Some of you may have personal experience with the once-popular canine heartworm preventative, ProHeart 6. It was marketed from June 2001 to September 2004, until the FDA recalled it after thousands of adverse reaction reports crossed its desks. And now, almost four years later, it's making a comeback (that's the plan, anyway).
According to the FDA, 5,552 ProHeart 6 reactions were reported after dogs received this every-six-month injection. 500 dogs died, though definitive causality in these deaths was not established.
Fort Dodge, the manufacturer, claims a total of 18 million doses were sold during this period, implying that the risk of reaction is one per every 3,242 injections.
I saw two of them. One was not terrible, just some mild muscle pain and a low-grade fever for two days. The other was comparably horrendous, LOTS of pain and a high fever for three to four days. Fluids and pain relievers treated both cases successfully. I’m not so sure we reported the first reaction (it was so mild and he wasn’t my patient) but I’m sure we reported the second one.
The generic name for ProHeart 6 is moxidectin. Fort Dodge stands by it. It’s been used in Europe and Australia for over a decade with relatively few complaints. The Aussies even use it in its ProHeart 12 form as a once-a-year heartworm preventative. Beats heartworms, they say.
Here in the US, about 250,000 of our dogs are infected with heartworms every year. That’s in spite of the widespread use of heartworm preventatives.
Why? Because some of us refuse to seek preventative medical attention for our pets. And the rest of us who manage a heartworm-positive status for our pooches? We simply forget to give the meds as prescribed.
Fort Dodge says it seeks to cut into the latter group’s prevalence with an every-six-month approach. And it’s true, client noncompliance is probably the biggest source of heartworm disease in this country these days.
Some vets like it, too, since it requires that owners come in and see the vet twice yearly (though most of us don’t charge for an exam at the same time).
But I’m largely unmoved. My position with respect to ProHeart 6 stands: The drug has its place. But it’s a very limited one in my practice.
Why?
1-Noncompliance is a major source of heartworm disease but by far the largest subset of this group includes those who refuse any preventatives at all.
2-Noncompliance in my area (where year-round heartworm meds are a must) means owners don’t come back in a timely fashion for their ProHeart 6 shot. (That’s what happened when we carried it, despite our reminders.)
3-The risk/reward axis is mighty high with ProHeart 6 relative to alternative means of heartworm prevention.
Then why would any vet use ProHeart 6?
Plenty won't. Yet despite my reservations, I likely will. That’s because some of my clients will swear there’s no other way they’ll consider using heartworm preventatives (yes, I swear I have clients like this). And, remember, I live in Florida.
Fort Dodge is making sure any of us who plan to use this product at least understand their basic rules. Veterinarians can only access ProHeart 6 through a limited distribution approach. An online seminar must be completed before a veterinarian can place an order.
And that makes sense to me. Though I seriously doubt that any reactions were caused by veterinarians administering an injection incorrectly, as the company infers may have been the case in the past, setting a bar (even a low one like this) helps ensure we vets know what we’re in for when we use it.
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Has Fort Dodge ever come out with an explanation for what exactly killed all the dogs with the "old" Proheart6 and how the "new" Proheart6 has been corrected for whatever that was?
YesBiscuit! June 16th, 2008 02:50:00 PM
Their statements have been very measured on this point. In the AP piece I cited, Fort Dodge has “concerns about how the [FDA] interpreted these complex data...Based on a thorough evaluation of FDA’s data and consultation with independent experts in veterinary medicine and epidemiology, Fort Dodge Animal Health stands behind ProHeart 6.”
In other words, they don't buy the severity and/or number of the reactions. They believe their significance was overblown by the FDA.
Dr. Patty Khuly June 16th, 2008 03:12:00 PM
Oops, sorry, I see I didn't exactly address your question properly. It's the same drug. Is its injectable base different? I don't think so but anyone else can correct me if I'm wrong. The only difference, from my understanding, is that the distribution will be limited to veterinarians who will be provided with explicit guidelines as to its use.
Dr. Patty Khuly June 16th, 2008 03:18:00 PM
If it's the same drug that killed so many dogs before, I won't be signing up.
Fort Dodge seems to think that by limiting its first-run to only "the best and the brightest" of dogs, consumers will be fooled into believing the product is safe if/when minimal reactions are reported. Savvy consumers know that for a drug to be "safe", it needs to work for MOST dogs in MOST conditions - not just the healthiest select few.
YesBiscuit! June 16th, 2008 03:27:00 PM
From what I understand Proheart 6 is being released with restrictions placed on it by the FDA. It can't be administered within a month of any vaccines, pre-admin blood work has to be pulled (but not reviewed), it can only be given to animals 6 month to 7 years of age, can only be given to healthy animals (no chronic disease), and should be used with caution in animals with allergic disease. The client is expected to foot the bill on the pre-admin CBC and chemistry (to be done before each dosing).
