Question

juliemule

The main reason to test:    To prevent spreading the disease. Yes, I know prevention is SUPPOSED to 'prevent' that, but I know first hand it does not always work!

Historically vets have maintained that the main reason to "test" was in order to GIVE the preventive (because giving a dose strong enough to kill all microfilaria and potentially kill some adult heartworm can cause the dog's system to shut down from debris in the blood and it can kill).  It should *be* to prevent the spread of the disease.  

But that's MY main problem with people doing the "slow treatment" imrproperly and only giving it once a month -- there's never been any documented proof that *I* have seen that says you will **for sure** get a clear occult in a year just giving a monthly dose of preventive and my fear is that it's contributed to the new wave of heartworm who are "resistant" to ivermectin.  In my humble opinion (sorry -- I know that's a stretch) it's never been the sane way to do it because it leaves a dog out there 29 or 30 days of the month who IS certificably heartworm positive who can spread the disease (at least until the adult heartworm respond enough to become sterile)

All the word "prevention" in heartworm prevention means is that it prevents the life cycle of any microfilaria in the body at that time from reaching maturity so they can reproduce.  But if the dog gets bitten by a mosquito tomorrow (after "prevention";) the dog is once again viable to transmit heartworm.  Or, if the dog is already known to be positive -- ivermectin only stays in the body 24 hours.  That's all.  The whole word "prevention" has always been pretty much a misnomer for what it was actually supposed to do.

Unfortunately once again (sorry private soapbox) corporate greed has caused more problems.  Because instead of only marketing to the breeds known to be "ok" with ivermectin, they instead made the dose SO small that it was not effective and once again vets were taught to base part of their practice on "annual testing" rather than educating owners in proper treatment that they CAN afford. 

Everyone has been led to believe that the chewable tablets were so superior because they were "easy" and less messy and no measuring ... and instead they were a marketing marvel and dogs are now payin the price.  It's unfortunate that this discussion even needs to take place.

Sorry -- off my soapbox now -- but I agree totally with Gina.  I just come at it from a different perspective -- it's neither logical nor helpful.

Giving a "preventative" to a dog with a failing liver would be very questionable.  A "preventative" is not a medicine.  It is a pesticide. 

However, I would DEFINITELY test (just the cheaper microfilaria test if no "preventative" is being given).  Any dog with microfilaria in its blood can spread heartworms to the mosquitoes in the area.  That makes dogs in the surrounding area more likely to get heartworms if they are not on a "preventative" (or the owner is late with a dose).

A failing dog with microfilaria means that greater than normal steps need to be taken to keep the dog away from mosquitoes.  However, another dog in the family who is on a "preventative" would not be at risk from the failing dog.

The rescue in question is using a "black & white" set of rules without regard for the fact that we live in a "gray" world.  They "require heartworm tests", but should "require heartworm tests unless there is a medical reason that prevents treatment for heartworms".  Other medical care factors should be used by the rescue to assure themselves that a "preventative" and yearly tests would be given to the newly adopted, healthy dog. 

A letter from the vet who is caring for the failing dog should be adequate for the rescue's needs.  If not, one should find a more reasonable rescue. 

ASIDE:  Sometimes it takes a lot of patience to deal with the people in this world that really need "black & white" rules in order to function.  However, I try to remember that those folks get very frustrated (and confused?) when dealing with a "gray" world.  I feel a little sorry for some of them. 

I once met a woman who maintained that one had to call God "God" in order to go to heaven.  When I asked if she meant that one had to speak English to go to heaven, she became rather confused.  This individual really had problems!! 

janet_rose

However, another dog in the family who is on a "preventative" would not be at risk from the failing dog.

All of my dogs have ALWAYS been on prevention, and three are now positive. One that was adopted from the humane society, was tested, then I had her tested, BOTH  times showed negative, ahe has not missed one dose, or been late, and she is now positive.

I worked as a vet tech for 10 years, I understand quite a bit about HW, the medication and treatment. YES they are at risk when the medication is not working- the vet is not sure if it is resistance, yet even interceptor has some positive cases in this area, three county wide so far. I live in TN, near wetlands. We have TONS of mosquitos. Lots of dogs that are strays and lots not on any type of prevention. Mine were, are, and always have been.

 Heartgard and triheart claim to also have a one week "grace" period. My dogs get this medication on the first, sometimes even earlier due to my work schedule.

juliemule, as you know from your vet tech experience, many clients don't give meds properly.  Many cases of "failure" of a product or medication are a failure to administer properly.  I'm not saying you didn't properly dose your dogs. I'm sure there are instances when a product is not effective and resistance can occur. 

