Starr was responsible for a marketing budget in excess of £50m across leading cat- and dog-food brands including Pal, Whiskas and Frolic. It is not known whether he has another job to go to.
His predecessor, Ann Francke, also left Masterfoods abruptly, at the end of 2002 after three years in the job, before emerging as Boots' strategic marketing director in 2003.
Starr was previously a regional director for Masterfoods in South-East Asia.
Separately, an unnamed Masterfoods European petcare marketer is poised to join Muller Dairy UK as its marketing director. The individual will replace Mike Driver, who is leaving the company after 10 years to join management consultancy firm Myriad Consulting as a managing partner.
Driver's exit is the latest shake-up in Muller's marketing operations since Andrew Harrison joined the company from Nestle Rowntree earlier this year.
Last month it was reported that Masterfoods was using Agency Insight to review the direct marketing activity for its Whiskas, Cesar and Pedigree brands.
No one at Masterfoods was available for comment on the moves.