Fort Dodge is offering a temporary discount, something along the lines of 10%- that will not cover the separate office call required to give PH6 (seeing as it can't be given with vaccines), nor will it cover the blood work.
This is a trial phase as part of the FDA testing, of sorts- If I were the person in charge of ordering (still have a few years left of school) I can't see this as being a great product. FD is placing a lot of the cost of drug testing on the client (or at least it seems that way). They made minor alterations to the adjuvent of the formulation but the drug is essentially the same.
It is used in Australia with significantly less bad press than it had in the states. I'd be inclined to sit back and wait a few years and see what happens. But after reading a bit about what happened to the FDA vet who first revealed there may be a problem with PH6, I'm also inclined to read a bit more and become a more informed consumer before picking suppliers once I get into practice. My boss is going to love it!
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bella w June 16th, 2008 08:02:00 PM
I wouldn't use Prohart 6 and will not recommend it to my adoptors.
Frankly, there is a much better solution for preventing HW disease - which would be to make monthly hw pills available over the counter. The precaution of testing dogs for hw before using monthly preventive has pretty much been proven unnecessary, I believe. In fact, some vets now treat hw positive dogs with HeartGard or a generic formula. And the dosage in these monthly pills is so minor that most collies can even tolerate it - and a label warning about sensitive breeds would solve that problem.
I've been told that monthly hw pills are available over the counter in other countries.
I think a lot more people would use the monthly preventive if they could get it OTC without having to pay for a vet visit.
Mary June 17th, 2008 01:12:00 PM
let's make a comparison:
10kg dog (22lbs)
Heartgard at 6 monthly doses of 68mcg ivermectin would be 408mcg total ivermectin
Proheart injection at rec dose of 0.5ml would be 1700mcg moxidectin
Moxidectin is reportedly more active due to it's pharmcokinetics:
http://www.ncbi.nlm.nih.gov/pubmed/17847063?ordina...
Then again, the injection vehicle has some interesting compounds. Perhaps
this is responsible for a lot of the allergic type reactions, where none of the
typical avermectin overdosage symptoms are experienced.
It would be interesting to know, because moxidectin has potential for the treatment
and prevention of mites.
eli June 19th, 2008 12:23:00 AM
Heartworm preventative for a large dog costs at least 50% more than for a
small dog, yet the production expense for the pharmaceutical company is only
increased by a few cents.
Why? Pharmaceutical companies have done their market research. They know
that large dog owners are usually willing to pay more, and vets expect to make a
little more off a large dog client. It's kind of ridiculous, but it works.
As a matter of fact, the preventatives could be priced at three or four dollars
for a years supply and still be profitable, but they aren't. Covering less animals
maximizes profit. That is not necessarily a bad thing.
eli June 19th, 2008 01:06:00 AM
eli: Good point on the price of doses. That's true for Heartgard and Interceptor but some drugs have less steep pricepoints, sizewise (Revolution, for example). Revolution makes up for it by charging a zillion for the kitty doses (which is nonetheless still less than the dose-per-dose price of Advantage or Frontline). I KNOW you're right on their strategic marketing approach. Revolution is most popular in cats, that's their leading parisiticide, in fact. The dogs are just gravy, since other HW preventatives have consistently outperformed them. Hence the pricepoint/size skew. In the case of Heartgard, et al, dogs are their bread and butter. Again, therein lies the strategy for pricing.
Honestly, I see nothing nefarious about this. If I ran a drug company I'd do the same. It's not dishonest or unfair. Neither is it dishonest or unfair for me to buy the big dog sizes of the flea drugs and split the doses to keep my outdoor strays flea-free.
As far as profitability goes, i'm not sure that the Heartgard brand would be profitable if the product was priced as you suggest. Too much has gone into their marketing over the years. Sure, they've got a cash cow on ther hands and it's true they might save more dogs if they priced the product more affordably, but IMHO, they've earned their right to do so by leading the market so far in advance of their competitors.
Dr. Patty Khuly June 20th, 2008 09:02:00 AM
I do the same with my Frontline. Two extra-large doses can be split to provide flea protection to my 2 large dogs and 3 cats. But most vets don't tell you this unless you specifically ask about it.
Shellie June 20th, 2008 11:24:00 AM
Dr. Khuly,
You are right. The profitability of the market seems to keep the companies
on their feet with newer and better products. In the long run, this means
we get more safety and efficacy per dollar spent. Had the profitability not
been there, we might be stuck with narrower spectrum products. In which
case you just end up buying more products and/or tests to cover the bases.
eli June 21st, 2008 04:19:00 AM
Speaking of Revolution, are than any other options for heartworm preventative in cats? Also, how prevalent is heartworm in cats? When I talked to my vet about preventative for my cat last year he said he'd never heard of a feline heartworm case locally (WV). He generally doesn't recommend a preventative for cats because the infection is less prevalent in cats and its a low risk region even for dogs (true). However when I asked to have my cat tested for heartworm with his other labs they had to send it out and acted like it was a weird request. If they test that infrequently how would they know the prevalence? Of course about six months ago another vet in the area sent out "What you don't know could hurt your cat" postcards promoting Revolution. I've read lots of great articles/studies about heartworm in dogs but haven't found much info for cats.
