How observant of you Brietta. I hadn't noticed that it was Keela in the boot of the car and NOT Eddie
http://www.mccannfiles.com/id167.html
labelled "The full length video", but Eddie playing with CC missing. So any other things missing?
1.25.00 approx Keela entering the car
1.27.50 approx Keela in boot
1.28.38 approx. Keela alerting by silently pointing
1.30.59 approx Keela out of car
So the alert in the boot was not by Eddie and was of blood from a living person.
It was NOT a cadavar alert.
So that so called alert to cadavar odour, in the car boot, goes out of the window too .
Well done Brietta. 
Why didn't Keela search any of the other apartments but only 5A? Because there wasn't blood in any of them? No Wrong! Because Eddie detected what he is trained to find and only when that happens Keela comes in to check for blood. Eddie didn't need to go in the boot as he detected the odour he is trained to find coming out from the car i.e. the source. Martin Grime's professional opinion is the important one in this case:
SUMMARY
The tasking for this operation was as per my normal Standard Operating
Procedures. The dogs are deployed as search assets to secure evidence and
locate human remains or Human blood.
The dogs only alerted to property associated with the McCann family. The dog
alert indications MUST be corroborated if to establish their findings as
evidence.
Therefore in this particular case, as no human remains were located, the only
alert indications that may become corroborated are those that the CSI dog
indicated by forensic laboratory analysis.
My professional opinion as regards to the EVRD's alert indications is that it is
suggestive that this is 'cadaver scent' contaminant. This does not however
suggest a motive or suspect as cross contamination could be as a result of a
number of given scenarios and in any event no evidential or intelligence
reliability can be made from these alerts unless they can be confirmed with
corroborating evidence.