Hola M
Yes, you're right - the Xolo dog could have been mentioned in our reader. For those who are curious, there's the figure of a dog called "Xolo" that guides people who guides the souls of the deceased and it's often represented in the Día de los Muertos.
When we write our texts, there is a limit on paragraphs and sometimes we need to leave some details behind because it's not possible to include everything, unfortunately. But it's very useful that you mention it on the forum for other students to learn about this too.
Gracias y saludos
Inma