http://www.danielpipes.org/comments/120729
(from Sahih Muslim, Book 024, Number 5246)
“A’isha reported that Gabriel (peace be upon him) made a promise with Allah’s Messenger (may peace be upon him) to come at a definite hour; that hour came but he did not visit him. And there was in his hand (in the hand of Allah’s Apostle) a staff. He threw it from his hand and said: Never has Allah or His messengers (angels) ever broken their promise. Then he cast a glance (and by chance) found a puppy under his cot and said: ‘A’isha, when did this dog enter here? She said: By Allah, I don’t know He then commanded and it was turned out. Then Gabriel came and Allah’s Messenger (may peace be upon him) said to him: You promised me and I waited for you. but you did not come, whereupon he said: It was the dog in your house which prevented me (to come), for we (angels) do not enter a house in which there is a dog or a picture.”
Also; Sahih Muslim, Book 024, Number 5248:
“Then on that very morning he commanded the killing of the dogs until he announced that the dog kept for the orchards should also be killed, but he spared the dog meant for the protection of extensive fields (or big gardens).”
My interpretation is that mohammad hated dogs because they barked and alerted the villagers and tent-dwellers to the approaching gang of mohammad and his raiding parties. The story about an illusionary angel is typical of mohammad’s cunning. He simply wanted to eliminate the alarm system of his intended victims.
Thanks Fred Nerks!