Dog Heartworms

Dog Heartworms is a disease that can be treated if caught in
time.  Prevention is best and done by administering your
dog a periodic heartworm preventative.  Mosquitos carry the
disease and so if you live in an area with mosquitos, you are
in a heartworm endemic area.

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Heartworms in Dogs

Dog Heartworm disease is caused by a nematode called
Dirofilaria Immitis.  Larvae, or heartworm babies,  are picked
from a heartworm positive dog by a mosquito; the mosquito
then injects larvae into another dog.  The larvae grow and
migrate gradually from the skin area to the heart making the
journey over about six months.  Heartworm preventatives
work by killing any larvae that are approximately a month old
or less.

Once in the heart the adult heartworms often migrate into
the arteries going to the lungs.  This inhibits blood flow to
the lungs which causes the right side of the heart to enlarge
as it works harder to pump blood through heartworm
infested arteries.  With a heart that is having to work harder
than usual  at every beat, these dogs show signs of
exercise intolerance or a lack of energy.  As the lungs
themselves become inflamed, coughing is another
symptom.  Eventually, weight loss occurs and sometimes
fluid even backs up into the abdomen causing a pot-bellied
appearance.

If dog heartworm disease is caught in time, it can be
treated quite successfully.   Your veterinarian will want to do
some blood work to check for other diseases and to check
to see if your dog’s liver and kidneys are up to being treated
with the heartworm medication.  In addition, chest x-rays
will assist in determining how severe the heartworm disease
is in your dog.  Once this is done, a treatment course will be
planned for your pet.  The heartworms themselves are killed
using an immiticide that is given by injection.

After the immiticide is given, your dog will need to be kept
exercise restricted for 30-60 days; the dead and dying
worms are left to decompose in the heart and lung arteries.  
With too much activity, the decomposing pieces may go
downstream and cause “emboli” in the lings (clots).

Above all, prevention is best.  Make sure that your dog is on
a heartworm preventative and tested every year for
heartworm disease.

- Sam D. Meisler DVM

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been evaluated by the FDA and are not intended to
diagnose, treat, cure, or prevent any disease.