# Coccidia in Cats: Symptoms to Watch For Coccidia in cats symptoms are mostly digestive, and diarrhea is the main sign owners notice [1]. Many cats shed these tiny intestinal parasites without looking sick at all, so a mild case can be easy to miss. The tricky part is that coccidia diarrhea looks like diarrhea from many other causes, which is why a fecal test matters more than guesswork. This article is educational and is not a substitute for veterinary diagnosis or treatment. ## Quick Answer - The main sign of coccidiosis is diarrhea, and kittens are the ones most likely to get sick from it [2][1]. - Coccidia are host-specific single-celled parasites, and the common ones in cats are Isospora (Cystoisospora) felis and Isospora rivolta [2]. - A cat can test positive for coccidia and still have normal stools, so a positive fecal result does not always explain the diarrhea [2]. - Diagnosis is made by finding oocysts in a stool sample, usually with a flotation method [1]. - Treatment is prescription antiprotozoal medication, and the dose is calculated by your veterinarian based on your cat's weight and health [1]. ## What Coccidia Symptoms Look Like in Cats ### The classic sign: diarrhea Diarrhea is the main clinical sign of coccidiosis [1]. In cats, that diarrhea can range from soft stool to watery or bloody stool. In one study of young cats with diarrhea, watery or hemorrhagic diarrhea was seen in some cats infected with C. felis and C. rivolta [3]. So the stool can change a lot from one cat to the next. Coccidia diarrhea in cats often comes and goes. Some cats have a few loose stools and then seem fine. Others have ongoing diarrhea that slowly wears them down, especially kittens. ### Vomiting and other signs Coccidia vomiting in cats is possible but less typical than diarrhea. The parasites damage the lining of the small intestine, which can reduce nutrient absorption and cause loss of fluid and electrolytes [2]. When that happens, you may see vomiting along with the diarrhea, plus weight loss, a dull coat, or a kitten who is not growing well. Heavy infections can cause intestinal damage, and some Isospora species can cause bleeding [2]. That is when you might see blood or mucus in the stool. ### What normal looks like Normal cat stool is formed, holds its shape, and is easy to pick up. A healthy cat has no straining, no accidents outside the box, and no sudden change in appetite or energy. Kittens can have softer stool than adults, but it should still be formed. If your cat's stool is suddenly loose, watery, bloody, or black, that is not normal and deserves attention. ## What Else Causes Diarrhea in Cats? Coccidia is only one possibility. In a large United States laboratory review of fecal exams from client-owned cats, Giardia was the most frequently detected parasite, followed by Toxocara cati (roundworm), then Cystoisospora species [4]. That means when your cat has diarrhea, several common parasites are on the list, and sometimes more than one is present at the same time [4]. Other causes include diet changes, food intolerance, bacterial infections, inflammatory bowel disease, and chronic conditions that need long-term management [5]. Chronic diarrhea in cats has many underlying causes, and sorting them out usually requires testing instead of guessing [5]. | Cause | Typical clues | How urgent | |---|---|---| | Coccidia (Cystoisospora) | Diarrhea, often in kittens or cats from shelters or crowded settings, sometimes watery or bloody [2][3] | See a vet soon, same day if a kitten or if blood is present | | Giardia | Loose or greasy stool, often recurring, common in young cats [4] | See a vet soon | | Roundworms (Toxocara) | Potbelly, poor coat, visible worms in stool or vomit, common in kittens [4] | Routine visit, sooner if the kitten is thin or vomiting | | Diet change or food intolerance | Diarrhea started after a new food, cat otherwise bright | Routine visit if it lasts more than a day or two | | Chronic enteropathy or other long-term disease | Diarrhea lasting weeks, weight loss, vomiting, picky appetite [5] | Schedule a vet visit, sooner if weight loss is ongoing | | Toxoplasma | Usually no signs, occasionally diarrhea or other organ signs [2][6] | Discuss testing with your vet if your cat is at risk | If your cat has ear or urinary signs along with the digestive upset, those are separate problems with their own guides, such as [Ear Infections In Cats Symptoms](/knowledge/veterinary-medicine/symptom-guides/ear-infections-in-cats-symptoms) and [Symptoms Of Urinary Infection Cats](/knowledge/veterinary-medicine/symptom-guides/symptoms-of-urinary-infection-cats). ## Coccidia Symptoms in Kittens Kittens are the group most likely to get sick from coccidia. High fecal shedding of oocysts is linked to clinical signs of disease, especially in kittens [2]. Their small bodies lose fluid fast, and their immune systems are still developing. Stressed