Bucking at the start of a ride is one of the most mishandled saddle problems in western horses. The "cold back" label gets applied too quickly and too broadly — masking genuine physical problems getting worse every ride.
Cold-back behavior is a brief, stable, predictable reluctance that resolves within a few minutes. A horse that bucks with increasing intensity or frequency, shows back soreness, or reacts differently to different saddles is almost certainly experiencing genuine pain.
True cold-back is brief, predictable, and stable: a few bucks or hump through the back that resolves within minutes of movement. The behavior does not worsen over time. Back palpation shows no significant soreness. The behavior occurs with any saddle, even one known to fit well.
Worsening bucking behavior is not consistent with true cold-back, which is stable and predictable. Worsening behavior almost always indicates a physical problem that is progressing. Do not continue riding through worsening bucking while investigating.
Kicking at the girth, pinning ears when girthed, or bucking immediately after mounting often implicates the girth area rather than the saddle body. Check for girth galls. Check that the front cinch clears the elbow by at least two finger-widths during movement. Try progressive girthing — tightening in stages with walking between each stage.
A damaged tree creates unpredictable pressure because the tree shifts differently under different loads. A horse may work acceptably some days and react dramatically on others. This inconsistency is confusing but is a hallmark of tree damage. Always test the tree integrity of a saddle producing bucking behavior before assuming behavioral causes.
David Solum has been evaluating saddle fit problems for 40+ years. Call, text, or email him directly — he can advise on whether it's a fit issue, a tree problem, or a saddle you should replace.
See also: Free Saddle Tools · How to Fit a Western Saddle · Parts of a Western Saddle · How to Buy a Certified Used Saddle