cat drinking a lot of water and meowing
Cat Food and Hydration

Why is My Cat Always Thirsty?

It’s normal for a cat’s water requirements to increase as the weather warms up. Many cats are ancestral desert inhabitants that are careful about how much water they drink. Sometimes excessive drinking in cats, especially if they’re accompanied by other symptoms, can be a cause for concern.

If your cat is continuously seeking out bowls, cups, and puddles, it may have polydipsia (excessive thirst). A cat with polydipsia may drink over 60 ml per kg of body weight per day. There are several causes of excessive thirst in cats, ranging from behavioral to pathological, such as diabetes, hyperthyroidism, dehydration, and urinary tract disease.

However, cats are highly skilled at concealing signs of illness and disease. It may only be noticed via subtle behavioral changes, such as increased thirst or lethargy. Keeping an eye on your cat’s drinking patterns and other unusual signs can help you determine whether your cat’s desire to drink constantly is due to a weather change or an underlying health condition.

How Much Water Should My Cat Drink?

Cats should drink about 60 ml per kg of their body weight every day. For example, a 4 kg (8.8lb) cat should be drinking 240 ml or one cup of water daily to ensure it’s body functions optimally.

However, when deciding the amount of water your cat should drink every day, it’s also important to consider your cat’s diet. Dry food is about 10% water, whereas wet food can be as much as 80% water. Therefore, a 4 kg cat on a wet food diet may only need to drink 30 ml of water every day, whereas a 4kg cat on a dry food diet may need over 200ml of water every day.

If your cat is drinking more than the recommended amount or if its increased thirst accompanies other symptoms, such as increased or decreased urination, appetite changes, lethargy, vomiting, increased sleep or diarrhea, take your pet to the vet with a urine sample.

You can collect your cat’s urine sample by placing a non-absorbable litter or plastic wrap cut up into strips into a clean litter tray. Collect the urine in a clean jar after your cat pees, and take the sample to the clinic within 1 hour from collection or place it in the fridge for up to 12 hours.

What Are the Causes of Increased Thirst in Cats?

Cats are believed to be evolutionarily predisposed to consume their liquids with their solids. Cats feed frequently in the wild, hunting small animals throughout the day.

Supporters of this theory suggest that most cats meet their fluid requirements from the animal they’ve hunted (such as a small bird) – without the need for additional water intake. This explains why it’s normal for most cats not to drink much water.

If your cat’s drinking habits have changed suddenly, consider looking for the cause and other possible signs. There are three major causes of excessive thirst in cats, which include:

  • Compensatory Causes. Your cat’s diet is primarily composed of dry or high-sodium foods, which makes it thirstier.
  • Environmental Causes. Increased heat can cause your cat to pant more to cool itself, allowing it to lose more water.
  • Pathological Causes. Sickness can also increase your cat’s water requirements. Vomiting, diarrhea, diabetes, kidney disease, and hyperthyroidism are some examples of medical issues that can make a cat thirstier.

Medical Causes of Increased Thirst in Cats

If your cat has any of the following problems or conditions, set up an appointment with your vet. Older cats are more prone to medical conditions such as diabetes, kidney disease, and hyperthyroidism.

1) Fever

Cats can experience numerous types of infections that cause fever, but it can be difficult to spot whether your cat is feeling unwell. Sometimes fever can cause your cat to drink more water than usual. According to the Journal of Feline Medicine and Surgery, the most common cause of fever, or pyrexia in cats was infectious peritonitis, followed by inflammatory conditions.

The only way to tell if your cat has a fever is to take its temperature using a thermometer. Temperatures ranging from 100.4 to 102.5 degrees Fahrenheit are considered normal in cats. Anything above 102.5 degrees Fahrenheit indicates that your cat has a fever and a temperature higher than 106 degrees Fahrenheit can be harmful to its organs.

