Sykes is John and Sarah Barnaby's loyal and highly intelligent pet terrier, and has been a part of the Barnaby household beginning in Series 14. As the 'only child' of the Barnaby household Sykes grew used to the sole, undivided and loving attention of the Barnabys until Sarah became pregnant and they had a human child of their own. As their daughter Betty began to consume the Barnaby's time, Sykes became jealous and in the first episode of series 18 stole Betty's favourite toy, Pink Ted and hid it in strategic locations, such as John Barnaby's car.
In the first Episode of Series 19 (The Village That Rose from the Dead), it was revealed that Sykes had passed away and we see the Barnabys putting up a little memorial cross with Sykes' name on it.
Note: The reality was that at over 13 years old, Sykes' handler and trainer, Gill Raddings, informed the show that it was time to retire Sykes. Sykes had appeared in 29 episodes of Midsomer Murders.' '