When Stark lost consciousness while crossing the street, it was Hoover who started barking and caught the attention of a distracted driver who was about to crash into them. He also allerted passersby who were able to call for medical help.
Stark was able to have Hoover in his room while they treated him, but as Stark neared death, he asked that Hoover be brought over so he could pet him one more time. Stark soon passed away.
When House heard about Stark's death, he got out of his own hospital bed (he was recovering from a self-induced electrocution) and went to see him before he was brought down to the morgue. He soon noticed Hoover was dead too. Dr. Desai, who was a veterinarian before she became a physician, tried to put it down to the fact that animals commonly pass away soon after their owners, particularly when the animal is old as well. However, Dr. House remembered that Stark had been prescribed Ivermectin, which is also used in veterinary medicine. He turned to Thirteen and asked her if she had seen Stark actually take the pills he had been given. He confirmed with Dr. Desai that Ivermectin is deadly to English Sheppards, then searched the room and found a pill cup with dog teeth marks on it. House told Thirteen the appropriate answer was "No". They had correctly diagnosed Stark with strongyloides, but had mistakenly believed he had taken the Ivermectin and not gotten better. Instead, the pills fell to the floor where Hoover ate them and suffered a fatal adverse reaction.