Why is my puppy suddenly sad, not eating, and has a runny eye?

Hi Catherine! I'm sorry Gabbanna isn't doing well. It is concerning that she is lethargic and not eating, but this could be due to teething. She is at the age where puppies teeth, and that can make them lethargic and not want to eat due to pain. Try soaking her dry food in warm water to make it softer for her to eat, or you can give her wet food. I would get her a teething toy from the pet store that you can freeze in the freezer, as that will give her something hard to chew on it and the cold will be soothing to her gums. As for her runny eye, that can be a sign of an eye infection, allergy, or injury to the eyes. The eye is such a delicate and important structure that any problem with it should be considered an emergency. That's because leaving it untreated can lead to vision loss. I would take Gabbanna into a vet right away. The vet can diagnose what is causing her eye to weep and can prescribe medication for it. The vet can also examine her to see if she is teething or if there is another cause behind her lethargy and not eating, such as a systemic illness.