Friday, June 8, 2012

IDEXX Don't Know...

This post isn't going to focus on horses, but horse owners out there would probably benefit from the knowledge anyway...

Most people have heard my past rants regarding veterinary diagnostics. Sometimes good, sometimes not so good.

This is a "Not so good" story...


I took my 5 year old dog to the vet clinic yesterday for a routine heartworm test and to pick up this year's heartworm pills. Our climate is such that we don't use preventative medicine for vector-born diseases in the winter, since all creatures, intelligent or otherwise, hide during the deep freezes.

The wonderful "dog tick"... spreader of disease everywhere...

Technology is ever increasing, and there's a current uproar regarding Lyme disease in Canada. Testing concerns, confirmations, new areas becoming endemic and of course, where there's concern in the human population, the concern quickly spills over into our pets. No surprise then that IDEXX came out with a new SNAP test that goes beyond Heartworm. It includes Lyme and a bacteria known as Anaplasmosis.

My veterinary clinic took my dog into the back room, drew some blood (she's an awesome sport) and then brought her back to me. I waited. And waited. Some 5-8 minutes later the technician returned and flashed the little SNAP ELISA test at me. "All negative. Halo's clean," the tech says, promptly going about entering the data in the computer and making up my bill.

I pay and head home. Visit a friend for the evening and the BF calls to tell me that the vet called concerned because Halo tested +ve for Anaplasmosis.

Of course, like all pet lovers, my heart stopped. Anaplasmosis...I knew it was a tick-host disease, I knew she'd been in contact with plenty of ticks, and I knew that if it was like Lyme disease, treatable but dangerous if not stopped early on.

But despite all of this, one thing kept reverberating around my head. Why could I SWEAR I only saw ONE dot on the SNAP test when the tech brought it out to show me?? One dot is the +ve control and tells you that the test is functioning.

Your "typical" SNAP ELISA Test.

Did I just not notice? I hadn't done a SNAP test in years now, but remembered it being straightforward and easy back in my highschool days when I spent a month doing an internship at a local clinic. RIGHT in the middle of heartworm testing season : P That was a LOT of SNAP tests for one lowly summer student.

My dog seemed generally healthy (if a touch fat) and certainly not sick. She had a couple bouts of vomit in the last month, but that's not atypical for her. I had also run her on the treadmill when we got home (unaware she was "sick") and thought I saw something off in her gait and almost hyper extension of her left hind leg when trotting on the treadmill...Was it real?

And what to do?!


Well of course the first thing I did was send an email over to ex-vet tech friend H, asking her thoughts on this. Then I settled into the literature. I love literature...All while the BF made it clear we'll do whatever is necessary to make our sweet dog healthy again. Price is no option.

In a matter of minutes, I'd tracked down a paper from a neighbouring province on 3 infected dogs, with a colleague listed as one of the authors. I found an American university that had anaplasmosis specialists, and far more experience in these things then we have up here where it's not endemic. I found a number of publications by Canadian, American and Swiss vets regarding diagnosis and treatment of anaplasmosis.

I also tracked down the IDEXX test insert and FAQ.

H's email arrived in the early morning, backed by some veterinary guidance suggesting a do-over of the test. Experience is that the test must be read within that 8 minute mark. And that the whole scenario is a little a-typical, despite the fact that our dog could very well have the bacterium.


So I spoke with the vet this morning and was less then impressed by the responses I was receiving. He had zero idea of how long after the initial inoculation of the SNAP test that he read it. He said 14 days of doxyciclin as treatment, along with a CBC/Chem/Urinalysis/PCR...every diagnostic test in the books. He informed me that he called so late in the evening because there's very little experience with the bacterium here, so he needed to do some research.

He also promised to give IDEXX a call to see what their lab experts suggested.


While he was off doing that, I gave IDEXX a call. No surprise, they refused to speak to me about test specifics, since I was a "lay person". Instead they directed me back to the same FAQ I had found earlier that morning.

1. What is the read time for the SNAP 4Dx Test and is it really important?
The test result must be read eight minutes after the device is snapped. The test does not contain stop solution, and after eight minutes, color development may occur that is not related to the sample. Do not report results read after eight minutes.

The FAQ made me even more certain that I'm looking at a false +ve, or at the very least, I desperately need a retest.

As I often say, those that know me, know I hardly sit back and wait for information to come to me. Instead, I tracked down an expert at a Veterinary University and shot him a quick email. I mean, the worst that could happen is that he also tells me that he doesn't speak with "lay people".

Wasn't I pleased to find an email response almost immediately...

Dear Sandra,

Your case is quite interesting. Thanks for your message! :)
I am seated at the dentist's chair, so I will be brief.

Most likely the Snap test was sitting too long after deployed. This test is very time sensitive, therefore it should be read at exactly 8 min after started. Faint dots may show up after the 8th minute mark and they generally are false positive.

My recommendation for your dog would be repeating the Snap 4Dx test and read the results only at the 8th minute, than discart the kit.

Got to go. Please keep me posted. :)


Interesting, right?


So eventually a vet tech from my clinic calls back to discuss my "options" for treatment. And instead, I ask to speak with the vet.

