Coccidia
By Dr. Karen Burgess

What is Coccidia?
Coccidia are in a family of microscopic parasites called protozoa and are not visible to the naked eye like other worms.  There are several species of coccidia but Isospora is the most commonly seen in dogs and cats.  Coccidia reside in the small intestine, can cause severe watery diarrhea, particularly in the very young, and are not susceptible to commonly used dewormers.  While potentially life threatening in the very young, coccidian is typically of no concern in healthy adults.

How do cats and dogs get coccidia?
An animal infected with coccidia passes eggs or oocysts in their fecal matter.  Once in the environment oocysts mature (sporulate) and become infective to animals.  In some cases dogs or cats eat other animals (ex. mice) that are infected with coccidia thereby becoming infected themselves.  Pets from high density housing situations such as kennels, shelters, or breeders are commonly infected with coccidia.

What clinical signs do coccidia cause?
Once inside the body, sporulated oocysts burst open releasing smaller versions that then attach to a cell lining the intestine and start reproducing.  Eventually too full to be contained, the infected intestinal cell bursts releasing even more coccidia to infect additional intestinal cells.  Ultimately infected intestinal cells are destroyed preventing an animal from being able to absorb nutrients from their food and leading to bloody, watery diarrhea.  Puppies, kittens and the debilitated are particularly susceptible to coccidia infection and can develop life threatening dehydration from an infection.

How is coccidia diagnosed?
Coccidia is found on a microscopic examination of a fecal specimen.  It is important to note that it may be difficult to diagnose coccidian on a single fecal test.  If symptoms persist in a patient, repeated fecal exams may be necessary.

How is coccidia treated?
The immune system is often able to keep numbers of coccidia under control, thus why healthy adult animals often do not develop disease.  In the very young, the immune system can become overcome thus requiring treatment.  Albon is the drug of choice to treat coccidia.  Typically given once daily for ten days, albon slows down coccidia reproduction giving the pet’s immune system a chance to resolve the infection.

Is coccidia contagious to people or other pets?
The species of coccidia that most commonly infects dogs and cats (Isospora) is not infectious to people (other species of coccidia  including Cryptosporidium and Toxoplasmosis are contagious to people).  While other pets can be infected by exposure to coccidia that have matured in the environment, it is typically only a concern in the very young or debilitated.  Good hygiene and cleaning the environment with dilute bleach (1 cup bleach to 1 gallon water) can help prevent reinfection.