Study Suggests Hearworm Incidence is Rising
Heartworm disease is potentially fatal and completely preventable. The disease is caused by a blood parasite that is spread by mosquitoes. It affects both cats and dogs, although dogs generally are at greater risk. Heartworm disease can lead to heart failure and a plethora of other problems.
DVM Newsmagazine recently reported on a new heartworm incidence study released by the American Heartworm Society. The study was not rigorously scientific, but it does provide evidence that heartworm incidence is increasing in certain areas. The notable areas in the US include the gulf coast, east coast, and northern California.
The triennial survey was distributed to more than 40,000 veterinarians last fall. Ultimately, veterinary practices from some 2,200 counties were represented . . . [a]ccording to the most recent results, the number of positive cases rose per clinic in 31 states. The reasons likely are multifactorial, including increased heartworm testing, increased client base per clinic or even climate trends.
Actual incidence of heartworm may be increasing. It’s also possible that veterinarians are detecting more cases due to increased testing. Either way, Dr. Sheldon B. Rubin, president of the American Heartworm Society, feels that heartworm disease is inexcusable.
“There is no reason a dog should have heartworm disease today. If we can get more animals on prevention, we will get the numbers of heartworm-infected animals down. It is a serious problem.”
Monthly heartworm preventatives are readily available. They have excellent safety profiles. Many of them have the added benefit of eliminating intestinal worms that may be contagious to human beings. My pal Buster gets his on the first of each month.
I recommend that you talk to your vet about protecting your pet from heartworm.
Photo: Indy contracted heartworm before he was adopted.
You have questions. 
One of my rescued dogs went through the treatment….she had a bad case of Heartworms. She is HW free today and I would not wish that treatment on any dog even though it was necessary. We are so glad she is fine today and she is living a good life and not a stray anymore. Prevention is the key and I hope everyone on dogster is doing the monthly treatment if needed in their area.
We live in Texas and do the treatment all year.
The painful injections are NOT the only treatment option – there is a “slow kill” method used by vets during the Hurricane Katrina pet rescues – we’ve used it with 3 HW + shelter dogs and it WORKS – the dog is given oral doses of ivermectin (the same medication used in the shots) in pre-measured doses according to their body weight. THey are given it in their food once every 2 weeks (Heartgard chewables work, too, but they’re more expensive) The treatment kills off the baby and young worms, allowing the adults to die off naturally (usually takes a year or two). There is no stress on the dog, no crating and keeping quiet for 2 weeks, and much less expensive for the owner/guardian. Like I said, we’ve done this with 3 HW + dogs, and at their next checkup, they were HW -. OF course, vets don’t advocate this (no $$$ for them), but online research and helping out at our local shelter has made me aware of this treatment. We’re currently treating a 3-year old chocolate lab this way – poor Noble would have been PTS if we hadn’t been able to find someone to take him and treat his HW.
Ivermectin is not the medicine used in the main stages of heartworm treatment. It is used for heartworm prevention and to remove heartworm larvae from the bloodstream after the adult worms have been killed.
The medicine used to kill adult worms is melarsamine.
Giving ivermectin to a dog with a severe heartworm infestation can, in some cases, lead to shock and sudden death.
Waiting a year or two for adult worms to die naturally can lead to significant pathology. The worms can cause significant damage to the pulmonary blood vessels during this time. Heart failure can result.
The thought that vets recommend heartworm treatment simply for the money is laughable. If we cared about money, we would have gone to law school or business school.
Folks, be sure to check the accuracy of your sources before you implement home treatments for your dogs. There is a lot of misinformation floating around out there.
In our area a lot of people only treat for heartworm 6 months out of the year. Then stop through the cold winter months…as I did.
Each year before my vet would issue more heartworm medicine I had to have the dogs each retested.
One day my vet sat me down and showed me the cost of the yearly testing and the cost I would incurr if I just kept the dogs on year round heartworm medicine. It was like $20 difference! DUH!
My dogs are now on heartworm medicine year round.
Not only is it not hard on the budget …it is much easier on the heart than and pocket book than treating a pet for heartworm is!
SLaW to Ya All!
