Big Dogs, Big Heartworm: September 2011

Wednesday, September 28, 2011

Nice Article! Animals Getting Less Health Care in Poor Economy: Royal Oak Patch

---> Immiticide Unavailability!<---

We have our Google alert set to stun. No, wait, to Immiticide. Anyway, every time we see it we hope it's to say Immiticide is back on the market. So far no luck with that, but we've been reading about the shortage throughout the country.

In this blog, we haven't done a big copy/paste of one article, but this article really made a lot of sense and was well written (hope they have themselves on Google alerts), and demonstrated the cycle that is happening now. Yes, like the heartworm life cycle! Exactly.

Economy is bad - people cutting back here and there - including the annual HW test and monthly pills - more dogs are becoming HW+ - and with more dogs becoming HW+ - guess what - more dogs become HW+ because of the heartworm life cycle.

Not good.

Please promote this information. An ounce of prevention is worth a pound of cure. Or a few dollars a month can save the big cost down the line and save the life of your dog. Because the more people not using the monthly meds, the more chances that there will be HW+ dogs in an area.

So here is the article: http://royaloak.patch.com/articles/animals-getting-less-health-care-in-poor-economy#

And some quotes from it:

The poor economy is having a negative influence on the health care of animals. Veterinarians and animal shelters have reported an increase in illnesses, especially heartworm, along with a decrease in veterinary visits and preventive treatments.

“Before working at this practice, I worked at a much busier clinic," said T.J. Sharma, doctor of veterinary medicine and Ph.D.

"At that time, I only saw one or two cases of heartworm. Since the decline in the economy, I am seeing them much more frequently,” said Sharma, owner of Blue Cross Animal Hospital. “I have already treated 12 dogs this year.”

Preventive measures are the only way to block heartworms from reaching adulthood, Sharma said.

Because of the decline in the economy, many dog owners feel that they don’t have the money to invest in their animals. However, preventatives are less costly than treating a dog that has been infected with heartworms, Sharma said.

“It’s a huge problem,” he said. “Even with one infected dog in an area, it’s dangerous. When there are fewer dogs with defense, more mosquitoes are carrying the parasites, and dogs are becoming infected more rapidly.”

To complicate the problem, Immiticide, the only FDA-approved treatment for heartworm in dogs, is temporarily unavailable. A recent letter from the drug’s manufacturer, Merial, explained the importance of conserving current supplies of the treatment and said the maker is experiencing challenges in manufacturing the drug.

While the company stated that it is trying to resolve the problem, it was vague on the details and unsure when the treatment will be back on the market.

And more good info in the link.

Mila will check in next post!

Sunday, September 25, 2011

Heartworm Disease in Dogs: a Festival of Links

Throughout this blog we have used information from many resources. Today, we will fulfill the promise to collect them all in one place. We are sure it is a day you have been waiting for!

If you are just finding this from a Google search, we invite you to not only check out these links, but to read through the blog as well. You will find pictures of the heartworm treatment of Mila and we hope some easy to understand information that will help you help your dog, as we have broken down the complicated information from these sites into what we hope will make more sense to everyone.

Links after this:
---> Immiticide Unavailability!<---

These goals may be achieved by strict adherence to the following - basic overview:

1. Limit the activity level of the dog to reduce pathology. (Really important! More activity makes the dog SICKER FASTER)
2. Carefully place the non-protected dog on heartworm prevention. (see the PDF)
3. Administer doxycycline to reduce pathology and infective potential of heartworms. The doxycycline protocol would be 1 month on, 2 months off, 1 month on, 2 months off, etc.

All the details to review with your veterinarian are in that PDF. You should probably print and bring the whole PDF with you so they can see the source of the information and all the footnoting stuff.

Now the links!

Thank you to The Bark Magazine!

http://www.thebark.com/content/big-dog-big-heartworm
The Bark Magazine Facebook Page

Tuesday, September 20, 2011

Meet Mila's Dr. Bruno

---> Immiticide Unavailability!<---

In the last post about Mila, we talked about how sick she had gotten from her treatment: vomiting, not wanting to eat, lethargy.

This was with keeping her cool and inactive. Clots inevitably formed and she got sick.

