The National Office of Animal Health (NOAH) represents the UK animal medicines industry: its aim is to promote the benefits of safe, effective, quality medicines for the health and welfare of all animals.

This webpage presents the industries viewpoint that "There is no evidence that populations of dung beetles and flies are adversely affected by the use of endectocides", but they would say that woudln’t they?

They cite Wratten, S.D. and Forbes, A.B. (1996) Environmental assessment of veterinary avermectins in temperate pastoral ecosystems, Ann. appl. Biol, 128, 329-348. and the page is dated October 2007.

More recent research has confirmed the drastic effect ivermectins are having on dung insect population, and their dependents down the food-chain, especially bats.

Of course if you found research from 1996 to support your position way back in 2007, why would you want to update your webpage?