Everyone is aware of canine parasites, both internal and external. You've likely even treated your dog for roundworms or fleas. But one category of parasites you may not have heard of is protozoa. Canine protozoan infections are more common than you might think. It's important to know how to prevent these organisms and treat them should your furry friend become infected.

Protozoa Basics

Protozoa are one-celled parasitic organisms. The two types of protozoa that are of concern to dog owners are coccidia and giardia. Both are similar in how they infect their host and the symptoms they cause, and both can infect humans, so good hygiene is important when dealing with an infected animal.

Giardia and coccidia are both transmitted to a dog through ingestion of oocysts or eggs. These oocysts hatch in the dog's digestive tract, and the adult organisms attach to the lining of the small and/or large intestine. There, they damage the cells, feed on nutrients in the bloodstream, and return to the oocyst stage. They are then passed in the feces, and the cycle of infection continues.           

Symptoms and Treatment

Giardia and coccidia infect mostly puppies, dogs with compromised immune systems, or older, debilitated dogs. It occurs most commonly in puppies and dogs who are housed together, such as in a kennel, pet store, or animal shelter, especially where overcrowding or unsanitary conditions exist. The most common symptoms are diarrhea and malnutrition; however, some dogs are asymptomatic. It's still important to treat an asymptomatic infection, as the animals can re-infect themselves as well as continue to transmit oocysts to other dogs. Your veterinarian can diagnose a protozoan infection through a fecal exam.

After diagnosing a protozoan infection, your veterinarian will likely treat your pup with a regimen of medication specific for giardia or coccidia. It may take several rounds of treatment to fully eradicate the infection. In severe cases, they may also use an antidiarrheal medication. For dogs who have had a severe infection and are dehydrated or malnourished, support fluids may be administered.

To avoid reinfection, it's very important to remove feces as quickly as possible, and don't house any other dogs in the same enclosure with an infected dog. Steam clean the infected dog's enclosure or use an ammonium disinfectant. Bathe the infected dog and trim the hair around the rectum to prevent oocysts from sticking to the hair and re-infecting your furry friend. And don't forget to wash your own hands frequently to prevent you from picking up these pesky parasites.