Generally, a greyhound's career will end between the ages of four and six – after the dog can no longer race, or possibly when it is no longer competitive. The best dogs are kept for breeding and there are industry-associated adoption groups and rescue groups that work to obtain retired racing greyhounds and place them as pets. In the United Kingdom, according to the BBC, one in four retired greyhounds finds a home as a pet. An UK industry produced report for DEFRA in 2018 showed that actually only 1 in 7 racing greyhounds were not found a home when they retired.  In the United States, prior to the formation of adoption groups, over 20,000 retired greyhounds a year were killed; recent estimates still number in the thousands, with the industry claiming that about 90% of National Greyhound Association-registered animals are either adopted or returned for breeding purposes (according to the industry numbers upwards of 2000 dogs are still euthanized annually in the US while anti-racing groups estimate the figure at closer to 12,000. ) Other greyhounds are sold to research labs, such as Liverpool university animal training school, who have received the remains of dogs killed at Manchester's Belle Vue stadium. A trainer in Lincolnshire was also exposed offering 'slow' dogs to the Liverpool school. Additionally dogs are sent to foreign racetracks such as Spain and sometimes in developing countries.  In the North East of England a man is believed to have destroyed as many as 10,000 healthy greyhounds with a captive bolt gun.