Ideas
Pets including horses, are missing from every premade townie household that comes with pets when I start a new save. For example, all the pets in Chestnut Ridge and Brindleton Bay. They show in the Manage Household picture but when I enter the household through CAS or when I load into the household in live mode they are missing. I have repaired the EA app and uninstalled/reinstalled the sims 4 but that has not resolved the issue. I am not using mods. It does not seem to be happening in saves created prior to the August update so I am guessing that the problem started after the update.
This is happening to me too! I thought it was one of my mods, but I disabled all of them, repaired the game, and started a new save, but I had the same issue where all pets are gone.