Many animals that appear to be depressed or grieving begin to exhibit self-destructive behavior that sometimes ends in death.[2] In 1845, the Illustrated London News reported that a Newfoundland dog had been acting less lively over a period of days before being seen "to throw himself in the water and endeavor to sink by preserving perfect stillness of the legs and feet".[2] Every time he was rescued he attempted to do this again before he finally held his head underwater until death.[2] Other dogs, as well as ducks, have also drowned themselves.[3] One duck did so after the death of its mate.[4] At Overtoun Bridge in Scotland, many dogs have been known to leap to their deaths; although long reported to be suicide, many scientists have now attributed it to the smell of mink.[5] Some dogs will refuse food after the death of their owner until they die as well.[4] In 2009, 28 cows and bulls mysteriously threw themselves off a cliff in the Swiss Alps over the span of three days.[6] One deer leapt from a cliff to its death so as to avoid being captured by hunting dogs.[4] Another famous example of animal suicide is the case of the dolphin which most often portrayed Flipper, on the 1960s television show Flipper. According to trainer Richard O' Barry in the film The Cove, Kathy, the dolphin, drowned itself before him.[7] Suicidal behavior has been observed more in female animals than male and in more vertebrates than invertebrates.[8]

Source: en.wikipedia.org/wiki/Animal_suicide