INDUSTRY INSIGHT
PET HEALTH
SPONSORED CONTENT
PITTSBURGH VETERINARY SPECIALTY & EMERGENCY CENTER
HEARTWORM
AWARENESS MONTH
A
pril is heartworm awareness month and in preparation
for summer and the reappearance of the mosquito, this
is a good time to discuss this dreaded and completely
preventable disease and review the importance of making sure
your pet is protected from contracting a heartworm infection.
Heartworm infections have been reported in all 50 states
and the incidence is rising and spreading to new areas of the
country every year.
Heartworm disease is caused by
long thin worms called Dirofilaria
immitis that reside in the blood
vessels of the lungs of infected
animals and, if left untreated, can
lead to irreparable damage to the
lungs, heart and other organs in the
body. Although heartworms can reside in various mammalian
species such as wolves, foxes, coyotes, and even cats, dogs
are their natural and preferred hosts, and the most at risk.
Dogs have the ideal environment for the heartworms to
mature, reproduce, and become a source of infection for other
unprotected dogs.
So just how does this transmission occur?
Heartworm disease is not
spread by direct contact
between infected animals,
but rather it requires the
help of a mosquito. Mature
female worms residing in
infected animals will begin to
produce “baby” worms called
microfilaria, which circulate
throughout the bloodstream.
When a mosquito feeds on
the infected animal, it picks
up the microfilaria which will then mature into the infective
stage larvae inside the mosquito over a period of ~2 weeks.
When that mosquito bites another susceptible animal, the
larvae enter via the mosquito bite and begin to mature over
a period of about 6 months and the cycle begins again. The
adult heartworms have a lifespan of approximately 5-7 years
in the dog and with each mosquito season, unpro tected and
susceptible animals risk developing an increased worm burden
with each new infection.
How do I know if my dog is infected?
Early signs of heartworm infection in dogs can go relatively
undetected. A veterinarian will perform a yearly blood test
to look for a heartworm infection. Due to changing weather
patterns, heartier mosquitos, and various wildlife carriers, the
American Heartworm Society recommends that dogs remain
on heartworm preventive medications year-round and have a
heartworm test performed yearly by a veterinarian.
As the heartworms grow and mature, they begin to cause
increasing damage to the host, and signs such as coughing,
listlessness, exercise intolerance, a decrease in appetite, and
weight loss can occur. Dogs with very advanced disease can
develop abdominal swelling caused by right-sided congestive
heart failure. In its most severe form, heartworm disease can
be fatal by causing cardiovascular collapse due to blockages of
large blood vessels.
The good news is that the earlier a heartworm infection is
detected, the better chance the animal can be successfully
treated and make a full recovery.
When should my dog be tested?
All dogs should be tested yearly, regardless of the type or
frequency of preventive medication they are receiving. Puppies
under 7 months of age can begin heartworm preventive
medications without a heartworm test, but should be tested 6
months after their initial visit, again 6 months later, and then
yearly. Dogs over 7 months of age that have not been receiving
medication should be tested prior to starting one and retested 6
and 12 months later.
What if the test is positive?
Don’t panic, and remember that most infected dogs can be
successfully treated and make a full recovery. Your veterinarian
will first confirm the positive test with a different test to make
sure that your pet is truly positive. If your pet is confirmed
for a heartworm infection, your veterinarian will recommend
exercise restriction and will make sure your pet is stable prior
to treatment. Treatment for adult worms involves a series of
injections and oral medication tailored to your pet’s condition,
as outlined by the American Heartworm Society. Once your
dog has been successfully treated for the infection it will be
important to continue him/her on year-round heartworm
preventives as recommended by your family veterinarian. Unless
protected, your dog can be reinfected because a prior infection
does NOT mean your dog is immune to heartworms. There are
many heartworm preventives available for our pets, and your
family veterinarian will help guide you as to the best choice for
your pet based on his/her individual needs.
This Industry Insight was written by Eva K. Sikorska,
DVM, DACVIM (Cardiology)
Dr. Eva Sikorska is a board-certified veterinary
cardiologist at Pittsburgh Veterinary Specialty &
Emergency Center (PVSEC).
Dr. Sikorska enjoys both interventional cardiology and
management of chronic cardiac disease and heart
failure. She aims to better the life of her patients and
provide clients with knowledge and understanding
regarding the various disease processes.
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