Canine Heartworm Disease
Roundworms, Hookworms & Whipworms
Heartworm Disease
Heartworm is a parasitic
disease that can affect any dog regardless of age, sex
or habitat. It is found in virtually all parts of the
United States and many parts of Canada. Heartworm is
spread by mosquitoes, and tends to have a higher
incidence in areas heavily populated by mosquitoes. Dogs
are considered the most common host for heartworms,
however heartworms may also infect more than thirty
species of animals (including coyotes, foxes, wolves,
domestic cats, ferrets) and even humans, though
transmission from animal to human (zoonotic infection)
is extremely rare.
What are
heartworms?
Heartworms
are parasites that live in the blood of a dog’s heart and
adjacent blood vessels. They can grow from four to twelve
inches in length, reach maturation one year after infection
and live for approximately five to seven years. Adult
heartworms living in the heart produce offspring, known as
microfilaria, which circulate in the animal’s blood. When a
female mosquito bites an infected animal, it sucks out the
blood containing the microfilaria. When the mosquito bites
another pet, the infected larvae are transmitted. In many
cases the infected dog will not show symptoms in the early
stages.
Heartworm is the most serious
common parasite for dogs because it stresses the dog’s heart
by restricting blood flow and also damages other internal
organs. The heart may enlarge and become weakened due to an
increased workload, and congestive heart failure may occur.
Left untreated, the disease can be fatal to dogs.
Blood screening tests can verify the presence of heartworms.
Radiographs and x-rays are used to detect the disease in its
later stages. Prompt detection prevents needless suffering.
Heartworm treatment and
prevention
The good news is that most dogs with heartworm can be
successfully treated, usually with drugs (adulticide,
microfilaricide) that kill adult heartworms and their
offspring. But prevention is the best cure - it’s safer,
less expensive, and better for your pet!
There are a variety of options for preventing heartworm
infection, including an injectable, monthly topicals and
monthly chewable tablets. Preventative medications are
extremely effective and when given properly, on a regular
basis, can completely prevent your pet from contracting
heartworm. But remember, year-round heartworm protection is
as good as your diligence in remembering to give your pet
the prescribed medication, as directed by your veterinarian!
Canine heartworm symptoms
include:
- Difficulty
breathing
- Coughing
- Fatigue, a dog that tires easily
- Listlessness
- Weight loss
- Rough hair coat
Ask your
veterinarian
Because
of the regional and climate-dependant nature of the
heartworm cycle, it is crucial to consult your veterinarian
before giving any medication to your pet. Your veterinarian
is your best reference, with expert knowledge of the
heartworm cycle and transmission patterns in your region,
along with the individual health and activity profile of
your dog. Before starting a preventive program, all dogs
that could possibly be affected with mature heartworms
should be tested as preventive medicines may cause severe
reactions in dogs that are already hosts to adult
heartworms. A dog that is on a preventive medicine should be
tested routinely to ensure on going protection- especially
when a dose has been missed or forgotten.
Can you catch heartworm and other
parasites from your pet?
Mosquitoes transmit heartworm, not
pets. Humans are unnatural hosts for heartworm- therefore
cases of infection are rare. Many heartworm preventative
medicines for pets do eliminate other parasites such as
hookworms, whipworms and roundworms, which are more commonly
seen in humans. Parasitic infections that can be transmitted
from animals to humans are known as parasitic zoonoses :
1. Hookworms
In dogs, hookworm infection occurs
through ingestion or skin penetration of hookworm larvae
found in the stools or soil contaminated by feces of an
infected animal. The larvae then develop and migrate to the
intestines where they hook onto the intestinal wall and
feast on the host’s blood. The larvae of hookworms can
penetrate the skin and infect humans through contact with
soil or sand contaminated by feces of host dogs or cats. In
a human host, the hookworm larvae do not migrate to the
intestines and become blood-sucking adults as they do in
pets. Instead, they move around under the skin and
eventually die causing an inflammatory skin reaction known
as cutaneous larva migrans, or “creeping eruptions.” It is
important to keep your pet free of hookworms with good
hygiene, preventive medication and regular veterinary check
ups. Also, keep stray dogs and cats out of sandboxes and
gardening areas.
2. Roundworms
Roundworms are parasitic worms that
are round in shape, live in the dog’s intestines and consume
partially digested food. Unlike hookworms, they do not
attach to the intestinal wall, but literally swim in their
food. Adult worms resemble spaghetti and may come out in the
feces or vomit of an infected dog. Transmission to dogs is
through eggs in feces, eating a prey animal that is a host
(usually rodents), mother’s milk, or in utero. In dogs,
roundworms cause diarrhea, vomiting and in extreme cases
pneumonia and intestinal obstruction. In humans, roundworms
can cause a serious condition known as visceral larva
migrans. Most victims are children who are infected when
putting contaminated fingers into their mouths. Once
ingested, the roundworm larvae, though not in its usual
host, tries to complete its lifecycle. The roundworm gets
lost in the human body, usually in the eye, dies and
generates an inflammatory reaction that can cause blindness.
Proper hand washing can prevent infection.
Pet deworming of puppies and preventive medication will
reduce environmental contamination.
3. Whipworms
The only way a dog can contract
whipworms is by ingesting the eggs. When a dog walks on
ground infected by eggs, they are picked up on the paws and
travel into the mouth when he licks his paws or any
contaminated toys or food bowls. Whipworm eggs can survive
extreme exterior conditions for months and even years.
Within one to three months after the eggs are swallowed they
hatch in the dog’s intestine, attach to the wall and begin
to suck blood and lay eggs. In dogs, whipworm can cause
diarrhea, weight loss and in some cases, anemia. Whipworm
infection in humans is extremely rare.
Be safe, not sorry
Children are
more prone to contracting zoonotic parasites, as they tend
to kiss and play more readily with pets. Parasite larvae are
shed in the pet’s feces and may contaminate soil and sand.
When children play in the contaminated areas and place their
fingers in their mouths this allows the eggs to be ingested,
causing infection. Hookworm larvae are capable of infecting
a host through penetration of the skin. Be sure to pick up
feces promptly and avoid eating while playing with your pet.
Frequent hand washing, as well as good general hygiene for
people and dogs, is recommended. Routine check ups by your
veterinarian - including a diagnostic test for worms and
heartworm –as well as a physical exam along with medical
prevention, will not only keep your dog healthy but will
reduce any risk to you and your family.
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