Most dairy cows in Europe and the US have no horns. But this is mostly an artefact. Typically, the ability to grow horns is removed by means of so-called disbudding which, even when it is done with the use of local analgesia in combination with painkillers, may have long term negative effects on animal welfare. This suggests the need to seek alternatives. One alternative approach makes use of the genetic disposition not to grow horns (called polledness), which occurs naturally among domestic cattle but is not widespread within the typical dairy breeds. For economic reasons, the achievement of 100% polled dairy cattle through conventional breeding has a very long time-horizon. Gene-editing, most likely by using CRISPR-Cas 9, is an obvious alternative technique that has been shown to work. In this paper we consider whether using gene-editing is preferable to disbudding and conventional breeding from an ethical and a regulatory perspective. We discuss four kinds of ethical concerns: (1) naturalness; (2) respect for animal integrity; (3) animal and human welfare; and (4) human health and safety. Regarding (1) we argue that gene-edited cows are not significantly more unnatural than other modern cattle. Regarding (2) we argue that gene-edited individual cows are not disrespected. Regarding (3) we argue that there may be short-term significant negative effects on animal welfare, but that in the longer term there will be significant positive effects; and regarding (4) we argue that the well-being and safety of those working with the cattle is a strong argument in favour of polled cattle, while potential issues for consumer health are negligible. Our conclusion is that gene-editing dairy cattle for polledness seems to be a potentially acceptable and feasible solution. However, regulatory changes, either in the EU or in the US, will be required before the solution will work in practice. Recent developments in the US indicate that regulatory changes are very likely.