Preventing & Treating Common Parasites in Dogs

Many of the common intestinal parasites of dogs can easily be spread to people. Children are especially prone to acquiring these parasites because they tend to spend more time with their hands in their mouths. Many can cause gastrointestinal problems; others can migrate through the skin and organs of people. It important to be aware of the possible human health implications of our pets, and always do as much as possible to prevent infestations of our animals and our environment.


  • Routine deworming.

  • Good sanitation of our homes and our pet’s living area.

  • Cover sandboxes when not in use.

  • Keep dogs indoors when not under direct supervision to minimize exposure.

  • Do not allow dogs to consume wildlife.

  • Monthly flea and tick prevention (for tapeworms).

  • Clean up all feces immediately. Many of the common intestinal parasites can actually inhabit the environment, or may not become infective for the first 24 hours. Therefore immediate cleaning of feces in your backyard or in public places is very important to prevent environmental contamination.

  • While diluted bleach or ammonia is effective at killing many of the parasite eggs, some require extreme heat (boiling water, steam, propane treatment). Therefore sanitation, treatment, and prevention are the best methods for environmental control.



  • Deworming at 2, 4, 6, 8 weeks of age, then monthly heartworm preventative.

  • Fecal testing 2-4 times in the first year of life.

  • Puppies require repeated treatment because they are repeatedly exposed to hookworms and roundworms while nursing, and many of these parasites have complex life cycles. During the early stages of infection (first 2-3 weeks) hookworms and roundworms are migrating through their body and treatment will ONLY kill the parasites present within their gastrointestinal system.

  • Also important to deworm pregnant dogs and cats during their pregnancy.

Adult dogs

  • Monthly heartworm preventative.

  • Fecal testing every 6-12 months.

  • Adult dogs that are positive for roundworms and hookworms on routine testing should be dewormed once, and then 2-3 weeks later before considering retesting to ensure adequate treatment.



      • Protozoan single celled organism.

      • Complex life cycle with many different stages.

      • Transmission via contaminated environment and through ingestion of intermediate hosts (mice, rats, etc).

      • Very host specific, therefore coccidia cannot be spread from dogs to cat or vice versa.

      • Invade and destroy intestinal cells, causing poor digestion and absorption.

      • Eggs can survive in the environment for very long periods of time (1+ year) in the right conditions.


      • Diarrhea, weight loss, dehydration, rarely bloody stool.

      • Can progress to vomiting, depression, and loss of appetite.

      • Puppies are most commonly affected, and will eventually clear the parasite as their immune system develops.

      • Adult dogs do not usually show clinical signs of coccidia unless their immune system is compromised.

Human Health Concern: None

  • Giardia


      • Protozoan single celled organism.

      • Most commonly found in stagnant and running water.

      • Signs usually dose dependant (more exposure = more likely to have signs).

      • Most adult dogs have natural immunity.


      • Watery diarrhea.

      • Occasionally vomiting.

Human Health Concerns:

      • Different strains of Giardia infect dogs, cats, and people.

      • It’s unlikely, but possible for a dog with Giardia to spread it to their owners.

      • Most Giardia is spread from human to human, or from drinking contaminated water.