Hi Doctor I Have A Six Year Old English Springer

hi doctor I have a six year old english springer spaniel i feed her once a day at around 4:00pm and she eats well every day 5 days ago she stopped eating she will eat the odd treat and i gave her alittle bit of my pork chop last night which she ate readily but other than that has no interest in her usual food. she does not appear systemically ill drinking well running around like usual she is drinking fine sleeping fine she appear quite normal other than no interst in eating.............Thanks for your help Steve