Greetings!
Another way to do it would be to introduce a 3rd field in your data that can be called Header. This field would contain only one value repeated for each of the records. So in my example:
RecordID Value Header
1 cat Data
1 dog Data
1 horse Data
You can accomplish this easily by bringing in a Formula Tool, creating a new string field called Header and using the expression:
"Data"
Now bring in a CrossTab Tool. Here you will Group by RecordID, select Header as your Header Field, and Value as your Data field. In the Methodologies section choose Concatenate, and change the separator from the default comma to the semicolon (you can also use a semicolon and a space if you want your records to be visually spaced a little bit.