Somewhere else on here there is a mention of clearing the 'wheel arch' ie just in front of the hind legs, on very woolly ewes so the lambs can find the teat easily, but there is a stretched piece of skin there which it is very easy to cut accidentally.
For dagging, if the back ends are very dirty with a mass of wet lumpy dags this could create issues during lambing itself, especially if you have to assist.
For feet, we have the occasional ewe who has drying mud stuck between the two halves of the foot - this is easy to remove if you can take hold of your sheep easily, and can prevent the development of foot rot. For seriously overgrown feet - firstly, it's always good practice to trim the feet when the ewes go in with the tup at the end of the year and most will get through from then to lambing without major problems, but there are always one or two who can't quite last that long. Here, we pick out that sheep individually at feeding time and trim her feet, just about up to lambing. Our sheep are fairly used to being handled (except one or two who we have no chance of catching up on their own so they would just have to hobble until they lamb

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It is perfectly possible to handle in-lamb ewes without stressing them, but when you are doing it for the first time then now is not the time to practice. I suppose it's a question of just how daggy your ewes are and just how overgrown their feet - if they are down on their knees and unable to walk or feed properly then that is a problem, whereas if you have simply noticed that their feet are overgrown but they are walking ok then there is no need to intervene.
In my experience, bringing someone else in to handle your sheep is not always the answer - they may well not treat them as gently as you would wish.