In northern California and across all states in the U.S., heartworm is a serious affliction that can impact your pet. Pets that contract heartworm are exposed to a lengthy treatment and recovery process. And, unfortunately, not all pets survive. The good news is that prevention is easy and effective requiring only a single chewable tablet or topical treatment once a month.

What is heartworm?
Heartworm is blood-based parasite that finds its way to your pet’s lungs, heart and pulmonary artery — where it grows. The mature parasite reaches nearly one foot in length and is best visualized as a strand of spaghetti. As it matures and multiples within the lungs, heart and arteries, it inflames or destroys vessels and tissue. Ultimately it obstructs the flow of blood through the circulatory system — increasing the stress on your pet’s body. An advanced stage can appear like a large ball of spaghetti within the heart and lungs. Untreated heartworm can lead to congestive heart failure and death.

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How does a pet contract heartworm?
Heartworm is transmitted to pets through the bite of an infected mosquito. Mosquitos themselves become carriers when they bite an infected animal (such as a cat, dog, wolf, coyote, fox, bear, ferret, etc.) — acquiring microscopic worms, called microfilaria, that circulate in the bloodstream of the bitten animal. The larvae are then injected when the mosquito bites your pet.

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What is the incubation period of heartworms?
It takes approximately six months for the larvae within a bitten pet to transform into mature heartworms. Once mature, heartworms can live for 5 to 7 years in dogs and up to 2 or 3 years in cats.

Does heartworm equally impact dogs and cats?
No. Cats are naturally more resistant to heartworm compared to their canine counterparts — but this doesn’t mean they don’t need monitoring and protection. When afflicted, cats may possess only one to three mature heartworms whereby dogs are can be afflicted with several hundred. Consequently, the impact to dogs is much more severe.

How do I know if my pet has heartworm?
A simple blood test conducted in our office will reveal if your pet has heartworm. The results are evident on a blood smear placed under a microscope. The tests needs to be conducted during the annual wellness checkup and is required before a preventative prescription can be issued. In advanced situations, X-rays can also be used to help identify and diagnose the presence of heartworms.

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How do I prevent my pet from heartworm?
A simple chewable tablet or topical treatment administered on the same day of every month is generally all that is needed to protect your pet. It is vital that no month be skipped or the treatment date be substantially altered. Not adhering to a strict schedule can create a window for mosquitos to infect your pet as most preventative medicine is only able to kill larval stages of the parasite up to 51 days in age. However, once your pet is infected, preventative treatment must cease and your veterinarian must develop a new course of treatment to eradicate the parasite. If you’re concerned about the ability to keep to a precise schedule, a twice-annual injection administered in our office is available for dogs.

What are the signs that my pet might have heartworm?
Often pets show no overt signs. However, as the disease progresses, potential signs include: 

  • Mild persistent cough
  • Vomiting
  • Shortness of breath
  • Lethargy or extreme tiredness after exercising
  • Loss of appetite
  • Weight loss

Signs that a pet is in an advanced stage of heartworm infection include sudden onset of labored breathing, pale gums and dark bloody or coffee-colored urine. If your pet exhibits any of these symptoms, please contact us immediately.

What happens if my pet is diagnosed with heartworm?
As the treatment for heartworm requires a special medicine, named melarsomine, that must be precisely administered. Over the treatment regimen, the arsenic-based medicine gradually kills the heartworm and allows the body to absorb the dead parasites. The treatment pace must be slow and consistent and your dog must remain on restricted physical activity. Elevated activity could cause larger volumes of the parasites to die — overwhelming your pet’s body’s ability to remove them or inducing cardiac or respiratory failure.

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How can I best help my pet?
Prevention is the best course of action to ensure the health of your pet. The annual wellness exam is the ideal time to ask any questions. We’ll conduct a heartworm test to ensure your pet is safe and issue a prescription for the preventative medicine. If you ever have any questions, please contact us.