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Coccidia in Dogs

Coccidia symptoms in dogs generally present as watery diarrhea coated in mucus. Other symptoms may include:

  1. Vomiting
  2. Lethargy
  3. Abdominal pain
  4. Loss of appetite
  5. Dehydration
  6. Weight loss

Your vet can look at your dog’s stool sample under the microscope to confirm coccidia’s presence.

Diagnosis And Treatment To Resolve Coccidia

Coccidia infection in dogs can be diagnosed by identification of the unsporulated oocysts with any of the fecal flotation methods commonly used to diagnose parasitic infections

Upon diagnosis, your vet will recommend an antiparasitic medication.

Several medicines including sulfonamides, sulfonamides with antifolates, amprolium, spiramycin, diclazuril, toltrazuril, totrazuril sulfone (ponazuril) and combinations of these have been used to treat coccidiosis in dogs.

The medication is typically given orally for 5-7 days.

The best medication for your pet will depend on a number of factors, including the type of coccidia infection, the severity of the infection, and your pet’s overall health. Your veterinarian will discuss the best treatment options for your pet with you.

It is important to note that some coccidia parasites have developed resistance to certain antiparasitic medications. If your pet does not respond to one medication, your veterinarian may recommend switching to a different medication.

In severe cases, it may be necessary to repeat treatment.

What is Coccidia

Coccidia is a single sell protozoan.

Protozoa are single-celled organisms that are found in all types of environments, including water, soil, and inside other organisms. Protozoa can be parasites, meaning they live off of another organism, or they can be free-living.

Coccidia parasites have a complex life cycle that involves both asexual and sexual reproduction.

Asexual Reproduction

Coccidia reproduces asexually through a process called merogony. Merogony is a type of binary fission, in which the parent cell divides into two identical daughter cells.

The first step in merogony is the formation of a meront. A meront is a multinucleate cell that contains many nuclei. The meront is formed when the coccidia parasite infects a host cell.

Once the meront is formed, it begins to divide into many smaller cells called merozoites. Merozoites are the immature form of the coccidia parasite.

When the meront is fully divided, the merozoites are released from the host cell. The merozoites then infect new host cells and begin the merogony process again.

The number of times that the merogony process repeats depends on the species of coccidia parasite. In some species, the merogony process may repeat dozens of times before the parasite is ready to reproduce sexually.

Here is a more detailed breakdown of the merogony process:

  1. The coccidia parasite infects a host cell.
  2. The parasite divides into a multinucleate cell called a meront.
  3. The meront divides into many smaller cells called merozoites.
  4. The merozoites are released from the host cell and infect new host cells.
  5. The merogony process repeats.

The merogony process is a very efficient way for coccidia parasites to reproduce. A single coccidia parasite can produce hundreds or even thousands of merozoites during the merogony process. This allows coccidia parasites to quickly infect and damage the host’s intestines.

Asexual reproduction is the primary mode of reproduction for coccidia parasites. However, coccidia parasites can also reproduce sexually.

Sexual Reproduction of Coccidia

Sexual reproduction in coccidia parasites is a complex process that involves the fusion of two gametes: a male and a female gamete. The male gamete is called a microgamete, and the female gamete is called a macrogamete.

The microgamete is produced by the male coccidia parasite. It is a small, motile cell that swims through the host’s intestines in search of a macrogamete.

The macrogamete is produced by the female coccidia parasite. It is a large, non-motile cell that remains in the host’s intestines.

When the microgamete finds a macrogamete, it fuses with it to form a zygote. The zygote then undergoes a series of changes to develop into an oocyst.

The oocyst is the infectious stage of the coccidia parasite. It is a hard-shelled structure that can survive in the environment for long periods of time.

When an animal ingests an oocyst, the coccidia parasite inside the oocyst is released into the animal’s intestines. The parasite then undergoes a series of changes to develop into an adult coccidia parasite and begin the reproductive cycle again.

Sexual reproduction is necessary for coccidia parasites to produce oocysts, which are the infectious stage of the parasite. Oocysts are shed in the feces of infected animals and can contaminate the environment. When other animals ingest oocysts, they become infected with coccidia parasites.

Sexual reproduction is also important for coccidia parasites to maintain genetic diversity. Genetic diversity helps coccidia parasites to adapt to changes in their environment and to develop resistance to antiparasitic medications.

Where Do Oocysts Live In The Dog’s Body?

In a study (Lepp and Todd (1974)), an infected dog was necropsied daily from 1 to 12 days post-inoculation of oocytes.

The prepatent (period of time between infection with a parasite and the appearance of symptoms) period was 142–146 hr. The patent (the time between infection and the appearance of infectious stages of the parasite in the host’s feces or other bodily fluids) period was 13–23 days with an average of 19 days. Developmental stages were located throughout the small intestine and rarely in the colon. The distal part of the ileum was the most parasitized site (Mahrt, 1967).

