Silver blaze

In Devon, a valuable racehorse, Silver Blaze, had disappeared; its trainer, John Straker, was found dead.
Silver Blaze was ready to run in an important race in a few days' time. On the night he disappeared, a stable-boy was guarding him. The boy had a dog with him, and two other boys were sleeping above the stable.
A girl who was taking the boy his supper saw a stranger near the stables. She ran back to the house to get help, and the stranger ran away. The stable-boy said that the stranger had asked him, "Will Silver Blaze really win the race?" The boy said he hadn't opened the stable door.
At about midnight, John Straker, the horse's trainer, told his wife he was still worried about the horse. He went out, towards the stables, taking a sharp doctor's knife with him.
The next morning, the stable door was opened. The horse had gone, and the stable-boy was unconscious. Opium was found in his food. Usually, you can taste opium, but he had strong meat for supper, and that had hidden the taste.
John Straker was found out on Dartmoor. He was dead, his head crushed. His coat was hanging over a bush. Near him was his knife, and a scarf which was recognized as the stranger's.
The police found and arrested the stranger, Mr. Simpson. They said he had drugged the boy, stolen the horse and killed Straker. Simpson denied it all, and they still didn't know where the horse was.
Colonel Ross, the horse's owner, then sent a telegram to Sherlock Holmes, asking him to find the horse. Holmes and his friend, Dr. Watson, were at their flat in Baker Street in London. They had read the whole story in the newspapers. Holmes took no notice of the telegram, saying that Silver Blaze was somewhere on Dartmoor, and would soon be found.
Two days later, Holmes understood he was mistaken, and he and Dr. Watson took a train to Tavistock, in Devon. They went to the place on Dartmoor where Straker's body was found. There, Holmes found a match. Then they searched the place, and finally found the tracks of Silver Blaze. Some of the prints were alone, pointing towards Colonel Ross's stables; others had the footprints of a man with them, and pointed towards another stable.
Holmes and Watson talked to the owner there, and he finally admitted that he had stolen Silver Blaze, taken him home and hidden him. He wanted his own horse to win the race. He said he knew nothing about the murder.
Now, said Dr. Watson, the mystery was over. The police had found the murderer, and they had found the horse. Sherlock Holmes didn't agree. When they went back to Colonel Ross's stables, Holmes asked, "Was there anything wrong with any animals on the farm?" A farm-worker said that three of the sheep had gone lame.
If Simpson, the stranger, had drugged the stable-boy, he was very lucky. He couldn't know that there was meat for supper. And how did he put the drug in the food?
The two boys sleeping hadn't woken up. So the dog hadn't barked. So the dog knew the thief.
Who carries a doctor's knife for self-defence? A knife like that is for something different — like making a horse lame.
Someone who isn't a doctor would have to practise an operation of a horse's leg — perhaps he would practise on some sheep.
A man who hangs his coat on a bush, and strikes a match, doesn't run after thieves. He's going to do something difficult; like operating on a horse.
The scarf? Straker must have found it near the stables, and decided to tie the horse's legs with it. Silver Blaze became frightened, kicked back, and killed Straker.
Why would Straker want to lame a horse which he trained? Because he had bet money on another horse. Elementary, my dear Watson!