Home » Diseases » In cats » Coccidiosis (Parasitic intestinal infection caused by coccidia)

Coccidiosis (Parasitic intestinal infection caused by coccidia) in cats

Occurrence: common
Location of illness: Abdomen/pelvis

Author: Dr. med. vet. Gisa Löwe | Last modified: 03.12.2025

When to visit the vet?

Non-urgent see a veterinarian within 2–3 days

If the condition worsens / symptoms persist, consult a veterinarian.

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 cats, supplemented by 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, can be found here: https://petsvetcheck.de/fachbeitrag/magen-darm-probleme-bei-katzen/

Coccidiosis is a parasiticParasitic refers to diseases or conditions caused by parasites. Parasitic infections can affect the digestive tract, skin, and other organ systems. intestinal 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 cats caused by single-celled parasites called coccidia. These parasites affect 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 and can lead to severe illnesses, especially in young or weakened animals.

The most important facts at a glance

Coccidiosis in cats is caused by single-celled parasites called coccidia, mainly Isospora felis and Isospora rivolta. These parasites multiply in the intestineThe intestine is the medical term for the gut, including the small intestine (intestinum tenue) and the large intestine (intestinum crassum). It plays a central role in the digestion and absorption of nutrients. and are usually transmitted via the fecal-oral route, with 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. being particularly high in multi-cat households. Symptoms are mainly diarrheaDiarrhea refers to the condition of frequent, watery bowel movements, which can be a sign of infections, digestive disorders, or other health problems., sometimes also weight loss or fever, with young cats being more at risk. 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 microscopic examination of the feces for coccidia oocystsOocysts are resistant, dormant forms of certain parasites, especially protozoa, that can survive in the environment. They are an important stage in the life cycle of some parasites that can cause diseases such as coccidiosis in dogs and cats. or by specialized tests such as PCR. Antiparasitic drugs are used for 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 good care and adequate fluid intake are important. Hygiene plays a central role in preventing new infections, especially in households with several cats. 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 with timely 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., but there is a higher risk of complications in young or immunocompromised animals. Preventive measures include regular cleaning of the litter box, limiting outdoor access, and regular veterinary examinations. Research focuses on the life cycles of coccidia, better diagnostic methods, and the development of vaccines. Environmental factors and drug 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. are also being investigated to improve the spread and 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. of the disease.

Causes

Coccidia belong to the protozoa, a group of single-celled microorganisms that are widespread worldwide. In cats, the species Isospora felis and Isospora rivolta are particularly important. These parasites multiply in the cat’s intestineThe intestine is the medical term for the gut, including the small intestine (intestinum tenue) and the large intestine (intestinum crassum). It plays a central role in the digestion and absorption of nutrients. and cause inflammatory processes there.

The transmission of pathogens usually occurs via the fecal-oral route, meaning that cats become infected by ingesting infectiousInfectious describes the ability of a pathogen to be transmitted from one individual to another and trigger an infection. It also refers to diseases caused by such pathogens. feces containing the oocystsOocysts are resistant, dormant forms of certain parasites, especially protozoa, that can survive in the environment. They are an important stage in the life cycle of some parasites that can cause diseases such as coccidiosis in dogs and cats. of the coccidia. These oocystsOocysts are resistant, dormant forms of certain parasites, especially protozoa, that can survive in the environment. They are an important stage in the life cycle of some parasites that can cause diseases such as coccidiosis in dogs and cats. are extremely resistantResistant means being insensitive to a substance, drug, or treatment. In dogs and cats, resistance can refer to the ineffectiveness of antibiotics against certain bacterial strains or the insensitivity of parasites to certain pesticides. and can remain infectiousInfectious describes the ability of a pathogen to be transmitted from one individual to another and trigger an infection. It also refers to diseases caused by such pathogens. in the environment for a long time. 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 particularly high in multi-cat households or animal shelters.

Another important aspect is that most 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. cats develop a certain immunityImmunity is the body's ability to protect itself against infections, diseases, or foreign substances. It can be natural, as with innate immunity, or acquired, as with adaptive immunity, which develops after an infection or vaccination. to coccidia, which makes them less susceptible to severe infections. However, they can still excrete the pathogenA pathogen is a microorganism or virus that can cause disease in its host. Pathogens include bacteria, viruses, fungi, and parasites. and thus represent a source 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. for other cats.

Symptoms

Very common symptoms:

Common symptoms:

Rare symptoms:

The symptoms of coccidiosis in cats 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 age and health of the affected cat. Severe symptoms often occur in young cats or immunosuppressed animals.

