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Pyelonephritis (Kidney Pelvis Inflammation) in Dogs

Occurrence: rarer
Location of illness: Abdomen/pelvis

Author: Dr. med. vet. Gisa Löwe | Last modified: 06.11.2025

Pyelonephritis is an inflammation of the kidney pelvis and the surrounding kidney tissue in dogs, usually caused by a bacterial infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease..

The most important facts at a glance

Pyelonephritis in dogs is an inflammation of the kidney pelvis caused by ascending bacterial infections, mostly from bacteriaBacteria are microscopic, single-celled organisms that exist in almost every environment on Earth. Some types of bacteria are beneficial or even essential to life, while others can cause disease. of the intestinalIntestinal refers to the intestine, the part of the digestive tract that extends from the stomach to the anus. Intestinal diseases affect the small and/or large intestine. flora such as Escherichia coli. These bacteriaBacteria are microscopic, single-celled organisms that exist in almost every environment on Earth. Some types of bacteria are beneficial or even essential to life, while others can cause disease. typically enter the kidneys from the bladder via the ureters. Factors such as urinary tract abnormalities, urinary stones, or a weakened immune systemThe immune system is the body's defense system against infectious agents such as bacteria, viruses, fungi, and parasites. It comprises a complex network of organs, cells, and molecules that work together to protect the body. increase the risk. Common symptoms include Fever, painful and frequent urination, and foul-smelling urine. DiagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients. is made by physical examination, blood tests, and urinalysis to identify bacteriaBacteria are microscopic, single-celled organisms that exist in almost every environment on Earth. Some types of bacteria are beneficial or even essential to life, while others can cause disease. or signs of infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease.. Imaging procedures can reveal structural abnormalities in the kidneys. Treatment typically includes antibiotics tailored to the specific bacteriaBacteria are microscopic, single-celled organisms that exist in almost every environment on Earth. Some types of bacteria are beneficial or even essential to life, while others can cause disease., as well as measures to support kidney function such as fluid administration. Surgery may be required for anatomical abnormalities. The prognosisThe prognosis is the prediction of the likely course and outcome of a disease based on the general state of health, the nature of the disease, and the response to treatment. It can provide information on how a disease is expected to develop. is good with early treatment, while chronicChronic refers to a condition or disease that is long-lasting or permanent. Chronic diseases often develop slowly and can lead to persistent or recurring health problems over time. cases have a more guarded prognosisThe prognosis is the prediction of the likely course and outcome of a disease based on the general state of health, the nature of the disease, and the response to treatment. It can provide information on how a disease is expected to develop.. PreventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring. aims to avoid Urinary tract infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease. and maintain good health, through regular veterinary examinations, balanced nutrition, and adequate hydration. Research focuses on developing new diagnostic methods, antibiotic resistanceResistance refers to the ability of microorganisms to withstand the effects of antibiotics, antifungals, or other antimicrobial drugs. Resistance can also refer to the body's ability to be insensitive to diseases or toxins., and genetic predispositions to improve treatment and preventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring.. Phage therapyTherapy refers to the treatment of diseases or disorders with the aim of alleviating symptoms, promoting healing, or improving quality of life. Therapies can be medicinal, surgical, or through other medical interventions. and vaccines are also being investigated as potential new approaches.

Causes

The kidneys are vital organs responsible for filtering waste products from the blood and forming urine. Pyelonephritis specifically affects the kidney pelvis, the part of the kidney that collects urine before it enters the ureterThe ureter is the tube that connects the kidneys to the bladder. There are two ureters that transport urine from the kidneys to the bladder.. This inflammation usually results from bacteriaBacteria are microscopic, single-celled organisms that exist in almost every environment on Earth. Some types of bacteria are beneficial or even essential to life, while others can cause disease. ascending from the lower urinary tract, eventually infecting the kidney tissue.