Imagine if she had been allowed to be active - even mildly. The minor clots that were helped by the prednisilone could have been major.

Her illness could have turned severe, even fatal.

And that's how it is with heartworm disease treatment.

Your dog can be doing so well, that you forget that 12 inch long worms are dying off inside their heart and lungs, and that their body is working overtime trying to absorb all of that, in a system that is not meant to do such a job. It doesn't take a lot of worms to kill the dog, it takes one worm.

Don't take chances. Keep your dog quiet, keep your dog cool. "One little (fill in the blank with the activity - potty off leash, day out of the crate moving around, romp in the yard)" is not worth your dog's life. Those activities are what can tip the scales between a successful heartworm treatment and a tragic heartworm treatment. And as we've seen, even if you keep them quiet and keep them cool, they can still get seriously ill. Why risk it?

Mila was sick for about a week. During that time, we developed a scale, similar to the pain scale in humans:

But we called it the Dr. Bruno scale.

Throughout history (okay, TV history) there have been handsome, dashing doctors whose charisma and charm contribute to their patients' recoveries.

From the Internet we learn of Dr. Kildare:

Dr. Steven Kiley:

Dr. Phillip Chandler:

Dr. Doug Ross:

Dr. House (okay, maybe not the typical charisma and charm but a pretty good cure rate):

And now we can add Dr. Bruno:

Mila loves Bruno. He's a fun little mix (don't tell him he's little) and she cannot get enough of him. Most of the time, the feeling is not entirely mutual. He can get enough of her! But Bruno has been a therapy dog, and is a natural healer, so when Mila was sick, Bruno knew his job and was at her side.

I feel awful, but I have my Dr. Bruno

Each day we could rate how Mila felt by how she reacted to Bruno when she was out for potties and pills. If she perked up, we could tell she was feeling better. On the downslide days, she would be aware of him near her, but would not give him a special greeting. And Bruno would get closer to her, and watching his reaction would also tell us how well, or unwell, she was feeling.

So each day, with the new meds, different food combos, and careful monitoring, the Dr. Bruno scale was a huge part of evaluating how Mila was doing. We knew she'd turned the corner when Bruno was not allowed to go out to potty with her because it was too exciting for her, and too tempting for her to want to follow and play with him.

Another successful case for Dr. Bruno

Bruno has done this before with other fosters and pets - alerting to physical health problems - and has done this in his hospital visits when we did therapy work, so we really did trust his insight in this matter. Amazingly, he was accurate again, but the best part in this was that he not only was able to alert to Mila's illness and the subtle improvements or worsening, but he was also able to help impact how she felt, with his charm and charisma.

Of course, good vetting helped too! We want to thank her vets, BDBH rescue, and everyone for their good thoughts for Mila during this difficult time in her treatment. And of course, thanks to Dr. Bruno.

Thanks for making me feel better, everyone!

On February 17th, 2012 Dr. Bruno was taken to the vet and underwent emergency surgery/splenectomy.

While the spleen removal was successful, it is thought that Bruno threw a clot, and he never came back, despite the incredible efforts of all at the veterinary office.

He is greatly missed.

Thursday, September 15, 2011

Why So Much?

---> Immiticide Unavailability!<---

Before we talked about the cost of treatment versus the cost of prevention.

We said you could buy 7 years of monthly medicines for the same price as one heartworm treatment.

Definitely a bargain there. But treatment is necessary, and well worth the price to get rid of the heartworms and stop the attack on the dog's heart, lungs, kidneys and liver. As we said before, the only choice you do not have is not to treat. So this is definitely not a message of save money, don't treat! Treat, treat! But better, know what the costs are and prevent, prevent!

When we said $700, we were using our local prices, from vets we have worked with.

So we are asking readers: do you know how much it costs for heartworm treatment where you live?

Right now it's a theoretical exercise without the Immiticide. But if you can find out, you can figure out how many months of heartworm meds you can buy with the cost of treatment.

What goes into the cost of heartworm treatment? This information will help you to get an estimate.

