I'm very sorry to hear for your colleagues' troubles
You may be advised to check however as dogs may only arrive at LHR may only do so in the hold (unless guide dogs on domestic services). This lets their paperwork be checked before they enter the UK.
http://www.heathrowairport.com/plan-...ling-with-pets
I'd advise you to check carefully on the requirements as well, since it's still quite onerous to import pets into the UK.