Why Is My Cat Drinking More Water Than Usual? Understanding Polydipsia in Cats

Increased thirst (polydipsia) in cats can signal common diseases like kidney disease, diabetes or hyperthyroidism. Learn what to watch for, what to tell your vet, and next steps.

When to See a Vet

If your cat is drinking noticeably more water than usual, schedule a veterinary appointment promptly to rule out medical causes. Increased thirst (polydipsia) is a common early sign of potentially serious diseases in cats — especially chronic kidney disease, diabetes mellitus, and hyperthyroidism — and should not be ignored.

Seek immediate veterinary or emergency care if your cat also has any of the following: vomiting, collapse, severe lethargy, wobbliness, trouble breathing, or if urine output has suddenly stopped (Red Flags section below).

What is “excessive” thirst?

Normal water intake varies, but an adult cat typically drinks roughly 40–60 mL/kg/day (about 200–300 mL/day for a 4–5 kg cat) when fed a dry-food diet. Polydipsia is commonly defined in veterinary medicine as water intake well above expected for body size and diet — often >100 mL/kg/day — but trends are more important than a single number. If you notice a clear and sustained increase in how often or how much your cat drinks, get it checked.

Medical Causes (common and important)

Many medical conditions cause increased thirst in cats. Always rule out these causes first.

• Chronic kidney disease (CKD). Very common in older cats. Diseased kidneys lose the ability to concentrate urine, so cats pass more dilute urine and must drink more to compensate.
• Diabetes mellitus. High blood glucose causes an osmotic diuresis (glucose in urine pulls water out with it), producing large volumes of urine and increased thirst. Often accompanied by weight loss and increased appetite.
• Hyperthyroidism. Excess thyroid hormone increases metabolic rate and can cause increased appetite, weight loss, and increased thirst and urination.
• Liver disease. Can alter fluid balance and thirst mechanisms.
• Hypercalcemia. High blood calcium from various causes can produce polyuria/polydipsia.
• Pyometra (infected uterus). Intact older female cats can develop this life-threatening condition, which may include increased drinking among other signs.
• Medications. Glucocorticoids (steroids), diuretics, and some other drugs increase thirst and urine production.
• Diabetes insipidus (rare). A disorder of water regulation leading to large volumes of dilute urine.

Behavioral and Environmental Causes (non-medical)

Not all increased drinking is illness-related. Consider these non-medical causes if your cat appears otherwise well and a vet has ruled out disease:

• Dry (kibble-heavy) diet. Wet food contains a lot of moisture; switching to more canned food often reduces drinking.
• Warm weather, heat, or increased exercise/activity.
• Salty treats or human food (high-salt snacks increase thirst).
• Changes in environment or routine (stress can alter eating/drinking patterns; rarely, psychogenic polydipsia — a compulsive thirst — is seen).
• Increased access to water sources (new bowl or fountain) or owner reinforcement (offering water after the cat drinks).

How to Tell the Difference: Medical vs Behavioral Indicators

Key differences to help you and your vet decide whether thirst is likely medical or environmental:

• Timeline and onset

• Other clinical signs

• Litterbox and urine

• Response to diet

Because signs overlap, a veterinary exam plus simple diagnostics (bloodwork, urinalysis, thyroid testing) are the only reliable way to differentiate causes.

What to Observe and Record Before Your Vet Visit

Gathering clear information helps your veterinarian make a faster, more accurate assessment. Track the following for 24–72 hours if you can:

• Estimated daily water intake. Measure how much water you put out and how much is left each 24 hours (household measuring cup).
• Number of litterbox visits and urine volume (small/normal/large), and whether urine looks dilute or darker than usual.
• Appetite and weight changes (if you have a recent weight, bring it).
• Vomiting, diarrhea, coughing, sneezing, breathing changes, or behavioral changes.
• Any new medications, supplements, or recent exposures (antifreeze, houseplants, salty snacks).
• Diet type: percentage of wet vs dry food; brand changes.
• Environmental changes: new people, stressors, heat, or new water sources.
• How often the cat drinks and where (bowl, faucet, toilet, puddles).

What Your Vet Will Likely Do

Most veterinarians will perform a physical exam and recommend baseline tests: complete blood count (CBC), serum biochemistry (including kidney values and glucose), symmetric dimethylarginine (SDMA) if available, total T4 (thyroid), and a urinalysis with urine specific gravity. Based on those results they may recommend further tests such as urine culture, abdominal ultrasound, blood pressure, or specific endocrine testing.

Next Steps — Action Plan Based on Severity

• If your cat is showing red-flag signs (vomiting repeatedly, collapse, severe lethargy, not urinating, or difficulty breathing): go to an emergency veterinary clinic immediately.

• If your cat has increased thirst but is bright and otherwise stable: book a veterinary appointment promptly and bring your observations (see above). Baseline bloodwork and urinalysis are the minimum tests.

• If a medical cause is diagnosed: follow your veterinarian's treatment plan. Examples:

• If no medical cause is found: consider environmental management. Increase wet food, add additional water bowls and a cat fountain, reduce salty treats, keep the home cool, and provide enrichment to reduce stress. If psychogenic polydipsia is suspected (rare), a veterinary behaviorist or your veterinarian can help with behavior modification and monitoring.

Red Flags — Seek Emergency Care

Immediate veterinary attention is indicated if your cat has any of these along with increased thirst:

• Sudden collapse, inability to stand, or severe weakness
• Continuous vomiting or severe diarrhea
• Not urinating (anuria) or straining to urinate
• Difficulty breathing or pale/blue gums
• Sudden severe lethargy or obtundation

Practical Tips for Owners

• Measure water if possible for a few days to quantify the change.
• Switch some or all meals to wet/canned food to increase fluid intake and reduce the need for drinking.
• Use multiple shallow bowls around the house; many cats prefer running water—try a cat fountain.
• Keep bowls clean and in quiet, low-traffic areas to encourage normal drinking behavior.
• Avoid offering salty human foods and limit treats.

Key Takeaways

• Increased thirst in cats (polydipsia) is a common but important sign that should prompt veterinary evaluation.
• Common medical causes include chronic kidney disease, diabetes mellitus, and hyperthyroidism; all require testing and often long-term management.
• Behavioral and environmental causes exist but are less common; rule out medical causes before assuming a behavioral problem.
• Collect measurements and observations before your vet visit: daily water intake, litterbox habits, appetite, weight changes, and any other clinical signs.
• Seek emergency care if your cat has severe systemic signs (vomiting, collapse, breathing difficulty, or not urinating).

Sources and Further Reading

• Merck Veterinary Manual — Polydipsia and Polyuria in Small Animals
• American Veterinary Society of Animal Behavior (AVSAB) position statements and resources on behavior and environmental enrichment
• Veterinary internal medicine textbooks (clinical resources on feline CKD, diabetes, and hyperthyroidism)

Frequently Asked Questions