Worming Nightmare

Flibble

Flibble

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Friend keeps her horse at a yard that is on a poo picking worm count type program. She was not happy that it was being managed correctly so Wormed her horse 2 days ago and when she turned up this pm ran out of her stable throwing up.

Piles of poo in stable littered with worms from description I guess tapeworm and yet externally her horse looks as fit as a fiddle.
 
The trouble with worm counting is that there is quite a lot of evidence that eggs congregate in one area of the dung, therefore unless you put the entire poo through a blender, there is a high risk of a false positive. Which is why I have abandoned worm counting and gone back to a chemical programme.
 
Better out than in I suppose!

As much as a worm count/poo pick program works, a dose of praziquantel (with IVM or MOX - Equimax Duo etc or Pramox) or a double dose pyrantel still needs to be included for tapeworm.

Tapeworm eggs can be difficult to see in "normal" egg counts - they look like little chips of glass so can easily be dismissed as bits of debris or airbubbles if you don't know what they are! They are also heavier than normal strongyle eggs (large and small redworms) so don't always float as well in salt solution. Get her to ask the worm count people if they count tapeworm eggs - I've noticed some companies only count ascarids (found in foals and youngstock) and stronglyes.
 
I was so shocked when she told me I went into Drifs stable as he was wormed yesterday morning and waited for a fresh dump. Got a shovel and put it in a bucket popped on me Marigolds and went through each lump. No monsters lurking so far and it was a lovely consistency!
 
That's right, tapeworm don't show up in a fecal egg count, you need an ELISA blood test but only a vet can do it and it's expensive, so most people who worm count will still worm autumn and spring for tapeworm.
 
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The trouble with worm counting is that there is quite a lot of evidence that eggs congregate in one area of the dung, therefore unless you put the entire poo through a blender, there is a high risk of a false positive. Which is why I have abandoned worm counting and gone back to a chemical programme.

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I've not seen any published evidence for this (willing to be corrected though!) I know someone who is doing his entire PhD thesis on this in sheep faeces and he certainly wouldn't agree! Worm counting does have limitations as it doesn't provide an accurate estimation of parasite burden (the "hidden" immature stages in the gut do not produce eggs) but they do provide information on the level of pasture contamination being produced and identify the high shedding horses - in any population roughly 80% of nematode eggs on pasture are passed by 20% of horses. With anthelmintic resistance on the increase I wouldn't advocate a chemical only program...what happens when your wormer fails? How would you know when it's no longer effective without worm counts?
 
I do two worm counts a year, but also worm in September for tapeworm and December for encysted redworm (usually combine this with something that also treats bots or tapeworm). I don't think you can do without any wormers unless you also do the blood tests.
 
Oops, just read that back - sorry if it's a tad defensive and just realised I've written an essay no-one asked for
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Bad day at the office, roll on the weekend!
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I know what you mean! I saw a horse at post-mortem that had a worm egg count of 100 eggs per gram (low in other words) - it had an estimated 3.6 million worms encysted in the gut. Horse was put down with completely unrelated problems and no way would I have guessed he was carrying such a high burden! Such is the problem with parasitology! Tapeworms are also amazing at breaking up into little segments so it may be lots of bit of the same worm...not sure that helps, but it's true!
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The trouble with worm counting is that there is quite a lot of evidence that eggs congregate in one area of the dung, therefore unless you put the entire poo through a blender, there is a high risk of a false positive. Which is why I have abandoned worm counting and gone back to a chemical programme.

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I've not seen any published evidence for this (willing to be corrected though!) I know someone who is doing his entire PhD thesis on this in sheep faeces and he certainly wouldn't agree! Worm counting does have limitations as it doesn't provide an accurate estimation of parasite burden (the "hidden" immature stages in the gut do not produce eggs) but they do provide information on the level of pasture contamination being produced and identify the high shedding horses - in any population roughly 80% of nematode eggs on pasture are passed by 20% of horses. With anthelmintic resistance on the increase I wouldn't advocate a chemical only program...what happens when your wormer fails? How would you know when it's no longer effective without worm counts?

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OK, as explained by my vet - it's 10yrs since I did parasitology at Uni so laymans terms.

Basically there are several different techniques for undertaking worm counts. The ones commonly used by the labs which do the 'send off a sample' kits are only looking at the sample given, and apparently there is a high degree of false positive as there is a lot of evidence that eggs congregate in one area of the dung. Because it is a small sample, there is a high chance that you will get a false positive. One way round this is to 'blend' an entire dung before taking a small sample. The other is to use one of the count techniques which requires a lot more dung, but these are more expensive (obviously).

Apparently there is published evidence to show that the eggs do tend to be found in one area of the dung, but I have no access to any of the journals to search (nor any reason to doubt my vet!).
 
sorry this is going to be along post

nn, do you have access to papers? I will happily try and find some references for you.

Its been a few years since I was involved (I did sheep poo too) and I think the situation can get a bit complicated.

My take on it is I am all for worm counting but it has to be done properly to be effective and give a true indication of the problem and people need to take the advice available for them from the commercial suppliers (was of these was online the other week and I was quite pleased with her answers) but i don't think people ask enough questions or understand the results they receive, even more so when done on a yard system.

When I had the facilties to do my own on as much poo as I like as often as I liked I did do worm counts but I tend to use a minimal chemical program now. I think the more poo you take and the more frequently take it the better the understanding of the burden in any one horse will be. My concern about horse FEC are that aggregation within the droppings may be more of a problem than in their sheep equivalent due to the size of one dropping. not sure what is done commercially but in sheep it is viable to mix (in a blender) and entire dropping and take a sample from it prior to weighing if you so wish (though I dont think we did) I know we tested 3g, which would proportionately be much less of a horse poo and hence increasing the chances of a misleading result.
I think its poss that worms also have daily cycles so time of day may also make a difference.

