A search for "Cat" returns one result in this example

A search for "Dog" also returns one result. As this is a category field. we can add a search filter to quickly narrow down our search criteria.  Click "Admin" once you have logged in with Administrator credentials.

Select the ellipsis (...) button on the category field. In this example, we have called the field "animalcategory". 

Filter options
Use as filter 

Do you want to use this field to filter your standard search results? Ticking this option will allow you to drill-down into your result set based on the contents of this field.

Additive filter 

Check this to make the filter additive so that users can select multiple options for this filter.

Number of options to show in result filter 
*

This is the maximum number of option links shown by default for this filter. Where the number of options is higher than the value configured here, the less popular options will be hidden behind a 'More' link.

Order filter values by:
Most popular first (Default)
Ascending order (A to Z)
Descending order (Z to A)

Choose your option for "Sorting" and click "Save"

Now search results can be filtered down to either of the "Terms" in our category field -  "Cat" or "Dog" in this example.

Now we can filter our search to either the "Terms" in our category field -   "Cat" and "Dog" for this example.

Add a filter to the search page