The "red eye" phenomenon in photographs is caused by the reflection of the camera's flash off the back of the eye. This happens because the pupil dilates in low light, allowing more light to enter the eye. The light from the flash then reflects back out through the same path, creating the red glow.
If you're noticing your toy poodle's eyes appearing red at night, it's likely due to the way the light is reflecting off their eyes, especially if they are in a dark environment. However, if you're concerned about your dog's eye health, it's always best to consult a veterinarian. They can check for any underlying health issues and provide guidance on proper eye care.