Causes of Fever in Cats

Fever in cats usually occurs when the immune system has been triggered by conditions, such as:

  • A bacterial, viral or fungal infection
  • Injury from trauma
  • A tumor
  • Certain medications
  • Diseases such as lupus
cat drinking a lot of water and throwing up

Signs and Symptoms of Fever in Cats

Conditions that cause fever in cats often result in other obvious behavioral changes as well. Certain behavioral changes are evolutionarily designed to help cats cope with illness and conserve enough energy to have a fever. Fevers are a good thing. They fight disease by activating the immune system and slowing down the growth and development of pathogens in the body.

Oftentimes, fever may be accompanied by other signs, some of which include:

  • Loss of appetite
  • Grumpiness
  • Depression
  • Lethargy or lack of activity
  • Increased or decreased drinking
  • Decreased grooming
  • Rapid breathing or shivering

Your cat may also show other specific signs of sickness, such as vomiting, sneezing, and diarrhea.

How to Check Your Cat’s Temperature

To check whether your cat has a fever, use a digital pediatric rectal thermometer with some lubricant (e.g., Vaseline) applied to the tip. You may need to retrain your cat with the help of another person. Alternatively, you can cradle your cat’s body with one arm using a firm grip.

Lift the tail gently and insert the thermometer into your cat’s anus. Twist the thermometer gently and carefully from side to side to help the muscles relax. Next, gently insert the thermometer one inch into the rectum. Don’t force this step. Remove the thermometer once you hear the beep and clean it with alcohol before reading the temperature.

If your cat hasn’t been vomiting, finish off by offering it a treat.

How to Take Care of a Cat with Fever

If your cat has a high fever for more than 24 hours, take it to the vet. Your vet may perform some tests to determine the cause and suitable steps to resolve the underlying issue. For example, if your cat has a bacterial infection, your vet may prescribe antibiotics. If your cat has moderate to severe dehydration due to fever, intravenous or subcutaneous fluids may be necessary.

2) Kidney Failure

According to Veterinary Pathology, kidney disease is the most common metabolic disease in domestic cats. In many cats, kidneys tend to fail with age, and if left untreated, the condition can cause severe complications. Cats are obligate carnivores and protein is a major part of their diet. This means that a cat’s kidneys have to work harder, making it prone to kidney disease as it gets older.

In the case of chronic kidney disease, there is no cure available. However, early diagnosis and proper home care can help elevate the length and quality of your cat’s life.

Some kittens can also be born with kidney disease. Toxins, trauma, and infection are other causes. There are two types of kidney failure in cats:

  • Acute Renal failure. This type develops suddenly within days or weeks and is often reversible if diagnosed early. It can happen in cats of all ages due to poisons such as toxic plants (e.g., lilies), antifreeze, cleaning products, and certain human medications, as well as trauma to the pelvis or bladder, shock, dehydration, kidney infection, heart failure, and urethral blockages.
  • Chronic Renal Failure. This occurs mostly in middle-aged and older cats and can take months or years to develop. Chronic kidney failure is harder to treat, and its exact cause isn’t understood. Some vets believe it may be due to kidney blockages and infections, high blood pressure, thyroid issues, advanced dental disease, and cancer.

Signs and Symptoms of Kidney Failure in Cats

Cats with kidney failure may drink a lot of water because it is trying to replace the water lost due to frequent urinating – another sign of kidney disease. Kidney failure can cause your cat to urinate more because it isn’t able to hold water any longer. Frequent urination outside the litter box is another telltale sign. Also, your cat may be drinking a lot of water and losing weight.

cat drinking a lot of water and losing weight

Other signs to look out for include:

  • Decreased appetite and weight loss
  • Bad breath (ammonia-like smell)
  • Vomiting
  • Diarrhea
  • Bloody, cloudy urine
  • Brownish tongue
  • Dry coat
  • Mouth ulcers on the tongue and gums
  • Constipation
  • Weakness
  • Apathy

Feline Kidney Disease Diagnosis and Treatment

During diagnosis, your vet will perform blood and urine tests, an ultrasound, X-rays and/or biopsy to determine whether your cat has kidney disease. If your cat has kidney disease, treatments may include IV fluids, specialized diets, medications and surgery to remove any blockages. Homecare may include injecting fluids under your cat’s skin.

