Sick dogs often refuse food. Call your vet if accompanied by other symptoms.
Anxiety from change in homes, schedules, or family members can suppress appetite.
Sadness from loss of owner, companion animal, or move can lead to disinterest in food.
Painful teeth and gums prevent dogs from eating.
Some dogs simply become bored with the same bland routine diet.
Certain meds like antibiotics may cause decreased appetite as a side effect.
Obese dogs self-regulate by eating less out of instinct.