How accurate should worm counts be?

[Jambarissa]

I get my counts done by a local lady but there's a new mobile one who let's you look and gives an immediate result.

I dropped off my samples at my usual place but then the mobile woman was at the yard that evening and it looked fascinating and since my horse obliged I got her to do one.

You know where this is going, they were miles apart, 600 (new one) and 1350. Both in the 'needs worming' category anyway but still, that's a huge spread. I went straight to the tackshop for a westgate pack and did it the next morning. Result less than 24 hours later 175 - borderline for worming.

I'm going with westgate from now on but what's happened here? I'm sure counts can vary but not that much surely? There's no point in doing it at all if they can go from 1300 to 175 on different samples.

 

[meleeka]

I had a wildly different result with Westgate too. Same pony, a few days apart, one low, one high, so I'm not sure I trust any of them (and yes, I did fill the little tub up as instructed).

 

[rextherobber]

Do you mean you think the companies are being inaccurate/ inventive with their results? Or that the number of eggs per sample can differ wildly, so don't completely believe your result?

 

[PaulineW]

I think it can vary depending on the sample given too. I try to take pinches from different poo balls, and cram the tiny pot.

Recently I sent a sample away to Poopost, which came back as 100. Not bad but due to the pony’s age and unknown history they recommended worming with a double dose. He dropped huge white worms for two days. Follow-up test was under 50 score.
So I guess sometimes the eggs are not present but the worms are there, just not coming out.

 

[meleeka]

Do you mean you think the companies are being inaccurate/ inventive with their results? Or that the number of eggs per sample can differ wildly, so don't completely believe your result?

The latter. I can only assume that the samples had different amounts of eggs, even though I took small bits from multiple piles. I wish the amount sent could be bigger to get a clearer picture.

 

[rextherobber]

The latter. I can only assume that the samples had different amounts of eggs, even though I took small bits from multiple piles. I wish the amount sent could be bigger to get a clearer picture.

Agree. It does seem a tiny amount.

 

[TheMule]

The process of counting eggs per gram itself is very simple and will given you an accurate result for the area sampled. What is not accurate is the representativeness of the sample (more eggs are shed in some parts of the poo than others, more are shed in certain environmental conditions etc) But you also need to remember that the number of eggs counted in the poo has a very weak correlation to the actual worm burden of the horse. So, in short, it's actually pretty pointless!

 

[Abacus]

Also possible that the number of eggs varies in different droppings (time of day etc). Wonder what the results would be from one pile*, thoroughly mixed up, and send several samples to each lab (labelled as different horses). Has anyone?

*by which I mean one dropping from one horse

 

[Goldenstar]

Tbh I have never had much faith in a single worm count .
Horses do a lot of poo and parasites don’t pass out of the gut at an even rate .
I am not in the least suprised you got differing results and it’s not necessarily in any way linked to competence of the people doing the test .

 

[Fieldlife]

Tbh I have never had much faith in a single worm count .
Horses do a lot of poo and parasites don’t pass out of the gut at an even rate .
I am not in the least suprised you got differing results and it’s not necessarily in any way linked to competence of the people doing the test .

I do them every 8 weeks, as I harrow back into field, but I know the reliability is limited as worm shedding will vary across the droppings passed.

A positive count means there is a worm burden. A negative count means were no worms found in the nuggets of poo submitted. I try to get some from 4 nuggets when I send a sample.

 

[criso]

A positive count means there is a worm burden. A negative count means were no worms found in the nuggets of poo submitted.

This and not everyone takes samples for a few poos.

I would hope that if you're doing it regularly over a period of time, then you will pick up issues.

 

[Jambarissa]

I am torn between mixing up a poo sample and sending 2 to each of the 3 places to see what happens, or just giving up.

There is no point if they are that different!

 

[criso]

I am torn between mixing up a poo sample and sending 2 to each of the 3 places to see what happens, or just giving up.

There is no point if they are that different!

Unless you use some highly technical method of thoroughly mixing the samples, you could still end up sending them samples with different burdens.

 

[Abacus]

Unless you use some highly technical method of thoroughly mixing the samples, you could still end up sending them samples with different burdens.

I agree but it might still reveal some results about accuracy. It is why I suggested a test (which would be expensive!) in sending several samples to each lab.

If the results are similar within each lab but different across the labs, it would indicate that their methods are different.
If all of the samples are wildly different it just shows how inaccurate the whole thing is. Either because of their methods or because different bits of one poo can be very varied.
If they come back similar across all the samples/labs, maybe they are quite accurate after all.

Scientifically this isn't a perfect test. Would be better if we could send samples with known counts of course, but I can't see how this is possible.

 

[criso]

There is a bit here about how Westgate process their sample. The interesting thing here in terms of comparison is they split the sample once centrifuged, then take the average between the two. So if a single sample when split differs, then sending it to different labs could just show this difference, not any difference in methodology or competence.

Is it worth asking the different providers about their methodology.

