Coccidia

Coccidia are microscopic parasites that cause digestive problems in dogs. 

The parasite causes diarrhea with a mustard-like consistency, sometimes accompanied with dehydration, blood, and vomiting. 

These symptoms are often seen in puppies of 4 to 6 weeks old, or some time after, and in those whose immune system is weakened by stress, such as when they are adopted for example. 

Dogs acquire the parasite by ingesting infected stools or contaminated water. 

The parasite housed in the intestines of the cat lays eggs, which are still harmless at this time, and they are expelled with the feces. They become infectious once in the environment. 

When a cat ingests these eggs, sporozites, the infectious form of the parasite, will be released in the digestive tract. Afterwards, these will penetrate the cells of the mucosa of the cecum where the parasite will mature and multiply.

Once full of the parasites, the affected cells will break and free them. These can then overtake the adjacent celles and continue to multiply. 

The fertilisation will complete the parasite's cycle by creating new eggs, which are very resistant in the environment, which will be expelled in the cat's feces. 

The life cycle of Isospora canis, the specie of coccidia that affects dogs, lasts from 9 to 11 days. 

This can parasite can live up to one year in the environment.

It is possible to see the parasite found in the stools under a microscope. 

Their shape is slightly ovoid and they have a thick double lining with a dark inner portion and a clear outer portion.

There exists a safe and effective medication, sold under prescription, to kill this parasite. 

Additionnal treatments aimed at treating the diarrhea may be required.