Hi there
Just thought I would add, I am an eye doctor so I had to learn about the differences in animals vs human eyes. Nancy 1999 is very correct, all animals who have 'nocturnal' or night time visual needs have a tapetum lucidum. It's part of their Retina's. A human's eye is pink/red in the back thus "red eye" I have seen the tapetum lucidum during dissections and it's super pretty
almost like the inside of an oyster shell!
Just thought I'd add
If anyone had doggy eye questions I'd be happy to help