As we spring towards summer and the days become warmer, we begin to spend more time with our pets outside. Playing with our pets helps both us and our companions get much needed exercise and enrichment. When pets are in the outdoor environment, foraging and inquisitive behaviors are often exhibited. Unfortunately, these behaviors (sniffing, licking and nibbling) can expose the pet to a variety of fecal parasites and pathogens that were shed by other pets and animals. Below is a review of parasites and pathogens that can potentially cause problems with dogs and cats and pose a possible human heath risk (i.e. zoonotic potential).

Roundworms: Roundworms are very common intestinal worms in dogs and cats. Long slender adult worms can be seen in the feces. They will shed up to one million microscopic eggs per day that can be identified when your veterinarian performs a fecal flotation test. In puppies, the worms are most likely transferred from the mother through nursing or through placental migration. In adults, the eggs are most commonly ingested by fecal/oral route or found in contaminated soil. Common signs of infection can include diarrhea, vomiting, “pot bellied” appearance, and stunted growth. There is a human health risk if feces or contaminated soil/organic matter are ingested. Not being the natural hosts, the roundworms will migrate throughout the human body and could cause a number of serious health issues, including blindness.

Hookworms: In the dog and cat, the transmission and clinical signs are similar to a roundworm infection. They can also cause significant blood loss in young or debilitated pets. Human health concern also exists. In a contaminated environment, the larval form of the hookworms can penetrate and migrate throughout the skin.

Whipworms: Often found in contaminated soil, whipworms can cause bloody diarrhea. This parasite does not typically affect very young puppies or kittens, as they must be in the outside world to come into contact with the eggs. Although not seen as a human health risk, the eggs of these parasites are extremely hardy and can remain infectious to dogs in the environment for long periods of time.

Tapeworms: Tapeworms are unique segmented intestinal worms that resemble a train pulling multiple box cars. These segments, which appear similar to a small grain of rice or sesame seed, are often found stuck to the hair around the anus of the infected pet. The segments, which contain numerous eggs, are not directly infectious. They require an intermediate host. Fleas are a common intermediate host. Flea larva will indiscriminately ingest the tapeworm eggs, which can then develop into the infectious form. In everyday grooming, fleas are ingested, infecting that pet with a tapeworm. Tapeworms do not often cause diarrhea. Clinical signs can include licking at the anus, or scooting their rear ends across the floor. Certain species of tapeworms can pose a human health risk

Giardia: Giardia is a protozoan (single cell organism). It is commonly found in contaminated water. When giardia is ingested it can cause a severe diarrhea, and further shedding of the organisms. This parasite is very contagious to other animals, as well as people.

Coccidia: Coccidia is a protozoan parasite shed in the feces and ingested by the new host. This can cause severe, life threatening diarrhea in puppies and kittens. This parasite can spread through litters very easily when the environment becomes contaminated.

What You Can Do
Cleaning up feces in the yard and cleaning litter boxes daily will help control your pets environment and decrease chances of parasitic infection or re-infestation. When outside of the home environment, steps should be taken to deter a curious pet from ingesting feces and organic matter. Pet owners should also use good personal hygiene when dealing with feces of the pet, especially if an infection is diagnosed. Supervision with young children/toddlers is important when interacting with pets in their environments, since they are more at risk for indiscriminate ingestion.

You should also consider protecting your pet and family from these parasites by giving your pet a monthly preventative containing an intestinal dewormer and having your pet’s stool tested by your veterinarian every 6 to 12 months. Always have new puppies and kittens evaluated and dewormed by your veterinarian. If clinical signs are noted (e.g. diarrhea, blood in stool, or unplanned weight loss) contact your veterinarian. All of the parasites listed are easily treated with medications and environmental management once a diagnosis and medical plan are made. – Peter Olson

Peter Olson, DVM, is a 2007 graduate of The Ohio State University School of Veterinary Medicine. He and his wife Beth share their home with two dogs, two cats, four turtles and a Russian Tortoise.