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.
Prevention:
 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)
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.
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.
Treatment:
Puppies
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
Types of Intestinal Parasites:
Roundworms
Transmission:
- Acquired from ingestion of contaminated soil, stool, or wildlife; also during gestation and while nursing
- Signs start within 2 1/2- 3 weeks of age.
- Even if an animal has been appropriately dewormed
throughout its entire life, it is common for worms to form cysts in their
tissue. These cysts are very resistant to treatment. These will become
activated when an animal is pregnant, and travel to the fetuses and
mammary tissue.
Signs:
- Distended (enlarged) abdomen
- Poor body and coat condition
- Diarrhea/Vomiting
Human Health Concerns:
- Acquired from handling/consuming soil containing
cat/dog/raccoon feces,
- Most commonly affect children.
Hookworms
Transmission:
- Eggs in stool from an infected animal,
- Puppies acquire via
nursing, through ingestion of larvae worms in infected wildlife, or through
the larval worms penetrating their skin.
- Time from ingestion/skin
penetration to laying eggs is approximately 2-3 weeks, but can be as soon
as 10 days in puppies
Signs:
- Hookworms feed on the blood
from the lining of the intestines, causing anemia (low red blood cells)
- Pale gums
- Distended (enlarged) abdomen
- Poor coat and body condition
- Diarrhea, vomiting, poor
appetite
- Respiratory signs (pneumonia)
through larval migration
Human Health Concerns:
- Larvae in environment penetrate
and travel through skin of children, adults. Red, itchy, infected skin
especially along bottoms of feet, legs, or hands. These will not develop
into adult parasites, and tend not migrate to other organs or the
gastrointestinal tract.
Tapeworms
Transmission:
- Tapeworms require an intermediate host, which is often prey of the
affected animal (Example: Cat and Mouse.) Infected animals shed
sections of adult worms (proglottids)
which contain eggs. When these are consumed by the appropriate
intermediate host, the larval cysts develop. When these intermediate hosts
(fleas, lice, rodents etc) are ingested by a dog, they will develop into
mature intestinal tapeworms.
- Time
from infection to shedding of proglottids is usually 2-3 weeks.
Signs:
- Weight
loss
- Perianal
(around the anus) irritation
Human Health Concerns:
- Ingestion
of infected fleas can cause mild gastrointestinal signs in children
- Rare
human infections
will develop cestode cysts that require drainage or surgical removal.
Whipworms
Transmission:
- Only affects dogs in the United States
- Direct fecal to oral life cycle
- Once eggs are produced and are in the environment they
are very resistant to temperature, dryness and sunlight.
- Become infective within 9-21 days,
- Can remain in
the environment for years
- Common in urban areas with high volumes of dogs
(dog parks etc.)
- Symptoms can occur without egg production causing negative
fecal float
- Very long period from exposure to signs (74-90 days)
Signs:
- Diarrhea
- Blood in stool
- Can be asymptomatic
Human Health Concerns: None
Coccidia
Transmission:
- 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.
Signs:
- 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
Transmission:
- 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
Signs:
- 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.
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