Having done many (hundreds?) necropsies (‘post mortems’) on sheep, and removed metres of Moniezia from their small intestines, I totally ‘get’ that farmers and others find it hard to believe that the common sheep intestinal tapeworm (Moniezia) is of minimal importance The segments in the dung are ‘in your face’ as well.
Please note we are not talking about larval cestodes (larval stages of tapeworms eg hydatids, sheep measles) or pathogenic tapeworms found in Africa for example.
Out of dozens of reported experiments looking at the effect of Moniezia on weight gain or scouring in sheep, only one (from NZ) that I am aware of showed any significant effect from treating specifically (using praziquantel) for tapeworms. This one report of course is gold for marketing people in pharmaceutical companies. They might have got 20% or whatever improved weight gains by treating for tapeworms in that one, solitary study, but it is almost certain that your result will be very close to zero (even less if you overlook the important sheep worms).
Treat for tapeworm if you like, but make sure at the same time you are doing a good job on the really important worms, the ones you can’t see so easily.
Many times I have done field investigations where the farmers used a combined tapewormer + broad-spectrum drench product where the tapewormer (praziquantel) probably worked very nicely on the tapes (by the way, there are reports of resistance of Moniezia to praziquantel), but the broad-spectrum didn’t work at all on scour worms because of resistance. Sometimes the lack of efficacy of the broad-spectrum drench was not clinically obvious, but the economic loss (lower weight gains and less quality wool produced) would have been significant (e.g. equivalent to several dollars or more per sheep per year).
So, don’t major on minors, or, as our American friends might say, ‘don’t sweat the small stuff’.
To keep tabs on the really important worms, you need to do regular WormTesting: worm egg count (WEC) monitoring. And regularly check drench efficacy by doing a WEC 10 days after the drench (in the case of short-acting drenches).
WECs are one of your best friends.
In NSW, the top worms of small ruminants (and alpacas) are barber’s pole worm (Haemonchus), the scour worms: black scour worm (Trichostrongylus) and small brown stomach worm (Teladorsagia (Ostertagia)), plus liver fluke (Fasciola) in some areas.
Regarding the pics:
Please respect the rights of the owners of these images. Contact them if you wish to use their images.
(I think it would be ironic if a pharmaceutical company, as a result of this WormMail, paid Jim to use his Moniezia pic in promotional material for their sheep tapewormer… 🙂
TO: WormMail mailing list (recip. undisclosed; approx. 400 subscribers)
WRML.20120124. WormFaxNSW December 2011
WormFax as you may know is a summary of WormTests in sheep from around NSW.
The summary data is supplied each month by the NSW DPI State Veterinary Laboratory (at EMAI, Menangle (Sydney), and Armidale-based private lab, Veterinary Health Research.
Many thanks to these laboratories for making possible this on-going service to the farmers of NSW.
The December issue is online.
Here are some highlights…. WormTests with the highest average WECs from around the state.
High WECs (say, >1000 epg) are mostly but not always due to Haemonchus
Clearly there is at least one mistake in the table above…. 🙂 Ooops. In this WormTest, the mean WEC (18240) was higher than the highest individual egg count(check the worksheet on line), and (my mistake), 4% not 80% of larvae were Haemonchus. More likely, the mean was 1824, not 18240.
Still, if you saw a mean WEC of 1800 or so, you might think the larval culture would be mostly Haemonchus rather than mostly Trichostrongylus.
Of course, we let these mistakes through to keep you on your toes… 🙂