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Schistosomiasis (Parasitic Infection Caused by Worms of the Genus Schistosoma) in Dogs

Occurrence: very rare
Location of illness: Abdomen/pelvis, General/Whole body

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

Schistosomiasis in dogs is a parasiticParasitic refers to diseases or conditions caused by parasites. Parasitic infections can affect the digestive tract, skin, and other organ systems. 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. caused by worms of the genus Schistosoma. This disease can lead to serious health problems, including liver damage and other systemic complications.

The most important facts at a glance

Schistosomiasis is a parasiticParasitic refers to diseases or conditions caused by parasites. Parasitic infections can affect the digestive tract, skin, and other organ systems. 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. that affects dogs and humans and is caused by worms of the genus Schistosoma. These worms go through a life cycle that includes freshwater snails as intermediate hosts. Dogs become infected when they come into contact with contaminatedContaminated describes something that has been polluted by harmful microorganisms, chemicals, or other dangerous substances. In veterinary medicine, this can affect food, water, toys, or the environment. water. The cercariae penetrate the skin, enter the bloodstream, and infest organs such as the liver. Symptoms in dogs include skin rashes, Cough, loss of appetite, and weight loss. 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 clinical examinations and laboratory tests, including fecal examinations and blood tests. Treatment involves the administration of anthelminticsAnthelmintics are medications used to treat worm infections in dogs and cats. They work by killing parasitic worms or promoting their expulsion from the body. There are various anthelmintics that are effective against specific types of worms, such as roundworms, tapeworms, and hookworms. The choice of the right anthelmintic depends on the type of worm infestation. such as praziquantel and may include additional measures to relieve symptoms. 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, but severe infections can lead to organ damage. PreventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring. focuses on avoiding contact with contaminatedContaminated describes something that has been polluted by harmful microorganisms, chemicals, or other dangerous substances. In veterinary medicine, this can affect food, water, toys, or the environment. water and controlling intermediate hosts. Research is working on better diagnostic methods, vaccineA vaccine is a substance that stimulates the immune system to develop immunity against specific pathogens without causing the disease itself. Vaccines may contain weakened or inactivated pathogens, toxoids, or recombinant antigens. development, and new treatment options. Modern approaches such as molecular biological techniques and GIS technologies help to better understand and control the spread 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.. Interdisciplinary collaboration plays an essential role in improving the health of dogs and public health overall.

Causes

Schistosomiasis is a zoonosis that can affect both animals and humans. It is caused by parasiticParasitic refers to diseases or conditions caused by parasites. Parasitic infections can affect the digestive tract, skin, and other organ systems. worms of the genus Schistosoma, which are found in freshwater environments. These parasites go through a complex life cycle that includes intermediate hosts such as freshwater snails.

The cycle begins when infected animals or humans release eggs of the parasiteA parasite is an organism that lives on or in another living being (the host) and feeds at its expense. Parasites can cause a variety of diseases in animals and humans. into the water via their feces. These eggs hatch into larvae, which then infect snails as intermediate hosts. In the snails, the larvae continue to develop and become cercariae, which are released back into the water. Dogs and other animals become infected when they come into contact with water infected with these cercariae.

In dogs, the cercariae penetrate the skin and enter the bloodstream. From there, they migrate to various organs, especially the liver and blood vessels. There they mature into adultThe term "adult" refers to an individual who has reached full physical development and is considered an adult. In veterinary medicine, this term is used to describe animals that have completed growth and are of reproductive age. worms and reproduce by laying eggs, which further contaminate the environment when excreted.

Symptoms

Very common symptoms:

Common symptoms:

Rare symptoms:

The symptoms of schistosomiasis 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 organs affected. The most common symptoms include weight loss, Vomiting, DiarrheaDiarrhea refers to the condition of frequent, watery bowel movements, which can be a sign of infections, digestive disorders, or other health problems., and loss of appetite. These symptoms often result from damage to the digestive tract and liver.

In some cases, respiratoryRespiratory refers to breathing or the process of breathing. Respiratory diseases affect the respiratory tract and can impair the ability to breathe effectively. problems may also occur if the worms infect the lungs or if there is an allergic reaction to the parasites. Other symptoms may include Lethargy, Cough, and in severe cases, anemia, which is caused by Blood loss and the destructionDestruction means “demolition.” In medicine, it refers to the destruction of cells, tissues, organs, or body parts. The growth of malignant Tumors is also usually accompanied by destruction of the surrounding tissue. of red blood cells.

Another possible symptom is ascitesAscites refers to the accumulation of free fluid in the abdominal cavity, which can lead to visible abdominal distension. It can be caused by various diseases, including liver disease, cancer, or heart failure., an accumulation of fluid 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. cavity, which indicates liver problems. Neurological symptoms may also occur if the parasites affect the central nervous systemThe CNS (central nervous system) consists of the brain and spinal cord. It is responsible for processing information and controls most functions of the body and behavior..

