If Your Dog Has High Fever and Hematuria — Causes and Treatment Timing for Pyelonephritis

KidneyDiseasesMeongsiljang Veterinary Advisory Board

Pyelonephritis in dogs is an upper urinary tract disease in which bacteria ascend from the bladder to the kidneys. Early antibiotic treatment is key to preventing kidney damage.

What Is Pyelonephritis in Dogs?

Pyelonephritis in dogs is an upper urinary tract infection caused by bacteria traveling up from the bladder through the ureters to inflame the kidneys and renal pelvis (the area where urine collects). Early treatment is essential. If your dog shows signs such as fever, pain when the lower back is touched, or significantly increased water intake, it may not be simple cystitis, and you should visit the vet within 24 hours. Delayed treatment can lead to kidney tissue damage and progress to chronic renal failure.

Causes and Pathogenesis

In most cases, the infection starts when bacteria like E. coli, which were in the bladder, travel up the ureters and reach the kidneys. The risk increases if cystitis is left untreated for a long time, or if there are underlying conditions that obstruct urine flow or weaken the immune system, such as bladder stones, prostate disease, or diabetes. Female pets are more susceptible because their urethra is shorter and closer to the anus, while intact male pets may develop the infection spreading from a prostate infection.

Key Symptom Checklist

Unlike cystitis, this condition is characterized by the presence of systemic symptoms.

Fever: Body temperature rises above 39.5°C, with warm ears and paw pads.

Back pain: The pet may flinch or whine when the back or sides are touched.

Polydipsia and polyuria: Excessive water intake and increased urine volume.

Hematuria and cloudy urine: Pink or brown discoloration with a strong odor.

Loss of appetite and lethargy: Skipping meals and remaining lying down.

Vomiting: May occur as kidney function declines.

If two or more of these symptoms overlap, seek veterinary care immediately.

Go to the Hospital Immediately for These Signs

If any of the following symptoms are present, it is an emergency. Go immediately to a 24-hour emergency animal hospital, even at night. • Persistent high fever above 40°C that does not subside • Complete inability to urinate or no urination for more than 12 hours • Repeated vomiting and inability to drink water • Pale or yellowish gums • Clouded consciousness and unsteady gait At this stage, the condition may be progressing to sepsis or acute kidney failure. Monitoring at home could be fatal.

How Is It Diagnosed at the Hospital?

To distinguish simple cystitis from more serious conditions, we need to look at several test results together. Typically, a urinalysis is used to check for inflammatory cells (white blood cells) and bacteria. Before starting antibiotics, a urine culture is performed to identify the specific causative bacteria and determine which antibiotics will be most effective. Blood tests are used to monitor inflammatory markers (such as an elevated white blood cell count with a left shift) and kidney function indicators (BUN and creatinine). In cases of acute pyelonephritis where the patient is well-hydrated and not dehydrated, kidney function values may still appear normal. An ultrasound can help identify upper urinary tract infections by revealing dilation of the renal pelvis or changes in kidney structure; however, since renal pelvis dilation isn't always present and ultrasound alone cannot provide a 100% definitive diagnosis, we make our assessment by synthesizing all test results. It takes a few days to receive culture results, which are necessary to accurately identify the causative bacteria and their antibiotic susceptibility.

How Is Treatment Conducted?

The key is using the right antibiotic for an adequate duration. Pyelonephritis is a deeper tissue infection than cystitis, so antibiotics are typically continued for several weeks. It is also crucial to identify and address any underlying conditions, such as bladder stones, prostate disease, or diabetes, as this is vital for successful treatment. We start with broad-spectrum antibiotics before culture results are available, then switch to a targeted antibiotic once the specific bacteria are identified. Fluid therapy helps reduce dehydration and lessen the burden on the kidneys, while severe vomiting or pain may require hospitalization for intravenous management. Do not stop medication on your own, as this can lead to recurrence or antibiotic resistance. Even if symptoms improve, complete the full prescribed course, and confirm a cure with a follow-up urine culture 1–2 weeks after finishing the antibiotics.