kittens and immunosuppressed cats may be at higher risk because dormant parasite stages in their own tissues can reactivate and cause disease [2]. That is one reason shelter kittens, rescue kittens, and kittens from crowded environments tend to show up with coccidia more often. Watch kittens closely for: - Watery diarrhea that soaks the litter box - Vomiting or refusing to eat - A tucked belly, crying, or weakness - Not gaining weight or losing weight - Blood or mucus in the stool A kitten with watery diarrhea can go downhill in hours. Do not wait a few days to see if it passes. ## Red Flags That Mean Emergency Care Now Some signs mean you should stop reading and call a veterinarian or an emergency clinic right away. - Bloody diarrhea, especially in a kitten - Repeated vomiting with inability to keep water down - A kitten who is limp, cold, or hard to wake - Sunken eyes, tacky gums, or skin that stays tented when you pinch it (signs of dehydration) - Diarrhea plus a swollen or painful belly - Any cat who stops eating and drinking for more than 12 to 24 hours These signs point to serious fluid loss or intestinal damage, and they need same-day or emergency care. Do not try home remedies first. ## What You Can Safely Do at Home While Waiting You cannot treat coccidia at home. Prescription antiprotozoal medication is needed, and only your veterinarian can choose it and calculate the dose from your cat's weight and health [1]. Still, a few safe steps help while you wait for your appointment. ### Keep your cat hydrated Offer fresh water often. If your cat is eating and drinking normally, keep meals small and frequent. If your cat refuses water or seems weak, that is a reason to call the vet now, not later. ### Protect the litter box and the household Coccidia oocysts pass in the stool, so scoop the box at least twice a day and wash your hands after. Clean the box with hot water and a pet-safe disinfectant. Keep food and water bowls away from the litter area. ### Isolate a sick cat from kittens If you have a sick adult cat and young kittens, keep them separated until your vet has seen the cat. Wash your hands between handling each cat. ### Do not give human diarrhea medicine Never give a cat human anti-diarrheal medication. Some of these drugs are toxic to cats, and none of them treat the parasite. ### Save a stool sample Collect a fresh sample in a clean bag or container and bring it to the visit. A fresh sample gives your vet the best chance of finding oocysts [1]. ## What Your Veterinarian Will Check and Test ### History and physical exam Your vet will ask when the diarrhea started, what it looks like, whether your cat vomits, and whether your cat goes outside or lives with other cats. They will check your cat's hydration, weight, belly, and overall condition. ### Fecal testing The standard test is fecal flotation, which uses a salt or sugar solution to concentrate and identify oocysts [1]. Your vet may also use a direct smear or a counting chamber to measure how heavy the infection is [1]. Because several parasites can cause the same signs, your vet may test for Giardia, roundworms, and other common intestinal parasites at the same time [4]. ### Blood work and other tests If your cat is very sick, a kitten, or not improving, your vet may run blood work to check for dehydration, electrolyte problems, and other disease. Chronic diarrhea sometimes needs more testing to find the underlying cause [5]. ### Treatment Antiprotozoal treatment can shorten the illness, reduce oocyst shedding, ease clinical signs, and lower the risk of secondary infections and death [1]. Your veterinarian will pick the drug and the dose for your cat. Follow the full course even if the stool looks normal again, because stopping early can let the infection come back. ## Prevention and Monitoring Coccidia are common, and complete prevention is not realistic. Good hygiene and regular fecal testing do most of the work. - Have stool tested at least once a year, and more often for kittens or outdoor cats [7]. - Test new kittens and new cats before or right after they join your home [7]. - Scoop the litter box daily and wash your hands afterward. - Clean food and water bowls daily and keep them away from the litter box. - Reduce stress for kittens and cats with chronic illness, since stress may allow dormant parasite stages to reactivate [2]. - Watch for diarrhea after any diet change, new pet, or boarding stay. If your cat has other recurring signs, such as head shaking or scratching, see [Ear Infection Cats Symptoms](/knowledge/veterinary-medicine/symptom-guides/ear-infection-cats-symptoms). If your cat strains to urinate or licks the genital area, see [Cat Urinary Infection Symptoms](/knowledge/veterinary-medicine/symptom-guides/cat-urinary-infection-symptoms). ## Limitations and When to Contact a Veterinarian A positive coccidia test does not always mean coccidia is the cause of your cat's