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What are Coccidiosis?

This common parasitic intestinal condition is acquired from contaminated soil or water, animal feces or consumption of an infected rodent.  Generally, the one-celled organism, coccidia, doesn’t require more than one host to achieve its life cycle and can be found in most commonly in young animals (usually picked up between 1 month and 1 year of age) who are housed or otherwise contained in small areas which have been contaminated with oocysts (the stage of development which is shed in feces).

Coccidiosis in dogs is generally defined as an invasion and destruction of intestinal mucosa by protozoa of the genera Isospora, Hammondia, and Sarcocystis.

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Symptoms of Coccidiosis in Dogs

This is one of those parasitic infections in which symptoms may or may not present in your canine.  Here are some of the symptoms which could be noted in your canine:

  • Watery diarrhea, sometimes tinged with blood or mucus
  • Vomiting
  • Loss or decreased appetite
  • Weight loss
  • Lethargy

Puppies are at risk for more severe infection, with dehydration and weight loss sometimes leading to death.  Additionally, your pet may have milder symptoms or may have no symptoms at all, while the cysts containing the parasite will still be shed in their feces.  


There are multiple species of coccidia which can infect the intestinal wall of your pet.  The species of coccidia are host-specific:

  • Dogs are known to have species of Isospora, Hammondia, and Sarcocystis
  • Cats are known to have species of Isospora, Besnoitia, Toxoplasma, Hammondia hammondi, and Sarcocystis
  • Neither dogs nor cats are known to have Eimeria 
  • Isospora is the most common in dogs and cats
  • Hammondia is one of the species which requires two hosts to complete its life cycle with rodents and ruminants being the intermediate and dogs and cats being the final host

Causes of Coccidiosis in Dogs

The cause of coccidiosis in dogs is the infestation of the canine’s intestinal system with the coccidian parasite. So, how does this infection occur?  First of all, it’s important to understand that the cysts are shed in the feces of infected dogs who may or may not be exhibiting symptoms.  These cysts can not only survive for a very long time outside the body of the host but also can become infective in certain environmental conditions.  

  • Your canine family member sniffs, eats or drinks something found on contaminated ground or in water which has the infective cysts contained in or on it
  • The cyst gets into the digestive tract and it breaks open
  • The feeding form of the parasite actually gets into a cell in the intestinal wall of the host
  • Reproduction (binary fission) takes place repeatedly once it has entered the cell
  • The cell bursts open, spilling out its parasitic contents and damaging the lining of the intestinal wall

While the species of coccidia which infects dogs doesn’t infect cats, the infected feces from one dog can infect another dog, with the same being true with cats.  This parasite is zoonotic in nature (meaning that it can be passed from animals to humans) and some species can be passed to humans, but, historically, it has been found to be unlikely that humans would become infected from the same species of coccidia which infects dogs and cats.

Diagnosis of Coccidiosis in Dogs

As always, when your pet is being evaluated by your veterinary professional, either for a routine regular examination or because you suspect a disease or other condition, your input is very important to ascertaining the final diagnosis.  You will need to provide a complete history of your pet’s situation which includes feeding products and schedule, bowel and urinary habits and their frequency, any appetite changes and any other unusual behavior noticed in your canine.  Your veterinary professional will do a physical examination and will require a stool sample for evaluation.  

Because this infection doesn’t always present with symptoms and because the evidence of the presence of the parasite isn’t always seen in one stool sample, it may be necessary to provide several samples at periods specified by your vet.  Microscopic examination of the stool sample will likely reveal the presence of the organism at some point, even if your canine family member is not exhibiting the classic symptoms of the infection.  After your vet has completed his assessment of your pet, he will develop an appropriate treatment plan for your pet’s situation.

Treatment of Coccidiosis in Dogs

The good news about coccidiosis in dogs is that the life cycles of some of the species of coccidia are self-limiting, meaning that they will spontaneously stop usually within just a few weeks, unless the dog is reinfected.  Since this condition is commonly found in overcrowded, confined areas, areas of poor nutrition, poor sanitation or following periods or episodes of stressors like weaning, shipping, sudden changes of diet or severe weather changes, your pet’s recommended treatment plan may include specific instructions in regard to sanitation of the areas common to your family pet, with emphasis given to removal and sanitation of areas commonly used for excrement relief.  

There is specific treatment for this malady in your canine.  Medications can be given which will slow down and stop the growth cycle of the parasite, decreasing the opportunity for reinfection.  This will shorten the length of time your pet suffers from the illness, will reduce the oocyst being shed in the afflicted dog’s feces (thus protecting other dogs from infection), assuage the possibility of hemorrhage and diarrhea, and reduce the chances of secondary infections and even death.  

While there are medications available for treatment, they are more for prevention of reinfection purposes as opposed to eradication purposes. It is, therefore, quite important that your sick doggy family member be kept away from otherwise healthy pets, facilitating appropriate medication administration and prevention of exposure to other animals in your household or kennel.  Supportive care, if needed, will likely be included in the treatment plan for your afflicted canine as well.

Recovery of Coccidiosis in Dogs

If you suspect coccidiosis in any of your pets, do not hesitate to seek medical attention for them.  The younger the animal, especially true for kittens and puppies, the more serious the infection can be, often requiring IV fluids and hospitalization if they become dehydrated.  Young kittens and puppies are at increased risk of death if not treated in a timely and appropriate manner.  Since the evidence of the parasite is difficult to find in a stool sample, it is imperative that you seek medical guidance if you even just suspect coccidiosis in your canine family member.  

It is likely that your vet will also treat for it automatically if it is suspected in an attempt to heal the afflicted dog as well as protect other animals who may have been or will become exposed in your kennel or household.  Be prepared to strengthen or change the sanitation and cleaning regimens which you may currently be employing as the fecal material is the source of the parasitic attacker which can infect and potentially kill your family pet, especially those who are young, debilitated or have a compromised immune system.