SimGuruSarah has answered some questions about the way pets will age in the upcoming Sims 4: Cats & Dogs expansion.
If you disable aging for your Sims then it will also disable aging for Cats & Dogs.
— Sarah Holding (@SimGuruSarah) October 10, 2017
You cannot manually age Pets up. They will age naturally.
— Sarah Holding (@SimGuruSarah) October 10, 2017