These days more and more museums have wonderful online access to parts of their collections - even items not on display in the regular exhibition halls. The Metropolitan Museum of Art has a lovely searchable set of horse-related items you can view online.
Browse the whole set of horse trappings here. Or take a look at this spectacular 16th century Italian saddle. It is described in part as "a rare example of a complete European war saddle" with "vividly hued silk velvet covering, highlighted with glistening gold thread." (Source: Saddle [Italian (Milan)] (04.3.252) | Heilbrunn Timeline of Art History | The Metropolitan Museum of Art )