SNAP test to diagnose $__________
Physical exam $__________
Blood panel $__________
Urinalysis $__________
Microfillaria smear (Knott's test) $__________
X-rays (generally 2 views) $__________
Some will do an Echocardiogram $__________
1 month doxycycline $__________
1 month probiotics $__________ (probably not provided through veterinary office)
Immiticide - treatment 1, injection 1 $__________
Possible pain management $__________
Possible Prednisilone $__________
Day boarding, injection fees as applicable $__________
Possible overnight board and observation $__________
Physical exam recheck prior to second treatment $__________
Immiticide - treatment 2, injection 2 $__________
Day boarding, injection fees as applicable $__________
Possible overnight board and observation $__________
Immiticide - treatment 2, injection 3 $__________
Day boarding, injection fees as applicable $__________
Possible overnight board and observation $__________
Possible pain management $__________
Possible Prednisilone $__________
Plus any additional fees your vet office may have $__________
Total estimate: $__________

Cost of heartworm medication every month? $__________

How many month of heartworm medicines could you buy for the cost of treatment?

Why do we do all those extra things? Heartworm Society helps us again with our summary in ( ):

PREADULTICIDE EVALUATION
The extent of the preadulticide evaluation will vary depending on the clinical status of the patient and the likelihood of coexisting diseases that may affect treatment outcome. (So how the dog looks, feels, acts, and any other health issues that they may have.)

Clinical laboratory data should be collected selectively to complement information obtained from a thorough history, physical examination, antigen test and usually thoracic radiography. (So those are the minimum things - history, exam, HW test, x-rays.)

The most important variables influencing the probability of post-adulticide thromboembolic complications and the outcome of treatment are the extent of concurrent pulmonary vascular disease, the severity of infection and the activity level of the dog. (The things that make it more likely the dog will have clot complications: 1. How much HW or other disease is impacting the blood circulation in the lungs 2. How bad their HW infection is 3. AGAIN [CAPS AGAIN] the activity of the dog AGAIN - please, if you have a HW + dog or a dog going through treatment, keep them quiet)

Assessment of cardiopulmonary status is indispensable for evaluating a patient’s prognosis. Post-adulticide pulmonary thromboembolic complications are most likely to occur in heavily infected dogs already exhibiting clinical and radiographic signs of severe pulmonary arterial vascular obstruction, especially if congestive heart failure is present. (Assessing heart and lungs is huge.)

Although a very crude method of assessing the severity of infection, the strength of ELISA-based antigen test reactions may provide an indication of whether an infection is light or heavy (see Antigen Tests - that's their ( ) but that is a good section in the link above).

Since radiographic signs of advanced pulmonary vascular disease may persist long after an infection has run its course, some of the most severely diseased dogs may have disproportionately low levels of circulating antigen by the time they are tested. Also some inactive dogs can have large worm burdens and be clinically asymptomatic with minimal radiographic changes. (So your vet needs to look at the whole picture - which is why they do all those tests)

Most expensive part of treatment? Anyone want to guess? That's right, the Immiticide.

AKA Melarsomine (made by Merial)

Melarsomine is the drug of choice for the first stage and is effective for killing adult heartworms living in the arteries of the lungs.
Melarsomine is an arsenic-based drug. Although these drugs are known to kill adult heartworms, the exact method of the killing action is unknown.
Melarsomine is a prescription drug and can only be obtained from a veterinarian or by prescription from a veterinarian.
http://www.petplace.com/drug-library/melarsomine-immiticide/page1.aspx

Next time you will meet Mila's personal doctor.

Monday, September 12, 2011

Aftermath of Mila's Second Treatment

---> Immiticide Unavailability <---

Mila flew through the first injection and first part of her treatment, earning her the name "The Mila Monster" from some of her friends on a web forum, because it was hard to control her. Mila is a spirited girl, lively, with great interest in every thing that is going on. She's the kind of dog who would sit on the front porch and gossip about the neighbors with you. She's a regular Gladys Kravitz, for those who remember the old Bewitched series.

Mila had her two injection treatment, as you saw from the photos in a previous post. One injection on a Monday, then home, and back to the vet Tuesday for her second injection.

Monday night, Mila was acting like not much had happened. Tuesday night she was pretty steady and we thought, wow, she is just sailing through this. Then on Wednesday, it hit. The pain and soreness from her injections.

