Alter Table script does not recreate Foreign Keys after dropping them
An Alter Table from the Object Explorer, is used to add/remove a column, or change a column's data type. The SQL Script produced by Toad drops Foreign Keys associated with the table, but does not recreate them after the table is recreated. This happens regardless of whether the column being changed is part of the Foreign Key. This issue does not occur if the column is simply renamed.
Waiting for fix in a future release of Toad for SQL Server.