Thank you all for your replies and interest in my posting. I want as many people to know about this incident and the fact that no one cares. The Animal Reception Centre an Heathrow did not appear to do their job very efficiently. They compiled a report (after a lot of pressure and 6 months later) in which they admitted that the plane landed at 14.30 but my dog was not available for me to collect until 19.30. This was on one of the hottest days of the year. NO ONE knows what happened or where she was for the 5 hours.
Capt Hangover, thank you for your kind enquiry. My little dog never fully recovered and very sadly died shortly afterwards.