I recently received the following e-mail from Dianne, who appears to be having trouble with coccidia in her puppy. The subject line read “Coccidia in a 6-month-old Yorkie mix.”

What can I use to disinfect our yard, which is artificial grass? Or should we tether him so he can’t reach the area he usually uses to eliminate himself, and clean that area? This is the second 10-day round of sulfadimethoxine he has been given.

Coccidia are microscopic intestinal parasites of dogs and cats that invade certain cells in the intestines. Diarrhea is the most consistent symptom, but in severe cases, the parasites may trigger nausea, poor appetite, and vomiting. Coccidia are generally species-specific, so a puppy with coccidia usually does not represent a health threat to cats or people. Many animals with coccidia will show no symptoms whatsoever.

Coccidia are opportunistic and ubiquitous. It is virtually impossible to prevent exposure to the parasites, but individuals with fully developed immune systems generally will not display symptoms. The symptoms therefore occur mostly in young, stressed, or chronically ill dogs. Coccidiosis (as symptomatic infestation with coccidia is known) primarily occurs in puppies and kittens. Most animals will stop showing symptoms once their immune systems tackle the bugs. However, some individuals may show symptoms for quite a while before that happens.

Simple stool tests are used to diagnose coccidia, but an asymptomatic puppy with coccidia in the stool may not need to be treated.

Sulfadimethoxine, or Albon, is the only approved treatment for cats and dogs. But there’s a catch: It doesn’t really work, and many puppies will require repeated treatments before they stop showing symptoms. Quite a few experts recommend a drug called Ponazuril, which appears to be much more effective, and also has a good safety margin. However, although its use is widely accepted, it is technically “off-label,” so some vets are hesitant to prescribe it. Other vets simply haven’t heard about it.

Dianne, it is not likely that your puppy is suffering from reinfestation due to contamination of your yard. It’s more likely that the Albon hasn’t done anything, and that your puppy has been continuously infested since the start. I recommend that you talk to your vet about switching to Ponazuril to clear up the problem.

Coccidia do not live for very long outside of the body. They may survive for a week in intact feces, but the parasites will die within a few days on clean surfaces that are exposed to direct sunlight. Therefore, if you use Ponazuril and you pick up your dog’s feces immediately, restrict his access to his litter area, and hose off the artificial grass, you shouldn’t have to worry too much about yard contamination.

In the long run, your puppy’s immune system is what will really solve this problem.