Skip to main content

Heartworm infection

The mosquitos are back!
The virus carrying, flying pest! Not only can the mosquito transmit heartworms to animals but there are many viruses it can transmit to people as well. There are people who don't think Arizona has mosquitos. They are wrong, Arizona does have mosquitos and they're here! Although it is not National Heartworm Prevention Month we believe heartworm awareness should be reminded all year round. Please read on for more information about heartworm transmission, testing, prevention and treatment of heartworms in your pets. 

So now that we've got your attention.

What are Heartworms?
Heartworms are parasitic worms that travel via the bloodstream and live in the arteries of the lungs as well as the right ventricle of the heart. While they can mature and replicate in over thirty host species, the most common pet owners who are aware of their existence tend to be dog owners.

What is Heartworm Disease?
Heartworm Disease is the condition caused by these worms. As mentioned, the worms migrate through the blood vessels until they settle in the lungs and or heart. They will cause severe damage and potentially death for your dog. The disease is easily preventable and not so easily treated.

Where is Heartworm Found?
Heartworm is found in many parts of the world where mosquitoes are present, including the US, Canada, South America, Europe, Africa, Asia and Australia. In the US, heartworm has been found in dogs in all 50 states. That means that YES, Arizona has heartworms!  

How does my dog get heartworms?
Adult female heartworms give birth to babies, called microfilariae and releases them into the animal’s bloodstream. Microfilariae cannot mature on their own without an intermediate host. Enter the mosquito.
The mosquito bites the infected animal and sucks up the microfilariae along with their blood and kind of baby sits it for a while. The infants mature inside the mosquito for about ten to fourteen days and grow into the infective larval stage.
Next the mosquito goes and bites another animal, and deposits the larva into the new animal’s bloodstream. There they travel along and approximately six months later develop into adult spaghetti like worms, where they will begin this process all over again.
Male heartworms can be anywhere from four to six inches long and females range from ten to twelve inches. According to the American Heartworm Society, dogs can have anywhere from one to two hundred fifty worms.

But I would know if my dog had heartworms, right? 


What are the symptoms of Heartworm Disease?

Dogs that are infected with heartworms generally show no symptoms in the early stages. As the worms grow and mature and infection progresses to mild disease, the dog may start to cough.
When disease reaches the moderate stage, they will cough and have a hard time with exercise. The veterinarian will also hear abnormal lung sounds at this stage.

Severe disease is really bad. In addition to the above, they can have difficulty breathing, the liver may become enlarged, temporary loss of consciousness (poor blood flow to the brain), fluid can build up in the abdomen, heart sounds will also become abnormal and the worst one, the dog can die. The good news is that it never, ever has to get past the early infective stage.

But my cats cannot get 
heartworms, right? 

What about my ferrets?

So, Are Heartworms Preventable?
Yes they are, and it really is quite simple. There are several medications on the market that you can give your dog for the prevention of heartworms. No dog ever needs to suffer the treatment of heartworms, or the damage these parasites can cause. Since there are so many products to choose from and their individual parasite control spectrums vary, you must consult your veterinarian to see which one would be best for your dog.

What Are The Approved Products For Heartworm Prevention?

Heartgard and Heartgard Plus both are manufactured by Merial. 
The prevention in both is ivermectin in a specific dose. Heartgard Plus adds a de-wormer and is labeled for treatment and control of hookworms and roundworms which can be transmitted to people as well. This transmission from animal to human is called zoonosis

Iverheart Plus and Iverheart Max are by Virbac. Iverheart plus contains the same ingredients as Heartgard Plus, while the Iverheart Max also contains a de-wormer for the control and treatment of tapeworms.

Tri-Heart Plus by Schering-Plough are chewable tablets with the same ingredients and spectrum of Heartgard Plus and Iverheart Plus

Interceptor and Sentinel are both made by Novartis. The heartworm preventative in these products is milbemycin. Sentinel adds a product for flea control that sterilizes adult fleas to prevent infestation, but does not kill them. They are labeled for the treatment and control of hookworms, roundworms and whipworms.

Revolution is put out by Pfizer and the medication is Selamectin. It is labeled for the prevention of Heartworms, fleas, some ticks, ear mites and certain skin mites. While not labeled effective for intestinal parasites, if purchased from a licensed veterinarian Pfizer will give free worming tablets that are effective against hookworms and roundworms. If you find you are getting ticks on your dog, Pfizer will also provide Preventic collars free of charge if purchased from a veterinarian.

Advantage Multi is manufactured by Bayer. Moxidectin is the heartworm medication and it also combines a flea control as well. This product does kill fleas. It is also labeled for treatment and control of hookworms, roundworms and whipworms.

Moxidectin has also been formulated into an injection called Pro-Heart6 and is manufactured by Fort Dodge Animal Health. It is a time release form and lasts in the dog’s system for six months. Pro-Heart6 was on the market several years ago and was recalled. It has been re-launched and is listed among the above mentioned preventatives on the website of the American Heartworm Society.

