Heartworm is an insidious disease that has spread to virtually all parts
of the US and many parts of Canada since the early 1970s. It is spread
only by mosquitoes; thus, areas heavily populated by these insects tend
to have a greater incidence of heartworm disease.
Heartworm can
strike both dogs and cats, although it is much more commonly seen in dogs.
As its name implies, heartworm lives in the blood of a dog's or cat's heart
and adjacent blood vessels. The adult heartworms living in the heart produce
offspring, called microfilariae, which circulate in the infected animal's
blood.
When a mosquito
"bites" an infected pet, it sucks out blood containing the microfilariae.
After about two weeks in the mosquito, the microfilariae become infective
larvae. This step is necessary for the transmission of heartworm. When
the mosquito bites another pet, the infective larvae are transmitted.
Canine Heartworm
Veterinary research
has resulted in medications and procedures that have improved the treatment
of canine heartworm disease.
Prompt detection
and early treatment are vital to a successful cure.
Highly effective
diagnostic testing and preventive medications have been developed in recent
years. It is necessary to have a heartworm test prior to using a preventive.
Severe or fatal reactions may occur if preventives are given to dogs with
heartworm disease, or may create diagnostic confusion at a later date.
A small amount
of blood is all that's necessary for a preliminary heartworm screening
test that is very accurate in detecting the presence of heartworm. In many
regions, this may be the only test needed before starting a preventive
program. If the dog shows heartworm symptoms or has visited a known heartworm
problem area, additional tests are recommended before a preventive or treatment
program is started.
Common blood
screening tests can verify the presence of heartworms. Radiographs or X-ray
films and other sophisticated laboratory tests are used to detect heartworm
disease.
Canine heartworm
disease symptoms include:
Difficulty breathing
Coughing
Tires easily
Listlessness
Weight loss
Rough hair
coat
In many cases,
there are advanced symptoms. Some dogs do not appear to have symptoms in
the early stages…others do. If not detected and controlled with proper
treatment, heartworm can lead to congestive heart failure and death.
As a safeguard,
many veterinarians recommend annual or biannual screening tests even for
dogs that are on heartworm preventives. In known heartworm areas, or if
dogs are traveling into these areas, veterinarians usually prescribe preventive
medications.
This medication
prevents the larvae from developing into adult heartworms. Prescribed medications
must be given as directed.
Today, the majority
of dogs with heartworm disease survive. Most are cured by medications.
Some require surgery. Prompt detection prevents needless suffering.
Feline Heartworm
Although heartworm
is seen less frequently in cats, the disease poses a much greater danger.
The outcome is often fatal.
There currently
are no drugs approved for fighting heartworm in cats. Cats can be treated
with canine medications, but this can lead to dangerous side effects, including
lung failure and death.
Another approach
to battle the disease is by treating the symptoms, with hopes of the cat
outliving the worms (heartworms live within a cat for about two years).
However, this approach can result in sudden death as the worms exit through
the pulmonary arteries to the lungs.
There are no
consistent clinical signs of heartworm in cats.
Common clues
include coughing and rapid breathing. Other signs include weight loss and
vomiting. However, all of these signs are also common in other diseases.
Diagnosis is difficult for veterinarians and may include outside laboratory
tests, radiographs, and ultrasound studies.
The good news
is that there are heartworm prevention drugs available for cats. If you
live in a heartworm infested area, or plan on visiting a heartworm area
with your cat, your veterinarian can prescribe a preventive medication.
These drugs are given once monthly and are very effective in cats and kittens.
Research continues
into all phases of heartworm disease. For the latest advice, consult your
veterinarian.
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Information Provided By
HealthyPet.com
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