Adding a second (or third) pet changes the math on almost everything — feeding, resting spots, and how much attention each animal gets.
Feeding takes more planning
Free-feeding usually breaks down fast in a multi-pet home, since one animal often eats more than their share. Separate feeding stations, and in some cases scheduled meals instead of all-day access, help make sure everyone's actually getting fed properly.
Resource guarding is common, not a character flaw
Cats and dogs can both guard food, beds, or toys from housemates. The fix usually isn't punishment — it's providing enough separate resources (bowls, beds, litter boxes) that competition drops on its own.
The "one per pet plus one" rule
This applies well beyond litter boxes — having one extra bed, bowl, or scratching post beyond the number of pets you have reduces most day-to-day conflict.
Watch for quiet stress signals
Not every conflict is loud. Hiding, decreased appetite, or avoiding shared spaces can be signs one pet isn't as comfortable as they seem.
Shop feeders and bowls to set up separate stations for every pet in your home.