Unfortunately for our feline friends there are quite a few internal parasites who love them as much as we do!  Some of these parasites cause unsavory symptoms such as stinky diarrhea and vomiting.  Some of these parasites my live in our cats’ intestines for undetected while spreading to others.  Read on for descriptions, treatment, and prevention of these internal nasties.

Coccidiosis

What is Coccidiosis?

Coccidiosis is an illness caused by a parasite called Coccidia.  Coccidia are one-celled protozoa that live in the intestinal cells of many types of animals, however each type of coccidia specifically lives in one species.  Cats become infected by coccidia by ingesting the immature coccidia called oocysts which are passed in the feces of another infected cat OR by ingesting mice that are infected with coccidia.  Once the oocysts are ingested it takes about 13 days for the oocysts to grow into mature coccidia at which time symptoms begin.

What are the Symptoms?

Symptoms of coccidiosis include severe watery or mucous diarrhea, dehydration, anorexia, weakness, vomiting, and occasionally fever.  Many adult cats who are infected with coccidia are asymptomatic, however can shed oocysts in their feces that can infect others.  Kittens and immunosuppressed cats are more likely to show symptoms of infection.

How is it diagnosed and treated?

Positive diagnosis of Coccidiosis can be obtained by viewing a fecal sample under a microscope, however since the Coccidia protozoa are very tiny, they are not always found.  A more sensitive test called a PCR test (polymerase chain reaction) can be done to confirm coccidiosis, but this test is expensive and takes time since a sample must be sent to a laboratory.  Often veterinarians prescribe medications for Coccidiosis based on clinical signs rather than confirmation.    Most vets have for years treated coccidiosis with oral sulfadimethoxine (brand name Albon) for 5-20 days.  This is often effective, though it takes time.  Sulfa drugs do not kill the coccidia, they only prevent it from reproducing – basically it slows the Coccidia down so that the kitten or cat’s immune system can catch up and eliminate it.  A more effective medication called Ponazuril has been found to kill the coccidia with only 1-3 doses.  Ponazuril (brand name Marquis) is manufactured for horses and used off-label for cats and dogs.  You may have to ask your vet to prescribe Ponazuril since many are not aware of its use for cats and dogs.  Additionally,  some kittens may need supportive care such as sub cutaneous fluids during treatment for Coccidiosis.

How is it prevented?

Coccidiosis is prevented by keeping the environment clean, disinfecting everything that may have come in contact with coccidiosis-infected cats with a 1:32 bleach water solution, and separating infected cats or kittens from healthy cats.

Giardiasis

What is Giardiasis?

Giardiasis is an illness caused by a parasite called Giardia.  Giardia are one-celled protozoa that live in the intestinal cells of many types of animals and can infect humans as well.  Cats become infected by giardia by ingesting the cysts which are passed in the feces of another infected animal.  Cysts can also be present in contaminated drinking water.  Once the cysts are ingested it takes around 5-16 days for the cysts to grow into mature giardia “trophozoites” at which time symptoms begin.

What are the symptoms?

The most common symptom of giardiasis is a sudden onset of foul-smelling diarrhea ranging from watery to soft or mucousy, often with a greenish tinge and occasionally containing blood.  Weight loss and dehydration often occurs and infection occasionally cause vomiting.  Many adult cats who are infected with giardia are asymptomatic, however can shed oocysts in their feces that can infect others.  Kittens and immunosuppressed cats are more likely to show symptoms of infection.

How is it diagnosed and treated?

Positive diagnosis of Giardiasis can be obtained by viewing a fecal sample under a microscope, however since the Giardia cysts are only shed in feces intermittently, they are not always found.  A more sensitive test called a PCR test (polymerase chain reaction) can be done to confirm giardiasis, but this test is expensive and takes time since a sample must be sent to a laboratory.  Often veterinarians prescribe medications for Giardiasis based on clinical signs rather than confirmation.    Giardiasis can be successfully treated with either Fenbendazole or Metronidazole.  Additionally, some kittens may need supportive care such as sub cutaneous fluids during treatment for Giardiasis.

How is it prevented?

Giardiasis is prevented by keeping the environment clean, disinfecting everything that may have come in contact with giardiasis-infected cats with a 1:32 bleach water solution, and separating infected cats or kittens from healthy cats.

Cryptosporidium

What is cryptosporidium?

Cryptosporidium is an illness caused by a parasite called Cryptosporidia.  Cryptosporidia are one-celled protozoa that live in the intestinal cells of many types of animals.  Cats become infected by coccidia by ingesting the cryptosporidia cysts which are passed in the feces of another infected animal.  Symptoms can begin 2-3 days after ingestion or as much as 2 weeks after ingestion, but generally around 5-7 days after ingestion.

What are the symptoms?