Choosing a laboratory for your horse’s worm egg count

www.westgatelabs.co.uk

 

[Goldenstar]

Ideally I bring my horses in the morning then at lunch time I hopefully have more than one dropping per horses take a bit from several places in each dropping mush each bag well together and take to vets hopefully early enough for them to looked at that day .
It’s a bit of a chew .

 

[Fieldlife]

I agree but it might still reveal some results about accuracy. It is why I suggested a test (which would be expensive!) in sending several samples to each lab.

If the results are similar within each lab but different across the labs, it would indicate that their methods are different.
If all of the samples are wildly different it just shows how inaccurate the whole thing is. Either because of their methods or because different bits of one poo can be very varied.
If they come back similar across all the samples/labs, maybe they are quite accurate after all.

Scientifically this isn't a perfect test. Would be better if we could send samples with known counts of course, but I can't see how this is possible.

I think you arent understanding the counting process.
If you could hyperthetically send precisely the same sample to 20 different testing companies, the results would be virtually identical.

The counting process is both simple and reliable.

The issue is not the accuracy of counting what is in the sample.

The issue is the overall volume of poo a horse produces, and the worm eggs are not evenly distributed across the daily poo output. So the bits of poo you send may or may not be an accurate reflection of a horse's actual worm burden.

 

[Fieldlife]

Ideally I bring my horses in the morning then at lunch time I hopefully have more than one dropping per horses take a bit from several places in each dropping mush each bag well together and take to vets hopefully early enough for them to looked at that day .
It’s a bit of a chew .

better than just sending a bit of one poo nugget, but still only a fraction of the poo in 24 hours being tested, and the worm eggs could all be the poo not being tested.

 

[Abacus]

I think you arent understanding the counting process.
If you could hyperthetically send precisely the same sample to 20 different testing companies, the results would be virtually identical.

The counting process is both simple and reliable.

The issue is not the accuracy of counting what is in the sample.

The issue is the overall volume of poo a horse produces, and the worm eggs are not evenly distributed across the daily poo output. So the bits of poo you send may or may not be an accurate reflection of a horse's actual worm burden.

On the contrary, I understand it well. My point is that if you get different results from one poo, there is something very wrong with the whole system - regardless of why. However any differences within and between labs would be interesting.

 

[Fieldlife]

On the contrary, I understand it well. My point is that if you get different results from one poo, there is something very wrong with the whole system - regardless of why. However any differences within and between labs would be interesting.

You can only ever analyse the nugget of poo you are sent? If you send a different nugget of poo from the same horse the results might be wildly different. Worm eggs are unlikely to be evenly distributed across every poo and within every nugget in each poo a horse does. that is known and is a limitation of poo sample testing.

 

[Jambarissa]

So what's the takeaway here?

Is testing completely pointless if you can get 175 and 1300 from the horse at the same time?

It looks like a low count tells you nothing about the horses worm burden.

Does a high count tell you anything? Does it mean they have a high worm burden or could it be low but that bit of poo just happened to have a high concentration of worms?

One of my horses hasn't been wormed for years because she's always sub-100 and good for the tapeworm test too. She could be full of the things!

 

[SEL]

So what's the takeaway here?

Is testing completely pointless if you can get 175 and 1300 from the horse at the same time?

It looks like a low count tells you nothing about the horses worm burden.

Does a high count tell you anything? Does it mean they have a high worm burden or could it be low but that bit of poo just happened to have a high concentration of worms?

One of my horses hasn't been wormed for years because she's always sub-100 and good for the tapeworm test too. She could be full of the things!

I read an article from a US vet who said they would worm if the worm count was positive irrespective of levels and they are really only worthwhile if done regularly.

 

[sideshow]

Really interesting discussion and I wish I’d seen it sooner to comment.

Worm Egg Counts are super important, we all know the chemicals we once relied on are ceasing to work and it’ll be a disaster once worms can’t be controlled.

When posting to a lab, you have to consider the freshness of the sample and the time it takes to get there, then you have to consider how it’s processed.

I personally prefer to go to yards and do the tests there with poo no older than the night before, or collect the samples and process at home the same day. It’s unbelievable how quickly eggs can develop at this time of year, and once the eggs have hatched, you could end up with a very inaccurate picture.

When samples are posted to me, I do an unfiltered test which will float any hatched larvae, before checking how fresh the sample is and how many eggs there are.

Some labs make much of the fact that they centrifuge samples, inferring it’s the most accurate way but I personally disagree. My centrifuge breaks larvae up, so no sign is seen and if all that’s left is a few eggs which didn’t hatch, then your result will be very inaccurate.

 

[Fransurrey]

I do my own worm counts (still have my lab access to the vet school!), and make sure I fill at least two pots, taking a ball from more than one poo for each. A fellow livery was asking me about this the other day and I advised her that if she was relying on worm counts, to do this and pay for two counts. In science there isn't a chance that we would take one sample and rely on that one point of data. You would take multiple samples and use the mean and standard deviation to gauge if differences were significant.

 

[Pinkvboots]

I had issues with worm counts some years ago I don't really trust it and I wouldn't rely on them totally.