Thanks!
Shannon Watts June 22nd, 2008 07:04:00 PM
I live in Australia and one month ago decided to use proheart inj. as a heart worm preventative for my 9 year old Newfoundland. In Australia the injection is given yearly. I was told that it is safe and as I have a busy life I thought this would be a great way to ensure my boy was protected. I asked the vet if he needed to be tested for heart worm prior to the proheart and she said no because the injection would be safe for him even if he had an adult infestation. I had previously used heartguard and proheart oral tablets but given that my boy weighs nearly 70kg they were very expensive.
The injection was given a month ago and just this weekend my boy was admitted to a vet hospital with an unknown illness that caused him to have weakened back legs for a brief time, a severe bout of bright yellow diarrhoea and shortness of breath particularly after some sort of exercise and movement. The diarrhoea was put down to a bacterial bug, the weakness in his legs was attributed to the pain in his tummy and the shortness of breath was also attributed to the pain. He was found to have spinal arthritis whilst in the hospital and is being treated both with conventional and unconventional arthritis treatments for this.
He has been discharged now and all the symptoms seem to be easing although the shortness of breath continues along with very mild weakness in his rear. I was looking on the net as I became suspicious when I wondered about the timing of his breathlessness in proximity to the administration of the injection of proheart. I had noticed that he had become more breathless recently and puffed after exercise like it was a hot day and it seems to have occurred since the proheart was given. He has had his heart checked and it seems to be fine, or at least none of the many vets that have examined him recently have said otherwise. I am going to go and ring one of the vets I use who deals with natural therapies as well as conventional medicine as I am now very concerned about what I have read. There has been no negative press about the proheart here in Australia. In fact it is quickly becoming the preventative of choice as heart worm is so prolific here.
Kerry.
Kerry September 24th, 2008 09:38:00 PM
The real perspective is that 250,000 dogs were diagnosed with heartworm in 2005, yet it's estimated that 27 million dogs out of the 75 million in the U.S. do not recieve regular heartworm medication.
Heartworm is self-limiting and seasonal in most areas of the U.S. Very few dogs get it, and very few need year-round monthly dosing for a disease that is ONLY spread thru mosquitoes and requires temperatures of over 57F for 2 or more weeks straight to even get to the life stage where it's transmissable to dogs. Even the American Heartworm Society admits that the only reason owners should give it monthly year round is because it's so 'complicated' to figure out when mosquito season starts and ends in their area, and they might 'forget'. No offence, but I find that view rather condescending and insulting.
Pai March 3rd, 2009 10:07:30 PM
What I know about ProHeart6 is tht 6 wees after his injection, my just turned 4 year old golden retriever was dead of autoimmune hemolytic anemia and 1. my vet said on day of diagnosis/medical chck, etc that when it came time for his next proheart injectionm we were going back to the monthly pills. He knew it was the ProHeart6 that caused it, the only thing different in Hunter's life the previous two full monhs, Hunter who had never been sick a day in his life 2. Reseach after his death showed me that AIHA was one of the reaction listed on the SECOND warning label change. Ironically, DEATH was isted on the 3rd change, the one made the day he got his fatal injection. 3. thru the web, forums, stories, I found or was found by about 45 others who had dogs come down with AIHA shortly after recieving ProHeart6 and at that time only 2 were still alive 4.It was touted as being so safe when out the first time They were denying it ws causing the reactions and deaths. Yet now, it is "reformulated. Why, if it was so perfectl safe the irst time. They know it was klloing our dogs. 5. When the CVA meeting was held on Jan. 31 2005 to try to get it back, Fort Dodge brought up who so few reactions/deaths were reported in Austalia and they wereasked if suspected reactions were investigated the same down there and the answer was yes. WRONG. According to severl Aussie that came to American health forums, etc looking for answers, down there they report to the proper government agency who then TURNS THE CASE OVER TO FORT DODGE TO IONVESTIGATE TO SEE IF THEIR PRODUCT CAUSED THE RECTION/DEATH. Isn't that rather like letting the fox investigate the hen house riad Do you think for one second they are going so say their product is at fault and lose out on money? Here the FDA investigate and decides if a product is at fault. 6. Monthly pills are actually more of a dewormer and get rid of any baby worms picked up in the preious month. It is only in theirsysterm about 36 hours. Proheart6 is in for at least 6, maybe 8 months. Once in, trouble developes, it can not be removed. That is just to dang risky to me. No dog of mine will ever again be injected with ProHert6.
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