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Heartworm; What is it and how can you protect your pets?

With the increased rain in South East Queensland so far this year, we have also seen a big increase in MOSQUITOS! Not only are these horrible critters annoying, but did you know they also may pose a big threat to your furry family members! Mosquitos can carry and transmit heartworm to your pets.

What is Heartworm

 Heartworm; what exactly is it?

Heartworm disease is a serious disease that results in severe lung disease, heart failure, other organ damage, and can even cause death in pets, mainly dogs. It is caused by a parasitic worm called Dirofilaria immitis. The worms are spread through the bite of a mosquito.

The dog is the definitive host, meaning that the worms mature into adults, mate, and produce offspring while living inside a dog. The mosquito is the intermediate host, meaning that the worms live inside a mosquito for a short transition period in order to become infective (able to cause heartworm disease).

The worms are called “heartworms” because the adults live in the heart, lungs, and associated blood vessels of an infected animal. It is a horrible, debilitating disease and treatment is expensive and takes a very long time for recovery.

What about cats?

 The mosquitoes that carry heartworm seem to prefer to feed on dogs over cats. So do cats get heartworm?

The simple answer is yes, but at a much lower incidence than dogs. It is also more common in the USA than Australia. The cat is not a natural host for the heartworm, so the migrating larval worm injected by the mosquito is unlikely to find its way to the heart. The cat’s immune system is very reactive against heartworm so the larval worms are often killed and the worms never make it to adulthood.

The symptoms of heartworm disease in dogs are related to the heart failure it causes.

In cats this is different – the symptoms are related to the strong immune reaction the cat has against the worm.

Cats develop breathing signs that can look like feline asthma, chronic vomiting and coughing. Sudden death can occur.

If a cat does get heartworm it can be very difficult to diagnose as the routine tests we use for dogs don’t work.

The worms produce proteins that we look for in the dog’s blood, but because the cat’s immune system does such a good job of mopping up these proteins we can’t detect them in the cat. Generally diagnosis is made with x-rays and an ultrasound of the heart.

Just like dogs, a preventative treatment can be given.


What are the symptoms?

Possible clinical signs of heartworms in dogs can include:
* Coughing
* Shortness of breath
* Loss of appetite
* Weight loss
* Fainting
* Nose bleeds
* Exercise intolerance
* Discoloured skin or gums
* Very dark urine
* Abdominal fluid build up

Possible clinical signs of heartworms in cats can include:
* Coughing
* Shortness of breath
* Loss of appetite
* Weight loss
* Fainting
* Lethargy
* Laboured or rapid breathing
* Asthma like symptoms
* Gagging
* Vomiting and/or Diarrhoea
* Seizures
* Abdominal fluid build up

How can you prevent your pet from getting Heartworm?

The best cure for heartworm is not a cure at all.. it is prevention! This horrible debilitating disease is thankfully preventable.

For Dogs; owners have the choice of a yearly injection, or monthly oral tablets

For Cats; there are monthly oral tablets

If your pet is currently on worming tablets, we urge you to check that heartworm prevention is included. Please also check your timeframes. Some intestinal wormers are fine to give your pet once every 3 months, but this will not protect your pet from heartworm. For the heartworm prevention aspect to work, treatments must be given monthly.

The main reason heartworm preventatives fail is owner failure to comply with dosing timeframes. For monthly chews, download a reminder or calendar app on your phone or device; or set up an alarm reminder


The cycle of Heartworm:

A mosquito picks up tiny larvae from the blood when it feeds on an infected animal. The larvae develop in the mosquito. 
Larvae are then transmitted when the mosquito feeds on another animal.
Once transmitted, the larvae migrate to the heart and lungs of the infected animal and they grow there into adult heartworms