Cat

Dogs are pets that Sims can own in The Sims: Unleashed, The Sims 2: Pets and The Sims 3: Pets.

The Sims: Unleashed
Dogs were introduced in The Sims: Unleashed. In The Sims, a family can adopt a dog by going to the Pet Center in Old Town, or a Sim can befriend and adopt a stray. However, the Create a Sim section of The Sims does not allow players to create pets.

Skills for dogs are Obedience, Tricks, and Housebreaking. Dogs must be housebroken by praising them when they relieve themselves outside and/or scolding them when they do it inside. A dog may or may not try to drive El Bandito the raccoon off a lot, but will ignore the burglar.

The Sims 2: Pets
In The Sims 2: Pets, dogs may be created in the Create a Pet section of Create a Sim. Sims can adopt dogs or puppies using the phone, by buying them on community lots that sell pets, or by forming a friendship with a stray dog and adopting them. Players can also get a pet dog in Apartment Life by buying the pet cage in the pets section of buy mode, although these dogs are "decorative", and are considered as small pets.

In Pets, dogs come in two sizes: small and large. A dog's size affects how long its adult life stage will last. A small dog will live for 25 days as an adult, while a large dog will be an adult for 22 days.

The wolves that are sometimes seen wandering the neighborhood, including the leader of the pack whose bite creates werewolves, are a variation of large dog. Other than the pack leader, they can be adopted like other strays. Wolves can be bred with dogs.

Unlike their counterparts in Unleashed, puppies in Pets are mobile and largely self-sufficient. They can feed themselves, if there is food available, and sleep on pet beds without the help of a Sim or their mother. Puppies can also learn Behaviors. However, puppies (as well as kittens) cannot go up or down stairs without the help of a Sim and they cannot get jobs or learn Commands. Puppies are all the same size, regardless of what size they will be as adults.

Dogs are also able to get their own careers. There are 3 pet careers: Show biz, Security, and Service.

Dogs have the same needs as human Sims, except they need to chew and they don't care about environment.

The Sims Pet Stories
Dogs in The Sims Pet Stories are just like the ones in The Sims 2: Pets, only now dogs can use story reward objects (such as a-frames, tunnels...) to work on for the pet show and doing that earning skills.

The Sims Castaway Stories
Dogs in The Sims Castaway Stories are actually Hyenas. Their appearance has changed, though all of the options from The Sims 2: Pets are still available (e.g., Stroke, Razzle, Feed treat, etc.).

The Sims 3: Pets
Dogs are featured in The Sims 3: Pets along with cats and horses, and appear to be largely similar to those found in The Sims 2. They are controllable and have their own traits and wishes. Dogs are able to form any type of relationship with cats and horses, except mating.

The dog needs consist of Hunger, Energy, Fun, Social, Bladder, and Destruction. When their Destruction need is too low, they must use the Chew interaction on an inanimate object, which can range from a toy to a statue. They can also use the Guard interaction on a wide variety of objects, from food bowls and toys to the entire house. They can get a job in The Sims 3 Pets for console, but not in PC version.

Trivia

 * The hyena skin from The Sims Castaway Stories can be imported to The Sims 2 (if the Pets expansion is installed) or The Sims Pet Stories. Copy the hyena skin from the PetBreeds folder for The Sims Castaway Stories and paste it into the PetBreeds folder for The Sims 2 or The Sims Pet Stories. In all three games, the PetBreeds folder is located under the  folder.
 * When a dog dies in The Sims 2: Pets, they will enjoy a last game of fetch with the Grim Reaper.