Why Your Pet Needs a Heartworm Test Every Year

If you have been to any of our clinics https://www.highlandshospital.org/cytotec with your dog for its yearly examination and vaccine visit, we have undoubtedly asked if your pet is on heartworm prevention every month, year-round.

If you answer “yes,” we’re thankful that you are diligent pet parents! Next, we will be recommending your dog to have its yearly heartworm test during the same visit. You might think to yourself, “But wait! I just said my pet is on heartworm prevention every single month year round. Why would I need that test?”

Below, we will explain why yearly heartworm testing is recommended for every dog, every year – including those fortunate dogs who are on prevention every month year round.

Monthly heartworm preventatives don’t stop mosquitos that carry heartworm larvae from infecting your dog with the immature stages of heartworms.

Instead, the preventatives kills the larvae before they start to mature and lead to adult heartworms. The monthly heartworm preventatives only work on certain larval stages. Any larvae too young to be stopped by the preventative when your dog is dosed will not be covered and killed until next month’s dose. Any larvae too old will be able to grow into adults that unfortunately cannot be killed by monthly preventatives. Therefore, any lapse in dosing could allow larvae to mature to adult heartworms leading to severe damage to your dog. (Learn more: Heartworm + Flea Preventatives: Does my Pet Really Need This?)

No commercially available test can detect heartworm larvae until they become adults that have inhabited the lungs, heart, and major blood vessels in your dog.

Because it can take up to 6 months once your dog is bit by a mosquito to develop adult heartworms, there is a limbo period when heartworms can’t be detected by a test or stopped by a preventative. With a yearly test, heartworm disease can be diagnosed before it causes extensive damage to your pet. If testing is skipped, the disease can continue to progress until clinical signs of heart failure and irreversible damage occurs.

Resistance to heartworm preventatives is growing.

This is due to previous veterinarians recommending heartworm preventatives as the sole means of treating and getting rid of heartworm disease in dogs. This has been proven to not be an effective means of treating a dog, but rather allowing heartworms to build a resistance to the medications.

The Mississippi Delta area has already been identified as an area where these type of heartworms are found. Yearly testing can help prevent resistance development and can help veterinarians and the American Heartworm Society know when resistant heartworms are in the area.

Product guarantees are offered by the manufacturers of heartworm preventatives.

If your dog is diagnosed with heartworm disease and your veterinarian can show that you purchased preventative without lapsing and did yearly heartworm testing, the manufacturer will pay for your dog’s heartworm treatment as long as your dog has a negative test on record each year.

As always, we recommend every dog (and cat) being on heartworm prevention every month, year-round.

This will dramatically reduce the likelihood of your precious pet contracting life threatening heartworm disease. We also recommend that every dog is tested yearly for heartworm disease, regardless of how many doses of heartworm preventatives were given to your dog in the past year.

Several types of heartworm medications are available through our online pharmacies. To shop online for your pet’s foods and medications, visit:

Fall Creek Place’s Online Pharmacy
Mass Ave’s Online Pharmacy
Fountain Square’s Online Pharmacy