Extra-intestinal stages were not found in sections of mesenteric lymph nodes, spleen, lung, liver, heart, skeletal muscle, or brain of dogs. However, biological evidence indicated that coccidia invaded the spleens and mesenteric lymph nodes of dogs fed oocysts; dogs fed individual extraintestinal tissues excreted oocysts (Dubey, 1978a). Oocysts sporulated within 96 h (Baek et al., 1993).

Where Could My Dog Have Picked Up Coccidia

It is prevalent worldwide and the ingestion of food and water contaminated with oocysts is the major mode of transmission (Dubey, 2019).

Mice, sheep, camel, chicken, turkey, pheasants, rabbits, donkey, pigs, beef, chicken, bison, goats, lamb, and water buffalo can be hosts for coccidia.

Weakened Immune System

Puppies and dogs with weakened immune systems are more likely to become infected with coccidia. This is because their immune systems are not as well-developed or as effective at fighting off infection.

Weakened immune systems may also be more vulnerable to other parasites.

If your dog has been infected with coccidia, your vet may also be checking the fecal sample for the presence of other antigens or parasites present.

Home Treatment and Prevention

There are some parasites that should be treated medically. This is one of them. Other safety measures you can do at home are:

  1. If your dog is raw fed, pause raw feeding until your dog is free from symptoms for six months so that their immune system has time to get stronger.
  2. Steam clean your floors with hot water.
  3. Wash all bedding, blankets, and toys in hot soapy water.

Food Recommendations For Strengthening The Lymphatic and Immune System After Treatment

After treatment for coccidia, I recommend the following:

  • Bone broth with every meal for at least six months
  • Manuka Honey (UMF 20 or higher and/or MGO 400 and higher) for one week. Add one small drop to your finger, and let your dog lick it off 2 to 3 times a day. Repeat it every month (for 7 days) for six months.
  • Cooked diets until the dog is free from symptoms for six months.
  • Daily probiotic for six months.

TCVM Vet Recommendation

Dr. Dennis Thomas

Holistic Health Care for Pets
1707 E. 11th Ave, Spokane WA 99202
Call: 509-214-2676

If you would like to contact him via email: DrThomasHolisticvet@yahoo.com

I use him for my own dogs, and refer clients to him when a TCVM vet isn’t available in your city.

In Closing

Coccidia is present worldwide.

When a dog presents with diarrhea with mucus that just won’t go away, lethargy, and loss of appetite it’s always recommended to bring a stool sample to your vet so that they can rule out parasites.

While natural remedies can be explored, in these cases I recommend that these parasites be treated medically.

After they are gone, you can work on strengthening the body’s lymphatic and immune system.

I hope this article was useful to you and I wish you and your dog good health.


Baek BK, Kim CS, Kim JH, Han KS, Kim YG. Studies on isosporosis in dogs. I: Isolation and sporulation of Isospora ohioensis. Korean J Parasitol. 1993 Sep;31(3):201-6. doi: 10.3347/kjp.1993.31.3.201. PMID: 8241078. https://www.parahostdis.org/journal/view.php?doi=10.3347/kjp.1993.31.3.201

Dubey JP, Lindsay DS. Coccidiosis in dogs-100 years of progress. Vet Parasitol. 2019 Feb;266:34-55. doi: 10.1016/j.vetpar.2018.12.004. Epub 2018 Dec 13. PMID: 30736946. https://pubmed.ncbi.nlm.nih.gov/30736946/

Dubey JP, 1978a. Life cycle of Isospora ohioensis in dogs. Parasitology 77, 1-11. http://refhub.elsevier.com/S0304-4017(18)30395-9/sbref0290

LEPP, D.L. and TODD, K.S., JR. (1974), Life Cycle of Isospora canis Nemeséri, 1959 in the Dog. The Journal of Protozoology, 21: 199-206. https://doi.org/10.1111/j.1550-7408.1974.tb03641.x

MAHRT, J.L. (1967), Endogenous Stages of the Life Cycle of Isospora rivolta in the Dog. The Journal of Protozoology, 14: 754-759. https://doi.org/10.1111/j.1550-7408.1967.tb02073.x

Author Biography

Hannah Zulueta obtained her Certificate in Canine Nutrition from CASI Institute. She is also studying for her Doctorate in Acupuncture, Traditional Chinese Medicine, and Herbalism from the esteemed Pacific College of Health and Medicine.

She resides in San Diego with her three dogs, Maggie, Orbit, and Mr. Higgins.

She is available for one on one consultations. Additionally, you can find her sharing free content on Instagram.

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