My hamster can’t open its eyes, something seems crusted over, and its tail area is wet.

Hello. Based on your description, with the hamster unable to open its eyes and a wet tail, wet tail disease is likely. Hamster wet tail is a gastrointestinal disease caused by bacteria, parasites, or fungus, with common signs of severe diarrhea, a wet and dirty tail, lethargy, weight loss, abdominal mass, lowered body temperature, and tremors, triggered by environmental change, improper diet, or other stress.

Treating wet tail usually requires glucose and electrolyte solution to prevent dehydration, plus antibiotics such as neomycin sulfate or gentamicin.