Heartworm Disease

April is National Heartworm Awareness Month. This week we will focus on what you as a pet owner need to understand about heartworm disease and how to prevent it. While there have been cases of heartworm disease reported in all 50 states, veterinarians in Louisiana reported some of the highest number of cases nationwide. The swamps of Louisiana are a breeding ground for mosquitoes, which are carriers of the disease.

What exactly are heartworms? Heartworms are parasites that can grow to be several feet long that live in the heart, lungs, and blood vessels of mammals. They are dangerous because they block blood flow and limit oxygen to the heart and other major organs. Heartworms can live in dogs, cats, ferrets, and wild mammals like coyotes and foxes.

Mosquitoes transmit heartworms between animals. When an infected animal is bitten by a mosquito, young heartworms called microfilaria are carried in the blood. In 10-14 days the microfilaria mature into infective stage larvae. At this point, when a mosquito bites a host, the larvae are transmitted. It takes about 6 months for the larvae to mature into adult heartworms, which are able to reproduce. This is why the American Heartworm Society recommends testing all dogs for heartworms starting at 6 months of age.

In the early stages of heartworm disease, young healthy dogs show very few symptoms. That’s why routine testing is so important. Extremely active dogs, those with severe infections, and those sick with other conditions can have a mild, persistent cough, get tired quicker after normal activities, have a decreased appetite, and begin to lose weight. Cats and ferrets can also contract heartworm disease; however, heartworms typically don’t mature in these animals and treatment options are limited. This is why utilizing prevention products is important.

Heartworm disease can be easy to prevent. There are a number of oral heartworm prevention products on the market that have been combined with preventatives for fleas and other internal parasites that should be given monthly. There is also an injectable heartworm preventative that lasts for 6 months. Talk with your veterinarian about which heartworm prevention is best for your pet. Regardless of what product you use, in Louisiana where winters aren’t typically cold enough to kill off the mosquitoes, keeping your dog on preventative year-round is essential.

In addition to utilizing heartworm prevention products, routine testing is necessary to make sure the products are doing their job. Puppies should be tested starting at 6 months old, and annually thereafter. If you are adopting a dog with an unknown history of being on heartworm prevention, they should be tested immediately, 6 months after being on preventative, and then annually. This is because of the 6-month maturity period of heartworms. Most veterinarians utilize a test that checks for the microfilaria. There are ways to check for adult heartworm infestations in dogs; however, they are typically more expensive than the microfilaria tests.

What happens if a dog does contract heartworms? Veterinarians can utilize protocols approved by the American Veterinary Medical Association to treat the disease. Depending upon the severity of the infestation and the health of the dog, treatment can have varying impacts. Your veterinarian would oversee the treatment of heartworm disease and administer the medication; however, your compliance with giving any oral medications and limiting activity at home are crucial to the dog’s health.

At Metairie Small Animal Hospital, we pair heartworm testing with annual vaccinations to ensure it is done on a regular basis. However, if you have missed two months of giving a heartworm preventative product or it has been over a year since the last test was administered, you can bring your dog in at any time during regular hours for a heartworm test (an appointment isn’t needed). Be sure to ask the staff about discounts and rebates for purchasing a year’s supply of heartworm preventative products. It typically makes it easier to remember to give the products when you already have them at home.

Below is a graphic of the life cycle of a heartworm in dogs and cats. For more information, please give us a call at any of our locations.