A veterinarian administering an IV drip to a puppy

Home Care Instructions

Home care during treatment and recovery is crucial in preventing recurrence.

Ensure adequate hydration: Provide 50–70 ml of fresh water per kg of body weight daily, placed in multiple locations.

Avoid holding urine: Encourage urination every 2–4 hours through walks or using a pee pad.

Maintain a low-sodium diet: Prioritize veterinarian-prescribed renal diets or low-sodium meal plans.

Complete the full antibiotic course: Continue medication for the entire prescribed duration, even if symptoms improve.

Schedule follow-up testing: A repeat urinalysis is essential 1–2 weeks after treatment ends.

Consult your veterinarian before using any home remedies or cranberry supplements.

Recurrence Precautions by Breed and Condition

Regular monitoring is essential in the following cases due to a high risk of recurrence: • Dalmatians, Schnauzers, and Yorkshire Terriers with a history of bladder stones • Middle-aged and senior dogs with Cushing’s disease or diabetes • Intact male dogs (who may have concurrent prostate infections) • Dogs unable to urinate properly due to spinal disorders In these situations, it is advisable to perform urinalysis 2 to 4 times a year to detect hidden reinfections. Even without symptoms, bacteria may persist in the urinary tract, a condition known as asymptomatic bacteriuria.

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

How is cystitis different from pyelonephritis?

Cystitis is an infection limited to the lower urinary tract (the bladder), with few systemic symptoms such as fever or back pain. Pyelonephritis, on the other hand, is an upper urinary tract infection that has spread to the kidneys, accompanied by fever, decreased appetite, and flank pain. Because it involves deeper tissue infection, the treatment course is significantly longer than for cystitis—often extending over several weeks—and may be further prolonged if underlying conditions are present. Therefore, it is important to distinguish between the two through diagnostic testing, as their management approaches differ.

I’ve been giving my pet antibiotics for two weeks, and their symptoms have improved. Is it okay to stop the medication now?

No, you shouldn’t stop the medication. Even if the symptoms disappear, bacteria may still remain in the kidney tissue. Stopping the treatment prematurely can lead to a relapse or the development of antibiotic-resistant bacteria, making future treatment much more difficult. Be sure to complete the full prescribed course, and confirm complete recovery with a follow-up urine culture test one to two weeks after finishing the antibiotics.

Does kidney disease cause permanent damage once it develops?

With early treatment, most pets can nearly fully recover their kidney function. However, if diagnosis is delayed or if infections recur, permanent damage to kidney tissue can occur, potentially leading to chronic kidney failure. Therefore, it is important to monitor kidney function and check for reinfection through regular check-ups for a certain period after the initial diagnosis.

Is there a way to prevent it?

While complete prevention is difficult, you can significantly reduce the risk. Ensure your pet stays well-hydrated and provide frequent opportunities for walks and bathroom breaks so they don’t have to hold their urine for long periods. For female pets, keep the area around the anus clean after elimination. If you notice signs of cystitis, such as frequent urination or blood in the urine, seek treatment early to prevent the infection from spreading to the kidneys.

How much does treatment usually cost?

Costs vary depending on the clinic and the severity of the condition, but for small to medium-sized clinics, outpatient care, diagnostic tests, and a two- to three-week course of antibiotics typically range from $100 to $400. Severe cases requiring hospitalization, intravenous fluids, and repeat cultures can exceed $700. Please contact your veterinary clinic directly for an accurate cost estimate.

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References

[1] Ettinger SJ, Feldman EC, Cote E. Textbook of Veterinary Internal Medicine, 8th Edition, Chapter: Pyelonephritis

[2] Nelson RW, Couto CG. Small Animal Internal Medicine, 6th Edition, Chapter: Disorders of the Urinary Tract

[3] Weese JS et al., International Society for Companion Animal Infectious Diseases (ISCAID) Guidelines for the diagnosis and management of bacterial urinary tract infections in dogs and cats, 2019