Oh ow, & I look like an unfinished Halloween pumpkin

Sweet Mila is almost 9.5 now and does have some minor ortho issues to begin with. Plus she has had a "Summer of George" here in terms of inactivity, losing some muscle tone. So she was understandably uncomfortable and was given some help with her pain medication.

After a few days, she picked up and started to feel better, upswinging on the weekend. Then Tuesday night, a week after her last injection, she vomited. Twice. This is unusual for Mila who has a pretty sturdy GI system. We called the emergency number for the vet office. She was still wagging, alert, gums good, drinking water (whoops), and with this, the vet we talked to said to bring her in first thing for blood work to check all her levels, in case the toxins of the treatment were impacting her liver and kidneys. She had a nice, firm bowel movement (in our spare time we talk about dog poop a lot) which was reassuring too, and we went back inside, where she promptly vomited all the water I had let her drink.

Wednesday morning at the vet office, Mila's blood work was stellar. Straight down the middle. She did get some fluids anyway. So did we all, since she didn't feel like holding still! She also got some meds to settle her stomach.

Holding still for a second

These worked on Thursday, but by Friday morning she was refusing food again. Mila's a good eater, so off to the vet again. She saw her regular vet, who felt that it was very possible (probable) that the heartworms dying off in Mila's system were making her ill. Mila started on prednisilone. It certainly makes sense.

We think those shots 2 and 3 got some things going. The worms go through veins that aren't meant to have things that size in them. Theoretically because she has no damage to her organs, no symptoms, and was rested as soon as we found out she was +, she should have a light load which lowers her risk. But we guess any adult worms are a danger. Those dreaded clots we've talked about are for real.

They say that it is inevitable during any heartworm treatment to have some little emboli, you just need to stay away from the biggies. Which we hope the pred and keeping her quiet and cool will do. Knock wood.

More on the prednisilone: Administration of diminishing anti-inflammatory doses of glucocorticosteroids helps control clinical signs of pulmonary thromboembolism.
http://www.heartwormsociety.org/veterinary-resources/canine-guidelines.html#10

Prednisilone: Dogs are on prednisone (a steroid) to help reduce inflammation in the lungs and vessels caused by the worms before and after they die. Prednisone also helps reduce the risk of the dog having an acute pulmonary embolism (clot) that can cause sudden death.

http://maplesmallanimalclinic.com/msac_heartworm_treatment.htm

Friday and Saturday, there was some improvement. By Sunday evening however, she was lethargic and not herself again. Monday was Labor Day, but her vet was in for a phone call and he decided to start her on an antibiotic, one that her sister was taking for a UTI. By Tuesday, there was improvement again, and improvement after that too. This upswing seemed steady. Knock wood.

Next time: Specific treatment cost, then waiting for the Mila Monster with Dr. Bruno

Thursday, September 8, 2011

Caval Syndrome Surgical Treatment

---> Immiticide Unavailability <---

We weren't even sure we were going to talk about this part of heartworm disease and treatment, but since it happens, we had better cover it.

First the good news from a study:

The authors therefore conclude that dogs with caval syndrome that undergo a transvenous heartworm extraction successfully and survive to discharge, possess a good long-term prognosis.

So that's a good result. They call it a minimally invasive surgery. Wonder what the definitions are for that - having someone put "basket forceps through the right jugular vein and into the right heart" seems a little more than minimally invasive, but then again, to us having someone take our temperature is pushing it boundary wise!

And since we used the quote from that page, we might as well include some gruesome photos so that you will want to keep reading about caval syndrome and the surgical treatment for it.

http://cardiology.vetmed.lsu.edu/Education/AcquiredCardiacDiseases/HeartwormDisease/tabid/448/Default.aspx

Warning - graphic! Seventy-one worms were removed from this patient's right heart. That's right, 71 worms. I am sure that causes a little hitch in your giddyup.

Are you ready? As someone said, if this stuff doesn't make you think about testing and using heartworm medicines, nothing will.

Here it is...

Okay, I feel a little faint. Restating the graphic warning again.

