Heartworms 101

I am often surprised by how little people really know about heartworms and the risk they pose to their dogs. I have worked in the Veterinary industry off and on and even went to school to be a Vet Tech so I have a lot of base knowledge about diseases and the health of pets. One of the biggest risks posed to your dog is heartworms. In this post I will go over heartworms and how to prevent them.

What are heartworms?

Heartworm is a parasitic worm that is passed to a dog through a mosquito bite. Heartworms reside in a dog's pulmonary arteries which causes damage to their lung tissue and vessels.

Where are heartworms?

Heartworms are found all across the United States. Wherever there are mosquitoes there are heartworms.

http://www.heartwormsociety.org/pet-owner-resources/heartworm.html#history

What is the life cycle of heartworms? 

Adult female heartworms release their young (microfilariae) into an animal's bloodstream. Mosquitoes become infected with the microfilariae when they take blood from an infected animal. It takes 10-14 days for the microfilariae to mature into the infective larval stage inside a mosquito. Once that happens when the mosquito bites another dog or susceptible animal the infective larvae enter into the bite wound. It then takes around 6 months for the infective larvae to turn into adult worms. Microfilariae are not able to mature into adult heartworms until they first pass through a mosquito.

What are the signs of heartworms in a dog?

Clinical signs of heartworm disease are hard to recognize in the early stages but as the number of the heartworms increases over a period of months and sometimes years the symptoms become more prominent. Dogs who are recently infected usually show no signs where as a dog who has been infected for a while might have a mild persistent cough, lethargy, become easily fatigued, have a decrease in appetite and even weight loss. 

How is heartworm disease detected?

Heartworm disease is detected by a snap test that your veterinarian can perform with only 3 drops of blood. The test uses an antigen to detect heartworms. Keep in mind though that it may take up to 7 months of infection for a test to show positive. Most veterinarians offer two tests, one which tests only for heartworms (referred to as a 1dx test) and another that tests for heartworms as well as three tick borne diseases (known as a 4dx test). In most cases you will want to do the 4dx test if you have never had your dog tested and have never had them on preventative. You will especially want to do the 4dx test if you have a large tick problem. The snap test only takes 10 minutes and while they wait for the results of that a technician will smear some of the blood onto a slide and look under the microscope to see if there are any microfilariae.

If the test is negative what do I do?

If the test comes out negative then you want to start your dog on heartworm prevention. This is a monthly pill that will prevent your dog from becoming infected. There are many different brands of heartworm preventative but the most common ones are Iverheart and Heartgard. Another preventative option is Trifexis which has a flea preventative in it as well. Personally I have Winston on Trifexis because it is cheaper in the long run because I don't have to buy one thing for fleas and another for heartworms. Remember that all of these products require a prescription from your Veterinarian in order to get them.

What if the test comes back positive?

Adult heartworms are killed with a drug that is injected into the muscle through a series of treatments. Usually a dog is kept at the hospital the day of the injection just to make sure no adverse reactions take place. When the dog goes home it should be exercise restricted and taken outside on a leash so it can't run around. You will want to restrict exercise for about 2 months. To prevent another infection a monthly heartworm preventative will be given. The heartworm pill will also kill any microfilariae. A positive test may not seem like a huge deal but in reality the treatment can be pretty expensive and heartworms can cause permanent damage.

In conclusion...

Make sure you consult your veterinarian about heartworms because they know how prevalent it is where you live and will be able to tell you much more than I can. The most important thing to take away from this post is that heartworms are a real concern and can cause many problems. You should test your dog once a year and keep them on preventative year round.