Heartworm Disease
Heartworm
disease (dirofilariasis) is a serious and potentially fatal disease in
dogs. It is caused by a blood- borne
parasite called Dirofilaria Immitis.
Heartworms
live in the heart and pulmonary arteries of infected dogs. They can live up to 5 years, producing
millions of offspring (microfilaria).
These microfilariae live
mainly in the small vessels of the blood
stream. The immature heartworms cannot grow
into adults without the involvement of mosquitoes.
The female
mosquito bites the infected dog and ingests the microfilariae during a blood
meal. The microfilariae develop further for 10 – 30 days in the mosquito. When the mosquito bites a dog the infective
larvae enter the blood steam and move to the heart and adjacent vessels where
they grow into maturity over 2 -3 months completing the cycle.
The disease
is seldom diagnosed in a dog less that one year of age because it takes 5 – 7
months for young worms to mature. Adult
heartworms cause disease by clogging the heart and major vessel leading to he
heart. They interfere with the valve
actions in the heart. By clogging the
main blood vessels, the blood supply is reduced to other organs and can cause
malfunction.
Most dogs
do not show clinical signs for as long as two years. Unfortunately by the time clinical signs are
seen the disease is well advanced. The signs of heartworm disease depends on the number of adult worms, location of
worms, length of time present, and the degree of damage to the heart and other
organs. The most obvious signs are soft
dry cough, shortness of breath, weakness, nervousness, listlessness and loss of
stamina. With severe infections dogs may
die suddenly during exercise or excitement.
Diagnosis
of heartworm disease can be made by a blood test run in the veterinary clinic
or laboratory. If a dog is positive on
the blood test then additional blood chemistry, EKG and x-rays may need to be
preformed to determine the severity of the disease.
Treatment
of heartworm disease in dogs is done by giving an injectable drug for 2 days
that kills the adult heartworms. The
adult worms die in a few days and start to decompose. They are carried to the lungs and small
vessels where they are eventually reabsorbed by the body. It is essential to keep the dog quiet and not
allow exercise for one month following treatment. The first week is very critical because the
worms are dying. Other supportive care
may be necessary depending on how the dog reacts to the treatment.
All of this
can be prevented by giving your dog a monthly preventative for heartworms. It is critical that the medication be given
each and every month at the same time all year long. Only start the preventative after your dog
has had a negative heartworm test and consulting your veterinarian. If you miss a dose contact your veterinarian
for advice.
Call us today to
schedule your dogs heartworm test.
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