What's causing my Shih Tzu puppy's red eye and stringy discharge?

Hello and thank you for reaching out to Petco Pet Education Center, formerly Petcoach. Red or inflamed eyes and discharge can be indicative or irritation or infection, or a condition called dry eye. Shih Tzu's are unfortunately prone to many eye problems, just based on the conformation of their faces. Chloe may have an aberrant eyelash that could be irritating the cornea, or she could have a bacterial or viral infection affecting her eye. Dry eye is a condition characterized by inadequate tear production, so the eyes dry out and excessive mucoid discharge is produced to try to lubricate the eyes. If her clinical signs do not resolve in 24 hours, I recommend having Chloe seen by a veterinarian. They can perform an ocular exam to look closely for evidence of distichia (abnormal eyelashes), a cornea scratch or ulcer, infection, or decreased tear production. I hope this is helpful!