Generally, if the thesis sentence contains three related points, there should be three body paragraphs, though you should base the number of paragraphs on the number of supporting points needed.
Each body paragraph is something like a miniature essay in that they each need an introductory sentence that sounds important and interesting, and that they each need a good closing sentence in order to produce a smooth transition between one point and the next. It depends on the idea you want to develop in your paragraph.
Depending on the specific style of the essay, you may be able use very short paragraphs to signal a change of subject or to explain how the rest of the essay is organized. Providing extensive background may interest some readers, but others would find it tiresome.
As we travel through our lives, we will identify many people as friends.
In truth, most of these individuals are simply acquaintances. Identifying a context can help shape the topic or thesis. Then, the writer selected friends as the context, dogs being good examples of friends.