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 schistosomiasis in dogs usually begins with a thorough clinical examination and a review of the 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.. Suspicious symptoms and possible contact with contaminatedContaminated describes something that has been polluted by harmful microorganisms, chemicals, or other dangerous substances. In veterinary medicine, this can affect food, water, toys, or the environment. water may provide initialInitial means beginning or at the start. In medicine, it can refer to the first symptoms of a disease or the first phase of a treatment process. indications 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..

Laboratory tests are crucial for confirming 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.. A fecal examination can help identify the eggs of the schistosomes. However, it should be noted that eggs are not always evenly distributed in the feces, which can make 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. difficult.

Blood tests can also provide evidence 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. by showing signs of anemia or increased liver enzyme activity. In some cases, 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. or X-rays can be used to detect changes in the affected organs.

Therapy

The treatment of schistosomiasis in dogs is usually done with anthelminticsAnthelmintics are medications used to treat worm infections in dogs and cats. They work by killing parasitic worms or promoting their expulsion from the body. There are various anthelmintics that are effective against specific types of worms, such as roundworms, tapeworms, and hookworms. The choice of the right anthelmintic depends on the type of worm infestation., i.e., medications that are specifically developed to combat worm infections. Praziquantel is one of the most commonly used drugs to treat this disease. It works by paralyzing the parasites, thus facilitating their eliminationElimination refers to the process by which waste products and toxins are removed from the body. This includes excretion via the kidneys (urine), intestines (stool), lungs (breath), and skin. from the body.

In addition to drug treatment, it may be necessary to alleviate the symptoms of the disease. This may include administering fluids to treat 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 electrolyte imbalances, as well as medications to support liver function.

In severe cases where organ damage has occurred, more comprehensive medical care may be necessary. This may include surgical procedures to remove fluid accumulation in the 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. or other specialized treatments.

Prognosis and follow-up care

The prognosis for dogs with schistosomiasis depends 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 degree of organ damage. 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. is usually good, and many dogs recover completely.

However, delayed 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. or severe 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. can lead to permanent organ damage, especially to the liver and kidneys. In such cases, 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 less favorable, and long-term follow-up may be required to maintain the animal’s quality of life.

Prevention

The preventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring. of schistosomiasis in dogs focuses primarily on avoiding contact with contaminatedContaminated describes something that has been polluted by harmful microorganisms, chemicals, or other dangerous substances. In veterinary medicine, this can affect food, water, toys, or the environment. water. Dog owners should be careful not to let their animals swim or drink in waters that may be infected with schistosomes, especially in known endemic areas.

Regular veterinary examinations and monitoring of symptoms can also help detect and treat 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. early. In certain regions, the use of preventive measures such as the regular administration of anthelminticsAnthelmintics are medications used to treat worm infections in dogs and cats. They work by killing parasitic worms or promoting their expulsion from the body. There are various anthelmintics that are effective against specific types of worms, such as roundworms, tapeworms, and hookworms. The choice of the right anthelmintic depends on the type of worm infestation. may be considered.

In addition, controlling intermediate hosts, such as the infected freshwater snails, can be an effective measure to reduce the spread of schistosomiasis. However, these measures often require comprehensive ecological and public health strategies.

Outlook on current research

Research on schistosomiasis in dogs is currently focused on developing more effective diagnostic methods to detect the presence of Schistosoma worms early. Rapid and accurate 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 crucial to control the spread 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. and initiate treatment in a timely manner. Modern approaches include the use of molecular biological techniques, such as polymerase chain reaction (PCR), which aim to detect genetic material of the parasiteA parasite is an organism that lives on or in another living being (the host) and feeds at its expense. Parasites can cause a variety of diseases in animals and humans. in the body fluids of dogs. These methods promise to be more sensitive and specific than traditional microscopic examinations of stool samples.

Another important area of research is the development of vaccines against Schistosoma infections. While progress has already been made in developing vaccines for human use, efforts are being made to transfer these findings to dogs. The focus is on modulating the immune responseAn immune response is the immune system's reaction to foreign substances (antigens), such as microorganisms or proteins. It involves a series of processes aimed at recognizing, fighting, and eliminating these antigens. of dogs so that they can effectively fight the parasiteA parasite is an organism that lives on or in another living being (the host) and feeds at its expense. Parasites can cause a variety of diseases in animals and humans.. Preclinical studies with various antigens of the Schistosoma worm are underway to evaluate the efficacy and safety of potential vaccines.

