Oh! That's a 'My Beautiful Horses' model! Or at least that's what the line was called in the UK
I've an extensive collection myself, built up from the ones I had as a kid. The line included magazines with free models, packaged ponies like yours, and playsets. It ran in the 90's, but sadly fizzled out. The same moulds are used now for a different brand called 'I Love Ponies', but the quality is much, much lower than MBH. The Sheltand you have there is actually a boy named Major!
I hope you enjoy him, My Beautiful Horses are quite difficult to come across now, even more so on card, though their MOC price doesn't compare to My Little Pony unfortunately! If there's ever a time when you might consider selling him, I'd love it if you dropped me a PM