Strangles blood test grey area

[daydreamer]

I want to move yards at the start of March and have a stable available at the new yard from the start of March. They asked for a strangles test to be done and the vet has just rung me with the results - negative is 0.2, positive is 0.5 and my horse is 0.3. Gahh!!

The vet says I can either wait 10-14 days and have another blood test or have a guttural pouch wash. I'm really umming and ahhing over what to do and have lots of questions - how likely is it the blood result will fall in 2 weeks? should I just shell out for a GPW (horse was scoped (negative) for ulcers in Jan and has slightly raised liver enzymes so vets are advising a liver tonic they sell so it's been an expensive start to the year already), should I ask the new yard to reserve my stable for a bit and re blood test? Hopefully the yard I am at would let me stay a bit longer if needed as we are currently 3 horses down from 4. Why do they even have this grey area with the test?! I will talk to the new yard but imagine they will say they need a definitive negative. We've had an unsettled year or so, yard 1 from very young until Feb '23 then move to yard 2, back to yard 1 for a month Aug '23 then to yard 4 in Sept '23. In about October he did have a period of being very snotty but no other symptoms and we all just put it down to a virus so I wonder if it was that.

Any ideas/opinions welcome!

 

[HelenBack]

I'd probably just go for the pouch wash if you can afford it, especially as you say he was a bit snotty a while back. My experience has been that the bloods don't really come down in the two week period so you run the risk of having to have the pouch wash anyway and then you're two weeks down the line and have spent even more money. A lot of yards in my area ask for tests nowadays and while some are happy for you to take the wait and see approach, others would just ask you for a pouch wash straight away after having an inconclusive test. So it might worth speaking to your new yard to see what they say as that might make your mind up for you anyway!

If you're worried about the pouch wash itself, my horse has had one done and it's fine and probably took all of five to ten minutes. I know there are some horror stories about them but really there's nothing to it.

 

[Ambers Echo]

The gray area exists because the blood test can't detect strangles directly. It is looking at antibodies to strangles

0.2 or less = consistent with historical exposure
0.5 or more = consistent with active infection
0.3 could be either - as it could be historical exposure within last few months so it's falling but still above 0.2 - or it could be rising if it's a recently acquired infection.

Plenty of horses are above 0.2 but won't be positive on the wash. Amber had strangles years ago and still registers above 0.2 despite scoping clear. I don't really think bloods drop that fast so I'd do the wash too.

 

[ester]

I’d wash too so I knew my plan

 

[atropa]

I had this happen once a few years ago when I was bringing my horse back from loan, she was just above the negative cut off and I was offered the same two options. I opted to wait and retest and she was by then definitively negative, however the horse in question had had a negative test result approx 3 years earlier and I was fairly certain no exposure since.
It caused a slight bit of friction with the loaner who got a bit a****y about having to keep her a few extra weeks, but saved me a few hundred in vet fees.

 

[expanding_horizon]

I had same 3-4 years ago. 0.3.

Yard vet said I needed to both gutteral pouch wash and repeat blood tests. Fairly expensive!

Maddeningly, the vets re-ran both new bloods and old bloods. And second time original bloods were 0.2 and so were new bloods. I was told the testing has a very high error margin so this is possible.

GW was negative.

IMO yard were being over dramatic asking me to do both tests. Something about the risk of an old latent infection and or the risk of a very recent exposure.

I spent several thousand ££££ extra on this, only to discover the original bloods were ok on re-testing! (Cost of 2 vets for GW, cost of two blood tests, cost of 2.5 extra weeks of livery at sales yard (£250 per week), cost of place being held for me at part livery yard I was moving horse to. [My vets were damned expensive for the GW as charged for two vets to be present. Other practices do not do this and accept a competent owner as one person helping with procedure.]

The whole strangles testing in an expensive minefield. My horse's original 0.3 result was within the bounds of potential error in the test, versus him actually having sufficient strangles antibodies to count. Three blood tests (actually 6 but that complicates it), 0.2, 0.2 and 0.3 ARGHHHH

Lesson learnt, next horse I buy, sale will be subject to producing an negative strangles test, whatever testing that takes.

 

[HelenBack]

There is a different blood test now that gives the results in a different way. I don't know the detail of it but it's meant to be better than the one with the whole grey area thing. Seemingly not all vets are using it yet though. Also I know of a lot of yards that are just asking for a pouch wash straight away now as the blood test isn't that great anyway. Not all people want to do that though so it's difficult.

