A warning has been issued by royal parks police after a dog carried out a "relentless" attack on a deer that had to be put down.
Footage shows the dog savaging the red deer in London's Richmond Park.
Cases of pets worrying deer in London's eight royal parks have shot up during lockdown, police say. They are urging owners to keep dogs on leads.
Separately, on Sunday, a 10-year-old child was injured by a herd of deer being chased by a dog in Bushy Park.
Police said the incident in the park in Richmond-upon-Thames, which left the child needing hospital treatment, underlined the need for people to keep their dogs on a lead if they are unsure how they will react to deer.
'Shocked and sorry'
On Friday, Franck Hiribarne, 44, from Kingston in south-west London, admitted causing or permitting an animal he was in charge of to injure another animal, in relation to the Richmond Park attack.
Wimbledon magistrates heard the doe suffered deep wounds, then received a broken leg when it was hit by a car as it tried to flee from the dog. Witnesses described the attack as "relentless".
The deer had to be put down by a gamekeeper after the attack in October.
Mr Hiribarne, who reported the matter himself to the Royal Parks Office, said he usually walked his red setter Alfie on a lead until he was well away from any grazing deer, and that the dog had been responding well to "off-lead" commands.
The dog owner, who was fined £600, said in a statement: "I was genuinely shocked and sorry for what had happened and since then I have refrained completely from letting Alfie off the leash in any park.
"I have also taken a special dog trainer specialised in gundogs to control more accurately any of his hunting instincts. He has made great progress."
Four deer have died from dog attacks in the royal parks since March 2020, while there have been 58 incidents of dogs chasing the herds - a big increase on previous years - according to the manager of Richmond Park.
Part of the increase is thought to be down to new dog owners who are unfamiliar with the best conduct around wildlife.