As a dog owner, you are probably needing to know what causes heartworm in dogs and how it affects your four-legged babies. First and foremost, heartworm is a disease that is serious and sometimes fatal and affects pets throughout many parts of the world.
Like with anything else, the more you know about heartworm, the better you can be prepared to avoid it with your pets. To help you become more familiar with heartworm and its causes, symptoms, and treatment, we have put together some information for you.
Table of Contents
- 1 All about what causes heartworm in dogs
- 2 How do you know if your dog has heartworm?
- 3 Is my dog at risk of heartworm?
- 4 When should your dog be tested for heartworm disease?
- 5 What should you do if your dog tests positive for heartworm?
- 6 How can you prevent heartworm in dogs?
- 7 Online resources to learn more about what causes heartworm in dogs
All about what causes heartworm in dogs
What causes heartworm in dogs?
The first canine heartworms in the United States were first discovered in 1856 according to Stanford University. Heartworm disease is caused by, well, heartworms (Dirofilaria immitis). Heartworms are parasitic roundworms that can grow to over a foot long and that live in the lungs, heart, and blood vessels of infected pets. These worms can cause major health issues for your dog, including, heart failure, lung disease, organ damage, and death. Dogs can be affected as can other mammals, including humans (although this is rare).
These worms mature after six months and can live in your dog’s body for seven years. The female heartworms are 6–14″ long (15–36 cm) and 1/8″ wide (3 mm) while males are half the size of the female worms.
Once a dog is infected with heartworms, the worms will mate and procreate. An untreated heartworm case can multiply into hundreds of worms living inside of one dog. A case like this can create lifelong damage to a dog. This is why heartworm prevention is so incredibly important.
How does heartworm spread?
The mosquito is a big factor in the spread of heartworm and is the vector. In other words, heartworms cannot spread directly from dog to dog, but require mosquitoes as an intermediate host. The mosquito will bite an infected animal and pick up the larvae that are in the bloodstream of the animal. Inside the mosquito, the larvae will grow through three larval stages. Once, they are in the third larval stage, they will infect a healthy animal when the mosquito bites it and transfers these parasites.
Once in the dog, they will grow into a fourth stage. At this point, it will migrate into muscles and blood stream. They then grow some more into adult worms and will migrate into the heart. Once in the heart, the adults will continue to grow and mature. After about seven months post-infection, they start to mate and produce microfilariae which will get picked up by mosquitoes, starting the cycle over again. Heartworm can live in a dog for five to seven years.
How do you know if your dog has heartworm?
Evidence of potential heartworm disease can appear through a variety of symptoms you may notice in your pet. During the beginning stages of heartworm disease there are often no or very few signs. However, as the infection gets worse and the disease progresses, the more symptoms that will appear. These signs include fatigue and disinterest in physical activity, decreased appetite, weight loss, and mild cough.
As the infection gets worse though, you should be aware that the symptoms get much more serious. If your dog is showing signs of a swollen belly, pale gums, labored breathing, or dark brown urine, you should get your dog to the vet as soon as possible. When the infection is at this level, very few dogs survive without surgery to remove the heartworms. Therefore, early diagnosis is vital in the treatment of heartworm as it provides a greater chance for rapid recovery.
If you do not treat heartworms, they can cause significant damage to your dog’s heart, lungs, blood vessels, kidneys, and liver. In severe cases, your dog will not survive treatment. Some dogs may require lifetime treatment for heart failure.
Is my dog at risk of heartworm?
While you may not think that heartworm is a big issue in your area, you might be surprised. They may actually be quite common in your area. If your city tends to have a high number of strays, this will put your pet at risk. If you live in a more rural area, wildlife are often carriers of heartworms. Even a quick trip to another area could have put your dog at risk for heartworm.
Indoor pets are at risk too. Especially during the summer months when you are more likely to have open windows and doors. Wherever there are mosquitoes, there can be heartworm issues.
With milder winters and wetter and warmer periods, mosquito season is growing longer. So, you really need to protect your dog and keep them safe and healthy.
When should your dog be tested for heartworm disease?
In addition to testing your dog when, and if, they start to show symptoms, you should also test them for preventative reasons. Dogs should be tested for heartworm disease annually once they hit seven months of age. This annual testing can easily be done during your pet’s annual veterinarian check up.
What should you do if your dog tests positive for heartworm?
The first stage to treating heartworms in your dog is to confirm the diagnosis. Treatment is high-cost, so your vet may want to perform supplementary tests to reaffirm the diagnosis for your furry friend. You may also need to have x-rays done as another method to confirm the disease.
Once you have verification, your dog will be given a series of injections to kill the adult heartworms and another drug to kill the microfilariae. The most common drug used to kill the adult heartworms is melarsomine dihydrochloride. It is administered by deep intramuscular injection into the lumbar region of the dog. Then imidacloprid or moxidectin will kill the microfilariae in the bloodstream.
These injections are usually done in stages. And then you will need to take the following steps:
- Force rest. If you have a hyper dog, this one will be difficult, but it is important to make sure your dog is resting during this time. Your dog must rest for at least 30 days after injection. This is of critical importance as the heartworms are dying and decomposing within your dog. This can cause severe cough and breathing issues.
- Stabilize your pet’s condition. You may want to instantly start treating, however, depending on their condition, you may have to stabilize with other measures first. This is due to the fact that physical exertion increases how quickly the heartworms can damage your dog’s organs.
- Treat. Once your dog is rested and stabilized. It is then that your vet will want to begin regular heartworm treatments.
- Retest. Once your dog has been treated for heartworm and you have waited approximately 9 months, it will then be time to retest your dog for heartworm to ensure that the worms are gone and your dog is healthy.
In very rare cases, your dog may need surgery to physically pull out the worms. Some dogs may require a lifelong treatment for heart failure after heartworm treatments, these include, ACE-inhibitors, beta-blockers or cardiac glycosides, and special low-salt diets. We know whatever it takes to help keep our fur babies alive is worth the effort.
How can you prevent heartworm in dogs?
The treatment process of heartworm is hard, expensive and sometimes risky, which is why veterinarians recommend early testing and administration of preventives as there is currently no vaccine for preventing the parasite. The FDA has recommended some other means of preventing the parasite. They include:
- Application of FDA-approved mosquito repellents.
- The use of mosquito traps and limiting your dog’s outdoor activity at dusk and dawn, which is the prime feeding time of mosquitoes.
- Check you dog every year for heartworm, including dogs that are on heartworm prevention medication.
Be sure to consult your local veterinarian to find out the best preventive scheme for your dog. Caring for your pet by keeping its health at the forefront of your priorities will help make heartworm prevention achievable and your pet healthier and happier.