"Dogs eat more than cats."
Translation:Hunder spiser mer enn katter.
"more than" = "over" when you're not comparing, e.g., "She earns over $10,000 per month." Or, "She earns more than $10,000 per month."
However, if you're comparing, you can't use "over," e.g., "She earns more than he does." You can't say, "She earns over he does."
I'm adding a new hint to the English sentence, but it may take a few days before the change is visible.