Whether either of the above are significant issues I am not sure on atm I will have a bit of a look.

I am very concerned about the development of resistance and recently went on a v. interesting talk from a very emminent (sp) researcher at Bristol where I am based I posted this at the time which may be of interest to people. I might actually email him and see what he says about the aggregation issue and how much droppings they test as I know they do some horse testing

'Yesterday evening I went to a talk at the vet school where I am based on the development of resistance to chemical wormers by worms (round/red worms particularly) given by someone who has been studying them for years and thought you might like to know the most relevant bits.

This is a real developing problem, we will never wipe out worms completely and need to treat them appropriately. There have been at least 2 cases in the uk where sheep farms have had to close down as they have developed worm populations resistant to all the available drugs. In 2008 a throughbred farm in Brazil reported ‘triple resistance’ meaning all groups of wormers do not work, I assume they also had to close.

Firstly you should worm horses on pasture, not really keep them in after worming like many livery yards do. Similarly you should not worm and then turn out on to clean pasture, this is infact the worst thing you can do, but goes against traditional practices. Both of the above are due to the same reason. If you worm and put on to clean pasture any worm eggs then expelled are from worms resistant to the wormer used. On clean pasture 100% of the worm eggs on that pasture are now resistant to that wormer and hence the numbers of resistant worms will then perpetuate. If you turned out on dirty pasture the worms resistant are diluted which slows the evolution of resistance. – I for one had never really realised this.

In fact ideally we should keep a ‘refugia’ for the worms to maintain a susceptible population.

Poo-picking, due to the time taken to hatching and the environmental conditions in the uk once a week in the winter and twice a week in the summer will be sufficient to minimise exposure.

Sheep are excellent hoovers of horse worms if they are turned out together as there is very low species cross over.

Worm eggs can persist on hay 6months + after cutting, although it is likely to be minimal it is possible that you may import resistant worms on hay purchased (suspected less likely on haylage) this has been shown in sheep but no real idea of prevalence I believe.

Using worm egg counting: the worm population is overdispersed, this means that most of the worms are in the minority of the population therefore taking counts from a group of horses and treating only those horses with high counts it is a good idea. However these horses will not necessarily be the same ones year on year dependent on their other health etc.

I have saved the best till last! If you purchase a new horse, you should keep it on separate pasture for 28 days (this is longer than in sheep or cattle due to the worms generation time) worm it with ivermectin (it think- I didn’t write it down) on the first day, take a worm egg count on day 28 and if there is a significant count get rid of the horse! as it will be introducing resistant worms to your pasture and pass them on to all of your horses.' - I liked this last bit as we all know how hard it is to find a horse in the first place
 
wow that was my longest post ever!

I loved host parasite interactiony things at uni. I have always thought it a bit of a shame we kill them off cos they are not cute and fluffy.

Would have like to do have done my PhD into that sort of thing but thre is limited money these days and its not where my work took me.

Edt to add, flibble something went wrong there, I would suggest that your friend takes control of her own worm counts/blood tests in future so she knows what is going on.
 
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Firstly you should worm horses on pasture, not really keep them in after worming like many livery yards do.

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Sorry... can you explain why the horse shouldn't be kept in after worming? In what way is it counterproductive?

Sorry if it's in text. I've read it, but have a stonking head cold right now and am sure the obvious just isn't reaching my brain tonight.
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No of course I can explain, its one of those things like farmers worming and then moving to fresh pasture it is really great to developing a resistant worm population.

Basically I think he said that if you worm any worms expelled are not going to contribute to reinfection of the pasture once they are outside the animal so even if they are paralysed rather than killed by the drug, so basically just not necessary to keep them in I think rather than truely counterproductive if I remember


Also (I think from the moving on to clean pasture perspective) importantly if you worm and there is any worm in there which just happens (due to random genetic change- which is how any evolution starts) to be resistant to the drug you used it will survive the treatment. Then all of the eggs expelled from that animal onto the clean pasture will be resistant to the drug so that all of the larvae able to reinfect will be resistant to the drug. It is better to slow the evolution of resistance by having a mixed population type of worms on 'dirty pasture'.

Ideally if there was no animal welfare issue associated with it you would keep an animal that you didn't worm to keep your worm population mixed
 
Great posts Ester and I totally agree with you.
There is so much misunderstanding of worming.

Worm counts are a 'blunt tool' but still a very useful one if used correctly and backed with proper worming advice, certainly better than blanket use of worming drugs.

I run Westgate Labs where our mission has always been to improve worming knowledge and practise. It's a long job!
 
Blimey Ester I really opened a 'Can of worms' here. Excuse the pun.

My friend is taking worming into her own hands as it were and has filled one of my plastic feedsacks (she only had a tesco carrier bag which wasnt good enough) with evidence for the Yard Manager.

Suddenly I dont mind my horse not getting tons of turnout!!
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i thought the precise same as you that a 'wormy' horse would look poor (im first to admit im novicey with worm issues)

my horse is on livery yards worming prog as recommended by wormers and vets.

had worm count done all fine, had blood test 4 tapeworm done and she had a medium count !! she looked exceptional and is wormed properly so i didnt understand it and was very shocked.
 
I'm slightly worried now as my pony 16 years ago when we first got him had really bad red worm and once wormed we found them all in his poo. A few weeks ago he suffered bad colic and the vet has tested again and has bad red worm and tape worm problems (he had been out on loan and not looked after) we have followed worming programmes but have not seen anything come out in his stable or the field. Should i expect to see anything? My vet said i wouldn't as wormers now days break them down so they dont come out as full worms??
 
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