Cryptosporidium is a water-borne illness most often seen in young dogs who play in bodies of fresh water. The parasite starts its life as an egglike cyst excreted when another animal defecates in the water. Accidental ingestion while swimming internalizes the parasite, which moves to the small intestine and multiplies, burrowing into the tissue and causing severe, watery diarrhea. This irritation in the bowel can severely hinder nutrient absorption, especially in younger animals, leading to weight loss and malnutrition. Dealing with a Cryptosporidium infection is of concern to the human owner- the disease is highly transmissible, and if care is not exercised while cleaning contaminated materials, the owner can be infected. The egglike cysts of Cryptosporidium are highly resistant to most cleaning solutions including bleach. A 5% ammonia solution is recommended to kill the organism, which can be infective for months in a cool, damp environment.

Owners who notice their dog experiencing extreme diarrhea and gastrointestinal distress should see a veterinarian immediately, as dehydration is a concern with this infection. A veterinarian will examine a sample of the animal’s stool under a microscope. The sample is stained with a dye that preferentially labels the microorganisms and examined using phase-contrast microscopy. The organism can be difficult to detect with normal light microscopy. Additional diagnostic techniques are ELISA, which detects antibodies against the disease, and PCR, which replicates the DNA of the parasite in collected feces enough to be detected.

Often, the most effective treatment is supportive care while the animal clears the infection in 3-12 days. Supportive care can include hydration in the form of IV fluids to make sure the dog does not become dehydrated, nutrient IVs, and warming blankets to protect against hypothermia in cases of severe illness. There are a number of antiparasitics available that may be of some benefit, but most dogs do not require it.

Recovery is often manageable at home, with plenty of water and easy-to-digest foods like rice and boiled chicken. If there is any suspicion that the dog’s drinking water may have been infected, provide fresh, previously-boiled drinking water and keep your pet from drinking out of the toilet or any pools of water that may be present near your home. Most dogs make a full recovery 3-12 days.

Puppies, older dogs, and dogs with depressed immune systems may require medication including antiparasitics and antidiarrheals that can help fight the infection and stop the loss of water from the animal’s body. Infections with this degree of severity should be monitored carefully. Don’t hesitate to bring your pet in for follow-up appointments if you believe their condition has worsened. Make sure to continue giving any medication until the last dose is reached to ensure a full recovery.