고양이 신우신염(세균성 신장감염) 증상과 원인, 진단·치료와 관리 포인트 총정리

If Your Cat Is Constantly Lethargic — Symptoms and Treatment Timing for Feline Pyelonephritis

KidneyDiseasesMeongsiljang Veterinary Advisory Board

Feline pyelonephritis is a serious infection caused by bacteria ascending to the kidneys, leading to symptoms such as fever, difficulty urinating, and frequent urination. Early detection and appropriate treatment are crucial.

What Is Feline Pyelonephritis (Bacterial Kidney Infection)?

Anatomical diagram of the feline kidney and urinary tract, highlighting the site of infection

Feline pyelonephritis, or bacterial kidney infection, is a serious condition that occurs when bacteria travel up the urinary tract and infect the kidneys. It can present as either an acute or chronic condition, and without early treatment, it can lead to permanent kidney damage. Senior cats and those with a history of urinary tract issues are at higher risk. When a bacterial infection reaches the kidneys, it can cause a range of symptoms, including pain, fever, and changes in urination. Early detection and appropriate treatment are key to saving your cat’s life. Since the kidneys are vital organs, prevention and consistent care are essential.

What Are the Main Causes of Pyelonephritis?

The primary cause of pyelonephritis in cats is a bacterial infection in the lower urinary tract, such as the bladder, that ascends to the kidneys. If lower urinary tract infections are not treated promptly, bacteria can travel up to the kidneys, leading to pyelonephritis. Risk factors include urinary tract stones, abnormal urinary tract anatomy (urinary tract malformations), immunocompromised states, endocrine disorders like diabetes mellitus, and the presence of indwelling urethral catheters. These factors make it easier for bacteria to establish themselves in the kidneys, increasing the risk of infection. Extra caution is needed, especially in senior cats or those with underlying conditions, and urine culture testing is essential to accurately identify the causative bacteria. Early diagnosis and prevention are key.

Microscopic image of E. coli found in a cat's urine

Check for Key Symptoms and Signs

Feline pyelonephritis can present with a variety of warning signs. If you notice any of the following, your cat needs to see a veterinarian immediately.

Fever: Your cat’s body temperature rises, and they may appear lethargic or less active than usual.

Pollakiuria (frequent urination attempts): They visit the litter box often but may only pass small amounts of urine each time.

Dysuria (difficulty urinating): They may sit in the litter box in apparent discomfort, straining without producing much urine.

Hematuria: Blood may be present in the urine, giving it a reddish or cloudy appearance.

Abdominal or renal pain: Your cat may show signs of pain when their abdomen or kidney area is touched, or they may be reluctant to move.

Loss of appetite and lethargy: They may suddenly eat less and appear weak or listless. If you observe any of these signs, prompt veterinary examination is essential.

Emergency Signs Requiring Immediate Veterinary Visit

If your cat develops a fever, severe pain, is unable to urinate at all, or shows signs of shock accompanied by vomiting, seek veterinary care immediately. These symptoms can lead to a rapid decline in kidney function or sepsis, so prompt treatment can be life-saving.

Diagnostic Methods for Accurate Diagnosis

Pyelonephritis can be tricky to diagnose because its clinical signs are often vague and there is no single definitive test, so we rely on a combination of diagnostic tools to make an accurate assessment. - Urinalysis: Checks for the presence of white blood cells (pyuria), blood (hematuria), and bacteria. - Blood tests: Evaluates kidney function values and provides an overview of your pet’s general health status. - Ultrasound: Visually assesses kidney size and structure, though ultrasound alone is insufficient to confirm pyelonephritis. - Urine culture and sensitivity testing: This is a key test that identifies the specific bacteria causing the infection and predicts which antibiotics will be most effective. Culture is especially important because diluted urine can cause bacteria to be missed. - Palpation of the kidney area: Gently presses on the kidneys and bladder to check for pain responses. We combine the results from these tests to determine the likelihood and severity of pyelonephritis.

An image of a cat undergoing a renal ultrasound.

Treatment Methods and Step-by-Step Management

The cornerstone of treating pyelonephritis is administering antibiotics that target the causative bacteria. Based on urine culture and susceptibility test results, an appropriate antibiotic is selected, and it’s essential to complete the full course prescribed by your veterinarian. Stopping medication prematurely or altering the regimen on your own increases the risk of recurrence. If kidney function is compromised, drug excretion may be delayed, necessitating dosage adjustments. Pain management is also provided to alleviate your cat’s discomfort. In severe cases, hospitalization may be required for intravenous fluid and medication administration. Even after treatment, regular check-ups are necessary to continuously monitor kidney function and watch for any signs of recurrence.

Administering antibiotics to a cat via intravenous injection

Home Care Points

During the treatment period, it’s important to keep your cat’s environment stable. Provide fresh water frequently and increase their fluid intake by offering wet food. Keep the litter box clean and ensure it’s comfortable for your cat to use. Administer medications at the exact prescribed times, and contact your veterinarian immediately if you notice any adverse reactions. To reduce stress, provide a quiet space and maintain a consistent daily routine. Regular vet visits and check-ups are also essential.

Creating a stable treatment environment for cats

Preventing Recurrence and Breed-Specific Precautions

Cats with a history of urinary tract stones or recurrent urinary tract infections, senior cats, and those with underlying conditions such as diabetes are at a relatively higher risk of pyelonephritis recurrence. Early detection through regular urinalysis (including urine culture when necessary) and kidney function tests is crucial. Additionally, maintaining adequate hydration supports urinary tract health.

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

Can feline pyelonephritis be treated?

Yes, most cases can be fully cured with appropriate antibiotic treatment and care. However, if the treatment period is not properly followed, the condition may recur, so it's important to strictly adhere to the medication schedule.

What tests should be done if pyelonephritis develops?

We need to accurately determine the cause of the infection and assess kidney function through urine tests, blood tests, ultrasound, and if necessary, a urine culture.

Could my cat’s inability to urinate be pyelonephritis?

Yes, the complete inability to urinate can be an emergency. This may indicate a urinary tract obstruction, which requires immediate veterinary attention.

What should I do if pyelonephritis recurs?

If the condition recurs, we need to reevaluate the underlying cause and check for antibiotic resistance. Long-term management to support urinary tract health is also essential.

How can I encourage my cat to drink more water?

Offering wet food, refreshing water frequently, and using a flowing-water fountain can all help increase your cat’s water intake. Many cats are also drawn to the sound of running water.

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References

[1] Langston, C.E. et al. (2023) Small Animal Critical Care Medicine, 3rd Edition. Elsevier.

[2] The Cat, Clinical Medicine and Management, 2nd Edition (2022). Wiley-Blackwell.

[3] Plumb's Veterinary Drug Handbook, 9th Edition (2023). Wiley.