Coccidiosis in Cats
Dawn Skupin, Stedam American Shorthairs
Coccidiosis is a single celled organism that infects the intestine. This microscopic parasite affects many animal species including, but not limited to cats, dogs and humans. Most mammals and birds can be infected, pets and livestock alike. The diseases caused by these parasites are referred to, collectively, as coccidiosis. Coccidia is the most prevalent protozoan infection world-wide, second only to giardia.
Many species of coccidia infect the intestinal tract of cats. All species appear to be host-specific. Cats have species of Isospors, Besnoitia, Tosoplasma, Hammondia, and Sarcocystis. The most common coccidia in cats is Isospora.
Coccidiosis is usually not a great threat to a healthy cat, but animals that are sick, debilitated or have some immunosuppressed issues can become extremely sick with a coccidia infection followed by death if left untreated. Kittens less than six months of age are much more susceptible to severe coccidia infections than adult animals are. Clinical signs include watery diarrhea with or without blood and mucus, weight loss, anorexia, dehydration, vomiting, abdominal pain, mental depression, anemia or even death in severe cases. Most adult cats carry coccidia, but their immune system keeps it in check. Some adults may shed cysts in the feces. Symptoms can reappear if the cat is stressed or if the immune system has been compromised by another cause, such as FIV. It is important to note that the two less common forms of coccidia, toxoplasmosis and cryptosporidium, are zoonotic, meaning that they can be transmitted to humans.
Transmission of coccidia begins when the immature coccidia, or oocysts, are passed in the feces from an infected cat into the environment where they mature and are ingested by another animal. Transmission also can occur when a cat eats an animal such as a rodent that has previously been infected with the Isospora parasite. Additionally, oocysts can also be swallowed by a cat when it grooms or licks dirt off itself. Once the oocysts mature they become infective, (a sporulted oocyst). Each oocyst contains four sporozoites in each of two sporocysts. The “zoites” invade the intestinal cells and develop to the schizont stage. The schizonts release more zoites which invade new cells and thus begins the next generation of schizonts. There are three generations of schizonts. Zoites released from the last generation of schizonts invade cells and form gametocytes. The male gametocyte releases gametes which fuse with the female gametocytes and form oocysts. This is how thousands of intestinal cells can become infected and destroyed as a result of swallowing a single oocyst. As the intestinal cells are destroyed in larger and larger amounts, the intestinal function is disrupted and a bloody, watery diarrhea results. This fluid loss can be dangerously dehydrating to a young kitten.
Diagnosing coccidia is not easy. Even when it appears that an outbreak is evident, the oocysts may not be shedding in every single stool. Therefore a negative report does not rule out coccidia. The most thorough way to assess is to collect a sample from every single stool produced for 48 hours. Each sample must be tested to assure proper diagnosis.
The most frequently used medications used against coccidia are called coccidiostats. They inhibit coccidial reproduction. The most universal treatment for coccidia is using a sulfadimethoxine drug such as Albon, Bactrovet or Tribrissen. Data regarding acute and chronic toxicities of sulfadimethoxine indicate the drug is very safe. A typical treatment course lasts a week to two weeks. It is important that the medication should be given until the diarrhea resolves plus an extra couple of days. Medication should be given for at least five days total. Some cats require treatment for as long as a month for complete resolution of the problem.
Another medication worth mentioning is Ponazuril. Ponazuril actually kills the coccidia, which makes for a faster response to treatment and a shorter course of therapy. The problem for small animals is that Ponazuril is manufactured for horses and comes in a paste that is impractical for small animal use. The paste can be diluted and used orally in cats, however it must be compounded by a pharmacy or your veterinarian.
Treatment and prevention are most effective when started early. Cattery owners can reduce exposure by reducing stress, such as overcrowding and poor sanitation. It is recommended that raw meat should not be fed if the cattery owner wants to control the outbreaks of coccidia. A routine fecal test for new additions to the cattery is important in preventing an outbreak of coccida. All newly introduced animals should be separated from the general cattery population until negative cultures can be obtained. Additionally, once a year testing for this parasite is a good idea for proper animal husbandry.
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