Those are worms. For crying out loud, you just could never imagine having that in your heart, could you?

So, now that we have all of our attention, and probably all of our stomachs in our throats (and it will go back there if you watch the video at the end of this post), what is caval syndrome? From the AHS with our attempts to interpret in ( ).

(First how it starts) When juvenile heartworms (makes them sound like delinquents, which they totally are) first reach the lungs, the blood pressure forces them into the small pulmonary arteries. As they grow and increase in size, they occupy larger and larger arteries until they become fully mature.

The eventual location of the mature adult worms appears to depend mainly on the size of the dog and the worm burden. A medium-sized dog (e.g., Beagle) with a low worm burden (i.e., 10) usually has worms mainly in the lobar arteries and main pulmonary artery (these are locations we are not familiar with exactly but here is a link to a picture). Oh look! Someone did it with the heartworms included!

As the worm burden increases, worms are also located in the right ventricle. Dogs with more than 40 worms are more likely to have caval syndrome, where most of the worms migrate into the right ventricle, right atrium and the caudal vena cava, thus interfering with valvular function and/or blood flow.

Now this is interesting and we wish we could understand it better, but talk to your vet, those of you with HW+ dogs awaiting treatment because this is potentially important information regarding activity and your dog and caval syndrome. Unfortunately, it's written in cardiologist (link there) and that does not translate in babelfish.

The exact reason or reasons that a large number of heartworms invade the right heart are not completely understood. It has been noted that caval syndrome is most common in dogs with many heartworms. In one study of experimental dogs, one group of dogs with a large worm burden developed caval syndrome while another group with a similar worm burden did not. In this study, the group of dogs that developed caval syndrome had an average mean pulmonary artery pressure of 60 mmHg while the dogs that did not develop caval syndrome had an average mean pulmonary artery pressure of 30 mmHg. Consequently, it appears that a large worm burden and moderate to severe pulmonary hypertension may be precipitating variables. It should be noted, however, that another study has documented caval syndrome in dogs with an average of only 40 worms and as little as 12 worms in one dog (range from 12 to 125 worms). Also, many dogs in this study had a mean pulmonary artery pressure less than 30 mmHg.

How is diagnosed? From the AHS again - oh and if you follow the link, more pictures of caval surgery:

The diagnosis is based on a sudden onset of severe lethargy (click here for what exactly that means - very interesting article) and weakness accompanied by hemoglobinemia and hemoglobinuria (uh, huh...ask your vet). (Merck also says respiratory distress - and good link here for that info) Caval syndrome can be confirmed conclusively by echocardiographic visualization of heartworms within the tricuspid orifice and posterior vena cava (and of course that is also for a vet).

The clinical course usually ends fatally within two days, if surgical extraction of the worms is not pursued promptly.

And we know if it is pursued promptly, there are some good outcomes. As always, talk to your vet about this.

So those are the three types of heartworm treatment. This treatment is a little extreme, but necessary as caval syndrome is almost immediately fatal (as opposed to the slower death of heartworm infection that has moved there) if not treated once signs are seen.

To cap this off, we are going to post an incredible video shared by one of Mila's friends on a German Shepherd forum.

Remember to get your pet tested and get started on heartworm meds if you are not doing so.

Next, a Mila update.

Monday, September 5, 2011

Again?

--->Immiticide Unavailability<---

Mila headed back to the vet for her second and third injections. She was so happy to go somewhere again. Mila tends to get quite excited in the car. Crating and restraining ramps her up more. It is interesting (to us anyway) that Bella, who we imagine may be her sister, has the same car behaviors, though a little less raucous and a little more nervous than Mila's. Bella seems to be imagining going to terrible places where she is the center of attention, whereas Mila seems to be imagining going to wonderful places where she is the center of attention.

So with list in hand, Mila and I headed out. The list just has some information that we state and restate even though we know the vet office knows it already - Mila needs to be kept quiet, the bag with the food in it is her food, please leash walk Mila, as if they would just open the door and let her run wild after her injections. Well, it makes us all feel better, I guess. And the vet office gets treats for putting up with the compulsive herding behaviors of some foster people!

