The Top Ender Magazine August September 2023 Edition

HEARTWORM
PREVENTION IS BETTER THAN TREATMENT
Preventing heartworm infection is cheap and can be as
easy as giving your pet a monthly tablet or yearly injection.
Treating a heartworm infection on the other hand, can be
costly, require months of medication and life-threatening.
WHAT IS HEARTWORM DISEASE?
Heartworm (Dirofilaria immitis) is a parasitic roundworm
that lives in the heart, lungs and associated blood vessels
of affected pets, causing severe lung disease, heart failure
and damage to other organs in the body.
• Dogs - the dog is a natural host for heartworms, which
means that heartworms that live inside the dog mature
into adults, mate and produce offspring
• Cats - the cat is an atypical host for heartworms, and
most worms in cats do not survive to the adult stage.
HOW DOES HEARTWORM SPREAD?
Heartworm cannot be transmitted directly from cat-tocat
or dog-to-dog - transmission via mosquito is the
only method of infection (not that we
needed another reason to dislike
mozzies!).
Heartworm is transmitted when an
infected animal is bitten by a mosquito,
which sucks up the tiny heartworm larvae
in the blood. The larvae live in the gut of
the mosquito for up to 30 days, and when
that mosquito bites another animal, it
injects these larvae into their
bloodstream. The larvae circulate in your
pet's body, eventually making their way to
the heart and blood vessels of the lungs
where they spend around six to seven
months growing.
SYMPTOMS
It can take up to five years for a dog to
show symptoms of heartworm infection. By
this time, it is likely that your dog already
has hundreds of heartworms living in their
heart or the blood vessels of their lungs
which can cause blockages or reduced
blood flow to the entire body.
The early symptoms of heartworm
infection in dogs can include:
• A dry, persistent cough
• Lack of energy or tiring easily
• Shortness of breath or difficulty
breathing
TESTING FOR HEARTWORM
To test if your pet has a heartworm infection;
blood is collected by your veterinarian and a
test is run (very similar to a covid or
pregnancy test) – results take about 15
minutes. Once an animal is infected by a
mosquito it takes at least 6 months for
worms to mature and test positive. In some
cases, your veterinarian may request a repeat
test in 6 months.
TREATMENT
The most common treatment is a series of
injections accompanied with antibiotics, and
sometimes other medication and
hospitalisation. For dogs with a very severe
heartworm infection, surgical removal of
worms from the heart may be necessary. All
treatments for heartworm infection carry
some level of risk, and in severe infections,
even with treatment, the dog may still pass
away.
PREVENTION
Dogs should start heartworm prevention by three
months of age, which can be given as a monthly
tablet or an injection. As puppies are actively growing,
their heartworm prevention protocol involves an
injection at 3 months of age and again at 6 months of
age. Adult dogs only require a yearly injection. Please
note that the injection protects against heartworm
only – this does not include other intestinal worms or
fleas/ticks. Although cats have a lower risk of serious
disease from heartworms, we still recommend treating
cats even if they live indoors as mosquitoes can still
make their way inside.
Some heartworm preventative products do require
you to have your pet tested for heartworm before
commencing treatment. This is because if there are
already worms present in your pet, treating them with
certain medications can kill the worms and this can
cause blockages or other issues in your pet's heart and
blood vessels. Therefore, any dogs over six months of
age should be tested for heartworm before starting a
preventative program. If you have any suspicion that
your dog has been off heartworm prevention for more
than one month or if you missed a dose of heartworm
medication, you should seek advice from your vet as
soon as possible about a heartworm test.
CHECK THE LABEL
Beware of some products
advertised as an “Allwormer”.
This term refers to treatment of
intestinal worms only, and many
products sold for intestinal
worms do not prevent
heartworm. You must check the
product information to be sure
you have selected a product that
clearly indicates it can be used
for heartworm prevention.
Written by All Pets
allpetsvet.com.au
58 The Top Ender | Tri-Services Magazine Incorporated AUGUST/SEPTEMBER 2023 59