And usually, I would say "She loves dogs"! But that's not important right now ;) "σκύλοι", "σκυλιά", same thing. "the dog" is (a) "ο σκύλος", plural nominative "οι σκύλοι", plural accusative "τους σκύλους", or (b) "το σκυλί", plural nominative and accusative "τα σκυλιά". As you can see, there is nothing wrong with your sentence, but the missing "tónos" from the first word! "σκύλος" can also sometimes mean specifically "male dog".
for elephants in one previous exercise was "τους ελέφαντες", using the nominative plural
No -- using the accusative plural.
(Which, for this word, looks like the nominative plural. But the article is different: οι ελέφαντες, τους ελέφαντες)
and not ending in "ους", as the dogs case. Why is this?
Because σκύλος is second declension and ελέφαντας is first declension.
They're both masculine, but they have different sets of endings.