Worming

Joined
30 May 2013
Messages
32
Has anyone had a pony with a very high worm count (7000 epg!) despite regular worming as directed by our vet.
All other horses on the same land are clear or low levels (less than 1000epg) and management is the same through all of my horses so it’s a problem isolated to one horse in our herd.

What could have caused it?
 

supsup

Active Member
Joined
5 January 2015
Messages
695
Yes and no. I took over care on a very old mare in poor condition a couple of years ago. She originally had a high count (I think in the 3000 range, though I don't quite remember). She was carefully dewormed with follow-up resistance test to make sure the wormer was effective (which it was). I fully expected her to maintain a low count afterwards, given that all the other horses in the fields usually have no eggs seen. However, she always ended up with an appreciable count again after not too long a time (sometimes at the very next FEC, sometimes at the one another 3 months later). However, her levels never got that high again, and were usually in the medium range (above 200, so should be treated, but remaining in the 300-500epg range). I put it down to her age and poor immunity that her count always went up again, while the other horses managed to maintain a low count.

However, 7000 is very high, and according to Westgate labs, a range between 200 and 1150epg is actually a medium count that should be treated, and not a low count. If other horses regularly get back up to ~1000, then I'd suspect that the programme isn't fully effective. Is the yard doing follow-up resistance tests to ensure the chemical used is effective? If not, then I think that's what I'd do. Maybe the vet recommended chemical is one that the local worm population has become resistant to.
 
Joined
30 May 2013
Messages
32
Thankyou Sup.

I have a small herd of 3. The others have always been less than 50 however recently came back around the 500 mark at the end of summer. The third was around 1100. I wormed with the lab reccomended program and both the other two came back at less than 50 although stupidly I did not retest the higher mare (the other two were retested at the vets for other reasons)

The land is managed well. Minimal grass as expected for the time of year but is rotated regularly (3 fields split into winter and summer paddocks) but I do put Hay out for them. I also poo pick regularly.

I can’t understand why the third mare is so high, she is healthy and looks well. To look at her there wouldn’t be any indication that she has a high worm burden.
She has been wormed now with panacur instead but I am conscious of making sure this doesn’t happen again and plan to check in a week or so that this has worked, although I can’t see why it happened in the first place!
 

supsup

Active Member
Joined
5 January 2015
Messages
695
If I remember correctly, studies have shown that 20% or horses carry the majority of the worm burden in a population. I think it is just natural variation that some horses develop more natural immunity to parasites than others. If you can rule out worm resistance and just happen to have a horse who doesn't have strong natural immunity then you'll just have to treat her more frequently than the others. I guess that's what the "targeted" worming strategy is all about - identify and treat those who really need it. It sounds as though you are already doing what you can in terms of field management.
 
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