Your cat’s diet will have to be low in protein and phosphorus and enriched with omega-3 fatty acids, and vitamin D. Introduce new foods to your cat’s diet gradually. Your vet can advise you on how you can make the transition easier, for yourself and your cat.

Take your cat for regular checkups and offer it plenty of fresh, clean water and a comfortable environment for it to relax in.

3) Diabetes Mellitus

A large number of cats develop diabetes mellitus, which is the body’s inability to respond to or produce sufficient levels of insulin. Insulin is a hormone required by the body to balance blood sugar levels. If left untreated, diabetes can lead to weight loss, dehydration, loss of appetite, stress and anxiety, severe depression, motor function problems, coma, and even death.

There are two types of diabetes: type-1 and type-2. In type-1 diabetes, a decrease in insulin production in the body causes glucose concentrations to exceed normal levels. In type-2 diabetes, cells in the body are unable to respond properly to insulin, causing glucose levels to increase. Most cats suffer from type-2 diabetes.

Signs and Symptoms

Increased thirst (polydipsia) and increased urination are the main symptoms of diabetes. Diabetes is also more common in overweight and obese cats.

If your cat is drinking a lot of water and eating more, it may be due to diabetes. Diabetes is the body’s inability to process a cat’s main source of fuel: glucose. Therefore, cats with diabetes often have an insatiable appetite because their bodies cannot derive enough fuel from their diet.


Diagnosis of feline diabetes involves conducting blood and urine tests to check glucose concentrations. Be prepared to answer questions regarding any clinical signs, such as weight loss, increased appetite, increased thirst, and increased urination.


The primary goals of treating feline diabetes include:

  • Glycemic control
  • Minimizing weight loss
  • Minimizing increased urination and thirst
  • Restoring the appetite
  • Preventing low blood glucose levels using therapy

Insulin Therapy

Oral drugs designed for humans rarely work for feline diabetes. Cats with diabetes are typically treated with insulin injections, which are to be administered at home according to your doctor’s instructions.

Dietary Control

To improve the levels of blood glucose in your cat’s body, your vet may recommend giving your cat a low-carbohydrate diet.

According to Veterinary Medicine: Research and Reports, most commercial dry foods have 60% of their energy from carbohydrates. On the other hand, feral cats that hunt animal prey have an average energy intake of 52% crude protein, 46% crude fat and about 2% carbohydrates.

It’s also critical that you can eliminate weight loss caused by diabetes by feeding multiple times per day or allowing access to food throughout the day. If your cat is overweight, talk to your vet about a weight loss program to help it maintain more stable blood glucose levels.

old cat drinking a lot of water


There is no cure for feline diabetes, but it can be managed with proper diet control, appropriate education and support from the cat’s owner.

Even if your cat has diabetes, it can live a long and quality lifestyle if its condition is managed well. Some cats may even stop needing insulin treatments – however, even in such cases, it is vital that you keep a lookout for recurring signs of diabetes and maintain a low-carbohydrate diet.

4) Hyperthyroidism

Hyperthyroidism is a common glandular disorder in cats often caused by an overactive thyroid gland. An overactive thyroid gland will produce excessive amounts of thyroxin hormone, resulting in a higher metabolism, high heart rate, and high blood pressure.

Hypothyroidism can occur in all breeds and genders of cats, but it’s most common in older felines, with an average age of 12-13 years.

Signs and Symptoms

The most common clinical signs of hyperthyroidism are increased appetite (67-81%) and weight loss (95-98%). Other signs include excessive thirst, hyperactivity, increased urination, panting, diarrhea, a messy appearance, and increased shedding. Your cat may also be drinking more water and throwing up due to hyperthyroidism.


There are many treatment options for feline hyperthyroidism. Each treatment may have varying levels of benefits and disadvantages.

Oral Medication

Antithyroid medications such as Methimazole can be effective in rectifying the condition within 2-3 weeks. However, some cats may have side effects, such as vomiting, loss of appetite, lethargy and blood cell abnormalities. Occasionally, there may be severe adverse effects such as blood clotting disorders, liver problems, and self-induced trauma.

