"The dog and the cat eat meat."

Translation: Le chien et le chat mangent de la viande.

[karashocks]

Why is 'le chien et le chat mangent la viande' incorrect? Why do I need 'de la?'
How can I tell when to use 'la/le' and when to use 'de la/le?'

[poopheaderic]

I think in this context, meat is a mass noun and not a count noun ...

[Mathew87]

Why is "la chatte" incorrect?