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Perirenal Pseudocyst (Fluid Accumulation around the Kidneys) in Dogs

Occurrence: rarer
Location of illness: Abdomen/pelvis

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

A perirenal pseudocyst in dogs is an abnormal accumulation of fluid between the renal capsule and the renal parenchyma. This fluid accumulation is not surrounded by an epithelial membrane, which distinguishes it from true cysts.

The most important facts at a glance

Perirenal pseudocysts are fluid accumulations between the renal capsule and the kidney in dogs. These pseudocysts differ from true cysts because they are not surrounded by a cell layer, but are bounded by the surrounding tissue. The causes are varied and can be divided into primaryPrimary refers to the first or original cause of a disease or condition, as opposed to secondary causes or symptoms that develop from it., such as traumas, and secondary causes, such as systemic diseases. Symptoms can include an enlarged kidney, increased thirst, increased urination, Vomiting, and loss of appetite. 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. is made by clinical examination, 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 blood tests to assess kidney function. If necessary, fine needle aspiration can be performed. The treatment depends on the size and symptoms of the pseudocyst. Small, asymptomaticAsymptomatic means that there are no recognizable symptoms of a disease. An animal can have a disease or infection without showing visible signs, which can make diagnosis and treatment more difficult. pseudocysts are often monitored, while larger ones may need to be punctured or surgically treated. 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. depends on the size of the pseudocyst and the underlying cause. Preventive measures include regular veterinary examinations and a balanced diet to promote kidney health. Research focuses on the causes, 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 options for perirenal pseudocysts, including minimally invasiveInvasive describes medical procedures or pathogens that enter the body or penetrate tissue. In medicine, invasive procedures can range from minimally invasive techniques to open surgery. techniques and pharmacological approaches. Advances in research contribute to improving the quality of life of affected dogs.

Causes

The kidneys are responsible for filtering waste products from the blood and regulating the body’s water balance. Each kidney is surrounded by a capsule that is normally tightly adhered. In a perirenal pseudocyst, fluid collects in the space between this capsule and the kidney itself. This fluid accumulation can have various causes and does not always have to be associated with direct damage to the kidney.

A key difference between pseudocysts and true cysts is that pseudocysts are not lined by an epithelial membrane. True cysts have a clear cell layer that encloses the fluid, while pseudocysts are only bounded by the surrounding tissue.

The causes of perirenal pseudocysts are not fully understood, but can be divided into primaryPrimary refers to the first or original cause of a disease or condition, as opposed to secondary causes or symptoms that develop from it. and secondary causes. PrimaryPrimary refers to the first or original cause of a disease or condition, as opposed to secondary causes or symptoms that develop from it. causes refer to direct changes or damage in the area of the kidney or renal capsule. These include traumas that can lead to Bleeding or fluid accumulation.

Secondary causes can include systemic diseases that indirectly lead to fluid accumulation. 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 diseases, such as 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 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., can also lead to fluid accumulation because they impair kidney function and disrupt normal fluid regulation.

Another possible cause is the blockage of lymphatic or blood vessels, which hinders fluid drainageDrainage refers to the removal of fluid from body cavities, Wounds, or inflamed areas, often using a tube or other device. It is used to prevent infection and promote healing. from the region. Infections or inflammatory conditions can also play a role by promoting excessive fluid production or accumulation.

Symptoms

Very common symptoms:

Common symptoms:

Rare symptoms:

Lethargy

The symptoms of a perirenal pseudocyst can be variable and often depend on the size of the fluid accumulation and the resulting pressure on the kidney and surrounding structures. With small pseudocysts, the symptoms may be mild or non-existent.

Common symptoms include lethargy and general malaise. This may indicate that the kidney is not functioning optimally and the dog is not feeling well overall. Another indicationIndication refers to a valid reason or rationale for using a specific treatment, medication, or medical procedure. It is based on the diagnosis and the patient’s clinical condition. may be a reduced food intake or loss of appetite.

With larger pseudocysts, 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. pain may occur, which is noticeable through Sensitivity to touch or defensive behavior when palpating. The dog may also show signs of Nausea or Vomiting, which can be caused by pressure on the gastrointestinalGastrointestinal refers to the gastrointestinal tract, a system that extends from the oral cavity to the anus and is responsible for the digestion of food and the absorption of nutrients. tract or by Kidney function impaired.

