Dogs can lose their appetite when they have pink eye. It's very common to have loss of appetite when having pink eye. It will also cause sneezing,coughing,nasal discharge,fever,lethargy. Just a simple eye irritation.
Conjunctivitis or "pink eye" in dogs can make them quite uncomfortable. In mild cases from environmental causes the appetite of your animal should not be affected. Now if there is a more serious underlying cause, that could cause a decreased appetite. If your animal has seen a vet and was prescribed oral medications, those medications could also decrease the appetite.
When a dog is not feeling well it is very possiblefor them to lose their appetite. Especially if they are on antibiotics, it might upset their stomach.
