It is typical to deworm and give CD & T 30 days before lambing/kidding
Of course every flock/herd is different. We give CD & T but do the deworming on a case by case basis.
Never used prohibit. Kind of "overkill" IMO
Is that the only dewormer that works for you?
Different drug choice in this country, but sheep are still sheep. Worming is highly advisable at 4-6 weeks before lambing, and vaccination against common pathogens (we use a heptavalent vaccine including Pasteurella over here).
During the late weeks of pregnancy the ewe's immunity drops off dramatically. Nature does this to allow the growing lamb to not be seen by the body of the ewe as a 'foreign body' and to reject it (the genetic make up of the lamb is only an approximate 50% match to the ewe) Foetal cells enter the maternal circulation across the placenta during late pregnancy and during delivery, so the fall off in immunity is Nature's way of allowing the lamb to to not be rejected. Unfortunately, the reduced immunity also affects the ability of the ewe to fight off parasites/worms etc, so worming at this stage is important. Check that the wormer is safe in pregnancy and that the wormer covers local worms and resistances.
Vaccination allows the ewe to produce antibodies which cross the placenta and protect the lamb in the first 4-6 weeks of life. Lambs are then vaccinated at 4-6 weeks and approximately 6 weeks later to allow them to produce their own antibodies.
Thanks everyone. I've had very few issues with worms until this year's wet summer. Ordinarily I have great luck with homeopathic treatments and Prohibit when absolutely necessary. Prohibit is just what my feed store happened to have and I haven't needed to change drugs. I finally found the info I needed and the ewe is responding well.