In chemotherapeutic research, new drugs and treatment strategies are being investigated. While praziquantel is currently the most commonly used drug against schistosomiasis, research is being conducted on alternative active ingredients that may offer a shorter treatment duration or better tolerability. A promising direction is the exploration of combination therapies that use multipleMultiple means manifold or repeated and is used to describe conditions or events that occur in multiple instances or at different locations. In veterinary medicine, this may indicate multiple lesions, tumors, or other pathological changes. active ingredients simultaneously to avoid 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 increase effectiveness.

Ecologically oriented research aims to better understand the life cycles of Schistosoma worms and their intermediate hosts. By studying the ecological conditions that affect the survival and spread of intermediate hosts, such as certain snail species, strategies can be developed to break the chains 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.. This could be achieved through changes in the environment or through biological control of these intermediate hosts.

Another exciting development in research is the application of geographic information systems (GIS) and remote sensing technologies to identify hotspots of schistosomiasis and monitor the geographic spread 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 technologies make it possible to better understand environmental factors that promote the spread 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. and to take targeted preventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring. and control measures.

Overall, research on schistosomiasis in dogs shows a broad spectrum of innovative approaches aimed at improving 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., treatment, and preventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring. of this parasiticParasitic refers to diseases or conditions caused by parasites. Parasitic infections can affect the digestive tract, skin, and other organ systems. 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.. Through the interdisciplinary collaboration of parasitologists, immunologists, ecologists, and veterinarians, progress is being made that can improve both the health of dogs and public health in the long term.

Frequently asked questions (FAQs)

What is schistosomiasis in dogs? Schistosomiasis in dogs is a parasiticParasitic refers to diseases or conditions caused by parasites. Parasitic infections can affect the digestive tract, skin, and other organ systems. infection caused by worms of the genus Schistosoma. These worms live in the blood vessels of infected animals and can infest various organs, especially the liver and bladder, leading to a variety of health problems.
How do dogs get infected with schistosomiasis? Dogs become infected with schistosomiasis by swimming or drinking in waters that are contaminatedContaminated describes something that has been polluted by harmful microorganisms, chemicals, or other dangerous substances. In veterinary medicine, this can affect food, water, toys, or the environment. with the free-swimming larvae of Schistosoma worms. These larvae penetrate the skin and enter the dog’s body, developing into adultThe term "adult" refers to an individual who has reached full physical development and is considered an adult. In veterinary medicine, this term is used to describe animals that have completed growth and are of reproductive age. worms.
What symptoms does a dog with schistosomiasis show? The symptoms can vary, but often include Fever, weight loss, blood in the urine or stool, Abdominal pain, and Vomiting. In severe cases, liver or kidney damage can occur, which can be life-threatening.
How is schistosomiasis 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 usually made by detecting eggs of the parasiteA parasite is an organism that lives on or in another living being (the host) and feeds at its expense. Parasites can cause a variety of diseases in animals and humans. in stool or urine samples from the dog. In addition, serological tests or molecular methods such as PCR can be used to confirm 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..
Can schistosomiasis be treated in dogs? Yes, schistosomiasis can be treated in dogs. The most commonly used drug is praziquantel, which kills the worms. Treatment should be monitored by a veterinarian, as additional medications may be needed in some cases to treat Inflammatory conditions or secondary infections.
How can schistosomiasis be prevented in dogs? To avoid 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 be kept away from known 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. areas and stagnant waters. Regular veterinary examinations and control of intermediate hosts such as snails can also help 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..
Is schistosomiasis in dogs transmissible to humans? Schistosomiasis in dogs is not directly transmissible to humans. However, humans can become infected in the same contaminatedContaminated describes something that has been polluted by harmful microorganisms, chemicals, or other dangerous substances. In veterinary medicine, this can affect food, water, toys, or the environment. waters as dogs, as Schistosoma worms can also cause disease in humans.
Are there vaccines against schistosomiasis for dogs? There are currently no approved vaccines against schistosomiasis for dogs. However, research in this area is ongoing, and there is hope that effective vaccines can be developed in the future.
How common is schistosomiasis in dogs? The frequency of schistosomiasis in dogs varies depending on the geographic region. In areas where intermediate hosts are common, the prevalence may be higher. However, in many parts of the world, schistosomiasis remains a relatively rare disease in dogs.
What long-term consequences can a schistosomiasis 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. have in dogs? Untreated schistosomiasis can 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. health problems, including severe liver or kidney damage. These complications can significantly impair the dog’s quality of life and ultimately be life-threatening if not treated in a timely manner.

You can find an interesting overview of 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. problems in dogs, supplemented with information on 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. microbiome and the importance of probiotics, here: https://petsvetcheck.de/fachbeitrag/magen-darm-probleme-beim-hund/