Coccidia in dogs is one of the most common causes of diarrhea in canine companions. Puppies are most commonly affected, but coccidia can cause problems for adult dogs as well. 

According to the Companion Animal Parasite Council (CAPC), coccidia infections are present in almost 40 percent of dogs in North America. Fortunately, coccidia are easy to treat, and if treated properly, prognosis for dogs is good.

What is Coccidia?

Coccidia, also called coccidiosis, is the catch-all term for a group of parasites that infect dogs and other mammals. Coccidia are microscopic parasites that live in the wall of a dog’s intestine. There are many species of coccidia, and dogs are most often affected by the species of coccidia called Isospora. 

While you cannot see them with your naked eye, coccidia eggs are routinely detected by veterinary staff on microscopic fecal exams. They look like transparent eggs with very thin walls.

Coccidia can be tricky to diagnose because a dog can be infected and not show any signs at all. Alternatively, coccidia can cause watery, bloody diarrhea and weakness in dogs, and can be life-threatening to very young or very small dogs.

What Causes Coccidiosis in Dogs?

As a responsible dog owner, it is important to know how coccidia is transmitted from dog to dog. 

Coccidia eggs, which are called oocysts, are passed in poop. Within 12-26 hours, these eggs mature and can infect animals that accidentally swallow the infected poop. 

Coccidiosis is very common in young dogs that are housed together, like dogs that are housed in a shelter, rescue, kennel, or breeding facility.

Coccidia are very common in the United States, and these parasites don’t just infect dogs. Mice, houseflies, cockroaches, and other bugs can all become infected and become a source of infection if they are eaten by pet dogs. In addition, dogs can become infected by consuming any part of a carcass that is infected with coccidia.

Most of the time, dogs are infected with species of coccidia that only infect dogs, and the most common species of coccidia do not infect humans. Some other species, such as Cryptosporidium and Toxoplasma, can be transmitted to people, but these types of coccidia are rarely transmitted from dogs to humans. 

Symptoms of a Coccidia Infection in Dogs

As previously discussed, coccidia can cause severe watery, bloody diarrhea, weakness, and anemia in puppies. However, in normal, healthy adult dogs, coccidia can cause no symptoms at all. 

Whether or not a dog develops clinical signs related to coccidiosis depends on the dog’s immune system, which is often weaker in puppies than in adult dogs. Stress can also reduce the strength of the immune system, and coccidiosis can develop in dogs that have been recently stressed by rehoming, other infections or disease, or surgery.

Coccidia makes its home in the lining of a dog’s gut. When an infectious oocyst is swallowed by a dog, it breaks open and releases tiny particles that infect intestinal cells—cells that line the gut. These tiny particles reproduce rapidly inside the intestinal cells causing them to burst. If enough intestinal cells burst at the same time, then the dog develops watery, bloody diarrhea.

Additional symptoms of coccidiosis in dogs include:

• Weight loss
• Dehydration
• Loss of appetite
• Vomiting
• Lack of energy
• Death (only in severe cases)

Diagnosing Coccidiosis in Dogs

Coccidiosis in dogs is diagnosed with a combination of history (where you dog is from, what his habits are, recent travel, kennel stays, doggie daycare, etc.), signalment (age, breed, gender, neutered or not), physical exam findings, and laboratory tests.

Coccidia are easily diagnosed by examining your dog’s feces under the microscope for the presence of coccidia oocysts (eggs). Fecal float tests are routine tests that are easily run at your local veterinary office. To run a fecal test, your veterinarian will need a fresh sample of poop from your dog, ideally collected the same day as the test and kept in a sealed container. 

A technician mixes a small amount of feces with a solution that is heavier than parasite eggs, which forces the eggs to float to the surface and adhere to a microscope slide. In some cases, the sample may be spun in a centrifuge to further help eggs float to the surface. The microscope slide is then removed and examined under a microscope, allowing visualization of the eggs.

Sometimes a dog can be infected with coccidia but not show any eggs on the fecal float test. In these cases, if your veterinarian is suspicious of a coccidia infection, she may still recommend treatment for coccidia, or she may recommend repeating the fecal float test to look for parasites. 

How to Treat Coccidia in Dogs

There are two ways to treat coccidia infections in dogs: coccidiostat drugs and coccidiocidal drugs.

Coccidiostat drugs are the traditional and most common medications used to treat coccidia infections. Coccidiostat drugs stop coccidia from reproducing and allow the dog’s immune system to eradicate the infection. 

How long coccidiostat drugs take to eliminate the infection depends on how many coccidia are infecting the dog and how strong the dog’s immune system is. Typically, dogs are treated for 5-25 days with Albon, the most commonly prescribed coccidiostat drug.

Coccidiocidal drugs kill coccidia. Ponazuril and toltrazuril are both coccidiocidal drugs that are commonly used in farm animals for coccidia infections. Both of these drugs can be compounded into dog-friendly formulations by your local pharmacist, and only require a few doses in comparison to longer treatments with Albon. 

General Cost to Treat Coccidia in Dogs

The cost of diagnosis and treatment for a coccidia infection range based on geographical location. In general, associated costs can include:

Exam: $40-$70

Fecal Float Test: $30-$50

Medication: $35-$100, depending on type of medication, length of treatment, and size of dog

How to Prevent Dogs From a Coccidia Infection

Reinfection with coccidia is likely because the parasite is so common in the environment. If your dog has been diagnosed with coccidia, it is important to disinfect the environment.

Remove any feces as soon as possible to prevent reinfection. Oocysts in the soil can be killed by spraying a diluted chlorine bleach solution at a dilution of 1 cup of bleach to one gallon of water. 

To avoid infection, prevent your dog from eating feces or potentially infected hosts such as mice or insects. 

Remember that not all dogs that have coccidia have symptoms, so be sure and have your dog’s poop tested yearly for parasites at your local veterinary office. 

Related Conditions

• Diarrhea
• Anemia