Excessive thirst in cats can be caused by several reasons that include weight loss, diabetes in cats, chronic kidney disease, Hyperthyroidism, Cancer, Cardiac disease, Polydipsia and Polyuria in Cats.
So:
- Is your cat drinking a lot of water suddenly?
- Is your cat drinking a lot of water and meowing?
- Is your cat drinking a lot of water and losing weight?
- Is your cat drinking lots of water and eating more?
- Is your cat drinking a lot of water and throwing up?
- Is your cat drinking a lot of water and diarrhoea?
When it comes to caring for your cat, I have a few simple recommendations:
- Maintain a safe environment (keep him indoors)
- Feed a high-quality food (e.g., a meat-based protein)
- Think proactive measures (like an annual physical examination, laboratory tests, and the appropriate vaccines)
- Provide lots of exercise and affection
By following these simple steps, you can help keep your four-legged, feline companion healthy—potentially for many years! But as a cat owner, you need to be aware of five “silent” killers in cats that make them thirst excessively.
Knowing what the most common silent killers are, you can know what clinical signs to look for. With most of these diseases, the sooner the clinical signs are recognized, the sooner your cat will recover once treated.

Excessive Thirst in Cats [Causes, Symptoms and Cure]
Chronic kidney disease
One of the top silent killers of cats that bring about excessive thirst in cats is Chronic Kidney disease (CKD). This sometimes called chronic kidney injury or chronic renal failure.
Semantically, these terms mean the same thing and translates to 75% of both kidneys not working and ineffective. Clinical signs of CRD include:
- Excessive urinating
- Excessive drinking
- Larger clumps in the litter box
- Weight loss
- Bad breath (due to toxins building up in the blood and causing ulcers in the mouth, stomach and oesophagus)
- Hiding
- Lethargy
Causes of CKD include:
- Poisons
- Trauma involving a broken pelvis or burst bladder
- Kidney infections
- Heart failure with low blood pressure
- Rapid dehydration or shock from losing a lot of blood
- Urethral blockage
Thankfully, with appropriate management, cats can live with CKD for years (unlike dogs where CKD usually progresses more rapidly).
Chronic management may include a low-protein diet, regular blood work, increasing water intake (e.g., with a water fountain or by feeding a gruelling canned food), medications and even fluids under the skin (which many pet guardians do at home, once properly trained).
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Hyperthyroidism
Hyperthyroidism is an endocrine disease where the thyroid gland produces too many thyroid hormones. This is seen in middle-aged to senior cats and can result in very similar clinical signs to chronic kidney disease, including:
- Weight loss
- Excessive thirst
- Increased water consumption/urination
- Vomiting/diarrhoea
However, as hyperthyroidism speeds up cats’ metabolism, it causes one defining sign; an unquenchable appetite despite weight loss. It can also lead to:
- A racing heart rate
- Severe hypertension (resulting in acute blood loss, neurologic signs, or even a clot or stroke)
- Secondary organ injury (e.g., changes to the kidney or a heart murmur)
Causes are:
- An over-functioning thyroid
- Age
- Fish-flavoured cat food
The good news is, treatment for hyperthyroidism works well and includes either a medication (known as methimazole, surgical removal of the thyroid glands (less commonly done), a special prescription diet called y/d® Feline Thyroid Health) or I131 radioiodine therapy.
With hyperthyroidism, the sooner you treat it, the fewer potential side effects or organ damage will occur in your cat.

Diabetes mellitus
Another costly cause of excessive thirst in cats is diabetes mellitus (DM). Because most cats are often overweight to obese, they are at even greater risk for DM.
Diabetes in cats causes failure to the pancreas and prevents it from secreting enough amounts of insulin (Type I DM) or causes resistance to insulin (Type II DM).
Insulin is a natural hormone that drives blood sugar (sugar) into the cells. Once the cells starve for glucose, the body produces more and more glucose, leading to hyperglycemia (i.e., a high blood sugar) and many of the clinical signs seen with DM.
Common clinical signs for DM are similar to those of chronic kidney disease and hyperthyroidism and include:
- A decreased or ravenous appetite
- Abnormal breath (e.g., acetone breath)
- An obese or overweight body condition with muscle wasting (especially over the spine or back) or weight loss
- Excessive urination and thirst
- Larger clumps in the litter box
- Lethargy or weakness
- Vomiting
- Walking abnormally (e.g., lower to the ground)
Causes of diabetes in cats:
- Weak pancreas
- Failure of the pancreas to balance insulin and maintain blood sugar levels
DM treatments can be quite expensive, as it requires twice-a-day insulin injections that you have to give under the skin.
It also requires changes in diet (to a high protein, frequent blood glucose monitoring, low carbohydrate diet, and frequent veterinary visits).
With chronic management and supportive care, cats can do reasonably well; however, once diabetic complications develop (e.g., diabetic ketoacidosis, hyperglycemic, hyperosmolar syndrome), DM can be life-threatening.
Cardiac disease
Heart disease is every veterinarians and cat owners nightmare. That’s because, while dogs almost always have a loud heart murmur (i.e., one we that can be heard with the stethoscope) indicative of heart disease, cats often do not have a heart murmur present.
It’s estimated that 50% of cats with heart disease have no auscultate heart murmur. Clinical signs of heart disease include:
- A heart murmur
- An abnormal heart rhythm (e.g., an abnormal beat and rhythm)
- A racing heart rate
- Acute, sudden paralysis (e.g., typically of the hind limbs)
- Blue-tinged gums
- Cold, painful hind limbs
- Collapse
- Difficulty breathing
- Passing out (e.g., syncope)
- Increased respiratory rate
- Open-mouth breathing
- Sudden pain
- Sudden lameness
- Sudden death
Causes:
- Inherited at birth
- Old age
Once the cardiac disease is diagnosed (typically based on physical exam, chest radiographs, Cardiopet® proBNP Test, and an ultrasound of the heart called an “echocardiogram”), treatment may include emergency care oxygen therapy, diuretics, blood pressure support, and heart medications.
The long-term prognosis is poor, as the heart medication does not cure the heart disease; it prevents the cardiac disease from worsening. The exception is when the cardiac disease is caused by hyperthyroidism, which often gets better once the hyperthyroidism is treated!
Polydipsia and Polyuria in Cats
Polyuria means abnormally high urine production in cats, while polydipsia refers to the animal’s increased level of thirst.
Although serious medical consequences are rare, your pet should be evaluated to guarantee that these conditions are not symptoms of more serious underlying medical conditions.
Your vet wil want to rule out or confirm renal failure or hepatic diseases.
Polydipsia and polyuria can affect both cats and dogs and can be brought on by a variety of factors.