 

[callybbi]

I have had this before and opted to GW even though it is very expensive. Horse in question caught strangles as a 3 year old at a livery yard when a livery was bought into the yard from isolation early. Back then people were quite relaxed about the rules. Caused a huge number of horses on a large livery yard to catch it and end up in isolation in temp stables for a long while. Expensive, nightmare situation at the time. At 20 years old now he still tests above 0.2 but scopes clear.

 

[daydreamer]

I’ve decided to do the GW, I checked with the vets and it is an extra £260 compared to a blood test but at least I will know quickly and if it is negative be able to move yards as planned. I’ll just have to try not to think of the cost!!

 

[daydreamer]

There is a different blood test now that gives the results in a different way. I don't know the detail of it but it's meant to be better than the one with the whole grey area thing. Seemingly not all vets are using it yet though. Also I know of a lot of yards that are just asking for a pouch wash straight away now as the blood test isn't that great anyway. Not all people want to do that though so it's difficult.

I think the vet said the sample was being sent to Rossdales so it seems surprising that if there is a better test they didn’t use it.

 

[dougpeg]

I've just been through this and don't have much faith in the test accuracy. First test was 0.3, the same sample was tested by the same lab 2 weeks later and was 0.2. Operation variability plays a role apparently.

If I needed to move yards I'd probably just go for the wash based on this experience.

 

[Goldenstar]

That’s really bad luck but you are doing the right thing given you had the snotty nose thing ,

 

[Bernster]

I also had a bit of stress in moving yards and the first test came back with elevated readings. For 2 hoses that had previously had no issues and clear tests. We re ran it and sent to a different test centre and it came back fine. RVC said they’d had issues with the original test centre before - not sure why they didn’t send them to the 2nd one in the first place but it was all sorted.

 

[expanding_horizon]

I've just been through this and don't have much faith in the test accuracy. First test was 0.3, the same sample was tested by the same lab 2 weeks later and was 0.2. Operation variability plays a role apparently.

If I needed to move yards I'd probably just go for the wash based on this experience.

That was the experience described in more detail that cost me over £1,000. (Mainly due the the over conservative yard vet then demanding new bloods and GW test, and the double livery (one set was sales at £250 a week)

 

[Puzzled]

I’d just wash…the blood test isn’t great and there’s a good chance it won’t drop.

 

[Horsegirl25]

Go with the wash 100%, we had this situation on my yard when 3 liveries over the course of a couple months all moved to a yard requiring a strangles test. The blood tests ranged from 'grey area' to 'positive' between all the horses!
I am soooo glad they didn't choose to wait for rpt bloods (grey area horse, don't think positive get that option) the full dynamic on the yard was AWFUL!
2 out of 3 owners put them in isolation although don't think that is required however was greatly appreciated by anxious liveries lol.
Personally hate strangles blood tests, GW is the way to go for a clear answer.

 

[daydreamer]

An update in case anyone is reading this in the future. I had the guttural pouch wash done, it was pretty low stress as he was very sedated. One sample came out with some floaty bits which the vet said could be something or nothing, the other side was completely clear. Test done Friday afternoon, results back Monday afternoon. He was negative for streptococcus equi which causes strangles but was very slightly positive for streptococcus zooepidemicus which is apparently found in a lot of healthy horses and the vet wasn't worried about.

 

[dougpeg]

Glad all was well. I hope one day we will have better tests which prevent invasive procedures being done unnecessary.

 

[Sossigpoker]

The gray area exists because the blood test can't detect strangles directly. It is looking at antibodies to strangles

0.2 or less = consistent with historical exposure
0.5 or more = consistent with active infection
0.3 could be either - as it could be historical exposure within last few months so it's falling but still above 0.2 - or it could be rising if it's a recently acquired infection.

Plenty of horses are above 0.2 but won't be positive on the wash. Amber had strangles years ago and still registers above 0.2 despite scoping clear. I don't really think bloods drop that fast so I'd do the wash too.

Those figures aren't really true.
They just show that the horse has developed antibodies following exposure to the bacteria at some point ,.which might have been over a year ago. A higher figure absolutely doesn't mean active infection. It doesn't even mean a more recent exposure. It just means a stronger antibody reaction. This is why the blood test is so poorly understood and misleading.
My horse had a result of nearly 2 about a year after we had strangles (allegedly) at the yard. GPW obviously done and clear.

OP- your result suggests the horse may have been exposed to the bacteria at some point. I'd just do the GPW now. Only about 10% of horses end up being carriers so I wouldn't be overly concerned about that.
Even if the snotty nose was strangles, it's more than likely that he's not a carrier.