Dog

$$ 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 or by buying them on community lots that sell pets. 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.

Unlike their counterparts in Unleashed, puppies in Pets are mobile and largely self-sufficient. They can feed themselves (provided 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.

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. The appearance has changed though all of the options from The Sims 2: Pets are still there (ex. Stroke, Razzle, Feed treat, etc). The cat version in this game is the jaguar, Mata, only available during the story (though there is mod for adopting jaguars).

The Sims 3: Pets
Dogs will return in The Sims 3: Pets and appear to be largely similar to those found in The Sims 2. Dogs are able to form relationships with cats and horses. In the trailer, a burglar is seen running from three dogs; this could possibly be a helpful alternative to the burglar alarm. Dogs are also able to get jobs, much as in The Sims 2. Unlike in previous Sims games, dogs in The Sims 3: Pets can be controlled by the player, as opposed to the NPC pets in The Sims Unleashed and The Sims 2: Pets.

Dogs will also, like Sims, have their own traits such as Adventurous and Loyal.

Trivia

 * You can import hyena dog skin from The Sims Castaway Stories to The Sims 2 (if The Sims 2: Pets installed) and The Sims Pet Stories, just copy the hyena skin from The Sims Castaway Stories petbreed folder and paste it to the petbreed folder on The Sims 2 and The Sims Pet Stories. Both folder is located on the my document where your game data stored.
 * When a dog dies in The Sims 2: Pets, they will enjoy a last game of fetch by the Grim Reaper.