Three people are being treated for exposure to rabies after they were bitten by a puppy brought in to England from Sri Lanka.
The puppy was being held in a licensed quarantine premises in the south-east of England when it became ill and later died.
Initial tests showed positive results for a strain of rabies, the UK's Department for Environment Food and Rural Affairs said.
The three people are being vaccinated.
Other animals that have been moved from the kennels are being traced and monitored.
Rabies is a viral disease of the nervous system and can affect all mammals.
It is spread by direct contact mainly by saliva from the bite of an infected animal or through scratches.
British government vets said the incident had been contained and it was highly unlikely the disease had spread to other animals.
Acting Chief Veterinary Officer Alick Simmons said on Defra's Web site that while initial tests show that this puppy has tested positive for rabies, this shows that the system is working and the case has been picked up while the animal is in quarantine.
He said this means it is contained and the UK's rabies free status remains in place.
The puppy entered Britain on 18 April and died on Friday. The rabies virus can lie undetected for up to 10 days.
