If you own a dog or cat, chances are you’ve heard of heartworm before. After all, regular heartworm prevention medications are part and parcel of owning a pet. But that also means that many pet owners may discount the impact of heartworm. So let’s break down what heartworm is, what it does to our pets, and how prevention medications work.
What Is Heartworm?
Heartworm is a parasitic worm, similar to roundworms or tapeworms, that lives and breeds inside the organs of animals. Heartworm feeds on the animal’s vascular and lung tissues, growing into long thread-like worms that obstruct organ and blood vessel function over time. When these worms breed, the larva (microfilaria) travel through the bloodstream to other parts of the animal. If a mosquito happens to feed on an infected animal, those larva will be drawn up into the mosquito along with the blood. From there, that mosquito will feed on another animal, wherein the larva will be injected into that animal’s bloodstream, beginning the cycle anew.
What are the Symptoms of Heartworm?
The toughest part of treating heartworm is that symptoms can take a long time to appear post-infection. In some cases it can take years for a pet to show signs of heartworm, at which point treatment can be risky and very expensive. But leaving heartworm unattended is nearly always fatal – this is why prevention is the priority.
A dog or cat with mature heartworms will be experiencing blockages and disruptions in the functioning of their heart valves and lungs. This puts the heart under immense strain, which can cause symptoms like shortness of breath, lethargy, sudden weight loss and fluid in the abdomen. Again, many of these signs can be subtle – especially in elderly pets – making prevention the key form of treatment.
How Common is Heartworm?
Wherever there are mosquitoes, there is the chance of heartworm – plain and simple. While the true extent of heartworm prevalence in Australia is not 100% known (it’s basically everywhere except central Australia), it’s best to err on the side of caution and always use preventative measures.
Can Heartworm Be Treated?
Like we’ve mentioned, the best way to treat heartworm is to prevent infection from ever occurring. Early-stage infections will require expensive, daily medication for around three months. Late-stage infections will require highly invasive surgeries on vital organs and are not always successful, further cementing prevention as the key treatment.
So How Does Prevention Work?
Macrolytic Lactones (MLs) are a core component of nearly every worming medication, and are the most powerful weapon for preventing infection. They work by selectively binding to chloride ion channels, which are vital to the muscle and nerve cells of most parasitic invertebrates (mammals primarily use sodium ion channels). Any invertebrates (including but not limited to heartworm) that come into contact with MLs will be immediately paralysed by that selective binding, leaving them unable to feed or breed, and therefore killing them.
Preventative medications come either as a tablet or a topical gel that needs to be re-administered monthly, or a yearly injection from your vet (SR12). These ensure the ML levels in your pet are high enough to kill any heartworm larvae. Prevention needs to begin at a young age, typically between 8 and 12 weeks depending on the method, and missing a regular treatment can leave open opportunities for parasites to establish themselves and grow big enough to not be affected by the ML’s (around 30 days after infection).
Be warned that overdoses of ML’s can have adverse effects. Symptoms can include vomiting, high salivation and transient neurological effects, like tremors and ataxia.
Heartworm can be devastating to your pet’s health, but prevention is simple and easy so long as you stick to a regular schedule. Support your pet’s health and wellbeing with our range of Nugard for cats and dogs – the cheapest and most comprehensive flea, heartworm and intestinal worming treatment recommended by the AVW vet team! Shop our Nugard range today.
