Interbrew - which signed the UK licensing agreement for Castlemaine XXXX last month and takes control of the brand from January - has tasked Cow with devising a relaunch strategy for the lager.
Cow's fees will be derived from a £9m marketing spend on Castlemaine, pledged by Interbrew late last month.
Castlemaine has been brewed and marketed in the UK by Carlsberg-Tetley since 1993.
Ketchum currently handles PR for Castlemaine, in addition to work for the company's core brands, Carlsberg, Carlsberg Export and Tetley.
However, group account director Lisa Jedan said Ketchum had done 'minimum' PR for Castlemaine in recent years, as the brand had 'focused on promotions and advertising'.
Cow won a retained PR account for Hoegaarden in April last year (PRWeek, 20 April 2001). It has also handled work for Interbrew's Staropramen and Leffe beer brands.
'Consumers identify with Castlemaine's Australian heritage. Any PR strategy will probably be Australian-themed but we want to try to modernise,' said Interbrew UK PR manager Stephanie Dawson, to whom a four-strong Cow team will report.
Interbrew has also hired Shine Communications to work on its Murphy's Irish Stout brand on a retained basis. Shine had previously worked for the brand only on projects.