 I'm just not convinced that all or even most failures are resistance issues or even product failures.  I've talked to too many people who are hit and miss with all kinds of meds (even their own) and don't seem to grasp the importance of proper dosing and administration.   Dogs sometimes throw up medications and this can go unobserved.  Products can be stored at improper temperatures in warehouses and there are products from shady sources that may not be what they should be. 

janet_rose

However, another dog in the family who is on a "preventative" would not be at risk from the failing dog.

juliemule

All of my dogs have ALWAYS been on prevention, and three are now positive. One that was adopted from the humane society, was tested, then I had her tested, BOTH  times showed negative, ahe has not missed one dose, or been late, and she is now positive.

I should have said "who is on Interceptor would be at very little additional risk from the failing dog".  One HW positive dog is just not going to make that much difference at all when there are lots of infected mosquitoes in the area.  If a "preventative" is not working (or a young heartworm just doesn't get a sufficient dose), a "preventative" can fail to kill it. 

Heartgard's dosage is so low (so that dogs with the MDR1 gene can take it) that they have a lot of nerve claiming to be effective let alone claiming any kind of "grace" period.  Every 30-days gives two chances to kill a young heartworm and I want that extra chance to kill a young heartworm that was in an area of low blood flow and survived the first time around.  After about 45-days a young heartworm is too old for a "preventative" to kill it. 

It was my impression that Interceptor had an extremely low failure rate if given appropriately.  That means making very sure that the dog does not spit it out.

NOTE:  It is easy to test negative for heartworms, but still have them.  During the 6-7 months it takes for a dog with just young heartworms (injected by mosquitoes) to develop adult heartworms, it will not test positive for microfilaria (baby heartworms) or for adult females (antigen test) and those are the only two tests available.  It even takes several (6-7?) mature adult females to produce enough antigen for a positive antigen test.  There is no test for adult male heartworms.

I could understand one maybe being positive. Not all three. Talking with the vet here, several of the clients that had positive tests are pretty reliable. Not that a dose can't be missed, but for so many in such a short time to test positive, is not likely to be client related. Had it not been my own dogs I could see your point of view. The vets here actually don't know what to do for prevention now.

The intercepter cases are much lower than heartgard and triheart. They recommended advantage multi, we switched, had fleas after 2 months, and our small dog had a burn on her shoulder blades. This had been a major ordeal, and very costly at that!

I don't know what to think, but I do know that with my dogs the medication was given correctly. Maddie will try to spit out everything, so with her I am very careful to poke it down, and watch her close. I am now giving ivermectin injectable, as I think it was product failure rather than resistance. Until I know for sure I don't know what to give. My whole point here, just because the prevent "should" prevent it doesn't always. If I were to adopt a dog, I would want to know for sure that it is HW free, as well as the dogs at home.

Sorry if I am ranting, I have just been so frustrated that any of them were positive. My oldest mal is on lasix and doxycycline daily and is in bad shape. He has actually coughed up blood. Between the treatments, tests, and what to do about prevention I am ready to scream!

juliemule

Had it not been my own dogs I could see your point of view. The vets here actually don't know what to do for prevention now.

I am so sorry you are having to deal with this!!  How many heartworms (small number, large number, bad infestation?) does your vet think that each dog has?

Do keep in mind that dogs can gradually accumulate adult female heartworms and not test positive on the antigen test until there are enough to produce a sufficient quantity of antigen.  In that same time period the dog can accumulate any number of male heartworms. 

I don't know that this is true, but if the males are more resistant to the "preventative" than the females, one could wind up with a large population of males before there are enough adult females for a positive test. 

juliemule

I am now giving ivermectin injectable, as I think it was product failure rather than resistance.

With Heartgard I would not be at all surprised if this were true!

juliemule

If I were to adopt a dog, I would want to know for sure that it is HW free, as well as the dogs at home.

With a large number of infected mosquitoes in the area, it really isn't going to make much difference if a local dog is HW positive.  The effectiveness of the "preventative" is going to be the deciding factor in whether a dog gets heartworms. 

Unfortunately, one has to wait 6-7 months after a negative test and starting a dog on a "preventative" before one can be relatively sure that a dog does not have a serious number of heartworms.  A test at that time would determine if there were growing young heartworms at the time of the first test.  Most rescues don't (can't?) wait that long before trying to place a dog. 

One can never be sure that a dog is completely heartworm free - unless you have just done a heartworm treatment to kill adult heartworms.  The best you can say is that there are not a detectable number of baby heartworms and that there are no more than about 5 adult females. 

Emma was not on heartworm preventative, and I was turned down by a rescue because of that. It really bugged me, and I decided against adopting from a rescue, at that point. I am a VERY responsible pet owner, and did what was best for her. Heartworms don't matter, much, if you die of status seizure, so she never took it. She was tested, twice a year, not because I would have treated her, but because I felt the need to know EVERYTHING possible about her health. I used mosquito repellants (natural, of course, and had to pick and choose carefully) on her, and kept her in when they were worse. I worried about it, constantly. I even tried again, several times, with dire results.

It's ridiculous to rule out a fantastic home because a dog doesn't tolerate something. Some dogs are not your average, every day dog. They don't tolerate certain foods, certain drugs, or being handled in certain ways. We adjust.