Negative Lyme snap test...Odds she still has Lyme?
My boarder has a vague, all-over lameness/discomfort issue. The vet says it looks like Lyme, and she ran a snap test in her truck that turned out to be negative. So she is sending blood to a lab in Connecticut for further testing. What are the odds that this horse could still have Lyme, but the snap provided a false negative?
I just went through this. There is nothing more thorough then Cornell's Multiplex test for Lyme. Google it, lots of info.
Vets (and Cornell) say that the number one indicator for Lyme is Clinical symptoms, history with Lyme then blood test (using the Multiplex test).
My guy had strong clinical symtoms that came on sudden. He was fine/sound then got progressively quieter (complete attitude change), then finally almost 2 weeks later lameness that seemed to be everywhere. You couldn't really pinpoint where. At first glance the vet said looked like front feet were sore (hard ground).
But you have to know your horse and advocate for him/her based on your relationship. I knew he was not quite right, combined with the change in attitude, then we pursued the Lyme.
My guys Multiplex test came back chronic. After 10 days on a strong Doxy perscription he is back to his old self. He will stay on the Doxy for 20 more days.
Now that he's had it this bad, we have to watch him. Could become seasonal with reoccuring symptoms.
HollBear - do you recall what your guys level was? I think my girl has Lyme - the "only symptoms" is she's a bit grumpier and slow as a slug. She's not lame anywhere. But her OspF results were 2500+ (normal is 1000). Vet does not think it's Lyme, just because she doesn't have achyness/lameness elsewhere. I've got her on Doxy anyways.
I'd definitely do through a more thorough testing on the horse and not just rely on the snap test.
I believe, and I'm sure someone will correct me if I'm wrong, that the snap test essentially tests for antibodies to the lyme bacteria. So if the horse's immune system has not (yet) mounted much of an immune response to the bacteria, the test will come back negative even though the horse definitely is infected and symptomatic.
Thanks, guys. This is pretty much in line with what I was thinking. She really presents pretty classical Lyme symptoms... Depressed attitude, intermittent lameness that seems to be all over. Last Thursday/Friday she looked awful even at the walk. By Tuesday (soonest the vet could come out) she looked 90% better at the walk, but still trots really badly--hesitant, short stabbing steps, just looks very sore all over. I'm kind of "hoping" the follow-up test is positive, so we know what the issue is and can treat it accordingly. She's a 19-year-old retiree with a history of back soreness and various hind-limb ailments. We just want her to be comfortable.