Coccidia are single-celled parasites that can affect the intestinal tract of mammals of all species. The oocytes, or eggs, of the parasite are distributed into the environment through the faeces of infected animals. Dogs are commonly infected because they are in the habit of consuming grass and other items from the environment. Coccidia infections can also occur when the dog grooms after being outside. Often, these infections occur when many animals are housed together such as in a shelter or pet store.
How Infection Occurs
When the oocytes, or eggs, are ingested, they break open and the sporozoites, or immature coccidia, disperse into the digestive tract where they enter a single cell within the intestinal wall and begin to multiply. The sporozoites continue to reproduce until the cell can no longer handle the volume. The cells bursts, releasing the coccidia, which are now known as merozoites, which will then seek out new intestinal cells and begin the process over again. As the infection progresses, the dog will begin to exhibit symptoms of infection, most notably a watery and sometimes bloody diarrhoea.
The only way to detect the presence of a coccidia infection in a dog is to examine the faeces under a microscope to visually detect the presence of the sporozoites or merozoites. The faeces are mixed with a special solution designed to separate the parasite eggs from the fecal material and float them to the top, allowing them to be captured on a microscope glass. Dogs in the early stages of infection may be difficult to diagnose, as there may not be enough free sporozoites, or stage one immature coccidia or merozoites, or stage two immature coccidia, present in the faeces to detect. Several fecal examinations may be required to diagnose infection.
Treatment for a coccidia infection includes the administration of a medication that interrupts the parasite's replication mechanism, thus allowing the infection to die out. One such medication is fenbendazole, commonly marketed as Panacur. It is available as a powder or a liquid, which is administered orally for 5 days and will effectively kill the coccidia infection.
Fenbendazole is a very safe and effective antiparasitic medication. Side effects of using fenbendazole are rare but can include vomiting and diarrhoea. Using fenbendazole in dogs with coccidia infections should be done under close supervision to keep the dog from becoming dehydrated. Fenbendazole can be prescribed by a veterinarian or purchased over the counter at almost any pet or livestock retail establishment.
The long-term prognosis for dogs treated with fenbedazole for coccidia infections is good, however reinfection is common. Dogs should be routinely screened for the presence of coccidia and treated accordingly. Fenbendazole can also be used as a preventive medication in dogs that are considered at high risk of infection.