Another possible symptom is altered urination, either in the form of increased or decreased urine output. This may be an indicationIndication refers to a valid reason or rationale for using a specific treatment, medication, or medical procedure. It is based on the diagnosis and the patient’s clinical condition. that the Kidney function impaired.

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 a perirenal pseudocyst usually begins with a thorough clinical examination and collection of the animal’s medical 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.. The veterinarian will ask about symptoms and palpate the dog’s abdomenThe abdomen, also known as the abdominal cavity, is the part of the body located between the rib cage and the pelvis. It houses several important organs, including the stomach, liver, kidneys, intestines, and spleen. to check for any Pain or enlargements.

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. are crucial for 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.. An 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. can make the Fluid accumulation around the kidneys visible and helps to determine the size and extent of the pseudocyst. In some cases, computed tomography (CT)Computed tomography (CT) is an imaging technique that uses X-rays and computer technology to create cross-sectional images of the body. It enables a detailed view of bones, organs, and other structures and is used for the diagnosis of injuries, diseases, and for planning medical interventions. or magnetic resonance imaging (MRI)Magnetic resonance imaging is an imaging technique that uses strong magnetic fields and radio waves to create detailed images of the inside of the body. It is used in veterinary medicine to diagnose diseases of the brain, spine, and other organs. may also be necessary to obtain a more detailed picture of the kidney region.

Blood tests are also important to assess overall kidney function and rule out other possible causes of the symptoms. Blood values such as 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. and urea are typically measured. Urine tests can also be performed to obtain indications of an underlying Kidney function impaired.

In some cases, fine needle aspiration of the fluid can be performed under 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. guidance to obtain samples for cytological examination. This can help to identify Entzündungen, infections, or other pathologicalPathological refers to anything related to diseases or their processes. Pathological changes are those that deviate from the normal structure or function and indicate a disease. processes.

Therapy

The treatment of a perirenal pseudocyst depends on the size of the cystA cyst is a closed sac that may contain fluid, air, or other material. Cysts can occur in any part of the body and vary in size and cause., the symptoms, and the underlying cause. In many cases, conservative treatment with regular monitoring may be sufficient, especially if the pseudocyst is small and does not cause significant symptoms.

For symptomatic or large pseudocysts, drainageDrainage refers to the removal of fluid from body cavities, Wounds, or inflamed areas, often using a tube or other device. It is used to prevent infection and promote healing. of the fluid by puncture under 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. guidance may be necessary. This can reduce the pressure on the kidney and relieve the symptoms. However, there is a risk of the fluid reaccumulating, which is why regular check-ups are necessary.

In some cases, surgical intervention may be required, especially if the pseudocyst repeatedly causes problems or if there is an underlying condition that needs to be treated surgically. This may involve removing the cystA cyst is a closed sac that may contain fluid, air, or other material. Cysts can occur in any part of the body and vary in size and cause. or reconstructing the affected vessels or tissues.

Treating underlying conditions, such as infections or 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., is also crucial. This may include medications to support kidney function, antibiotics, or other specific therapies.

Prognosis and follow-up care

The prognosis for dogs with perirenal pseudocysts depends on several factors, including the cause of the cystA cyst is a closed sac that may contain fluid, air, or other material. Cysts can occur in any part of the body and vary in size and cause., its size, and the response to treatment. Smaller pseudocysts that do not cause significant symptoms and are not associated with a serious underlying disease may have a good 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..

In dogs with large or symptomatic pseudocysts, 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. may be more variable. If the fluid accumulation can be treated successfully and there is no serious underlying disease, the prognosis can be favorable. Successful surgical treatment can also lead to a good long-term 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..

However, if there is a serious underlying kidney disease or the pseudocysts repeatedly cause problems, 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. may be more guarded. Close monitoring and regular veterinary care are important here.

Prevention

The preventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring. of perirenal pseudocysts can be difficult, as the exact causes are often unknown and the development cannot always be avoided. However, a general measure to promote kidney health is regular veterinary examination to detect and treat signs of kidney disease early.

A balanced diet and adequate fluid intake are also important to support kidney function. Early treatment of kidney or urinary tract diseases can also help reduce the risk of complications such as pseudocysts.

Avoiding traumas that could lead to injuries to the kidney region is also a practical measure. Owners should ensure that their dogs live in a safe environment and do not get into dangerous situations that could lead to injuries.

