|Examine|| One proud little puppy. (Puppy)|
Looks like it's chewing a wasp. (Adult)
Bulldog was initially an Easter egg in the RuneScape Knowledge Base. However, players can now have a bulldog as a pet due to the release of the Summoning skill. A bulldog previously was seen roaming the streets of Yanille with his guardian, the Yanille Pet shop owner, before the release of the skill.
The Easter egg was revealed by one of Jagex's banner ads in early September 2007. It informed players about the Knowledge Base, and the search feature included in it. The word "bulldog" was typed in, and the search button was clicked. Search results were not shown in the banner ad.
However, this sparked many players' curiosity, and those who actually searched for "bulldog" were greeted with an article saying "Thanks for using the Knowledge Base!" and a picture of a man walking his pet bulldog. 
Jagex's wording of a Behind the Scenes article about Back to my Roots, which used the phrases, "sniffing around in the jungle" and "this quest's bark is worse than its bite" led many players to speculate that these bulldogs would be a part or a reward of this quest.
Jagex hinted that the Summoning update would include bulldogs. In the "Summoning: Part 1 - Concept" Development Diary, it said that the bulldog animation was "previously released as a teaser linked from a banner advert for the Knowledge Base". This hint was indeed true as bulldogs can be obtained from the Pet Shops in Taverley and Yanille at level 4 Summoning.
The Bulldog is a "pet" you can purchase from a Pet Shop and use at level 4 Summoning. This is a non-combat pet and the bulldog simply follows your character around. It has two stages, puppy and adult. The bulldog eats raw meat.
At level 14 Summoning, you can talk to the bulldog.
|Solomon's General Store|
|Squeal of Fortune|