Symptoms and Types
The most evident symptoms of these medical conditions are increased urination and excessive thirst in cats, causing them to drink more water than usual. Generally, there are no other behavioural changes.
Causes
The major causes of polyuria and polydipsia include congenital abnormalities and those linked with renal failure.
Congenital diseases can include decreased steroid production by the adrenal glands, diabetes, and some rare psychological disorders.
Kidney diseases, meanwhile, can be a result of a congenital disability, or can be linked to increased steroid production, steroid production, increased thyroid hormone levels, and hormonal or electrolyte disorders.
Other potential factors that cause polyuria and polydipsia are protein diets, medications that are prescribed for removing excess fluid from the body (diuretics), and age,
The younger and more active a cat is, the more likely it will have intermittent increases in thirst and urination.
Diagnosis
Your animal doctor will examine your cat to determine the true levels of thirst and urination by measuring water intake and urination output.
A baseline of normal fluid levels (hydration) and normal urination will be established for comparison. An evaluation will be performed to make sure that the increased urination and excessive thirst in cats are not signs of a more serious medical condition.
Standard tests will include a complete blood count (CBC), a urinalysis, and X-ray imaging to rule out or confirm any issues with the renal, adrenal, and reproductive systems.
Any other symptoms accompanying the increased levels of urination or excessive thirst in cats, even when appearing unrelated, will be taken into consideration during the final diagnosis.
Cancer
As cats and dogs live longer, veterinarians are recording more cases of cancer. The most common type of cancer in cats is gastrointestinal cancer, often due to lymphosarcoma.
Clinical signs of cancer include:
- Abdominal distension or bloating
- Diarrhoea
- Difficulty breathing
- Fever
- Lethargy
- Hiding
- Not eating
- Vomiting
- Weight loss
- Weakness
- Generalized malaise
Once diagnosed, the prognosis for cancer is poor. For this reason, the sooner you notice clinical signs, the sooner diagnosis and treatment may be initiated.
Note: Other common emergencies can cause deaths in cats, including poisonings, urinary obstructions, trauma, and more. When in doubt, to keep your cat safe, follow these simple five tips:
- Keep your cat indoors to avoid the slightest form of trauma (e.g., attacked by a dog, being hit by a car, accidentally poisoned, etc.)
- Ensure you keep your cat’s weight in check – this will help prevent expensive problems due to obesity such as diabetes down the line.
- Be a responsible parent and schedule an annual visit with your veterinarian. This is especially important as you can pick up on physical abnormalities sooner. Note that even if your cat is indoors, she still needs an annual exam; you may be able to skip some of the vaccines (and schedule them to every third year instead) but don’t skip on the exam!
- Keep the litter box clean: This might sound simple. Daily and frequent cleaning of the box is a must. Not only will this alert you to life-threatening emergencies like feline urethral obstructions, but it’ll make you aware if your cat is urinating more or less than usual — and help you pick up medical problems sooner!
- Ask for your veterinary help as soon as you notice any clinical signs – not months after your cat has been urinating and drinking excessively!
When it comes to your cat’s health, make sure you’re aware of these common silent killers. The sooner you notice the signs, the sooner your vet can do some blood work and diagnose the medical problem. The sooner it is diagnosed, the sooner they can treat it!
If you have any questions or concerns about excessive thirst in cats, you should always call or visit your veterinarian — they are your best resource to ensure the health and well-being of your pets.
We have an 18 year old cat that seems to be thirsty all the time, Is skin and bones due to weight loss, seldom eats but loves the gravy and now his meows have become like a long drawn out growl at the end. Because he eats very little he poops one small cat turd everyday but has no diarrhea. He is not lethargic. Has no problems walking. Any idea of the reason for the symptoms? He has also recently eaten scented cat litter.and vomited once so we got rid of it.
Sounds like old age.
I would recommend sticking to her former food (if you recently changed her food) and have her checked by a Vet ASAP.