Typical signs are diarrheaDiarrhea refers to the condition of frequent, watery bowel movements, which can be a sign of infections, digestive disorders, or other health problems., which may be bloody or mucous, weight loss, loss of appetite, and 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.. Especially in young kittens, life-threatening conditions can occur if fluid loss (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.) from diarrheaDiarrhea refers to the condition of frequent, watery bowel movements, which can be a sign of infections, digestive disorders, or other health problems. is not quickly compensated.

In some cases, vomiting, fever, and general weakness can also occur. In 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, a persistentPersistent means lasting or continuing for an extended period. In veterinary medicine, it can refer to chronic diseases or symptoms that do not subside. digestive disorder can be observed, leading to a poor general state of health.

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 coccidiosis is usually made by microscopic examination of the affected cat’s feces. The characteristic oocystsOocysts are resistant, dormant forms of certain parasites, especially protozoa, that can survive in the environment. They are an important stage in the life cycle of some parasites that can cause diseases such as coccidiosis in dogs and cats. of the coccidia are identified. A stool examination may include several samples, as the excretion of oocysts can be intermittentIntermittent refers to something that occurs at intervals or starts and stops temporarily, such as intermittent Pain that comes and goes..

In some cases, a specialized test, such as PCR (polymerase chain reaction)The polymerase chain reaction is a molecular biology technique used to replicate and analyze specific DNA sequences. In veterinary medicine, PCR is used for diagnostic purposes, including the identification of pathogens., can be used to determine the exact type of coccidia. However, these tests are generally more expensive and are mainly performed in research institutions or specialized laboratories.

It is important to distinguish coccidiosis from other causes of diarrheaDiarrhea refers to the condition of frequent, watery bowel movements, which can be a sign of infections, digestive disorders, or other health problems. in cats, as the 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. must specifically target the pathogens. A thorough 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. and clinical examination are therefore also essential.

Therapy

The therapy of coccidiosis in cats focuses on combating the parasites and alleviating the symptoms. AntiparasiticsAntiparasitics are medications or substances used to treat parasitic infestations, such as worms, protozoa, and ectoparasites. They work by killing the parasites or inhibiting their growth., such as sulfonamides or toltrazuril, are often used to eliminate the coccidia in the intestineThe intestine is the medical term for the gut, including the small intestine (intestinum tenue) and the large intestine (intestinum crassum). It plays a central role in the digestion and absorption of nutrients..

In addition to drug 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., it is important to take good care of the affected cat and ensure adequate fluid intake, especially if it is suffering from severe diarrheaDiarrhea refers to the condition of frequent, watery bowel movements, which can be a sign of infections, digestive disorders, or other health problems.. In severe cases, intravenous fluid administration may be necessary.

Another important aspect of the therapy is hygiene. The cat’s habitat should be cleaned and disinfected regularly to prevent re-infection. This is especially true in multi-cat households or animal shelters, where the risk of spread is higher.

Prognosis and follow-up care

The prognosis for a cat with coccidiosis depends heavily on its general health, age, and 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.. In many cases, especially with timely 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 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 good, and the cat can recover completely.

Young kittens or cats with 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. have a higher risk of serious complications. In these cases, the disease can be life-threatening if not treated quickly. Intensive care and timely medical intervention are crucial to increase the chances of survival.

In the long term, it is important to keep the environment clean and take preventive measures to avoid re-infection. Successful 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. usually leads to a complete recovery, but immunityImmunity is the body's ability to protect itself against infections, diseases, or foreign substances. It can be natural, as with innate immunity, or acquired, as with adaptive immunity, which develops after an infection or vaccination. to coccidia after 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. is often incomplete, so re-infection is possible.

Prevention

To minimize the risk of coccidiosis 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 cats, good hygiene is essential. Cat owners should regularly clean the litter box, as the coccidia are excreted in the feces. Daily cleaning reduces the risk of the parasites spreading and infecting other cats.

It is also advisable to keep cats indoors or limit their access to potentially 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. outdoor areas. Outdoor cats have a higher risk of becoming infected through contact with infected soil, water, or prey. If possible, contact with unfamiliar animals should be avoided to prevent the transmission of parasites.

A balanced diet strengthens the cat’s 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. and can help to ward off infections. Cat owners should also ensure that their pets are examined regularly by a veterinarian. These examinations can detect and treat 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. early on before it spreads further.

Finally, it is important to test new cats for coccidiosis before introducing them into a household with other animals. This can help prevent the spread of parasites within a household and protect the health of all animals.

Outlook on current research

In current research on coccidiosis in cats, scientists are focusing on better understanding the life cycles of the various coccidia species. These microscopic parasites, which belong to the protozoa group, have complex developmental stages that take place both inside and outside the host. A deeper understanding of these cycles could lead to more effective 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 preventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring. strategies. A particular focus is on researching genetic markers that could help identify and combat resistantResistant means being insensitive to a substance, drug, or treatment. In dogs and cats, resistance can refer to the ineffectiveness of antibiotics against certain bacterial strains or the insensitivity of parasites to certain pesticides. strains.