Cryptosporidium is characterized by a sudden onset of lethargy, watery diarrhea, anorexia, and occasionally fever.  Dehydration and weight loss can occur.  Many adult cats who are infected with Cryptosporidia are asymptomatic, however can shed cysts in their feces that can infect others.  Kittens and immunosuppressed cats are more likely to show symptoms of infection.

How is it diagnosed and treated?

Positive diagnosis of Giardiasis may be obtained by viewing a fecal sample under a microscope using specific staining techniques.  A more sensitive test called a PCR test (polymerase chain reaction) can be done to confirm Cryptosporidium, but this test is expensive and takes time since a sample must be sent to a laboratory.  While many medications have been tested to treat Cryptosporidium, only a few types of antibiotics show moderate efficacy – Paromomycin, Azithromycin, and Tylosin.  Generally the illness must run its course while the cat’s immune system catches up.  A high fiber diet and intravenous fluids may be needed during this time.

How is it prevented?

Cryptosporidium is prevented by keeping the environment clean, disinfecting everything that may have come in contact with cryptosporidium-infected cats using an ammonia-based cleaner or heat above 70 degrees, and separating infected cats or kittens from healthy cats.

Tritrichomonas Foetus

What is Tritrichomonas Foetus?

Tritrichomonas Foetus is a protozoal parasite commonly found in cattle, but more recently found in cats.  Many vets are still unaware of its existence and commonly misdiagnosis it as Giardia.  Cats become infected by giardia by ingesting the protozoa which are passed in the feces of another infected cat.  Tritrichomonas does not form a cyst and therefore does not survive once dry, though it an live in wet feces for several days.

What are the symptoms?

The symptoms of Tritrichomonas are foul-smelling diarrhea.  Weight loss and dehydration often occurs.  Many adult cats who are infected with Tritrihomonas are asymptomatic, however can intermittently shed the parasite in their feces and infect other cats.  Kittens and immunosuppressed cats are more likely to show symptoms of infection.

How is it diagnosed and treated?

Tritrichomonas Foetus is very rarely able to be identified in a fecal smear.  A more sensitive test called a PCR test (polymerase chain reaction) can be done to confirm, but this test is expensive and takes time since a sample must be sent to a laboratory.  Unfortunately false negatives are common.  Any cat that continues to show symptoms should be re-tested.  Tritrichomonas Foetus can be successfully treated with Ronidazole.  Proper dosage is important since Ronidazole can cause neurological problems.

How is it prevented?

Tritrichomonas Foetus is prevented by avoiding bringing carrier cats into your environment, separating any new or suspected carriers of TF from all other cats, and keeping the environment clean and dry.  Tritrichomonas Foetus can only survive about an hour unless it stays wet, however it is common for cats to infect each other by sharing a litter box and grooming.

Toxoplasmosis

What is Toxoplasmosis?

Toxoplasmosis is a disease caused by Toxoplasma Gondii – a single-celled organism that infects many mammals including cats AND people.  Usually cats are infected by consuming the oocysts which is a sturdy form of immature Toxoplasma Gondii like an egg.  These oocysts are shed in the feces of infected animals where they can be ingested by an intermediate host (usually a rodent) and later consumed by the cat.  Humans can become infected with Toxoplasma from contact with the feces of infected cats, contact with soil containing the oocysts, or eating improperly cooked contaminated meat.

What are the symptoms?

Usually Toxoplasmosis causes no symptoms.  If the cat is already immunocompromised, it may show symptoms such as respiratory distress, diarrhea, or eye disease, among other problems.  Toxoplasmosis also rarely causes symptoms in people, with the infected person only occasionally showing mild flu-like symptoms.  However Toxoplasmosis infection is a major concern for pregnant women due to the danger it presents to the developing fetus.

How is it diagnosed and treated?

Exposure to Toxoplasmosis in both cats and people can be determined by blood test and it can be treated with antibiotics.  A woman who has been exposed to Toxoplasmosis before becoming pregnant will not be at risk if she becomes pregnant in the future.

How is it prevented?

Keeping your cat indoors and only feeding fully cooked foods is the best way to prevent Toxoplasmosis.  However, since the main danger of Toxoplasmosis is to pregnant women, here are the best ways to prevent any potential danger – follow proper hygiene protocols when handling meat, cook meat thoroughly, wear gloves when gardening or scooping litter boxes (or have someone else do it!), wash vegetables thoroughly, and wash hands frequently.

Additional information regarding Toxoplasmosis Risk:

It takes 24 hours or more for the oocysts of Toxoplasmosis Gondii to develop into the infectious stage – completely dumping and sanitizing litter boxes each day will eliminate the risk of infection.  Additionally, the Toxoplasmosis oocysts and/or eggs are only shed in the cat’s feces for approximately 10 days after initial infection.  It is FAR more likely for a pregnant woman to come into contact with Toxoplasmosis in contaminated soil or uncooked meat.  Pregnant women should take every precaution necessary to avoid Toxoplasmosis in all sources, not just by avoiding cats and litter boxes.

