Reading over the other responses, I really like Lunameyza's suggestion of having simplified icons indicating which pieces of tack are present, rather than the image of the actual tack that was equipped. I agree that, on the entry page (especially for conformation shows), the most important information to display is whether or not the horse is tacked (with the appropriate tack for that discipline), not which specific tack they have. There could perhaps be a tool tip for each image that shows which specific piece of tack the horse has if you want to check.

That said, showing the actual tack images isn't entirely without use. For example, if someone is upgrading the tack on all their horses, the entry page is a quick way to see which horses still need upgraded tack - I use it for this whenever I buy a new team of horses to quickly see what quality tack they're each equipped with and swap out the low-quality pieces. But that's a very specific use case, and that information isn't needed all the time, and this is a bit of a work around for not being able to see that information easily anywhere else. Improving the inventory/equipping process so that the entry page doesn't have to be used for this would be the best option of course, but obviously not something that could be done in the near future. I'd still prefer having the simplified icons from an accessibility/ease-of-use standpoint, with possibly a toggle to switch between "icon" view and "tack" view, if it was possible without too much effort.

Or maybe a different approach to the problem: Is it necessary to show which kind of tack a horse exactly has on in such a small sphere? Isn't it more about if a horse has a certain tack on (for example, a saddle, a halter, carriage, just as a global category) because if the latter option is fine, why not remove the sphere (which also kind of doesn't fit in the style of the entire graphic design, it looks odd) and only add simple looking, one colour (dark grey?) shape of the category(s) of tack a horse has on it. Like simplistic icons. Would players really use the sphere with the tiny tack image inside to see if the horse is wearing a basic dressage saddle or a supreme one? I don't think so, I think players use these icons to just make sure the horse has the tack on that's needed, if they want to know what kind of tack exactly, they'd go to the horses profile I'd assume. This way you can display simplistic tack icons in a row for a quick and cleaner overview.

Do you have an idea which colour could work better?