To leave dogs outside of food shops

On Saturday evening I went to an M&S food store and a woman carried a dog round the shop, stopping at intervals and leaning into cabinets. When she had completed her shop she stood at the checkout and the assistant fondled the dog and then carried on checking food through. Other assistants came over and patted the dog too. I thought it was against hygiene rules to do this. I am very annoyed and considering not shopping with M&S in future