Dogs Not Eating After Being Sick?

I have a 5 year old Labrador and a rescue dog believed to be 9 (who we have had for a year now). Two days ago the Labrador was sick three times during the day and night, the day after he wasn't sick and he ate some food in the morning, but in the evening he refused to eat which was very unusual for him. The rescue ate much less then he usually does.

Today neither he nor the rescue are eating. This is very unusual for them, but they still seem happy enough and were eager for their morning walk. They are fed dry food by the way, in the morning and in the evening.

By Rick S.