There is nothing wrong with having questions based on other questions. Providing, each question is self contained. Providing linked questions (and answers) is a useful process for enabling people to navigate the website.
Josh's examples are good to provide illustration of this.
The example question you gave is not useful for the purposes of this discussion, as it is being discussed in length in two other meta posts, on three posts in beta and within chat. If the purpose of the question is to address questions like these, I suggest this question be closed as a dup.
Human medications on pets
When are medical questions on-topic?