no that will be offensive, rude
no i won't recommend to use the word perro for anything else but referring to the animal dog,

i'm translating an old story, so i'm thinking maybe it meant dog literally. so maybe it's a fairy tale type thing...

Ok in the context you are using is "But , give us water for our hands" wich is "pero" like "pero por que" wich is "But Why" now if you use Perro that is a dog wich now that i'm reading your context out of anger somebody can call somebody a dog hope I helped

Perro is dog, but in that context is a way to call someone (probably a servant or an attendant) in a very rude mode. It's more an insult to someone who cannot respond to it due to his low social level.

Quizás la persona estaba realmente refiriendose a su perro. Necesitaríamos más contexto...
¿La persona que lo dice, tiene sirvientes, o no? Porque si no los tiene, tal vez quería que su perro (su mascota), se convierta en sirviente, y les traiga agua para lavarse las manos, siendo de esa manera el animal más útil en la casa.

to refer a person "perro" is a very bad expresion. its mean that the person is compare whit dog

Do you know the meaning of the word "puno"?

Puno is the name for the inhabitants of the old Cartago about two centuries ago, ej. Los romanos atacaron a los punos.
Puño is fist.

This reminds me of some T-shirts that I used to see in Spain that said "Cono sin eñe es una figura matemática".

"Perro", applied to people means "swine", a despicable or worthless person.

Corrections: Cartago is the Spanish name. I meant "Carthage", and "millenia" instead of "centuries" (imagine the Romans still fighting two hundred years ago!).