The most common way for bacteriaBacteria are microscopic, single-celled organisms that exist in almost every environment on Earth. Some types of bacteria are beneficial or even essential to life, while others can cause disease. to reach the kidneys is through an ascending infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease.. This means that the bacteriaBacteria are microscopic, single-celled organisms that exist in almost every environment on Earth. Some types of bacteria are beneficial or even essential to life, while others can cause disease. travel from the bladder through the ureters into the kidneys. Predisposing factors may include urinary tract abnormalities, urinary stones, or a weakened immune systemThe immune system is the body's defense system against infectious agents such as bacteria, viruses, fungi, and parasites. It comprises a complex network of organs, cells, and molecules that work together to protect the body. in the dog. Sometimes, bacterial infections can also reach the kidneys from other parts of the body via the bloodstream, although this is less common.

Often, Escherichia coli and other gram-negative bacteriaBacteria are microscopic, single-celled organisms that exist in almost every environment on Earth. Some types of bacteria are beneficial or even essential to life, while others can cause disease. are the main causes of the infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease.. These bacteriaBacteria are microscopic, single-celled organisms that exist in almost every environment on Earth. Some types of bacteria are beneficial or even essential to life, while others can cause disease. are often part of the normal intestinalIntestinal refers to the intestine, the part of the digestive tract that extends from the stomach to the anus. Intestinal diseases affect the small and/or large intestine. flora but can cause problems when they enter the urinary tract. The risk of pyelonephritis can be increased by urinary outflow disorders or insufficient drinking water intake.

Symptoms

Very common symptoms:

Common symptoms:

The symptoms of pyelonephritis in dogs can vary, depending on the severity of the infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease. and the dog’s response to it. Common signs include Fever, loss of appetite, and depressionDepression refers to a state of reduced mood and activity. In dogs and cats, it can be triggered by various factors, including illness, trauma, or changes in the environment.. Dogs may also show signs of Pain or discomfort in the abdominalThe term “abdominal” refers to anything that concerns the belly or the abdomen. It is an adjectival expression used to describe the location, symptoms, or conditions that occur in the abdominal area. area, especially in the back area near the kidneys.

Another symptom may be increased thirst and frequent urination, which indicates impaired kidney function. Some dogs also show blood in the urine or foul-smelling urine. In severe cases, Vomiting, lethargy, and Weight loss may occur.

ChronicChronic refers to a condition or disease that is long-lasting or permanent. Chronic diseases often develop slowly and can lead to persistent or recurring health problems over time. pyelonephritis may have more subtle symptoms that develop slowly. These may include a gradual decrease in physical condition and sporadicSporadic refers to the occasional, irregular occurrence of diseases or conditions without a recognizable pattern or fixed time intervals. episodes of discomfort. Because the symptoms are wide-ranging, it is important to consult the veterinarian early if a kidney disease is suspected.

Diagnosis

The diagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients. of pyelonephritis usually begins with a thorough physical examination and the collection of the dog’s medical history. Particular attention is paid to symptoms that may indicate kidney problems. Blood tests are an essential part of the diagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients., as they can help detect signs of kidney dysfunctionDysfunction refers to an impaired or abnormal function of an organ or system in the body. This can be due to diseases, disorders, or damage and can affect the quality of life., such as elevated urea and creatinineCreatinine is a waste product that results from the breakdown of creatine, a chemical compound that provides energy in the muscles. The concentration of creatinine in the blood and urine is an important indicator of kidney function. levels.

A urinalysis is also important to look for bacteriaBacteria are microscopic, single-celled organisms that exist in almost every environment on Earth. Some types of bacteria are beneficial or even essential to life, while others can cause disease., white blood cells, or blood in the urine, which may indicate an infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease.. A urine culture can help identify the specific bacteriaBacteria are microscopic, single-celled organisms that exist in almost every environment on Earth. Some types of bacteria are beneficial or even essential to life, while others can cause disease. causing the infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease., which is crucial for choosing the appropriate antibiotic.

Imaging procedures such as ultrasoundUltrasound refers to sound waves that are above the hearing threshold of the human ear. In medicine, ultrasound is used for diagnostic imaging procedures to visualize internal organs, tissues, and blood flow. or X-rays can be used to detect structural changes in the kidneys, such as enlargement or abnormalities in the kidney pelvis. These examinations can also help rule out other possible causes of the symptoms, such as tumors or Nephrolithiasis (kidney stones).

