weeks to months. Your veterinarian will run follow-up blood tests, often starting two to four weeks after beginning treatment, then every few months. Many dogs improve noticeably within four to six weeks. Thirst often decreases within the first month, but some dogs need dose adjustments before you see full improvement. This is a lifelong condition, not a cure. The goal is managing signs and maintaining quality of life.

For diabetes: Once insulin treatment begins, expect several weeks of adjustment. Your dog may need blood glucose curves at the clinic. Thirst usually improves once blood sugar stabilizes, often within two to four weeks. Diabetes also requires lifelong management.

For kidney disease: The IRIS Staging Guidelines describe a framework for staging chronic kidney disease. Treatment focuses on diet, hydration, and medications to manage complications. Thirst may persist because the kidneys cannot concentrate urine. Improvement means stability, not a return to normal drinking. Monitoring is ongoing and lifelong.

For all three conditions, your veterinarian will set a recheck schedule. Expect more frequent visits early on, then less frequent once your dog stabilizes. Some dogs need medication adjustments at every visit. That is normal.

Frequently Asked Questions

How much water is too much for a dog? A general rule is about one ounce of water per pound of body weight per day, but this varies widely with activity, weather, and diet. A more useful sign is change. If your dog drinks roughly twice what it used to, or if you are refilling the bowl more than once a day when you used to refill it every other day, that is worth a call to your veterinarian.

Can Cushing's disease be cured? Most cases of Cushing's disease are caused by a benign tumor on the pituitary gland and cannot be cured. They can be managed. Medication controls the signs, and many dogs live comfortably for years. A smaller number of cases involve an adrenal gland tumor, which may be removable with surgery. Your veterinarian will determine which type your dog has through testing.

Will my dog need to take medicine forever? For Cushing's disease and diabetes, yes. These are lifelong conditions. For kidney disease, treatment is also ongoing, though it may involve diet and supplements instead of daily medication. The goal is to manage the disease and keep your dog comfortable. Your veterinarian will adjust the plan over time based on blood work and how your dog feels.

How soon will I see improvement after treatment starts? For Cushing's disease, many owners notice less thirst and urination within two to four weeks of starting medication, though dose adjustments are common. For diabetes, improvement often follows once insulin doses are stabilized, usually within a few weeks. Kidney disease management focuses on slowing progression, so you may not see dramatic changes, but your dog's energy and appetite can improve.

Is increased thirst ever normal? Yes, temporarily. Hot weather, more exercise, or a switch to dry food can increase water intake. If your dog has a one-day spike and returns to normal, that is usually fine. The concern is a sustained change lasting more than a day or two, especially if it comes with increased urination, weight loss, or a dull coat. That pattern points to an underlying issue.

What if my dog starts drinking more suddenly and also seems weak? This combination needs prompt attention. Sudden weakness with increased thirst can indicate conditions like diabetes with ketoacidosis, a serious metabolic emergency, or kidney failure. Do not wait for a routine appointment. Call your veterinarian immediately and describe the signs. They will tell you whether to come in right away or go to an emergency clinic.

Related Clinical & Scientific Guides

• How to Help Your Senior Cat with Mobility Issues: Tips and Products
• How to Prepare Your Cat for a Vet Visit for Kidney Disease
• What Blood Tests Does My Senior Dog Need and What Do They Cost?

References and Further Reading

• AAHA Senior Care Guidelines for Dogs and Cats
• International Renal Interest Society Staging Guidelines
• AVMA Pet Owner Resources
• MSD Veterinary Manual Pet Owner Version
• AAHA Pet Owner Resources

Related Articles

• Dog Cushing's Disease: How to Tell If Your Dog's Medication Is Working
• How to Tell If Your Senior Dog's Bad Breath Is a Sign of Kidney Disease
• How to Tell If Your Dog's Cough Is Heart Disease or Something Else
• How to Tell If Your Cat's Increased Thirst Is a Sign of Kidney Disease or Diabetes
• Dog Kidney Disease: How to Tell If Your Dog Is Dehydrated

This article is general educational information for pet owners. It is not a substitute for veterinary diagnosis, examination, or treatment. If your pet is showing severe or rapidly worsening signs, contact an emergency veterinary hospital immediately.