Previous shelter id numbers are unique numbers that some cities and counties use to identify animals in their system. Certain users may want to enter and track an animal's previous shelter id (and which previous shelter issued the id number) not just the partner that an animal is transferred from.
An animal's record can also have multiple previous shelter id numbers and they are all searchable via the advanced search field. This helps users easily reference and easily search for previous shelter id numbers since certain organizations only identify/recognize animals by this number rather than by microchip or name.
To enter a previous shelter id number during intake (and the fields on an animal's main mage associated with the previous shelter id number - previous shelter id type and previous id issuing shelter), go to Configuration > Intake and Outcome > Intake Forms. Enable the options for these fields in each intake form you'd like to enter information for (click the eye for each field you'd like visible and the star if you'd like it to be required on the form).
These fields will not automatically populate with the partner the animal is transferred from because the previous shelter id number may not have been issued by that partner. The animal may have been to different organizations between the time they were first issued a previous shelter id number and when they were transferred to you so these fields will not be linked with partners.