No idea depending on which MSM source you are reading?
"At 48 Benaroon Drive, police sniffer dogs picked up William's scent, but only within the boundaries of the property.
The day William Tyrrell vanished
"Police dogs were brought in and they managed to find William's scent, but only within the boundaries of the backyard."
William Tyrrell: The boy no-one can find
Re police dogs: the Where's William Tyrrell? podcast (episode 3: "One Last Roar", 08 July 2019) has an actor reading from a police statement by the senior constable who searched Benaroon Drive on 12 Sep 2014 with Police Dog (PD) Gov. It only talks about searching the neighbourhood, not the No.48 house and yard, so presumably this is only part of the statement? Transcribed by me:
"Upon my arrival, I assessed the area and found that tracking was impossible. This is due to the amount of time that had passed between William Tyrrell going missing and the time it took for me to travel to Kendall. During my assessment of the area I was told William Tyrrell was last seen at the rear of the house. The house is the last cul-de-sac, which is bound by thick bushland. It sits on the top of a hill. The easiest line of travel for a person leaving the house was downhill in an easterly direction. I decided it would be most effective for me to begin a search of all the yards heading downhill, away from the house. This was also the direction of travel to the Kendall township, which I believed to be the most likely place a child would walk. I started searching all the rear yards heading in a westerly direction down Benaroon Drive. I was followed by two general duties police and several members of the public, who started a line search approximately 20 metres behind me. PD Gov and I checked in the sheds, play equipment, garden, or any other area a child might hide in. The police behind me spoke to any residents they could find, and checked any houses that were unlocked. They also double-checked the areas PD Gov and I had searched. When we got to the last house on the northern side of Benaroon Drive we crossed to the southern side and began to search in the same way back up the hill towards the end of the cul-de-sac. At no time had I located a scent or a starting point for a search or track. No items of clothing or property relating to William Tyrrell were located during this search."
This link goes to the acast version, where the relevant bit started at 42:54. (On apple podcast it started at 43:25.)
I don't believe I have ever read an MSM article which quoted Fehon or police stating W's scent was found within the yard, or that W's scent wasn't found past the curb/driveway/property edge. Could be wrong, but I don't recall that. They were however, reported to have said that no scent was found, period.
Neither police sniffer dogs nor cadaver dogs had been able to pick up any sign of the boy, Fehon said.
William Tyrell search: police say sniffer dogs have found no trace of boy
Police Strike Force Rosann has been established as sniffer dogs fail to pick up any scent of William Tyrell, five days after he went missing on the NSW mid north coast.
....
Superintendent Paul Fehon says neither police sniffer dogs nor cadaver dogs have been able to pick up any sign of the boy, fuelling fears he may not have wandered away from home.
http://www.nbnnews.com.au/index.php...dogs-fail-to-pick-up-scent-of-william-tyrell/