Kitten Coccidiosis (Cystoisospora)
Coccidiosis is caused by microscopic parasites called coccidia that live in the intestinal wall. In cats, the main species are Cystoisospora felis and Cystoisospora rivolta. Many cats carry the parasite without ever becoming ill. The diseas...
What is it?
Coccidiosis is caused by microscopic parasites called coccidia that live in the intestinal wall. In cats, the main species are Cystoisospora felis and Cystoisospora rivolta.
Many cats carry the parasite without ever becoming ill. The disease mainly affects kittens a few weeks old, around weaning age, particularly when living in groups such as in catteries, shelters, or boarding facilities.
It causes diarrhea that may be mucus-like or bloody and can quickly dehydrate such a small animal.
Commonly observed signs
These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.
Related signs — each one links to its page:
Diarrhea, watery or mucus-like, sometimes containing blood.
Dehydration: the kitten appears limp, skin remains tented when gently pinched, and eyes appear sunken.
Loss of appetite and weight loss.
Abdominal tenderness, kitten becomes stiff when picked up.
Growth delay: the kitten grows slower than littermates.
None of these signs is specific to coccidiosis. It is mainly the age—a kitten at weaning—and the group living situation that raise suspicion for this disease.
An adult cat in good health with diarrhea lasting several weeks is not a typical case of coccidiosis.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
Ingestion of resistant parasite forms called oocysts shed in the stools of an infected cat.
Ingestion of prey such as a mouse or small rodent carrying the parasite.
The disease develops mainly when large numbers of parasites are swallowed in a short time, which occurs in places where many cats share the same space.
Kittens at weaning age.
Cattery, shelter, boarding facility, or any situation where many cats live in a confined space.
Stress: separation from the mother, transport, adoption.
Other infections or weakened immune defenses.
Transmission
Oocysts shed in stools become infectious in the environment and persist for a long time.
The kitten becomes infected by licking its paws or coat after contact with a soiled litter box, floor, or food bowl.
Hunting small rodents is another source of infection.
These coccidia are specific to cats and are not considered transmissible to humans.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
The vet examines the kitten, assesses dehydration and weight.
Diagnosis is based on a fecal analysis that reveals oocysts under the microscope.
Since many infected cats show no signs, the vet also looks for other causes of kitten diarrhea: other parasites, feline panleukopenia in an unvaccinated kitten, dietary errors.
The kitten's vaccination status is always checked, as feline panleukopenia causes much more severe diarrhea.
Treatment
An antiparasitic effective against coccidia is prescribed by the vet; not all common wormers are effective against them.
Rehydration is essential in dehydrated kittens, sometimes through intravenous fluids.
Appropriate, easily digestible food helps the digestive tract recover.
In a cattery or shelter, all exposed cats may be treated at the same time, according to the vet's recommendation.
Environmental hygiene is part of the treatment: without it, kittens reinfect themselves.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Remove feces from litter boxes at least once daily, before oocysts become infectious.
Clean litter boxes and food bowls with very hot water: oocysts resist many common disinfectants.
Avoid overcrowding and separate litters.
Have feces examined in newly arrived kittens.
Limit hunting when possible.
Possible complications
Severe dehydration, which can become life-threatening in a very young kitten in a short time.
Persistent growth delay.
Worsening of other concurrent diseases.
In a rapidly growing kitten, prolapse of rectal tissue through the anus.
When to see a veterinarian
Your kitten is very listless, has stopped eating, and appears dehydrated: consult the same day, urgently if very weak.
It has had diarrhea for more than a day or two.
You see blood in the feces.
It is vomiting, or it is not vaccinated against feline panleukopenia.
It is not growing as well as the other kittens in the litter.
In a male, straining in the litter box with nothing passed may indicate urinary obstruction: consult urgently.
Prognosis
With prompt treatment, kitten coccidiosis has a good prognosis in the vast majority of cases.
The outlook is more guarded in very young kittens, those that are severely dehydrated, or kittens with another illness at the same time.
Recurrence is common in multi-cat environments if housing hygiene is not improved.
Frequently asked questions
Coccidiosis or Typhus: How to Tell the Difference?
Feline distemper primarily affects unvaccinated kittens, comes on suddenly, and is accompanied by vomiting and marked lethargy. Coccidiosis more typically causes diarrhea in a kitten that remains fairly alert. In doubt, a lethargic kitten that is vomiting and has diarrhea should be seen the same day.
Is the usual wormer enough?
Not always. Coccidia are not worms, and many common dewormers do not work against them. The veterinarian prescribes appropriate treatment after a fecal analysis.
My adult cat has coccidia in their stool. Is that the cause of their diarrhea?
Not necessarily. Many cats carry them without being ill. In an adult, especially if diarrhea has lasted for weeks, the vet will also look for other causes.
Can I catch coccidiosis from my kitten?
Cat coccidia are specific to this species and are not considered transmissible to humans. Washing your hands after changing the litter box remains a good habit.
References
Content reviewed by the TunisieVet editorial team · Updated 11 October 2026
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