The Heffleys' Pig

The Heffleys' Pig is a baby pig owned by the Heffley Family, first introduced in Diary of a Wimpy Kid: The Long Haul. It seems that it is only fond of Manny, just like how Sweetie he is only fond of Susan and Gramma. It's the 2nd farm animal won by the Heffleys after a goat (mentioned in Diary of a Wimpy Kid: Cabin Fever) which was won by Greg for correctly guessing a goat's weight, but Frank didn't let them keep it, just like that case, Frank didn't want to keep it but Susan says she can't return it. Rodrick agrees to keep the pig.

The Long Haul
The Heffleys won the pig in the Highway 1 Country Fair for guessing the weight of a grown hog correctly. The baby pig was originally gonna be returned since Susan Heffley only entered the contest for fun. But the crowd was insulted, and wouldn't take no for an answer, which made her change her mind. The baby pig would eventually "imprint" on Manny.

The pig caused trouble for the Heffleys. They tried to bring it into the the second hotel they stayed at by hiding it in the cooler. While there, it caused a mess in one of the bathrooms, and ate all the food in both of the minibars. Later, while in the van, it woke up and caused chaos, which resulted in Greg Heffley getting bit by the pig. Because of all that Susan put the pig in a petting zoo. Manny was heartbroken by the news, while the Heffleys took Greg to a vet to check Greg's bitten finger. The Heffleys came back for it later, when they where aided by two Spanish men. At home, Susan managed to teach it some tricks.

Personality
The pig is suprisingly smart. It somehow opened 3 cans of soda and can use the TV remote to watch television with Manny. That makes Greg feel annoyed.

Trivia

 * According to the page 104 of Diary of a Wimpy Kid: The Long Haul, the pig is a male.
 * It is a domesticated pig as it is from a livestock of a farm, and farms have domesticated pigs.
 * The name of the pig is currently unknown, but it is likely that Manny named it due to him being Manny's closest friend.