Tack thet is a huge problem in the UK.
Then again a tackroom on a big yard is a gold mine for thieves. Often on a large yard one can have upwards of £60,000 worth of tack on site and generaly tack is not marked, not identifiable and very easy to sell on!
I personaly UV mark all my tack and it all has microchips, this makes my saddles hot to handle (and I have signs up to ensure any potential thief knows this) and I've yet to be broken into but others get hit regularly.
Often they also take any trailers, lorries and farm equipment at the same time
Tack theft is big business:
Hot Saddle News
£100,000 of tack stolen from saddlery in Droitwich - Equestrian news, equine news, horse news - Horse & Hound
Stolen £15,000 and £20,000 worth of tack stolen! [Archive] - Horse and Hound Forums
Stolen 22 Saddles Stolen - Wiltshire [Archive] - Horse and Hound Forums
Stolen Tack stolen in frensham [Archive] - Horse and Hound Forums