고양이 다음다뇨(PU/PD) 증상과 원인, 진단·치료와 관리 포인트 총정리

My Cat Keeps Drinking Water — Causes of Polyuria/Polydipsia (PU/PD) and When to Visit the Vet

KidneyDiseasesMeongsiljang Veterinary Advisory Board

Feline polyuria and polydipsia (PU/PD), characterized by increased urine output and excessive water intake, can be an early sign of serious conditions such as chronic kidney disease or diabetes. Early detection and accurate diagnosis are essential.

What Is Feline Polyuria/Polydipsia (PU/PD)?

An image showing a cat drinking water alongside a bladder icon.

Feline polyuria and polydipsia (PU/PD) is a condition characterized by an increased volume of urine output, accompanied by a significant rise in water consumption. This can be an early sign of impaired kidney function or metabolic disorders. Common underlying causes include chronic kidney disease, diabetes mellitus, and hyperadrenocorticism. It is important for pet owners to carefully monitor and record their cat’s daily water intake and urination frequency. Early detection is key to successful treatment. If symptoms persist, prompt veterinary evaluation is essential.

What Are the Main Causes of Polyuria/Polydipsia?

- Chronic kidney disease: As the kidneys’ filtering ability declines, urine production increases, leading to greater water intake. - Diabetes mellitus: Elevated blood sugar prompts the kidneys to excrete excess glucose, resulting in increased urine output. - Hyperadrenocorticism (Cushing’s disease): Excess cortisol disrupts fluid regulation, causing polyuria and polydipsia. - Electrolyte imbalances: Abnormal sodium or potassium levels can impair kidney function. - Infections or medications: Certain infections or drugs that irritate the kidneys may be responsible. Accurately identifying the underlying cause is the first step toward effective treatment.

An anatomical diagram illustrating abnormalities in kidney, pancreas, and adrenal cortex function.

Key Symptoms and Signs of Polyuria/Polydipsia

The main symptoms of feline polyuria and polydipsia (PU/PD) are as follows. We’ve compiled the signs that pet owners can easily notice in daily life.

Increased water intake: Your cat will drink noticeably more water than usual. However, since it’s difficult to accurately estimate a cat’s water consumption, track the amount in the water bowl over several days to monitor changes.

Frequent urination: The number of times your cat urinates increases compared to normal.

Increased urine volume: You may notice larger or more numerous urine clumps in the litter box.

Changes in elimination habits: Your cat may urinate outside the litter box or show a change in how often they use it.

Weight loss: Despite maintaining a normal appetite, your cat may lose weight or experience muscle weakness.

Increased fatigue: Activity levels decrease, and your cat may spend more time resting in the same spot.

A cat with urine scattered around the bathroom area

When Immediate Veterinary Attention Is Necessary

If your cat drinks more than 45 mL of water per kilogram of body weight per day, experiences a sudden increase in urine output, loses its appetite, or vomits repeatedly, immediate veterinary attention is necessary. These symptoms may indicate diabetes mellitus or acute kidney injury.

Diagnostic Tests for Accurate Diagnosis

- Blood tests: We check kidney function (creatinine, BUN), blood glucose levels, and electrolyte balance. - Urinalysis: We assess urine concentration (specific gravity) and the presence of protein to help identify the underlying cause. - Ultrasound: We visually examine the kidneys for size, structure, and any abnormalities. - Hormone tests: We measure cortisol levels to evaluate for Cushing’s disease (hyperadrenocorticism) and, if necessary, also assess total thyroid hormone (T4) levels. - Additional diagnostic tests: If needed, we perform urine culture or kidney biopsy (tissue examination) to determine the presence of infection and identify the specific type of lesion. We comprehensively analyze multiple tests, including CBC, blood chemistry, and urinalysis, to pinpoint the cause.

A veterinarian preparing blood and urine tests.

