06/11/2025
Happy Wednesday! Lets discuss Heartworm and prevention!
Heartworm: Why yearly testing is essential and monthly prevention is beneficial
What is Heartworm?
Heartworm is a serious and potentially fatal disease found in pets in the United States as well as other parts of the world.This parasite can live in the heart, lungs and associated blood vessels in the pet that can lead to heart failure, lung disease and other organ failure. Heartworms that live in a dog mature into adults, mate and produce their offspring. Heartworm can affect a dogs health and quality of life even after the parasites are gone. This is why consistent heartworm prevention is the best way to prevent the disease.
How is heartworm disease transmitted from one pet to another?
The mosquito plays an essential role in the heartworm life cycle. Adult female heartworms living in an infected dog, fox, coyote, or wolf produce microscopic baby worms called microfilaria that circulate in the bloodstream. When a mosquito bites and takes a blood meal from an infected animal, it picks up the microfilaria, which develop and mature into the “infective stage” larvae, this takes about 10-14 days. Then, when the infected mosquito bites another dog, cat, or susceptible wild animal, the infective larvae are deposited onto the surface of the animal's skin and enter the new host through the mosquito’s bite wound. Once inside a new host, it takes approximately 6 months for the larvae to develop into sexually mature adult heartworms. Once mature, heartworms can live for 5 to 7 years in dogs and up to 2 or 3 years in cats. Each mosquito season can lead to an increasing number of worms in an infected pet.
Signs of heartworm disease:
During the early stage dogs may show few or no signs at all. The longer the infection persists the more likely for symptoms to develop. Active heavily infected dogs will be more likely to show clinical signs. Signs can include mild coughing, increased fatigue after moderate exercise, decreased appetite and weight loss (please note symptoms may vary per patient-not all patients will have the same symptoms). As heartworm disease progresses the patient may develop heart disease and have a pronounce belly due to the increase in abdominal fluid. Large numbers of heartworms present can also cause a blockage of blood flow which can lead to cardiovascular collapse.
Heartworm testing:
Heartworm disease is a serious, progressive disease. The earlier it is detected, the better the chances your pet will recover. The test requires just a small blood sample from your pet, and it works by detecting the presence of heartworm proteins. Some veterinarians process heartworm tests right in their hospitals while others send the samples to a diagnostic laboratory. In either case, results are obtained quickly. If your pet tests positive, further tests may be ordered.
When should my pet be tested?
Dogs should be tested yearly as part of preventative care, here are some guidelines to follow based on timing and age.
Puppies under 7 months of age can be started on heartworm prevention without a heartworm test (it takes at least 6 months for a dog to test positive after it has been infected), but should be tested 6 months after your initial visit, tested again 6 months later and yearly after that to ensure they are heartworm-free.
Adult dogs over 7 months of age and previously not on a preventive need to be tested prior to starting heartworm prevention. They, too, need to be tested 6 months and 12 months later and annually after that.
What happens if my dog tests positive for heartworm?
Most infected dogs can be treated. The first step is to stabilize symptoms if there are any, next is to kill adult and microfilaria worms while keeping side effects of treatment to a minimum
Types of heartworm prevention we carry at New Hope:
Oral:
SImparica Trio (moxidectin, sarolaner, pyrantel pamoate)-protects against fleas, ticks, heartworm, hookworms and roundworms)
Interceptor Plus (Milbemycin and Praziquantel)- protects against heartworm, hookworms, roundworms, tapeworms and whipworms
Injectable:
Pro-heart (Moxidectin)- protects against heartworm and hookworm
*Please note other options for prevention are available, just not carried at our clinic, as long as pets are up to date on their heartworm test a prescription can be given for the preferred prevention type*
If you have questions or concerns about heartworm or prevention types it is encouraged to give our office a call to schedule an appointment to discuss what medication may be best for your pet and their lifestyle.
Resources from the American Heartworm Society:
https://www.heartwormsociety.org/pet-owner-resources/heartworm-basics
https://www.heartwormsociety.org/preventives
Founded During The Heartworm Symposium Of 1974, The American Heartworm Society Aims to further scientific progress in the study of heartworm disease inform the membership of new developments, encourage and help promote effective procedures for the diagnosis, treatment and prevention of heartworm dis...
