PubMed also allows searching through Medical Subject Headings (MeSH). This is a controlled vocabulary of subject headings that get assigned to all articles that are fully indexed within the database. Searching via MeSH allows for a more precise search while also allowing you to apply subheadings to narrow the scope of the broad subject heading search.
To search these subject headings, change the default PubMed search to MeSH:
Input your search terms. Notice how PubMed will automatically map entered terms to the controlled vocabulary:
Apply a subheading if you like, then click on "Add to search builder", then "Search PubMed" to see your results.
PubMed allows you to limit your searches by article type. Once you've executed your search, click on the Customize option on the left. Choose the article types you are interested in. They will now show up on the left hand side. Click on the ones that you want to limit your search to.
Another filter option that is useful for veterinary students is the "Other Animals" filter. This will limit the search results to those articles that are about any other animal than humans.