If you have a dog, you know that when you bring him in to The Animal Clinic of St Pete for his annual exam and vaccinations, one of the things we ask is, “Do you have your dog on heartworm prevention and are you giving it to him every month?”. If your response is “no” to either of those questions, your dog needs to be tested for heartworms as soon as possible. Also, if you purchase your prevention from an online pharmacy, we strongly recommend a heartworm test to make sure your dog is protected.
Why is that, you might ask? Well, in our wonderful hot and humid state of Florida, the state bird might as well be a mosquito. And mosquitoes are what carry and transmit heartworms. Listen to me when I say, mosquitoes are all over the place. Seriously, whether you are a mosquito magnet and are hyper-vigilant about them or you are barely aware that they exist, the fact is that they are everywhere. And yes, they can even get into your house, so unfortunately, your precious, potty-pad-trained, never-goes-outside, Gidget can fall prey to a microfilaria-carrying mosquito too.
Microfilaria, what the heck is that?
Microfilaria are the larval stage of heartworm development. Mosquitoes become infected with these larvae by biting a dog who is infected with adult heartworms that are actively reproducing. The mosquito then transmits the resulting larvae to the next dog it bites.
This is where heartworm prevention becomes extremely important. If your dog is getting heartworm prevention every month, it will kill the microfilaria in his bloodstream before it can develop into adult reproductive worms.
If your dog is not on heartworm prevention, or is not current on his prevention, testing is highly recommended to check for juvenile and adult heartworm. If your dog is negative for heartworm at the time of testing, we will recommend that a monthly heartworm prevention treatment be started immediately.
If you wait too long to get your dog started on prevention after testing negative, we will have to test him again. Believe me, this isn’t because we like poking your dog with needles. It is because your dog’s life depends on it.
Why is a Heartworm Test Necessary?
Heartworm tests cannot show a positive result until the tiny microfilaria reach 6-7 months of development. If your dog has contracted heartworms and you give him heartworm prevention after the microfilaria reach this stage of development, you can create a life-threatening, cardiovascular blockage. This is because the larger juvenile and adult heartworms die and begin to fragment and these fragments enter your dog’s bloodstream, which can create a dangerous blockage in your dog’s heart and blood vessels. Heartworms that are still in their early larval stage (younger than 6-7 months), can be killed using heartworm prevention without causing harm to your dog’s cardiovascular system because they are too small to cause blockages.
Allow me to use an an example:
You and your dog, Lucky, go for a walk in October and unbeknownst to you, Lucky is bitten by an infected mosquito. Unfortunately, Lucky is not on heartworm prevention and he becomes infected with heartworms.
Then in February, during Lucky’s annual exam, you decide to have him tested for heartworm. You are happy and relieved to find out that his test is negative (remember that larvae that are less than 6-7 months into development are tiny and undetectable). You buy heartworm prevention from your vet that same day, but for some reason, you don’t start Lucky on it at that time.
Then, in April, you decide to start treating Lucky with the heartworm prevention your vet gave you. Unfortunately, by the time you give Lucky the treatment, the larvae have grown into larger juveniles. Later, Lucky suddenly collapses. You rush him to an emergency vet clinic and after several days in ICU and hundreds of dollars later, Lucky lives up to his name makes a turn for the better. He survives against the odds.
Sadly, this is not always the case, thus regular testing to make sure the prevention is safe to use or to continue is imperative.
The safety issues surrounding heartworms and heartworm prevention is something that causes a little bit confusion for our pet owners. We often hear things like, “If heartworm could harm my dog, and heartworm prevention could harm my dog, then what am I supposed to do?”.
Rest assured that a dog that has tested negative for heartworm and then is immediately started on monthly heartworm prevention, is very unlikely to be harmed by heartworm or heartworm prevention. However, starting prevention without testing can be harmful, because once the heartworms reach a certain point in development, the killing off of the microfilaria in combination with juvenile or adult heartworm in the system can be damaging to your dog’s cardiovascular system.
Is Heartworm Infection a Death Sentence For My Dog?
If left untreated, infected animals will eventually die. Fortunately, heartworm treatment is highly effective. Once given a positive result on the heartworm test, your veterinarian will talk to you about an appropriate treatment plan for your dog, with the goal of returning him to a heartworm-free state.
Please, if there is anything holding you back from keeping your dog current on heartworm prevention, think about this; the cost of heartworm treatment and repairing the damage to your precious pup’s health is far higher than that of monthly prevention.
If you have any questions at all about heartworm, don’t hesitate to contact The Animal Clinic of St Pete at (727) 525-0966.