To make a service automatically update a patient's status, you'll need to access your products and services database and select the specific service. To do that:
Select 'Products' from the dropdown
Search for the product/service
Click the service
This will allow you to edit—and add an automatic patient status update to—the service.
Note: this is only available for services.
With the service page open, scroll to the bottom and click the 'Update Patient Status' box (pink). There you'll be able to update one of two statuses:
Female Spayed/Male Neutered
Select which status the service will update and click 'Save' to finish.