Treatment Methods and Step-by-Step Management

- Diabetes treatment: Insulin injections and a low-carbohydrate diet are key. - Chronic kidney disease management: Managed through a low-protein diet, fluid regulation, and medication. - Cushing’s disease treatment: Symptoms are controlled with hormone-regulating medications. - Infections or drug-induced causes: Symptoms improve once the underlying cause is removed. - Ongoing monitoring: Work with your veterinarian for regular check-ups and repeated blood and urine tests. Treatment requires long-term management, not just short-term control.

A veterinarian administering an insulin injection to a cat

Management Points at Home

- Water Access: Place water bowls in multiple locations and consider using a flowing water fountain to encourage drinking. - Dietary Management: Feed a veterinarian-recommended prescription diet to regulate protein and phosphorus intake. - Weight Monitoring: Weigh your pet weekly to track changes in body condition. - Urination Monitoring: Record any changes in urine volume, odor, and color. - Medication Administration: Administer medications strictly according to the prescribed schedule and dosage. - Regular Veterinary Visits: Continue regular check-ups every 1 to 3 months during treatment. Consistent home care is the cornerstone of successful therapy.

The scene shows multiple water bowls and special food placed around the house.

Precautions by Cat Breed

Feline polyuria and polydipsia can occur in various conditions such as chronic kidney disease, diabetes mellitus, and hyperadrenocorticism, and is particularly common in older cats (approximately 5-16 years old). Rather than focusing on specific breeds, it's important to carefully monitor water intake and urine output in daily life and have regular health check-ups.

Reviewed by a veterinarian

Dr. Tony — Punnawat Phongkittirak

Veterinarian

A veterinarian who majored in veterinary medicine at Khon Kaen University, Thailand, and completed the IVSA program at North Carolina State University in the United States. Drawing on clinical experience at animal hospitals, he works in the pet healthcare field and is dedicated to building a digital care environment that connects pet parents with veterinarians.

Frequently Asked Questions

Is it normal for a cat to drink a lot of water?

A healthy cat typically drinks no more than 45 mL of water per kilogram of body weight per day. If your cat consistently exceeds this amount, it could be a sign of polydipsia (excessive thirst), and you should consider visiting the vet.

Is polydipsia a symptom of diabetes?

Yes, diabetes mellitus is a leading cause of polyuria and polydipsia. When blood glucose levels rise, the kidneys produce more urine to eliminate the excess sugar.

What tests should be done if polyuria develops?

We start with a complete blood count, blood chemistry panel, and urinalysis, and add ultrasound and hormone testing if needed. Pinpointing the exact cause is the first step in treatment.

Can diabetes insipidus be treated?

Treatment is possible depending on the underlying cause. Diabetes mellitus and hyperadrenocorticism can be managed with medication, while the progression of chronic kidney disease can be slowed through proper management.

Can polyuria be prevented?

Regular health check-ups and monitoring of water intake and urine output are important. We especially recommend regular check-ups for senior cats.

Comparison of Characteristics by Cause of Polyuria/Polydipsia

Item	Main symptoms	Main tests	Treatment direction
Chronic kidney disease	Increased urine volume, weight loss, fatigue	Blood test (creatinine, BUN), urine test	Low-protein diet, medication, fluid supplementation
Diabetes mellitus	Drinking a lot of water, weight loss, increased appetite	Blood test (blood glucose), urine test (glucose)	Insulin injection, dietary management, regular monitoring
Hyperadrenocorticism	Drinking a lot of water, excessive urination, muscle weakness	Blood test (cortisol), ultrasound examination	Hormone-regulating medication, surgery (if needed)

Because symptoms and treatment direction differ depending on the cause, accurate diagnosis is essential.

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References

[1] The Veterinary Workbook of Small Animal Clinical Cases, Case 21, 2020

[2] The Cat, Clinical Medicine and Management, 2nd Edition, 2018

[3] Urinalysis in the Dog and Cat, 2019