Outlook on current research

The perirenal pseudocyst in dogs represents a relatively rare but clinically significant phenomenon. Current research focuses on understanding the development and optimal treatment options for this fluid accumulation that occurs between the renal capsule and the surrounding tissue. A key focus is on identifying predisposing factors and differentiating them from other pathologicalPathological refers to anything related to diseases or their processes. Pathological changes are those that deviate from the normal structure or function and indicate a disease. conditions affecting the kidney.

Studies suggest that the formation of perirenal pseudocysts often occurs secondary to other underlying kidney diseases, such as 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 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. or neoplasms. Research is intensively investigating how perirenal pseudocysts affect the function of the kidneys and what role inflammatory conditions play in their development.

Another area of research focuses on diagnostic methods for detecting perirenal pseudocysts. Imaging techniques 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. and magnetic resonance imaging (MRI)Magnetic resonance imaging is an imaging technique that uses strong magnetic fields and radio waves to create detailed images of the inside of the body. It is used in veterinary medicine to diagnose diseases of the brain, spine, and other organs. are being increasingly refined to enable a more precise 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.. Advances in imaging not only help to identify the pseudocysts, but also to assess their size and their impact on the surrounding structures.

Regarding treatment, both surgical and conservative approaches are being investigated. Surgical removal of the cystA cyst is a closed sac that may contain fluid, air, or other material. Cysts can occur in any part of the body and vary in size and cause. or draining the fluid may be necessary to relieve the symptoms and improve kidney function. New minimally invasiveInvasive describes medical procedures or pathogens that enter the body or penetrate tissue. In medicine, invasive procedures can range from minimally invasive techniques to open surgery. techniques are being developed to minimize the risk of complications and shorten recovery time.

In parallel, pharmacological approaches are also being explored that aim to reduce fluid accumulation and treat the underlying kidney disease. Experimental studies with anti-inflammatory and nephroprotective drugs show promising results that could potentially influence future treatment standards.

Genetic studies are also an important part of current research. It is being investigated whether certain genetic predispositions play a role in the formation of perirenal pseudocysts and whether genetic markers can be identified that indicate an increased risk for the development of this disease.

In summary, research on perirenal pseudocysts in dogs is a dynamic field that is constantly evolving. There is a growing understanding of the underlying mechanisms that lead to their formation and the best ways to optimize 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. Advances in research contribute to improving the quality of life of affected dogs and enriching veterinary medicine as a whole.

Frequently asked questions (FAQs)

What are perirenal pseudocysts in dogs? Perirenal pseudocysts are fluid accumulations that form between the renal capsule and the surrounding tissue of a dog. They are called “pseudo” because they do not have a true cystA cyst is a closed sac that may contain fluid, air, or other material. Cysts can occur in any part of the body and vary in size and cause. wall.
What symptoms can occur in a dog with perirenal pseudocysts? Symptoms can be non-specific and range from loss of appetite, Weight loss, 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. pain to changes in urinary behavior. In severe cases, Kidney function impaired may occur.
How are perirenal pseudocysts diagnosed? 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. is usually made through a combination of clinical examination, blood tests to assess kidney function, and 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 MRI, which can make the fluid accumulation visible.
What causes perirenal pseudocysts in dogs? The exact cause is often unknown, but they can occur secondary to other kidney diseases, injuries, or Tumors. Inflammatory conditions also play a role.
Can perirenal pseudocysts disappear on their own? In some cases, smaller pseudocysts may regress on their own, especially if the underlying cause is treated. However, larger or symptomatic pseudocysts often require medical or surgical intervention.
What treatment options are available for perirenal pseudocysts? The treatment depends on the size of the pseudocyst and the underlying causes. Options include surgical removal, puncturing to drain the fluid, or drug therapies to treat the underlying disease.
What is 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. for dogs with perirenal pseudocysts? 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. varies depending on the severity of the disease and the underlying cause. With 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 appropriate treatment, 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. can be positive, especially if kidney function is maintained.
Are certain dog breeds more susceptible to perirenal pseudocysts? So far, there are no specific breeds that are considered particularly susceptible. However, research is investigating possible genetic predispositions that could increase the risk.
How can I reduce the risk of perirenal pseudocysts in my dog? Regular veterinary examinations, a balanced diet, and treatment of underlying health problems can help reduce the risk. Early detection and treatment of kidney diseases are crucial.
Are there long-term complications associated with perirenal pseudocysts? Long-term complications can occur, especially if the pseudocysts remain untreated or impair kidney function. 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 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. or recurrentRecurrent refers to a disease that repeatedly returns or worsens after a temporary remission or improvement. fluid accumulations are possible complications.