Therapy

Treatment of pyelonephritis in dogs is usually done with antibiotic therapyTherapy refers to the treatment of diseases or disorders with the aim of alleviating symptoms, promoting healing, or improving quality of life. Therapies can be medicinal, surgical, or through other medical interventions. specifically tailored to the identified bacteriaBacteria are microscopic, single-celled organisms that exist in almost every environment on Earth. Some types of bacteria are beneficial or even essential to life, while others can cause disease.. Long-term therapy of two to six weeks is generally recommended to ensure that the infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease. is completely eliminated.

In addition to antibiotic therapyTherapy refers to the treatment of diseases or disorders with the aim of alleviating symptoms, promoting healing, or improving quality of life. Therapies can be medicinal, surgical, or through other medical interventions., supporting kidney function may be necessary, especially in more severe cases. This includes administering intravenous fluids to prevent dehydrationDehydration occurs when the body loses more fluid than it takes in. This can lead to a number of problems, including headaches, Dizziness, and in extreme cases, renal failure or Cardiovascular collapse. and flush the kidneys. Pain relievers may also be prescribed to relieve the dog’s discomfort.

In dogs with recurrentRecurrent refers to a disease that repeatedly returns or worsens after a temporary remission or improvement. infections or anatomical abnormalities that contribute to pyelonephritis, surgical intervention may be necessary to correct underlying problems. Regular follow-up examinations are important to monitor the success of the treatment and ensure that the infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease. does not recur.

Prognosis and follow-up care

The prognosis for dogs with pyelonephritis depends on various factors, including the severity of the infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease., the dog’s general health, and the speed of diagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients. and treatment. With early detection and appropriate therapyTherapy refers to the treatment of diseases or disorders with the aim of alleviating symptoms, promoting healing, or improving quality of life. Therapies can be medicinal, surgical, or through other medical interventions., the prognosisThe prognosis is the prediction of the likely course and outcome of a disease based on the general state of health, the nature of the disease, and the response to treatment. It can provide information on how a disease is expected to develop. is usually good, and many dogs recover completely.

Dogs with chronicChronic refers to a condition or disease that is long-lasting or permanent. Chronic diseases often develop slowly and can lead to persistent or recurring health problems over time. or recurrentRecurrent refers to a disease that repeatedly returns or worsens after a temporary remission or improvement. pyelonephritis may have a more guarded prognosisThe prognosis is the prediction of the likely course and outcome of a disease based on the general state of health, the nature of the disease, and the response to treatment. It can provide information on how a disease is expected to develop., especially if there is permanent impairment of kidney function. Close monitoring and, if necessary, adjustment of treatment are essential in such cases to ensure the dog’s quality of life.

Long-term complications can occur if the infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease. is not treated effectively, including the development of chronicChronic refers to a condition or disease that is long-lasting or permanent. Chronic diseases often develop slowly and can lead to persistent or recurring health problems over time. kidney disease. Therefore, adherence to the veterinarian’s treatment recommendations is crucial for a successful recovery.

Prevention

Preventive measures to avoid pyelonephritis in dogs mainly focus on preventing Urinary tract infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease. and maintaining good general health. Regular veterinary examinations are important to detect early signs of infections or other health problems.

A balanced diet and adequate hydration are essential to support kidney function and reduce the risk of Urinary tract infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease.. Dogs should have access to fresh water, and care should be taken to ensure that they can urinate regularly to flush the urinary tract.

In dogs that are prone to Urinary tract infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease. or kidney problems, the veterinarian may recommend special diets or supplements to promote urinary tract health. In some cases, prophylactic antibiotics or other medications may also be considered to minimize the risk of infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease..

Good hygiene, especially in dogs with long fur in the genital area, can also help prevent the accumulation of bacteria that could cause infections. Regular grooming and cleaning are simple but effective measures to support the health of the urinary system.

