All you Need to Know about Heartworm Disease

April is National Heartworm Prevention Month. The month designed for education, awareness, and emphasis for ongoing treatment of the potentially deadly disease. This week Dog Blog will give you some basic knowledge about the disease, how your pets can contact it, and what treatment and prevention options are available.

Firstly, let’s establish that heartworm isn’t a disease to ignore or put off, it is deadly serious, to the point of becoming fatal to infected pets. Heartworm is normally associated with dogs, but the parasite can also live in mammals like cats, wolves, ferrets, sea lions and coyotes. In some very rare instances, even humans can contract the illness.

How Does my Pet Catch Heartworm?

Mosquito’s play a pivotal role in launching the disease in most cases of heartworm. A single mosquito having a meal on the bloodstream of an infected animal becomes a carrier. As the insect moves from meal to meal, a series of “microfilaria” (or microscopic baby worms) are then passed to the bloodstream of the worms dining choice of the day. It takes about 14 days from the mosquitoes initial intake of the tainted blood to the time when they worms mature to an infective stage larvae.

Once the infected insect bites another animal, the larvae are then deposited on the skin of the new host and enter the body through the bite wound and launch into their new hosts bloodstream. It takes around six months for the larvae to develop into adult worms. From there they reproduce inside the animals body.

Once fully matured, a single heartworm can live for 5 to 7 years in a dog, 2 to 3 inside a cat, and grow to over a foot in length. Obviously, as the worms age, they have countless reproduction cycles inside the animal, cause an infestation that can spread to the lungs, kidneys, liver, or other organs.

What are the Signs that My Pet might be Infected?

Heartworms in dogs have very specific symptoms. The signs begin as a mild but persistent cough, avoiding exercise, overly tired after normal play or activity, loss of appetite, and visible weight loss. If left undetected or untreated, pets could develop heart failure. You might also notice a noticeably swollen belly.

As the number of worms increases over time, your dog is at risk of a cardiovascular collapse, The worms will block the heart, stop the blood flow and interfere with the normal heart beat and activity.

Once the worms have progressed to this state of control in the pets body, you’ll notice sudden difficulty breathing, pale gums, and dark urine. Immediate action needs to be taken to remove the parasites, and if not treated, few dogs survive.

Heartworm in cats is more difficult to see, as the symptoms are subtle and often unnoticeable. A cat might start coughing, could have periodic vomit, start to shy away from their food, and show visible weight loss. As the illness progresses,  the cat could faint, have seizures, have difficulties standing or walking, and have the rounded or swollen belly. In many cases the first sign of heartworms in a cat is when the animal collapses or dies, suddenly.

How likely is it that my Pet Could Contract Heartworms?

Research indicates that veterinarians sees approximately 300,000 cases of heartworms in dogs each year. Cats are not as easy to estimate, as they don’t see their veterinarians as frequently as canine counterparts. All 50 states have cases of heartworm and approximately 1 in 80 dogs are infected.

Reporting shows that infections are highest in moist, wet, humid areas (think Gulf and Atlantic southern coasts) or along river valleys where water will pool and settle. Northern California is also a hot bed for heartworm infections.

A 2022 “Prevalence Map” of reported heartworm infections shows that the South (Tex-arkana region),

Southeast (Mason Dixon Line south the Florida border), plains and prairie states (Kansas through Indiana) and North Dakota have the most reported cases. While New England, the West Coast, and Northern Great Lakes states have the least reported incidents.

To give an idea of how weather and climate impacts the outbreak of Heartworm Disease, the months after Hurricane Katrina showed a jump in cases among pets evacuated from the hurricane zone. Nearly 60% of dogs taken from the hurricane zone tested positive for heartworm. This was due to extreme moisture and the following hot and humid temperatures. The area became a major breeding ground for mosquitoes due to the standing water and extreme heat. Added the “perfect storm” for breeding, this area is traditionally poor in providing yearly veterinary care to their pets.

What can I do to Prevent Heartworm infection?

The American Heartworm Society urges you to “Think 12”. Every 12 month assure that your pet is tested for heartworm. Also, your pet should have heartworm prevention medication each of the 12 months of the year. A planned and executed routine of health maintenance and regular checkups will help to prevent or diagnose heartworms before they become deadly.

When Should I Test my Pets?

The nice thing about this type of testing is that it can be done during a routine health maintenance checkup. So, your pets yearly physical exam is a perfect time to handle this testing.

For dogs, you should think about heartworm testing early, before 6 months of age. If  they have that initial test, veterinarians recommend a second test 6 months later. Since it takes a minimum of 6 months for the larvae to mature, this assures that your pet is safe from heartworm as they mature. For adult dogs, it is suggested that you revert to that yearly exam.

If your dog hasn’t been on heartworm prevention medications, they will need to be examined before starting (or restarting) monthly prevention… then again in 6 to 7 months. After that they can start the yearly routine for examination.

Cats are bit different, as there isn’t any approved heartworm treatment after infection is detected. Prevention methods are the only way to assure your cat is heartworm free. See your veterinarian for details and to get the needed heartworm exam.

What if I Find Out my Pet Has Heartworm?

Don’t give up, there is good news. Most infected dogs can be successfully treated if infected with heartworms. The key is early detection and, once discovered, eliminating the parasite from the animal. Once this is done, a normal heartworm prevention and exam routine can be established.

During treatment the veterinarian will likely suggest you stop or restrict exercise, they will attempt to stabilize the disease and determine the stage of severity, and then start treatment to eliminate the heartworms. Once eliminated, it will be important for your dog to have an ongoing “Think 12” plan that is maintained.

Cats are a bit different. The feline body is not an ideal host for heartworms, often the situation resolves itself due to the cats immune system. Since there is not treatment for cats, there could be lifelong damage from the infection. Yearly heartworm testing and exams is critical to stop the infection before it starts. There are surgical options for heartworm removal for both dogs and cats, if the infection is that severe and it is life threatening.

As you’ve probably determined, the key to keeping your favorite fur kids heartworm free is a regular routine exam and testing, along with ongoing prevention treatments each month, year round. Prevention drugs are “parasiticides” that hunt for and eliminate the microfilariae in the bloodstream, thus stopping them from ever maturing to adult worms.  You can find combo heartworm/flea/tick medications on the market, as well. Your trusted wellness veterinarian likely has a favorite brand or type of heartworm prevention treatment.

Of all the potential illnesses or diseases your pet can contract in their lifetime, heartworms might be he easiest to prevent. It’s up to you, the pet parent, to assure you pet sees their veterinarian at least once a year for their annual physical checkup, which should include heartworm testing. Prevent is ongoing and the real key to stopping the infestation before it starts, so keep your “Think 12” plan on schedule the entire year.

That’s our report for April’s “Heartworm Prevention Month” and we sincerely hope you learned something and decided to put a new focus on prevention and examination. All of us on the FreddieSez team urge you to get your pet on flea, tick, and heartworm prevention routines. They can’t ask for it themselves, so you must be proactive to keep them safe.

Till we meet again next week with other topical and interesting Dog Blog, we hope you have a health, happy, productive, and Pet Friendly Week… #FreddieSez!