Casuey (South Texas term for “bucking”)

“Casuey” is a South Texas term for the “bucking” or “pitching” of a horse. The term (origin unknown) is rarely used today, even in South Texas.
   
           
Cowboy Poetry at the BAR-D Ranch
John “Twister” McBride
(1855-1922)
(...)
Most days
on the prod.  Scratch him! Powder River!  Let ‘er buck!  Frogwalk or sunfish or casuey, squeal and squall and cloud hunt or damn him! a pinwheel.  Bawl and bellow maybe every jump. Buck and
run, honest pitch or showboat, galves carving the 111’s deep showing him just what’s what. 
 
(Dictionary of American Regional English)
casuey v
Of a horse: to buck.
1921 Thorp Songs Cowboys 106 [Black], he ca-su-ied wid me, most ruinous,/Till ma haid jest popped de ceilin’. [Footnote:] Ca-su-ied, southern Texas word for bucking.
1944 Adams Western Words, Casueying—(ka-‘sooying) A South Texas term for pitching, but rarely heard in other sections.
 
Google Books
The Cowboys:
An Unconventional History of Civilization on the Old-Time Cattle Range
by Philip Ashton Rollins
New York, NY: Charles Scribner’s Sons
1936
Pg. 297:
The Northwesterner called the horrid motion “bucking” or “buck jumping,” the Texan termed it “pitching.” “Casueying,” as a further synonym, flourished a while in southern Texas, but rarely wandered beyond the region of its birth.
 
Google Books
Dictionary of the American West:
Over 5,000 Terms and Expressions from AARIGAA! To ZOPILOTE
by Win Blevins
Seattle, WA: Sasquatch Books
2001
Pg. 69:
CASUEYING (kuh-SOO-ying) A Texas term for the bucking (or in Texas, pitching) of a horse.