I seem to remember that sheep can pick up listeriosis from eating soil.
The problem we have with molehills is that, because we have a lot of iron in our soil, the sheep ingest this and it prevents the uptake of copper in the gut, which in turn leads to a copper deficiency. Copper deficiency, or more rightly the inability to absorb copper from the gut because of the iron, leads to greying in a band in the fleece in dark coloured sheep, with a more brittle fleece. It can also lead to some birth defects of the spine. It was very noticeable that when we got our friendly local gamekeeper to come and catch all the moles, our greying sheep turned black again
Our neighbour did complain about all our molehills (we did have rather a lot at one point
) and said that he had known of sheep breaking their legs in the holes so was worried about his flock. We were able to point out that all the moles appeared to be migrating
off his land
onto ours, not the other way round, probably because we use organic methods so have billions of earthworms for the moles to eat, whereas he uses chemical weedkillers and fertilisers etc and so has very few earthworms. So our sanctuary (
) for moles was helping him to get rid of them from his land.
Another problem can be if a ewe is lambing when the ground is frozen hard and a wet lamb lands on a molehill it is more likely to stick/freeze to it than to grass or snow - I haven't seen this but was told it is so by a different neighbour who has both moles and the Baltic weather we get.