There are two reasons that a dog will tend to eat faecal matter:
Dogs tends to gulp their food rather than chew it, so much can passed through
their system undigested.
Bitches often eat the faecal matter of their young as part of an evolutionary
response so that predators are not drawn to the den by the odour from faeces.
Deterrent is the answer!
We therefore looked at a logical approach to the problem – if the faeces
tastes and smells unsavoury, then the habit of eating faecal matter can soon
be broken. So the task is to have a product that is palatable when added to
their regular food, yet would deter the dog from eating it again after it had
passed through the digestive tract.