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Heartworm in Dogs: Myths vs. Facts


Heartworm disease strikes fear into the hearts of many pet parents, especially dog-lovers who are very wary about this potentially life-threatening disease. The good news is that there are now different ways by which the disease can be prevented. Sadly, many pet parents do not feel their dogs’ need to receive a heartworm preventative or even undergo heartworm diagnostic testing. It’s not because they don’t really want it but rather because they form their decisions based on misconceptions about the disease. To learn more about this deadly canine condition, here are some of the common myths that people have about the disease and the truth behind such assumptions.
 
Heartworm disease mostly affects outdoor pets.
 
This is one of the most common misconceptions about heartworm disease. Many pet owners believe that their pets are actually safe if they stay indoors. Unfortunately, one has to understand that heartworm disease is caused by a parasitic roundworm known as Dirofilaria immitis that lives in the arteries of the lungs and sometimes in the heart. Because the parasite actually lives in the blood of the host, it can be easily transmitted by a mosquito. As a matter of fact, experts say that the only way heartworm disease in dogs can be transmitted is through the bite of a mosquito. That being said, unless you have a mosquito-proof home that will help guarantee the absence of these insects inside your house, your dog will still be at-risk for heartworm disease.
 
My dog got infected with heartworm disease from a neighbor’s dog.
 
As already mentioned, the only way you can expect heartworm disease to be transmitted to your dog is by getting bitten by a mosquito that carries the parasite Dirofilaria immitis. Unfortunately, mosquitoes don’t go flying around waving signs that they have the dreaded filarial in their blood. Unlike mosquitoes that bring malaria and dengue, there is no specific species of mosquito that is solely responsible for the transmission of heartworm disease. So the next time your neighbor tells you that his dog got its heartworm disease from your dog, it’s time to set the facts and educate them about the true nature of the disease.
 
Mosquitoes cannot bite a dog with a thick coat.
 
There is a widely-held belief that dogs with thicker coats are immune to mosquito bites for the simple fact that the thickness of the coat makes it quite challenging for any insect to penetrate. Unfortunately, your dog’s coat is not made of a singular protective outer covering. Instead, it is still made up of individual strands of hair that can create spaces or gaps in between. Insects like mosquitoes can still reach your dog’s skin even though it has a thick coat. Additionally, there are other body parts that do not have as thick a coat as on your pooch’s body. For instance, the hair on the face especially the muzzle is not as dense as the rest of the body. Mosquitoes can still bite.
 
Heartworm disease is very easy to manage.
 
While the treatment for heartworm disease is quite easy to perform, it is exceptionally expensive, often costing upwards to $1,000. It is also very traumatic for your pet. It also poses a variety of risks since your vet will be injecting a series of arsenic-based medications known as Immiticides. For the cost of the medications alone, you’d be spending about $300 to $400. But it’s the preparatory stages of the treatment that will comprise the bulk of the veterinary cost. This includes a series of X-rays ad blood work as well as more extensive diagnostic tests to determine the extent and severity of the infection. It is easy to manage, why not; but are you prepared to shoulder $1,000 especially if you don’t have a pet insurance?
 
Heartworm preventatives and testing is very expensive.
 
If the treatment for heartworm disease in dogs can run up to several hundreds of dollars even up to a thousand, the cost of monthly heartworm preventative on a yearly basis will only set you back for about $35 to $80, often depending on the brand of heartworm preventative you are going to use as well as the weight of your canine friend. Heartworm preventives come in various formulations. There are those that come in tablet or pill forms as well as topical spot-on formulations that should be applied on a monthly basis. There are also those that can be given twice yearly as injections. Technically, a single monthly dose of heartworm preventative is no more expensive than 2 to 4 cups of Starbucks.
 
Since heartworm disease is transmitted by mosquitoes, I don’t have to give preventative in months that there are no mosquitoes.
 
The current recommendation from the American Heartworm Society is to give your dog heartworm preventative on a year-round basis. This is regardless of whether you see mosquitoes in your surroundings or not. While it is easy to miss a month’s dose of heartworm preventative, missing two or more consecutive months of dosing can increase the risk of your dog getting infected with Dirofilaria immitis. Moreover, many of the heartworm preventatives today also confer protection against intestinal parasites that are most often brought about by fleas. As such it is best to continue giving your dog its monthly heartworm preventative regardless of seasonal variations because of the other protective mechanisms at work in today’s heartworm preventatives.
 
If my dog gets treated with heartworm disease, this confers immunity against future infections.
 
Unfortunately, getting infected with Dirofilaria immitis and being satisfactorily treated does not mean your dog is not going to get infected ever again. It simply doesn’t work that way. As long as your dog is exposed to mosquitoes, there is a high chance that it will still be infected with heartworm disease. It is for this very reason that prevention is a must.
 
Only dogs can get infected with heartworm disease.
 
Since the parasite that causes heartworm disease actually resides in organs that have something to do with circulation, it is possible that other pets and animals can get infected, too. If a mosquito bites a dog that has heartworm disease, it effectively sucks out the filaria into its own circulatory system. When this same mosquito bites another animal regardless of whether it is also a dog or not, then the filaria gets transmitted, too. And the cycle continues. As such cats, sea lions, wolves, foxes, coyotes, ferrets, jackals, and bears can also be infected with the parasite. Did you know that it can also infect humans, although the incidence is quite rare?
 
Only dogs that forage in garbage tend to get infected.
 
As we have already pointed out, the only way one can transmit Dirofilaria immitis is through the bite of a mosquito. If it so happens that the dog was foraging in garbage that is also filled with mosquitoes carrying the filarial parasite, then this dog will surely get infected. The method of transmission is not because of eating or foraging in the garbage dump but rather because of the bite of a mosquito.
 
Heartworm disease only affects certain states.
 
While it is true that there is a greater prevalence of heartworm diseases in southeastern states, veterinary experts report that the infection has been reported throughout the nation. Additionally, there is a global trend showing the infection is spreading to new regions which were initially thought to be immune and safe from the disease. Don’t wait for the disease to strike your pet. A heartworm preventative won’t cost you as much as your weekly cup of coffee from Starbucks. So, save those 4 cups and buy instead a heartworm preventative for your pet.
 
Puppies are immune to heartworm disease because of the natural immunity conferred by the mother dog.
 
It is true that the colostrum provided by the mother dog is filled with immunogobulins as well as other immune system cells that help protect the young canine against infection. Sadly, the immune protection afforded by these natural maternal antibodies don’t last very long as they also get easily depleted. The only way the puppy can mount an active defense is by getting sick itself so that its immune system will create the necessary antibodies for that particular disease. Moreover, studies have shown that even when dogs get treated for heartworm disease, they are still vulnerable to reinfection. The same is true with puppies. So you’d better ask your vet when is the earliest age you could possibly give a heartworm preventative?
 
Heartworm disease is never fatal.
 
The infection primarily affects the lungs, the heart, and the blood vessels of the pulmonary tree. These organs all relate to oxygen delivery. If these organs are compromised, then you also compromise the efficient delivery of oxygen to the various cells and tissues of your dog’s body. At first, there will be difficulty breathing which can progress to chronic coughing, vomiting, and respiratory distress. Sooner or later, your pet will die because of the cellular death secondary to insufficient supply of oxygen.
 
There are many myths and misconceptions about heartworm disease in dogs. Hopefully this article provided you with enough insight and understanding on the truth behind these misconceptions. The next time someone tells you differently, you know better.