Once there Mila puts on her best "the scale is hot" show, jumping all over while we all tell her she needs to be quiet. We sign off on the paperwork, and the receptionist takes Mila back to the kennels and tries to find her the quietest one for the day.

As you saw in Mila's previous post, she was lucky enough to get some acupuncture treatments before her first injection. We picked her up late in the afternoon, and returned the next morning for injection #2. Or injection #3 if you count the first one a month ago. Mila showed no signs of discomfort after the first injection the previous month, and again with the first one this time.

However, the second (third total) injection was a different story. These injections, deep into the back, can really cause some pain for dogs, and Mila was uncomfortable for a few days after. Going up and down the four deck stairs was difficult, and her hind end was a bit saggy and weakened by the pain (not giving out - which would have been an emergency visit). It actually helped to keep her quiet. However, even with some medications to help with the discomfort, Mila was not feeling so hot. It is difficult to see a very spirited animal struggle as she was.

Once again, we offer these photos, taken by her vet office with our thanks, to remind people that heartworm infection can happen anywhere and that preventing the infection by giving your pet medications that will kill the heartworms before they can become adults, is so much better, easier, cheaper than allowing this to happen to your dog. If you haven't had your dog on heartworm meds, please get them tested and started on them.

All shaved and lining up her final injection

That is one big needle

So lucky that they ordered her Immiticide early


This picture helps to show how deep that needle goes

All the way. Into. Her. Back. Ouch.

These injections, this part of treatment, has been harder on Mila than her first was. Any good thoughts would be appreciated for her. Next time we will talk about the caval syndrome and treatment and then will update on her progress in the post after that.

Thursday, September 1, 2011

The "Slow Kill" Method of Treatment

---> Immiticide Unavailability<---

Pedigree Foundation Write a Post, Help a Dog (this is to help shelter dogs get a donation of dog food)

Back in the day, when Immiticide was available, people would talk about slow kill vs. fast kill. Right now, slow kill is all that we have but hopefully eventually (soon eventually, not eventually like putting a person on Mars eventually) we will once again be able to look at the decision between the two methods.

This is from an article by By Lorie Huston, DVM: There are a lot of misconceptions about heartworm treatment in dogs. One of the most common misconceptions is that using ivermectin-based heartworm preventive medications for a "slow kill" is the preferred way to treat canine heartworm disease.

People think slow kill is preferred. But it's not. As our 9th grade Spanish teacher used to say, "Repita, por favor." Slow kill is not the recommended method of treating heartworm disease.

Obviously, the American Heartworm Society has its recommendation, that we follow, of doing the fast kill with one injection, a month of cool inactivity, and then two more injections a day apart, and another month of cool inactivity.

We do typically give the dog Ivermectin based heartworm meds under the direction of a veterinarian for a few months prior to starting the fast kill though.

But this quote from information at Dog Aware is something that needs to be stressed - the only choice we do not have is not to treat.

Whether you elect to do the fast-kill method using Immiticide, or the slow-kill method using monthly Heartgard, either is preferable to leaving the dog untreated, or using unproven, alternative methods that may have no effect or even be harmful.

If someone is not able to work out payment plans at their vets, tries some of the great fundraising ideas on this website: http://www.imom.org/fa/pdf/fundraising.pdf and doesn't get anywhere, or if the health of their dog, as determined in consultation with their vet, could not handle the recommended method (1 shot 1 month, 2 shots the following month 1 day apart with 2 months of cool inactivity) then it is much better to do something to treat, then nothing at all. Without a doubt.

What is slow kill?

Monthly administration of ivermectin-based heartworm preventive medications alone are sometimes used as a second method of heartworm treatment. This is referred to as the "slow kill" or "soft kill" method.

How long does it take?

Slow kill can take 18-24 months. Yowza. That's a long time for a dog to be inactive. Oh, yes, the dog needs to be inactive during that time. Quiet in the house, crated if they can't be quiet, and leash walked for potties only. You know why. Yes, clots. (cha-ching - where is my clot reimbursement check? what? clots don't have money? there goes my blog paycheck!) Why else? Because the more active the dog, the sicker they get. Even if they have less worms. That's in the immiticide unavailability link at the top of this post if you need to review.