Intestinal Worms

Round worms

Roundworms are extremely common in cats with almost all cats becoming infected with roundworms at some point, most frequently as kittens.  The species of roundworms that commonly affects cats is Toxocara cati and another species that infects both cats and dogs is Toxocaris leonina. The worms are around 3-6 inches in length and swim freely through the intestines.  Adult cats usually show no symptoms and kittens often do not either, though they are more commonly negatively affected than adults.  Symptoms include abdominal swelling, dry coat, lack of appetite, vomiting, diarrhea, and slow growth.  Sometimes worms are seen in feces or vomit, but not always.  Most commonly transmission of the worms to cats happens when the roundworm larvae are passed from mother to kitten during nursing.  This can happen even if the mother cat has tested clear of roundworms since the worms are able to encyst in the tissues of the cat where they are unable to be detected.  Cats may also ingest roundworm eggs that have been passed in an infected cat’s stool or in an intermediate host such as a rodent, bird, cockroach, or earthworm.  Roundworms can be found using a fecal float and are easy to treat with deworming medications.  Most vets recommend that all kittens be dewormed starting at 2-3 weeks and every 2-3 weeks following for a total of 3 treatments.  Adults should be treated before breeding and your vet may recommend treating females in late pregnancy.  Some heartworm preventative medications also kill roundworms, so if you are using these medications check your labels.

Tapeworms

Tapeworms (or Dipylidium) are flat-segmented worms whose presence in cats is often unknown until the owner spots the rice-like segments around the cat’s anus or in the litter box.  The rice like segments that are shed in the feces contain the tapeworm eggs.  Unlike most other parasites in which the cat can become infected by ingesting the eggs or cysts, the tapeworm eggs must first be ingested be flea larvae.  Once the flea larvae mature into fleas and are consumed by the cat during grooming, the tapeworm eggs are released, hatch, and then attach to the cat’s intestine.  Most cats do not show any symptoms of tapeworm infection other than the noticeable passing of the worm segments.  Occasionally severe tapeworm infection can cause weight loss.  Tapeworms are not usually identified in routine fecal exams.  Controlling fleas on the cat and in the environment is the best way to prevent tapeworms though some deworming medications can eliminate tapeworms as well.

Hookworms

Hookworms are very tiny worms that anchor themselves to the cat’s intestine and consume the cat’s blood.  They are so small they are almost invisible to the naked eye.  Cats are not as frequently infected with hookworms as are dogs.  Infection occurs when cats ingest the eggs that are passed through an infected cat’s feces or when the eggs are passed to kittens in their mother’s milk.  Symptoms include tarry-looking stool, anemia, poor coat condition, and weight loss.  Symptoms are more common in young kittens than adults.  Hookworms can be identified in a fecal float examination.  Treatment is the same as with roundworms – deworming medications starting at 2 weeks of age for kittens and repeated every 2-3 weeks for a total of 3 treatments.  Adults may be treated occasionally and proper sanitation procedures will eliminate the eggs from the environment.


Most parasites are relatively common and while they are easily picked up and transmitted among cats, they are also easily cured.  However, Tritrichomonas Foetus is an exception!  While it is uncommon to find in most homes and yards, it is unfortunately common in untested catteries and is also difficult to diagnose.  Additionally, the treatment can be risky.  The best way to prevent Tritrichomonas is to purchase your kitten from a cattery that can provide clear PCR testing results.


References:

https://veterinarypartner.vin.com/default.aspx?pid=19239&id=4951548

https://vcahospitals.com/know-your-pet/coccidiosis-in-cats

https://www.uwsheltermedicine.com/library/resources/what-are-the-best-treatment-options-for-coccidiosis-in-a-shelter-setting

https://www.cdc.gov/parasites/giardia/prevention-control-pets.html

https://vcahospitals.com/know-your-pet/giardia-in-cats

https://www.merckvetmanual.com/digestive-system/giardiasis-giardia/overview-of-giardiasis

https://capcvet.org/guidelines/cryptosporidium/

https://www.uwsheltermedicine.com/library/resources/managing-cryptosporidiosis-in-a-shelter-setting

https://vcahospitals.com/know-your-pet/toxoplasmosis

https://www.merckvetmanual.com/cat-owners/disorders-affecting-multiple-body-systems-of-cats/toxoplasmosis-in-cats

https://vcahospitals.com/know-your-pet/roundworm-infection-in-cats

https://www.thedrakecenter.com/materials/feline-roundworm-infection

https://vcahospitals.com/know-your-pet/tapeworm-infection-in-cats

https://www.petsandparasites.org/cat-owners/tapeworms/

https://vcahospitals.com/know-your-pet/hookworm-infection-in-cats

https://www.petmd.com/cat/conditions/infectious-parasitic/c_ct_ancylostomiasis

Lori Denley
Author: Lori Denley

Breeder located in Western North Carolina and creator of verifiedbengalbreeders.com