diarrhea. Many cats carry these parasites with no signs at all [2]. Your veterinarian has to put the test result together with your cat's age, history, and exam findings. Call your veterinarian the same day if your cat has diarrhea that lasts more than 24 to 48 hours, vomits more than once, has blood in the stool, or is a kitten with any loose stool. Go to an emergency clinic now if your cat is weak, collapsed, severely dehydrated, or has bloody diarrhea with repeated vomiting. Schedule a routine visit if your cat has soft stool that comes and goes, mild weight loss, or you simply want a fecal test as part of yearly care. Individual cases need a veterinarian who can examine your cat and set the right plan. ## Frequently Asked Questions ### Can coccidia in cats go away on its own? Mild infections can clear without treatment in some cats, but you cannot predict which cat will get worse. Treatment shortens the illness and lowers the risk of serious problems [1]. If your cat or kitten has diarrhea, have it checked instead of waiting it out. ### How do cats get coccidia? Cats get coccidia by swallowing infective oocysts from contaminated soil, litter, food, or water. The parasites are host-specific, so your cat cannot catch the species that infects dogs [2]. Kittens and cats in crowded or stressful settings are at higher risk [2]. ### Is coccidia contagious to people or other pets? The common cat coccidia (Isospora felis and Isospora rivolta) are host-specific and do not infect people [2]. Other cats in the home can be exposed through shared litter boxes, so clean the box often and wash your hands. Toxoplasma is a different parasite with human health concerns, and your veterinarian can advise you if that is a worry [6]. ### How long does coccidia last in cats? It varies with the cat's age, immune status, and how heavy the infection is. Treatment can shorten the length of illness and reduce oocyst shedding [1]. Your veterinarian will recheck your cat if signs continue after treatment. ### Should I treat my cat for coccidia without a vet visit? No. The medication is prescription, and the dose depends on your cat's weight and health [1]. Giving the wrong drug or dose can harm your cat, and the diarrhea may have a different cause that needs different treatment. ## Related Articles - [Ear Infections In Cats Symptoms](/knowledge/veterinary-medicine/symptom-guides/ear-infections-in-cats-symptoms) - [Ear Infection Cats Symptoms](/knowledge/veterinary-medicine/symptom-guides/ear-infection-cats-symptoms) - [Symptoms Of Cat Ear Infection](/knowledge/veterinary-medicine/symptom-guides/symptoms-of-cat-ear-infection) - [Symptoms Of Urinary Infection Cats](/knowledge/veterinary-medicine/symptom-guides/symptoms-of-urinary-infection-cats) - [Cat Urinary Infection Symptoms](/knowledge/veterinary-medicine/symptom-guides/cat-urinary-infection-symptoms) - [Symptoms Of Bladder Infection In Cats](/knowledge/veterinary-medicine/symptom-guides/symptoms-of-bladder-infection-in-cats) - [Coccidia in Cats: Poop Signs and How to Clean](/knowledge/veterinary-medicine/parasitic-diseases/coccidia-cats-poop-cleaning) - [Coccidia in Cats: Treatment and Medication Options](/knowledge/veterinary-medicine/pet-medication-guide/coccidia-cats-treatment-medication) - [How Long Does Coccidia Last in Cats?](/knowledge/veterinary-medicine/parasitic-diseases/how-long-does-coccidia-last-cats) ## References 1. [Overview of Coccidiosis in Animals - Digestive System](https://www.merckvetmanual.com/digestive-system/coccidiosis/overview-of-coccidiosis-in-animals). Merck Veterinary Manual. 2. [Coccidiosis of Cats and Dogs - Digestive System](https://www.merckvetmanual.com/digestive-system/coccidiosis/coccidiosis-of-cats-and-dogs). Merck Veterinary Manual. 3. [Occurrence of Cystoisospora spp. and other intestinal parasites in dogs and cats with diarrhea](https://pubmed.ncbi.nlm.nih.gov/40690864/). Veterinary parasitology, 2025. 4. [Prevalence and epidemiologic patterns of feline parasitism detected by fecal examination in the United States, 2023](https://pubmed.ncbi.nlm.nih.gov/42184502/). Veterinary parasitology, 2026. 5. [Feline chronic diarrhea: causes and nutritional management](https://pubmed.ncbi.nlm.nih.gov/42502773/). Veterinary and animal science, 2026. 6. [Development and optimization of an ELISA method to detect Toxoplasma gondii oocyst infection in cats](https://pubmed.ncbi.nlm.nih.gov/40619535/). Parasitology research, 2025. 7. [Parasites in Cats - Cat Owners](https://www.merckvetmanual.com/cat-owners/caring-for-cats/parasites-in-cats). Merck Veterinary Manual. ## Further Reading - [Merck Veterinary Manual: Cat Owners](https://www.merckvetmanual.com/cat-owners) - [Cornell Feline Health Center: Health Information](https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information) - [American Veterinary Medical Association: Pet Care](https://www.avma.org/resources-tools/pet-owners/petcare)