Outlook on current research

Pyelonephritis in dogs is a serious disease caused by bacterial infections that affect the kidney pelvis and kidney tissue. Current research focuses on identifying the most common pathogens and developing more effective treatment strategies. There is increasing investigation into how different bacterial strains develop resistanceResistance refers to the ability of microorganisms to withstand the effects of antibiotics, antifungals, or other antimicrobial drugs. Resistance can also refer to the body's ability to be insensitive to diseases or toxins. to antibiotics, which makes treatment more difficult. Researchers are working to develop new antibiotics or alternative treatment methods to circumvent these resistances.

Another important area of research is the improvement of diagnostic methods. Currently, work is underway to develop faster and more accurate diagnostic tests that can not only confirm the presence of infections but also identify the specific pathogens. This would allow veterinarians to create more targeted and effective treatment plans.

In addition, studies are being conducted to investigate the genetic factors that may make certain dogs more susceptible to pyelonephritis. Some dog breeds appear to be more susceptible to Urinary tract infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease., which may be due to genetic predispositions. By deciphering these genetic factors, scientists hope to develop preventive measures that reduce the risk for susceptible breeds.

The role of the immune systemThe immune system is the body's defense system against infectious agents such as bacteria, viruses, fungi, and parasites. It comprises a complex network of organs, cells, and molecules that work together to protect the body. in defending against infections is also being intensively researched. Scientists are investigating how the immune systemThe immune system is the body's defense system against infectious agents such as bacteria, viruses, fungi, and parasites. It comprises a complex network of organs, cells, and molecules that work together to protect the body. of dogs responds to pyelonephritis and which immune mechanisms may be enhanced or modulated to promote healing. This could lead to new immunotherapeutic approaches that could be used alongside or instead of antibiotics.

Another exciting area of research is the application of phage therapyTherapy refers to the treatment of diseases or disorders with the aim of alleviating symptoms, promoting healing, or improving quality of life. Therapies can be medicinal, surgical, or through other medical interventions. in dogs. Phages are viruses that can specifically infect and destroy bacteriaBacteria are microscopic, single-celled organisms that exist in almost every environment on Earth. Some types of bacteria are beneficial or even essential to life, while others can cause disease.. Researchers are investigating whether phages can be used to combat the specific bacteriaBacteria are microscopic, single-celled organisms that exist in almost every environment on Earth. Some types of bacteria are beneficial or even essential to life, while others can cause disease. that cause pyelonephritis and whether this method can be used safely and effectively in dogs.

In the area of preventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring., studies focus on nutrition and lifestyle factors that could reduce the risk of Urinary tract infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease. and pyelonephritis in dogs. Research is being conducted to determine which diets and nutritional supplements could help promote a healthy urinary tract and immune systemThe immune system is the body's defense system against infectious agents such as bacteria, viruses, fungi, and parasites. It comprises a complex network of organs, cells, and molecules that work together to protect the body. to prevent infections.

The role of probiotics and prebiotics in supporting urinary tract health is also being examined. Researchers are investigating whether supplementing dog diets with specific probiotics can positively influence the balance of microflora in the urinary tract and thus reduce the risk of infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease..

In addition, there is ongoing research into the development of vaccines against common bacterial pathogens that cause pyelonephritis. These vaccines could help reduce the incidenceIncidence refers to the number of new cases of a disease or condition that occur within a specific time period in a specific population group. It provides information about the risk of contracting the disease. of the disease and prevent the occurrence of severe infections.

The investigation of environmental factors that can contribute to infections is also of interest. Studies are examining how factors such as cleanliness, stressStress refers to the state of an organism reacting to external stimuli or demands. In veterinary medicine, stress can have physical or psychological effects on animals, impacting their health and well-being., and exposureExposure refers to the Contact with or subjection to certain substances, environmental factors, or pathogens. In veterinary medicine, this can include Contact with toxins, allergens, or infectious agents that can cause health problems in dogs and cats. to other animals can affect susceptibility to pyelonephritis, and how management practices can minimize the risk.

In summary, research on pyelonephritis in dogs is progressing in various areas to improve diagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients., treatment, and preventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring. of the disease. These advances could lead to a better quality of life for affected dogs in the long term and to more efficient management of the disease by veterinarians.