We have a good conversation where I manage to corner him into agreeing that his reading of the SNAP test left us with a high likelihood of a false +ve. He debated that it didn't need to be read within 8 minutes until I explained what IDEXX was saying on their site. I made it clear I'd like my dog retested before going ahead with $400 in diagnostics, plus doxycyline according to a human physician I work with, is a very toxic and dangerous drug used in humans only on severe cases. Certainly not on an asymptomatic, otherwise healthy young dog with a questionable ELISA test.

The Vet concedes to a possible need for a retest and says he'll call IDEXX back to discuss read times. Of course, when I asked him if he told the IDEXX rep that he read the test at some unknown time interval after the initial reading, he said "no". Pardon me while I control my urge to beat my head on my desk.


I'm still awaiting my call back.

Who doesn't love a good blood smear?!

I suspect if he outright refuses to retest my dog (which if he does, I'll be watching every step from the blood collection to the SNAP inoculation, all with a stop watch on), that I'll take my dog to a more reputable vet for retesting. More for my piece of mind anyway.

The thing most folk aren't aware of, is that the IDEXX snap test in this case is not indicative of an active infection. It simply states whether the animal at some point, current or past, was exposed to the bacteria. Many dogs will have life-long +ve test results, even if they have cleared the infection from their system. That's why the SNAP test is for screening purposes. Not all dogs require treatment either. Much like Lyme disease, we *can* become infected and fight it off with our own immune system. But like all diseases, sometimes that doesn't happen and the disease progresses to a more severe form. Since my dog has never been tested using a 4DX test in the past (always just plain ol'heartworm), I have no way of knowing if she's had this antibody to Anaplasmosis for most of her life. This IS a dog that has had frequent tick exposure her whole life. Not sure if it can be transferred congenitally, but if there's possible...

Never mind that IDEXX doesn't recommend treatment in healthy dogs...

1. Should subclinical (no clinical signs) dogs that test positive for A. phagocytophilum on the SNAP 4Dx Test be treated with antibiotics?

At this time, there is no agreement about whether or not subclinical dogs should be treated with antibiotics. Some veterinarians may choose to treat positive dogs that are not exhibiting clinical signs, while other veterinarians may choose to monitor these dogs.
Until more data is available, treatment is not recommended in dogs that are clinically and hematologically normal.

The research also indicates 30 days of antibiotic treatment, and surprise, the vet later calls back to change his initial treatment plan. It's never a good thing when a patient is two steps ahead of the veterinarian. I don't believe in online "hype", random postings or "Yahoo Questions", but I can assure you that I'm a big believer in published journal articles in places like Journal of Veterinary Animal Sciences, or our own National Treatment guidelines developed by an expert panel of 6 Canadian Veterinary Pathologists and 2 GPs. Just last semester I spent 2 weeks evaluated peer reviewed publications for judging bias and confounders. I'm not standing out in left field going "This is what I want to hear!" or "The Internet told me so!"


Here's the thing folks.

It's up to US to make decisions when it comes to our pets health care. Yes, we rely on the world of veterinary medicine, but unless our vets are staying up to date on the current literature or have access to the best expert sources, things may be missed. And it's OKAY to question things. It's OKAY to double check and investigate yourself. It's okay to be a sceptic.

Does Halo have Anaplasmosis? I don't know.

Halo HAS traveled to Minnesota (2 years ago) which has a high prevalence of Anaplasmosis...

But I DO KNOW the best course of action is determining if a properly read IDEXX test will be +ve or not. And if it is, discussing with the veterinarian if it makes sense to treat a healthy dog with a dangerous drug. When it may or may not be a current infection.

This goes for all of our creatures. As awful as it sounds, veterinary medicine is a career. It pays the bills. It covers that trip to Disneyland and the Bahamas. It's a job.

Because let me promise you. If this IS a false +ve and my dog is healthy, I'm most fortunate that I raised the question mark. How many folks out there might be duped into expensive treatments for a non-existent infection?

And yes, it frustrates me.


  1. As someone who has worked in the natural pet industry for almost 20 years now, I feel your pain! We have seen owners told their animals need high doses of steroids when all they needed was a different protein or less grains. Vets (and human doctors too...don't EVEN get me started there!) are humans and I wish that they would admit that they, too, can make mistakes.

    Good for you for taking your dog's health into your own hands. It's so important to be informed of ALL of your options before turning to drugs that may or may not even be effective!!

    And I'm keeping my fingers crossed that the re-test comes back and it was all a matter of bad reading and your dog isn't sick anyway.

  2. Wow, I can't believe that they didn't want to consider retesting your dog! I work at a vet clinic and if a snap test is positive for something unexpected (there are no symptoms or it's unlikely) often we will redo the snap test just in case it was a false positive or it was run/read incorrectly. I wish more people were aware of some of the "behind the scenes" stuff that goes on so that they can make better educated decisions like you!

  3. Smart girl!...praying that was just a false-positive!

  4. I have an awesome vet and I always get sad when other people seem to get the run around (same with Dr's) hoping that it was a false positive!

  5. Seriously? They would not do a simple re-test before administering the treatment? It is so hard in the dog and horse world as a lay person. We rely on the professionals to guide us and help our animals. But more than once, I have been misguided and it is frustrating and angering. I feel that I let my animals down when this happens.

    I do my best to keep myself educated, but sometimes it is not enough. Good for you for doing what is best for Halo!