Even though I live in Vermont, my 3 dogs receive heartworm pills year-round for 3 reasons:
1) This way I never forget them & start too late in the season, which requires prior testing
2) The pills also prevent other worms.
3) We often travel with the dogs to visit family in Florida for the holidays & there are mosquitos there all year.
I wish the article had addressed 2 things:
1) In what areas are vets seeing an increase in heartworms –they have always been prevalent in the South?
2) Is there a hypothesis as to why this is occurring — such as it thought to be a function of global warming or rather a function of owners not knowing the importance of preventive treatment?
Lori,
Click on the link to the American Heartworm Society in the post for an in-depth answer to your first question. As I said in the post, the gulf coast, east coast, and northern California are experiencing notable increases in prevalence.
Why is heartworm prevalence increasing? There are several theories, ranging from climate change to evolution of heartworm lifecycles. Or, as I said in the post: “It’s also possible that veterinarians are detecting more cases due to increased testing.” No theory has been proved conclusively.
What are your thoughts on Doxycycline dosing prior to Ivermectin treatments for adult HW infection? It appears that killing the Wolbachia parasites in the worms reduces the risk of shock and embolism in HW-positive dogs, as well as sterilizing the female worms.
The ’soft kill’ method with Ivermection alone is only recommended for light infections in low-activity dogs. Personally, it seems to me that Ivermectin+Doxycycline treatments would the best choice.
The study that proved the basis for seasonal Heartworm prevention <a href=”http://www.journals.elsevierhealth.com/periodicals/ysvms/article/PIIS1096286798800108/abstract”is here. For those of us who are not vets, it’s conclusions are summed up here.
Some parts of the U.S. are endemic and at year-round risk for HW, so seasonal prevention is not something to do without knowing the status of your own region is first.
What are your thoughts on Doxycycline dosing prior to Ivermectin treatments for adult HW infection? It appears that killing the Wolbachia parasites in the worms reduces the risk of shock and embolism in HW-positive dogs, as well as sterilizing the female worms.
The study that supports the basis for seasonal Heartworm prevention <a href=”http://www.journals.elsevierhealth.com/periodicals/ysvms/article/PIIS1096286798800108/abstract”is here. For those of us who are not vets, it’s conclusions are summed up here.
Some parts of the U.S. are endemic and at year-round risk for HW, so seasonal prevention is not something to do without knowing the status of your own region is first.
If comments are moderated, it’d be good to have a message to that effect, so that newbies don’t assume their comments are simply being lost.
Pai,
Comments are not moderated. However, the spam filter on the blog occasionally sorts real comments out as spam. This usually happens if they have links to outside pages.
Anyhow, I was able to sort through the spam filter and post your comments. I hope I found them all.
My blog software proudly proclaims that it has protected my site from over 28,000 spam comments. I wonder how many of those were legitimate.
–Dr. B.
Oh, sorry for the double-post then. You can delete one of them if you like.
Hi Dr. B.
I rescued a cocker spaniel female who I’m fostering currently. She was strongly heartworm positive. The rescue didn’t want to pay for a chest x-ray but instead looked at the number of heartworms under the microscope for heartworm load to decide on course of treatment. I wasn’t happy about that because of her strong heartworm status. I don’t like taking shortcuts. But they argued and claimed that it wasn’t cost effective and that they treat all dogs this way. I asked them how would you know if her lungs and heart had a heavy burden? But they ignored that. In the end, the vet opted for the two immiticide treatments with doxycycline 2 weeks prior to the immiticide and for a month afterwards. We just discontinued it. We will retest her in a couple of weeks. She is still being confined except for potty breaks in an air conditioned room but is getting bored with it but I have to confine her. How much longer should be confine her before she is cleared for adoption. Some sources say 4-6 weeks and others state 8-12 weeks. I will do whatever is the best for this dog. She did have a marked appetite decrease but her gums stayed nice and pink, no jaundice noted. No brick red gums either. But she did cough within 3-7 days post injection(s) and the vet gave her some dexamethasone to help with that. She hardly coughed at all after that except occasionally.
They want me to post her on petfinder but I’m not sure she is ready yet.