There are many obvious exceptions to this so please don’t type up an indignant response about how much your trainer loved the custom halter you bought her new import last year but in general. At the end of the day you know your trainer best. In general, though, it might make sense to take a moment to step back and consider whether a horse-related item is really the best gift for your trainer.
Your trainer most likely gets almost exclusively horse-related gifts, be it tack, gift cards or home decor/clothes/jewelry. Multiply this by how many years your he/she has been in business and you can begin to imagine the amount of wine bottle holders made out of horse shoes that are collecting dust in the basement.
In addition to not really needing another piece of tack or equestrian themed throw blanket, keep in mind that in the same way that you don’t eat, sleep and breathe your job your trainer most likely has interests that lie outside of horses. It would mean a lot if you can acknowledge that slightly neglected golf or (insert here) hobby. If all else fails, wine is great. Restaurant gift cards are usually a huge hit.
In summary, our trainers are generally the polar opposite of us ammies, whose Christmas lists are typically comprised almost solely of horse-related items. They are steeped in horses 24/7/365. Sometimes they want to go home from the barn and not be surrounded by bit motifs and decorative horse shoe contraptions. Unless you know of something specific and special your trainer has been jonesing for, it may be better to go non horse-related for holiday gifts.
I’m just saying it because my trainer is too nice to say it! No offense meant, of course - if your trainer isn’t flattered you got him or her a gift at all than he/she is an ungrateful wretch!