Another significant area of research is the development of new diagnostic methods. Traditionally, coccidiosis is diagnosed by microscopic examination of stool samples, which is time-consuming and not always reliable. Modern approaches use molecular techniques, such as PCR (polymerase chain reaction)The polymerase chain reaction is a molecular biology technique used to replicate and analyze specific DNA sequences. In veterinary medicine, PCR is used for diagnostic purposes, including the identification of pathogens., to directly detect the DNADNA (deoxyribonucleic acid) is the molecule that carries the genetic instructions for the development, function, and reproduction of all known living organisms and many viruses. It is located in the cells of an organism and contains the information for heredity. of the parasites. These methods promise a faster and more 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., which is of great importance, especially in difficult-to-detect infections.

In addition, researchers are investigating 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 cats to coccidia infections. The aim is to understand how the animals’ 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. reacts to the infestation and which factors influence a successful defense. These findings could support the development of vaccines that protect cats from infections. Although there are currently no widespread vaccines against coccidia, 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. experimental vaccines are promising and could significantly improve the protectionProtection refers to safeguarding against diseases or harm. In veterinary medicine, this can include protecting animals through vaccinations, the use of parasite control products, or providing a safe environment. of cat populations in the future.

Another branch of research is dedicated to investigating environmental factors that influence the spread of coccidia. These include climatic conditions, hygiene standards, and the interaction between wild and domesticated animal populations. By analyzing these factors, scientists can better predict when and where outbreaks might occur and develop preventive measures to control the spread.

Finally, research into the development of 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 antiparasiticsAntiparasitics are medications or substances used to treat parasitic infestations, such as worms, protozoa, and ectoparasites. They work by killing the parasites or inhibiting their growth. plays an essential role. There is evidence that some coccidia strains have developed 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 common drugs. Researchers are working to decipher the mechanisms behind this 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 to develop new, effective 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. options. These efforts are crucial to ensure future 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. options and to effectively protect the health of cats.

Frequently asked questions (FAQs)

What is coccidiosis in cats? Coccidiosis is a parasiticParasitic refers to diseases or conditions caused by parasites. Parasitic infections can affect the digestive tract, skin, and other organ systems. 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. 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 coccidia, microscopic single-celled organisms that colonize 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. lining. Affected cats can suffer from DiarrheaDiarrhea refers to the condition of frequent, watery bowel movements, which can be a sign of infections, digestive disorders, or other health problems., 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 Weight loss.
How does a cat get infected with coccidia? Cats can become infected through Contact with infected feces or 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. objects. This often happens when they are kept in confined spaces with other cats or come into Contact with infected wild animal feces.
What symptoms do cats show with coccidiosis? The most common symptoms include diarrhea, sometimes bloody, loss of appetite, vomiting, and in severe cases, general weakness and weight loss. Young cats are often more affected than adult animals.
How is coccidiosis diagnosed in cats? 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 microscopic examination of feces, where coccidia eggs are detected. Modern methods also use DNADNA (deoxyribonucleic acid) is the molecule that carries the genetic instructions for the development, function, and reproduction of all known living organisms and many viruses. It is located in the cells of an organism and contains the information for heredity. tests, which can be more accurate.
Is there a treatment for coccidiosis in cats? Yes, treatment often includes the administration of antiparasiticsAntiparasitics are medications or substances used to treat parasitic infestations, such as worms, protozoa, and ectoparasites. They work by killing the parasites or inhibiting their growth. that are specifically effective against coccidia. Additionally, supportiveSupportive refers to supportive treatments that aim to alleviate symptoms and improve quality of life without directly treating the underlying cause of the disease. 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. may be required 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 nutrient deficiencies.
Can humans be infected by cats with coccidiosis? The specific coccidia species that affect cats are generally not transmissible to humans. Nevertheless, hygiene is important to avoid possible other infections.
How can coccidiosis be prevented in cats? Good hygiene practices are crucial. This includes regular cleaning of litter boxes, fresh water and food in clean containers, as well as avoiding Contact with unknown cats.
Which cats are most at risk? Young kittens, immunocompromised cats, and those living in crowded or unhygienic conditions are most at risk of developing severe coccidiosis.
Can other pets be infected? Yes, other pets such as dogs or rabbits can also develop coccidia infections, but usually through other specific species of coccidia.
How long can coccidiosis last in cats? Untreated, 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 last several weeks. With appropriate treatment, however, symptoms usually improve within a few days to weeks.