Could Your Dog Have Heartworm Infection and You Don’t Know it?
Heartworm disease is not a disease that develops overnight. In actual fact it takes years from infection to when symptoms become evident. The culprit in causing and spreading heartworm disease is the Mosquito – not dog to dog contact as many people still believe.
And it isn’t covered through regular intestinal worming with an Allwormer either – which many people also still believe. Heartowrm is NOT an intestinal worm. It has a life of it’s own.
In fact there is a lot of confusion surrounding Heartworm disease from how a dog becomes infected in the first place to how to prevent infection.
So what is a Heartworm exactly? Heartworm is a parasitic roundworm (Dirofilaria immitus) that is spread from host to host through the bites of infected mosquitoes. To keep it simple we’ll limit the host to the dog which is the most definitive although it can infect cats and other species too.
Adult Heartworms can grow to the size of between 23 – 30 cm depending on whether they are male or female. To create a simple picture imagine a piece of cooked spaghetti that length and you’ll have an idea of size.
How do they end up inside the dog? The heartworm actually goes through quite a few lifestages before it becomes an adult worm. Some of the intial larval developments actually occur within the mosquito itself. If an infected mosquito bites your dog, it then deposits the infective larvae (L3) in under your dog’s skin. The larvae then develop under the skin to the next laval stage (L4). The larvae then undergo further developments in your dog and migrate progessively from muscle tissue to your dog’s bloodstream where they then circulate around the body – growing as they go and finally lodging in the pulmonary arteries leading to the heart.
Here they grow to maturity (full size) and start to mate producing more larve for the next mosquito to suck up from the blood and reinfect another dog. So, depending on how many larvae actually reach maturity will determine how many mature heartworms your dog will have lodged in vessels surrounding the heart. So potentially anything from a single large worm – a whole bunch of them stuck in your dog’s blood vessels.
Heartworm disease can kill
The presence of a significant adult heartworms will cause irreversible damage to the Heart and surrounding blood vessels. Fist signs of this disease only develop once it’s far too late to reverse the damage. Symptoms include coughing, reduced exercise tolerance and in the case of a large burden – collapse or death.
The aim of heartworm prevention.
You can’t avoid your dog being bitten by mosquitoes but whether the mosquitoes are actually infected with heartworm will depend very much on climate. Not all mosquitoes carry the infective larvae. The warmer, tropical climate is the most suited to infective larvae production. So – if you live in our Northern States – Heartworm prevention is a must.
Down in the lower, colder areas like Victoria, it’s less likely the larvae can undergo their critical developmental stages in the mosquito to harm your dog when it bites. But there’s always a risk – especially during the warmer months and when it’s been wetter than usual creating lots of stagnant pools where mosquitoes breed. Simply put – more mozzies = more risk.
How do Heartworm Medications work?
Heartworm medications work by killing heartworm larve before they turn into adult worms. They don’t kill adult worms!
That’s why to keep your dog protected from heartworm infection, the medication needs to be given all year round to keep working on any active larval infections to prevent them from turning into adults. If medications are given on an ad hoc basis – you risk some of these larva maturing to a stage that’s no longer affected by the medication. So they keep growing while you continue to medicate. You just don’t know it’s happening.
Your dog won’t show any symptoms. It’s only years later when you have a number of adult worms lodged in the vessels that your dog will show evidence of Heartworm disease. By then much of the damge to the heart and surrounding vessels has already happened and it’s not reversible.
The Key to Preventing Heartworm Disease
Start Heartworm prevention before your dog is 6 months old. This means there hasn’t been an opportunity for potential larve to have reached a stage where the medication won’t kill them.
Continue giving topical or oral heartworm medications on time every month for continued protection. (Most Heartworm medications are given monthly)
If you miss a month or two – have your dog Heartworm tested a few months down the track to make sure no larva have escaped the meds during that time.
Better still – use the Yearly heartworm injection (proheart) from your vet. It saves the hassle of remembering to be on time each month.
Whys are Heartworm meds still a Prescription Only product in other parts of the world?
- If you give heartworm medication to a dog heavily infected with microfilaria (immature heartworm) – the sudden death of these all at once can cause your dog to go into shock and collapse.
- You have no proof that adult worms are not present to cause damage while you are only targeting the immature lavae with your medication. The real danger is overlooked while you think your dog is protected!
- By needing a prescription every time you buy heartworm medications accurate records about your dog’s heartworm status are maintained and mandatory testing is performed as necessary – both eliminating risk of intermittent infection.
That’s why your dog should be tested Heartworm free before starting medications after 6 months of age and tested on a regular basis if you’ve missed a dose on time here and there.
Most dog owners buy Heartworm products without fully understanding their function, limitations and risk in giving to an infected dog. And sadly – not all advice given by hungry retailers keen to make a sale is correct, often omitting the important advice that needs to be given when dispensing these medications.
Prior to becoming an open seller, your vet would ensure you were giving the medications to a Heartworm Free Dog. Now we know nothing. Until it’s too late..
Nowdays with these products freely available without the need for testing we shudder to think how many heartworm infected dogs are out there that you or we don’t know about.
We certainly perform far less tests that we did years ago. And when we did – it was suprising how many dogs from our local area tested positive for Heartworm infection. Nowdays – they simply go undetected and we continue to sell you these medications despite a potential risk. Why? Because we can’t refuse to.
Is this a good thing?
You be the judge.
Stay safe – Have your dog Heartworm tested from time to time if you’re not giving regular heartworm medications or opt for yearly Heartworm injections to avoid missing a dose to reduce the risk of contracting this deadly insidious diease.
P.S. If you lived in the U.S and called into your vet clinic to buy some Heartworm medications. The conversation would probably go something like this …..