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Heartworm and Heartworm Prevention FAQs for Better Pet Care

Heartworm disease is a serious disease that we sadly see too often at our Reisterstown animal hospital. The good news is that it’s a disease that can both be prevented from ever occurring and if your pet gets it, there are some good treatment options that are available to you from your veterinarian. Let’s take a look at some of the common questions that we get about heartworms here at TLC For Pets.


  • How does heartworm affect my pet? Heartworm disease can occur both in cats and dogs. This disease happens when tiny worms called microfilariae infect your pet's blood vessels. When these worms mature, their size (they can grow up to 12 inches in length) and movement throughout your pet's cardiovascular system can cause clotting, scarring, and other medical issues. The more heartworms your pet has in its system, the harder its heart has to pump to increase blood pressure and that can lead to significant heart and lung issues that may result in death.
  • How does my pet get heartworms? The tiny adolescent microfilariae worms are picked up and transmitted by mosquitoes.
  • Can a heartworm-positive pet infect my pet? Heartworm infections can't be directly transmitted pet to pet via things like slobber or drinking from the same dish. However, if a non-heartworm pet isn't on heartworm prevention, then it is at risk for being infected by a mosquito that bites first the heartworm-positive pet and then the non-heartworm positive pet. This is why heartworm prevention medication is so important.
  • Why do I need a prescription for heartworm prevention? We know it can be frustrating to get a prescription, but federal law currently requires it for all heartworm medication. This is because you cannot give heartworm prevention to a pet with adult heartworms as combining the two can result in serious illness and even death. Therefore, a heartworm blood test must be performed by your veterinarian before prescribing an annual preventative.
  • I missed a month, will my pet be okay? In most cases, yes. Remember, mixing heartworm medication and adult heartworms can be lethal. But it takes several months for the larvae to mature in this stage. If you miss a week or three, give your pet the medication as soon as possible and alert your veterinarian. If you miss more than a month, then you'll want to schedule a second heartworm test six months after the missed date to confirm no adult heartworms exist. 

Schedule Your Visit Today and Get Your Pet on Preventatives

Contact our friendly veterinarian team for more information about heartworms and heartworm preventatives, or to schedule your pet's annual heartworm exam. Heartworm prevention is an essential part of veterinary care. Call TLC For Pets in Reisterstown at (410) 833-1717 to keep your furry friend free of these dangerous pests.