Canine coccidiosis: What you need to know A relatively common parasite that can cause diarrhea in your dog Coccidiosis: What is it Coccidiosis is an infection by single-celled organisms (protozoa) known as coccidia (coccidiosis is often just referred to as coccidia). Research suggests that depending on the region, anywhere from 3 to 38% of dogs in North America are infected. Dogs are typically infected due to environmental contamination, when they ingest coccidia oocysts found in contaminated soil or the feces of other dogs. Most forms of coccidia are species-specific, and are not a risk to humans. Your dog also cannot get coccidia from an infected cat (and vice versa). But there are at least four types of coccidia that can infect dogs. Signs of coccidia in your dog One of the most common signs of coccidia is diarrhea. Many adult dogs may be infected with coccidia but display no signs of health problems. Puppies and immunocompromised dogs are more vulnerable and often have watery diarrhea; vomiting, weight loss, and dehydration may also be present. How is coccidia diagnosed in your dog? To diagnose coccidia, you will need to present a fresh (less than a day old) stool sample for testing. You can get a container from your veterinary clinic or carefully place the stool in a clean resealable plastic bag immediately following the bowel movement, storing it in your refrigerator for up to 24 hours. Your veterinarian may start with a fecal exam (a “fecal float”) to look for coccidia oocysts under the microscope at the clinic. Alternatively, many clinics will send your dog or puppy’s fecal sample out to a laboratory for analysis. Unfortunately, a failure to observe coccidia oocysts in a fecal float does not mean the dog is all clear; oocysts are very small and can be hard to observe. Some rare coccidial parasites are detected with a blood test. Treating your dog for coccidia There are two types of medications that are used to treat dogs with coccidia. Coccidiostats are medications that inhibit reproduction of the protozoa, and allow the dog’s immune system to clear the infection. Sulfadimethoxine (Albon) is a coccidiostat and currently is the only FDA approved drug for treatment of coccidiosis. Coccidiocidals are medications that kill coccidia. Ponazuril (Marquis) and toltrazuril are two examples of coccidiocidal medications that your veterinarian may prescribe to treat your dog. Although they are not FDA approved for coccidiosis in dogs, they are used off-label, with Ponazuril (Marquis) showing good efficacy in published studies. Some dogs may also need supportive therapy, such as intravenous or subcutaneous fluids, for dehydration or severe diarrhea. Multiple treatments, sometimes with multiple types of medication, may be necessary; dogs can also be re-infected if the environment is still contaminated. Treatment may also fail if coccidiosis is not the cause, or the only cause, of any signs of enteritis. Finally, some dogs may not need any treatment at all, especially adult dogs who are otherwise healthy and not symptomatic. Your veterinarian can advise you as to whether your dog needs treatment. Prognosis for dogs with coccidia When treated promptly, most puppies and dogs will recover fully. Puppies and immunocompromised dogs are most vulnerable to this parasite, and if untreated, they can die. A smaller number of dogs with coccidia may require time, multiple treatments, and supportive care to be rid of the parasite and fully recover. Environmental cleaning and prevention Environmental sanitation is critical to controlling coccidia outbreaks; infective oocysts can survive in a contaminated environment for months and oocysts can be resistant to disinfectants. Feces should be removed from any regularly used areas (yards, kennels) at least daily. Quick removal of feces decreases the risks of contamination. Stress can increase a dog’s susceptibility to a coccidia infection, especially when the stress is prolonged or severe. Stressful events can include separation from the mother, moving to a new home, a change in the dog’s routine, or travel. Sometimes stressors can lead a dog who would otherwise not be affected by a mild coccidia infection to become symptomatic. Living spaces should be kept clean and routinely sanitized. Diluted bleach (1 cup per gallon of water) can be used for cleaning areas, but bleach can damage some surfaces. Thorough steam cleaning can also remove oocysts. Routine disinfectants (e.g., products made with accelerated hydrogen peroxide) have not been proven to be effective against coccidia. All puppies should receive a fecal exam as part of their first veterinary visit and be treated (if needed/as indicated). Adult dogs should also have a yearly fecal test as part of a wellness exam.