Where there’s horse muck, there’s brass

‘Spotting a pile of horse manure my father would give a joyous shout of “Road apples!”, pull to a halt and jump out to gather the treasure.’ Photograph: Maureen Ruddy Burkhart/Alamy

Setting aside the general etiquette of picking up (or not) after horses (Letters, 19 January), there is in fact decent evidence that dog poo poses rather more of a public health risk than horse muck – in terms of pathogens, parasites, diet, and how long the stuff remains infectious.

This is not a new debate. As a sergeant in the mounted department in the 1990s, I once found myself dispatched to Radio Merseyside’s Roger Phillips phone‑in to defend our position during an entire programme devoted to complaints about police horses leaving their calling cards in the city centre.