LUCKNOW, May 28 -- A man allegedly killed a stray dog by slitting its throat, in Lucknow's Nigohan area, prompting outrage among locals and dog lovers after a video of the incident surfaced on social media, police said on Wednesday. The man was detained, and following a medical test, it was found that he was mentally unstable, police said, adding that he has been sent to a rehabilitation centre, till the investigation is on. A purported video of the incident, which has gone viral, shows the man pinning down the dog's body with his foot while using a knife on its neck. The video also appears to show blood splattered around the spot as bystanders can be heard asking him to stop. Nigohan SHO Anuj Kumar Tiwari said police were verifying the video and the circumstances surrounding the incident. According to separate complaints submitted by villagers and an NGO, the incident took place on Tuesday. The accused was identified as Ballu, son of Gaurishankar, and a resident of Nigohan village. Residents alleged that the man first repeatedly slammed the dog to the ground and later slit its throat with a knife....