Surgical Removal of the Thyroid Gland

Surgical removal may be needed if hyperthyroidism is caused by a benign tumor (thyroid adenoma). Luckily, most cats with hyperthyroidism have benign tumors that can be removed easily; following which patients will get cured. Anesthesia may be difficult in older cats with hyperthyroidism that has affected the heart or other organs.

Radioactive Iodine Therapy

This is the most effective treatment for hyperthyroidism in cats. No anesthesia is needed, and the treatment is carried out by injecting radioactive iodine, which concentrates in the thyroid gland and eliminates hyper-functioning tissues. The only downsides are that it requires 10-14 days of hospital stay and can be costly ($500-$1200).

5) Urinary Problems

If your cat has been drinking a lot of water but not peeing, it could be a sign of a urinary problem. With urinary problems, cats tend to strain more and have difficulty urinating. Urinary issues can cause significant discomfort in cats and require veterinary attention.

If you notice no urine coming out, your cat may have a blocked bladder. A blocked bladder is a medical emergency. Take your cat to an emergency veterinary center for immediate treatment.


Not all causes of urinary problems in cats are medical. In most cases, stress and anxiety caused by changes in the environment, new additions in the house, changing the litter tray or cat bed location and loud noises can contribute to urinary problems in cats.

A dominant cat intruding in your cat’s territory or a sudden diet change are other causes. Environmental stress can contribute to Feline Idiopathic Cystitis (FIC).

Another cause could be solid crystals forming in your cat’s urine, which can result in urethral plugs or bladder stones. Other, less common causes include urinary tract infections, urinary tumors or anatomical issues, all of which are referred to as Feline Lower Urinary Tract Disease (FLUTD).

Urinary tract disease is a painful condition that occurs in middle-aged, overweight, male, desexed and indoor cats. It can also occur in cats that are only given dry food. However, urinary problems can occur in any cat, so it is essential to keep a lookout for any unusual urinating behavior.

Signs and Symptoms

Signs of urinary problems that you will be able to see first are your cat constantly trying to urinate and straining while peeing. You may also notice that your cat’s urine trickles instead of coming out smoothly.

In severe cases, you may notice fatigue, vomiting, your cat crying out in pain and blood in the urine. If you see any of these signs, take your cat to the vet immediately as it could indicate a bladder blockage.


Stress can be a major cause of urinary problems in cats, so start by ruling out any possible sources of stress. Have you moved your cat’s litter tray recently, or is there a different cat that may be aggressive towards yours?

Problems with litter tray placements and sharing litter trays can be easily corrected. If there is competition for the litter box, make sure you place more litter boxes in different areas of the house.

If your cat has a bacterial infection, your vet may ask for a urine sample. Urinary tract infections are rare, but if it is diagnosed in your cat, your vet will prescribe a suitable antibiotic. In severe conditions, such as in the case of bladder stones or urethral obstructions, urinary catheters or surgery may be needed.

If your cat’s urinary issues are caused by urinary crystals, you may have to increase your cat’s fluid intake and modify its diet, especially if it’s normally given dry food only.

6) Dehydration

Dehydration can occur due to fluid loss or reduced water intake in cats. Overheating from hot and humid weather conditions, vomiting, increased activity, and diarrhea, and lead to fluid loss.

It’s important to give cats access to fresh water at all times because some cats may not drink any water until they’ve lost up to 8% of the water stored in their bodies.


The following are some general symptoms of dehydration in cats:

  • Panting
  • Increased thirst
  • Loss of appetite
  • Sunken eyes
  • Lethargy
  • Depression
  • Dry mouth
  • Elevated heart rate
  • Decreased skin elasticity

What To Do If Your Cat Is Dehydrated

To identify dehydration, gently lift the skin between your cat’s shoulder blades or the back of its neck. Unless your cat is very thin or overweight, the skin should return immediately.

If your cat is dehydrated, the skin won’t return to normal immediately. However, in most cases, dehydration cannot be easily detected and should, therefore, be diagnosed and treated by a veterinarian.