Heartworm Disease: Can You Afford Not to Prevent It?

A few days ago, we discussed the impact heartworm disease has on the rescue community. But how about we talk about the impact that it has on the dogs and their owners? By understanding the health issues that result from infection and the financial burden involved with treatment, we can better understand the importance of heartworm prevention and how pet owners and rescues struggle with these cases.

Heartworm disease is transmitted by mosquitoes.

First, a quick recap on heartworm disease. Heartworms are parasites that live in the heart and lung vessels of infected dogs (heartwormsociety.org). As the parasites grow, they cause heart and lung damage, as well as damage to other organs such as the liver. Although heartworms can be treated in dogs, the damage caused can result in heart disease as they grow older. Heartworms are transmitted by mosquitoes, so our pets can become infected whether they go outside or not. A mosquito bites an infected dog and transmits the disease when it feeds on another dog. Mosquitoes can fly for miles and they can survive during the winter, especially mild ones, making this a year-round problem.

When a dog is infected with heartworms, it takes the larva (baby worms injected by the mosquito) around 6 months to reach the heart and become adults. The test only detects the adult worms, so there is a chance that an infected dog will test negative during that period. Heartworm prevention kills the larva and works backwards, meaning that the pill you give your dog today will kill larva injected into your dog in the last 30-45 days. The reason you cannot give your dog heartworm prevention without testing is that, if they have a large load of microfilaria (the newborn heartworms that await a mosquito for transport), the medication can kill them too quickly and cause anaphylactic shock, a severe allergic reaction that can result in sudden death.

Dogs should be tested yearly for heartworm disease. This is done by collecting a blood sample and either running the test at the clinic or sending it to a veterinary laboratory. Newer test, like Idexx’s 4Dx, also test for tick diseases such as Lyme disease. Why test your dog yearly if they are on prevention? Because nothing is 100%, we can have many things going on in our lives which cause us to forget things, and because our dogs can be sneaky. A very responsible pet owner once came in to the clinic I was working at concerned because she pulled her couch forwards to clean behind it and found several heartworm pills that her dog was ‘spitting’ out.

Ok, so a dog has heartworms. Now what?

Chest x-rays and bloodwork are important to evaluate the degree of disease caused by the heart worm infection.

Dogs that are heartworm positive require bloodwork and x-rays of the chest to determine how much damage has been caused by the infection. They are given steroids and an antibiotic for 4 weeks to help decrease swelling and damage caused by the worms and decrease the risk of allergic reaction, as well as weaken the heartworms to make the treatment more effective. The medication used to kill the heartworms, Melarsomine, is given once at the end of the oral therapy and then twice a month later. The heartworms take a few months to die off and the body resorbs the dead worms. Because these worms are in the heart, there is a risk for fragments to be released to the bloodstream and cause blockage of vessels. If the blockage occurs in the lungs or brain it can result in death. This is why it is so important to keep dogs quiet during treatment. Because the test doesn’t distinguish between live and dead worms, treated dogs can test positive for a long time.

Now what we have been waiting for: How much does all this cost? Clearly treatment costs will vary based on veterinary facility and location. This chart is based on low and high averages we found from different veterinary cost sources throughout the US:

At our hospital, the average cost of treatment for a heartworm positive 50 lb. dog from start to finish (diagnostics, pre-treatment, and treatment) is $550 – $650. Some may be lower or higher depending on how sick they are, but most fall within this range. Now, compare this with the cost of heartworm prevention and yearly testing. The cost for a 4Dx test (heartworm and tick panel) at our wellness clinics is $17 and a year of Interceptor heartworm prevention for a 50 lb. dog is $102 (minus a $15 mail-in rebate). Our online pharmacy, available only to our clients, sells Iverhart Plus for only $47 for a year supply for a 50 lb. dog. $64 per year can help keep a 50 lb. dog safe. Ask yourself, if you cannot afford $64 a year, can you afford for your pet to get sick?

Stay tuned for a future article about how heartworm prevention for cats!

In case you missed the other posts in this heartworm  series view titles and links below:

Heartworm Prevention: It’s Not Just About Your Dog’s Health

Feline Heartworm Disease: It’s Not Just a Dog Problem


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