Worm counts

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Ninfapaola

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I have just had worm counts done for my two horses, Max & Tilly. Max's came back very low (insignificant) but Tilly's was a medium count.

They are grazed on an 8 & 4 acre fields (rotated regularly) with no other horses.

They are wormed regularly and at the same time, varying the wormers throught the year as required, the last one was Equest Pramox in mid August.

Neither I nor the lab technician could understand the vastly differing counts between both horses. Max is a 15.3hh, 15yo ID gelding and Tilly is a 15.2hh 17yo TB mare. They are both well covered, healthy and do not look wormy.

They are currently in the middle of a 5 day course of Panacur Guard

Could it be that Tilly has a resistant to certain chemicals in the wormers that prevent them from working - has anyone else ever come across this?

I would appreciate any feedback - thanks.
 
There isn't any evidence of resistance to moxidectin found in Equest & Equest Pramox. Panacur Guard however is a different story, and regarded as not very effective, so in Tilly's case I would recommend you get another fecal egg count done in a couple of weeks time to see if her worm count has reduced. Ideally worm count Max too in case his result was inaccurate.

If not, I would worm with Pramox. It is more usual to use this product in the autumn than in August as you did unless you have evidence of a tapeworm burden.

I don't know why Max and Tilly had different counts except, (a) perhaps Tilly spat her wormer out, or (b) perhaps she grazed on a more heavily infested part of the pasture or (c) did she go out to competitions? or (d) the worm eggs may not be uniform throughout the dung, so the result may not be accurate.
 
Thanks for your reply LadyArcher. It sounds more like it could be either b or d of your points as she is easy to worm with no objections and I supervise them both for a while once I've wormed them plus she hasn't been off the premises.

Will be sending another count off in the near future.
 
Hello, if I can add (from Westgate Labs) it is extremely common to find differing results like this from horses grazed together and treated in the same way. I don't recognize the names so I don't think we did your test? However I've been talking to someone today who had a very similar case with us.

In addition to the helpful comments from the last poster I would suggest: Horses differ in the effectiveness of their immune systems so there may be something to look at there. Older and younger horses are more likely to pick up parasites. The most usual cause is something in the worming history, often going back years so think about how long you have had them both and could that be a reason?

No-one really knows (as yet) why 80% of horses carry 20% of the worm population but that is indeed the case. More research is needed.

The reason might not be obvious but at least you are now aware of it and can take action.
 
Was going to say the same as GillB, horses treated and kept identically can have differing worm counts for no 'apparent' reason.
 
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