Frequently asked questions (FAQs)

What is Pyelonephritis in Dogs? Pyelonephritis is a bacterial infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease. of the kidney pelvis and kidney tissue in dogs. It can be acuteAcute refers to a condition that occurs suddenly and is usually of short duration. In a medical context, it describes symptoms or illnesses that can quickly become serious and require immediate attention. or chronicChronic refers to a condition or disease that is long-lasting or permanent. Chronic diseases often develop slowly and can lead to persistent or recurring health problems over time. and is often caused by ascending infections from the bladder.
What symptoms do dogs with pyelonephritis show? Symptoms often include frequent urination, Pain when urinating, blood in the urine, Fever, loss of appetite, Weight loss, and occasionally Vomiting. In severe cases, signs of kidney failureRenal failure is a condition in which the kidneys can no longer adequately perform their function of filtering and excreting waste products from the blood. It can be acute or chronic and requires immediate medical treatment. may also occur.
How is pyelonephritis diagnosed in dogs? DiagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients. is made through a combination of urinalysis, blood tests, ultrasoundUltrasound refers to sound waves that are above the hearing threshold of the human ear. In medicine, ultrasound is used for diagnostic imaging procedures to visualize internal organs, tissues, and blood flow., and sometimes X-rays. A urine culture can help identify the specific bacteriaBacteria are microscopic, single-celled organisms that exist in almost every environment on Earth. Some types of bacteria are beneficial or even essential to life, while others can cause disease. that are causing the infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease..
What treatment options are available for pyelonephritis in dogs? Treatment typically includes antibiotics that target the specific pathogens, as well as supportiveSupportive refers to supportive treatments that aim to alleviate symptoms and improve quality of life without directly treating the underlying cause of the disease. measures such as fluid therapyTherapy refers to the treatment of diseases or disorders with the aim of alleviating symptoms, promoting healing, or improving quality of life. Therapies can be medicinal, surgical, or through other medical interventions. and Pain management. In severe cases, hospitalization may be required.
Can pyelonephritis be prevented in dogs? While not all cases can be prevented, regular veterinary examinations, a balanced diet, and good hygiene can help reduce the risk of Urinary tract infection and thus also of pyelonephritis.
Which dogs are most at risk of developing pyelonephritis? Dogs with a historyThe medical history is the systematic collection of a patient's medical history through questioning. It includes information about previous illnesses, treatments, allergies, and lifestyle habits. of urinary tract problems, older dogs, and certain breeds that are more prone to Cystitis are at higher risk. Female dogs are also more susceptible due to their anatomyAnatomy is the scientific study of the structure of living things. It deals with the construction and organization of organisms, including their systems, organs, and tissues..
How long does it take to recover from pyelonephritis in dogs? Recovery time can vary depending on the severity of the infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease. and the response to treatment. Typically, antibiotic treatment lasts several weeks, and full recovery can take months.
Can pyelonephritis in dogs lead to chronicChronic refers to a condition or disease that is long-lasting or permanent. Chronic diseases often develop slowly and can lead to persistent or recurring health problems over time. kidney disease? Yes, untreated or recurrentRecurrent refers to a disease that repeatedly returns or worsens after a temporary remission or improvement. pyelonephritis can permanently damage the kidney tissue and lead to chronicChronic refers to a condition or disease that is long-lasting or permanent. Chronic diseases often develop slowly and can lead to persistent or recurring health problems over time. kidney disease. Therefore, early diagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients. and treatment are crucial.
Are antibiotics always necessary in the treatment of pyelonephritis? Yes, antibiotics are essential for treating bacterial infections such as pyelonephritis. The veterinarian selects the specific antibiotic based on the sensitivity of the identified bacteriaBacteria are microscopic, single-celled organisms that exist in almost every environment on Earth. Some types of bacteria are beneficial or even essential to life, while others can cause disease..
Can home remedies be helpful in the treatment of pyelonephritis? Home remedies alone are not sufficient to treat pyelonephritis. However, they can support recovery, for example through good hydration and the use of diets that promote kidney health. It is important to discuss all home remedies with the veterinarian.