What happens to the dog in those 18-24 months?

From Dog Aware again: Although heartworm treatment can be dangerous, so are the heartworms themselves. Adult heartworms are large, growing up to 12 inches in length and living as long as five years. They can plug up the pulmonary arteries, and when the infestation becomes severe, they will start to back up into the heart and eventually fill it. They can cause blood clots, and force the heart to work abnormally hard to pump blood through the clogged arteries. In addition, heartworms cause an extreme inflammatory response in the arteries that can affect other parts of the body, especially the kidneys and liver.

So basically damage to their heart, lungs, liver and kidneys. That's never good.

What are the disadvantages of the slow kill method?

Bottom line, only Immiticide kills the adult worms, and the adult worms are the ones that do the big damage.
From the AHS on About.com

The adult heartworm is responsible for the damage to heart and lungs that causes the symptoms of heartworm disease in dogs.

Melarsomine (alias Immiticide) is the only medication we have available that can kill these adult worms. Ivermectin kills the larval stages but not the adult worms. It also does not shorten their lifespan or render them sterile.

With time, as long the larval stages do not survive and no new infections occur, the adult heartworms will die of "natural causes." However, this may take as long as two years to occur.

As long as there are adult heartworms living in the heart and pulmonary arteries, the damage to these organs will continue. That means that while your dog is receiving only the monthly ivermectin medication, his heartworm disease will continue to progress and his heart and lungs can suffer severe damage.

Another reason that monthly ivermectin treatment is not recommended for heartworm-infected dogs is that some parasitologists believe that the "slow kill" method has contributed to the development of strains of heartworms that are resistant to heartworm preventive medications. (Dr. Byron Blagburn, webinar, Emerging Issues in Heartworm Prevention, presented by DVM360, 4/20/2011)

Another list from the VIN about what Ivermectin based meds do and do not do:

Ivermectin Only
This option has led to a great deal of misconception about the ability of ivermectin to kill adult heartworms. Let us lay the rumors to rest now:

Ivermectin does not kill adult heartworms.

Ivermectin does shorten the lifespan of adult heartworms.

Ivermectin does sterilize adult heartworms.

Ivermectin does kill microfilaria (keeping the dog from being a source of contagion)

Ivermectin does kill L3 and L4 larvae (preventing new infections).

This means that if you opt to treat a heartworm positive dog with an ivermectin-based heartworm preventive only, you can expect the dog to remain heartworm positive for as long as two years and the heartworm disease will be progressing during those two years. This is not good for the dog but certainly beats getting no treatment of any kind.

BUT, big giant but, if you and your vets determine it is safest and best to do slow kill then that you and your vet do what is best for your dog. This blog is just information from other sites, collecting and explaining their recommendations in words we can understand better, but it is not a substitute for individualized treatment plans, which is why we always say, talk to your vet. You now have a lot of information about the two most common types of treatment so that you can talk to your vet about both and know why the AHS and veterinary college hospitals all recommend the 3 injection fast kill method.

You'll probably notice that we keep saying Ivermectin based medicine (one example is Heartgard). We are not saying straight Ivermectin. We know that everyone knows someone who uses straight Ivermectin that they get from the farm supply, but that's not what we are referring to. We are talking about the meds you get from your vet and talk to your vet about.

We are also not referring to other heartworm medicines. Here's some good information as to why - some just aren't that into heartworms: http://www.marvistavet.com/html/body_heartworm_prevention.html

And here - oh my: If Interceptor (milbemycin oxime) at normal doses, or Heartgard at high doses, is used to kill microfilariae following heartworm treatment, anaphylactic shock can occur, especially in dogs with high microfilariae counts.

This website: http://www.2ndchance.info/heartworm.htmwas nice enough to explain this study: http://www.2ndchance.info/heartworm-ivermectinstudy.pdf which talks about adding Doxycycline to the Ivermectin based heartworm medicine. That is also recommended in the link at the top of the page.

Once again, the one thing we can not do - is nothing. While fast kill is generally the recommended method, if it is a choice between slow kill and nothing at all - your dog will benefit from treatment under a vet's supervision.

Next: Mila's second treatment

Big Dogs, Big Heartworm