Trifexis is a three way parasite protection against fleas, heartworm and hookworms, roundworms and whipworms. It is a monthly, beef flavored chewable and can be started at 8 weeks of age or older and at least 5 lbs.  Milbemycin oxime is used as a heartworm preventive. It kills the immature form of heartworm (Dirofilaria immitis) which is transmitted by a mosquito. Milbemycin also kills adult hookworms, roundworms and whipworms. The spinosad in Trifexis prevents and controls flea infestations by killing adult fleas. Trifexis does not kill ticks.
Thank you PetMd and The American Heartworm Society for letting us share your pages links to help educate dog and cat owners on Fleas, Ticks, Heartworms and Intestinal Parasites!

The preventatives listed above are not in order of recommendation!

Are Heartworms treatable?
Yes, heartworms are treatable, but it’s not a safe or comfortable treatment. The adult worms must be killed with an adulticide, which can be dangerous and painful injections for the dog.
The arsenic based injection is given into the muscle. The dog is kept for monitoring and comes back in thirty days for the next injection. This time a third injection is given the next morning. The dog is given antibiotics and anti-inflammatory medications by the veterinarian. 
During treatment, you MUST crate the dog and only leash walk outside to go to the bathroom. 

You MUST follow your veterinarian's 
instructions completely!! 

The treatment protocol is killing adult heartworms, of which there is no way of knowing the actual worm count inside the dog. Dead heartworms can block the flow of blood through the dog’s pulmonary arteries. So a dog with a few heartworms might do fine, whereas a dog with a very heavy worm burden could still die.

When Should I test my Dog for Heartworms?
A dog that is on a heartworm prevention regimen should be tested every year. Most vets will do this at their annual exam and vaccine appointment. A dog that has not been on prevention should not start on any prevention product prior to being tested. If on prevention but you missed some doses, check with your vet to see if your dog should be tested first. The amount of consecutive months off of prevention will determine that.

It is dangerous to give a preventative is given to a dog that already has heartworms. The prevention products kill certain life stages of heartworms and if the juvenile worms die off they can cause obstruction. They dog must be monitored and rested during the dying process, so if you are unaware of your dog’s heartworm status before giving the prevention, the results could be disastrous. A positive dog can also have an anaphylactic reaction and die after being given a preventative.
Best advice Az Pet Professionals can give? 
See your vet as soon as possible to have your dog tested for heartworm and comply with monthly heartworm prevention. See one of our amazing veterinarians if you don’t already have a family veterinarian. If you have a new puppy that is at least 6-8 weeks old and at least 5 lbs, talk to your veterinarian to make sure you start monthly heartworm prevention now!

Thank you to the un-named author of partial areas of this article for allowing us to re-post!

Popular posts from this blog



Article written by Kim MacCrone-CVT 

Okay, we all live in Arizona because the weather is almost perfect, the sun is almost always shining, the golf courses are luscious, there are multiple and beautiful wide open spaces and endless hiking trails! 

Surprisingly enough these are also places where some “not so delightful” inhabitants hang out in our state! You've heard the news this past week...... Snakes bites are on the rise!! Again! 
Here are a few simple tips to help keep you safe.

If you hike: 
 • Tap ahead of you with a walking stick before entering an area where you can't see your feet. Snakes will try to avoid you if given enough warning. • When hiking in an area known to have snakes, wear long pants and boots if possible
 • Consider purchasing a snake kit Avoid rock piles or tall green grass/bushes where snakes like to rest. 

About 150 people in Arizona are bitten every year. 
Some of Arizona’s rattlesnakes can also be lethal. 

Scottsdale is notorious for having snakebites and s…

National Adopt a dog month

National Adopt a dog month  And National Adopt a Shelter dog month

Are you thinking about adopting a dog? Has the thought crossed your mind in the past few months? If so, that's great! This is the perfect month for you to get down to business and do just that!

You might be looking simply for a companion, maybe a hiking pal, a friend for your grandparents or parents, how about an agility hopeful, or just a happy, warm face to welcome you home each day? Then this might just be the perfect timing!

Across the valley there are numerous places that you can choose from to adopt a dog. Many Shelters are full and have weekend discounts so they can open up space for new dogs. Unfortunately some will be placed on the E-List almost immediately due to its breed, temperament or health.

A dog that is on the "E-List" (to be euthanized) is commonly a dog that might have growled when captured or put into a kennel, but it doesn't necessarily mean they are aggressive.

They were SCARED.
I say …


Show more

Please Consider Donating

Your One-Stop Resource for hiring trusted pet services!

Your One-Stop Resource for hiring trusted pet services!

Shop Amazon!

White background photographs have been legally purchased for a Standard License for use by:

Royalty Free Licenses purchased from iStock and/or Eric Isselée/
License, Jill Flynn,,,