Bombarded with worming information re: encysted redworm

MissTyc

MissTyc

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Very long story very short

-- herd grazing, field rotation but not always rested as long as ideal (3-4 months rather than 4-6). Healthy herd, mix of competition and leisure horses
-- high redworm burden end summer - egg count
-- horses wormed Equest (Pramox, to also cover tape) September
-- two cases of encysted redworm eruption / mass migration less than 15 weeks after worming
-- both died - one because of late diagnosis and one due to complications during treatment (stopped eating and colicked)
-- vet advised use Equest again, so horses wormed Equest early January (all weighed, correct dosage + 20%)
-- resistance test done by westgate labs
-- herd "no resistance detected" other than 3 horses identified as low (100-150 epg)
-- lab recommends 5-day Panacur to address Equest resistance problems right now on basis that if any eggs found during resistance testing, then likely there are also encysted chaps still present. Lab believes encysted redworm greater risk than resistance right here and now
-- vet recommends NOT to worm now as more worming might contribute to resistance issues, doesn't appear concerned about remaining encysted chaps in the 3 horses. Vet believes resistance greater risk than encysted worms at this stage

Owners are confused! Owners are aware of wide-spread Panacur resistance. But are also concerned about apparent Equest-resistance. Owners generally not sure where to turn right now. Worried about the 3 horses in case they are harbouring resistance worms. Definitely don't want to add to resistance, also definitely don't want to risk the health of the herd or any individual within it. Trying to improve worm counting, worming and rotation. Everyone has an opinion - imposable to see the wood for the trees, feel free to add yours!
 
Have you spoken to Zoetis, the manufacturers of Equest? This should be reported to them as a suspected lack of efficacy case and they may well support some investigation to find out what is going on and what went wrong. Determining true resistance can be difficult, so it might be worth asking your vet to speak to a parasitologist for further advice on how to proceed, or the pharmaceutical company may well involve a specialist in determining how to manage the situation now and what strategy to adopt for future control.
 
I'd go with the vet TBH. Much as I love Westgate and use them for worm counts I dont use their advice re which product to use. I go with my vets advice. eg I worm with Strongid-P and then the following year Panacur as I have had horses lost to EGS and Ivermectin is implicated . I've had Westgate tell me not to use Strongid as they recommend that for tapeworm only. But it is a valid wormer for other types at single not double dose. I@d go with what your vet says.
 
If one of those was my horse I would definitely want to worm again, given the tragic outcome your yard has already suffered. How can this contribute to resistance? Worming horses with known worm problems is what it is all about. It is the yards where wormers are given over and over again in blind ignorance which are contributing to resistance.

I think it most likely that your yard is starting to have moxidectin resistance. I don't know for sure but using my intelligence it looks like it. Resistance does not mean that the wormer does not work at all. It may mean that enough worms survive to begin egg laying again before you would expect. So instead of lasting three months or more the horses might need need reworming after only eight weeks. You can find this out by monitoring egg counts more closely.

At the AHDA conference last week Prof Jacqui Matthews from the Moredun said that egg reappearance times as short as this have been found for moxidectin. There is some resistance to all wormer drugs with Panacur being the worst culprit and pyrantel the next likely. These drugs still have their place in some situations and for treating some worms of course.

There are always differing opinions on worming and sometimes several different courses of action are all correct.

I think your yard needs to do some close monitoring of egg reappearance times to try to find out what is going on. It's very scary that you have had such horrible experiences despite trying to do your best. If you contact us at Westgate we would be interested to talk to you about doing some extra monitoring as a case study. These would be complimentary tests of course. We have already been discussing doing some work on this and your yard sounds like a good case.
 
Just a small question. But when the horses were treated with pramox was the correct dose administered? Some people try to eak it out to save money there for under dosing so creating resistance.
 
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