Protecting Your Pets: Heartworm Disease

Lala is a 9-year old Terrier/Retriever mix available for adoption through Companion Animal Alliance in Baton Rouge, La. She is house, crate trained, and knows basic commands. Lala is spayed, microchipped, current on vaccinations, but she is heartworm positive. She was brought into the shelter as a stray - but it was quite obvious someone had owned her before. Lala is currently in a foster home brushing up on her manners but is looking for her forever home.

Lala is a 9-year old Terrier/Retriever mix available for adoption through Companion Animal Alliance in Baton Rouge, La. She is house, crate trained, and knows basic commands. Lala is spayed, microchipped, current on vaccinations, but she is heartworm positive. She was brought into the shelter as a stray - but it was quite obvious someone had owned her before. Lala is currently in a foster home brushing up on her manners but is looking for her forever home.


It is mid April in South Louisiana which means the swamps of the south are a breeding ground for mosquitos. Not only are they an annoyance, but they also carry the microfilariae (babies) of heartworms.  As the weather gets warmer, mosquitos are more prevalent, as is heartworm disease.  For this reason, April is Heartworm Disease Awareness month.  According to the American Heartworm Society, there have been cases of heartworm disease reported in all 50 states, but veterinarians in Louisiana reported some of the highest number of cases nationwide.

So what is heartworm disease?  And who is at risk?  Heartworms are tiny worms that live in dogs hearts and lungs, causing high blood pressure and blocking blood vessels that can result in death (not unlike a heart attack).  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.

Even in areas and seasons where mosquitos are rare, veterinarians usually recommend year round heartworm prevention.  One mosquito bite can transmit this potentially deadly disease. Prevention is generally well tolerated, and is much less expensive than treatment for heartworms. Preventions are most commonly given as a monthly chewable tablet, topical, or  6mth shot. Talk with you veterinarian about which preventative is best for your pet.

Many owners ask about natural preventatives for heartworm disease.  While natural preventions are desirable, they are not effective when challenged with an infected mosquito.  In fact, some “natural” preventatives, such as garlic, can cause toxicity.  Instead, FDA-approved heartworm preventions are available with a veterinary prescription. The FDA tests deworming medications for safety and efficacy, which are the active ingredients in heartworm preventions. 

It can be difficult remembering to give heartworm medication monthly.  Here are a few solutions to consider:

  • Use your reminders in your phone to send yourself a message to give heartworm prevention on schedule.

  • Give your heartworm prevention on an easy to remember day, such as the first of the month, or when you pay your monthly bills.

  • Discuss all forms of heartworm prevention with your veterinarian.  Long lasting injectable preventions are also available.

Lala is proving to everyone who’s met her that age is only a number.  Lala loves endless games of fetch and is skilled at jumping into the air to catch tennis balls.  It’s a guarantee that the human playing with her will tire first. Lala also loves toys, rolling around on the floor to show her excitement, car rides and snuggling on the couch. Don't miss out on this spectacular girl!

Lala is proving to everyone who’s met her that age is only a number.  Lala loves endless games of fetch and is skilled at jumping into the air to catch tennis balls.  It’s a guarantee that the human playing with her will tire first. Lala also loves toys, rolling around on the floor to show her excitement, car rides and snuggling on the couch. Don't miss out on this spectacular girl!

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.  Heartworm Treatment can cost up to $1,000 or more which makes giving a monthly preventive a bargain in comparison. Treatment requires painful, arsenic-based injections to kill the heartworms present inside the lungs and heart. In addition, this is followed by a 1-3 month period of limited physical activity and possible health complications. Surgery may be required for dogs burdened with large amounts of worms. The longer the worms are in the heart, the more damage they are doing. Contact your veterinarian to discuss treatment options.

Remember: It is much easier to prevent heartworms than to treat them!


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Posted on April 14, 2015 .