Aggressive is a pet trait featured in The Sims 3: Pets, The Sims 4: Cats & Dogs, and The Sims 4: Horse Ranch.
The Sims 3: Pets

Aggressive is a trait that is available for all playable pets - cats, dogs and horses. It conflicts with the friendly trait.
Aggressive pets aren't inherently mean, they usually just have a bad attitude when interacting with other pets. A bad attitude that usually leads to fights that is...[TS3P]
Aggressive pets love to show how tough they are by fighting with other pets and chasing Sims. It's best not to get between an Aggressive Pet and their food![TS3PETSC]
Attributes
- Pet will be more likely to get into fights with other pets.
- Pet will always catch burglars that come onto your lot.
- Pet will be more likely to chase the mailman.
- Aggressive pets are more likely to win fights against other pets.
Aggressive pets
The Sims 4: Cats & Dogs

The Aggressive trait is only available for dogs, but cats have a functionally equivalent trait called Territorial. It conflicts with the Friendly trait.
These dogs will be more hostile when greeting others and might attack others unless properly trained.
Attributes
- Dog may attack Sims and other pets.
- Sim can tell dog to "Be Aggressive To..." another sim or pet, causing the dog to pee on the target Sim, or attack the target pet.
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Aggressive pets
The Sims 4: Horse Ranch

The Aggressive trait is for only horses. It conflicts with the Friendly trait.
These Horses are cranky! They act meaner towards other Sims and are more difficult to train.
Attributes
- Horse is more mean to other sims as well as other horses.
- Horse will be more difficult to befriend.
- Horse will be harder to train.