Objective assessment of gait in xylazine-induced ataxic horses.
BACKGROUND
There is poor agreement between observers of equine neurological gait abnormalities using the modified Mayhew grading scale.


OBJECTIVE
To stimulate a dose-dependent ataxia in horses through xylazine administration and identify quantifiable relevant gait parameters.


METHODS
Balanced, randomised, 2-way crossover design.


METHODS
Eight horses were assessed before and after administration of xylazine (low dose and high dose). Gait analyses performed before and after xylazine administration included: 1) kinematic data collected on an equine high-speed treadmill (flat and 10% decline) and from accelerometers placed on head and sacrum; and 2) kinetic data collected on a force plate.


RESULTS
All horses developed dose-dependent ataxia. Horses developed a dose-dependent increased stride time, stride length, and time of contact (P<0.0001), and a decreased stride frequency (P<0.0002) after administration of xylazine. Although pelvic acceleration increased in the mediolateral direction (P<0.05) in horses walked on the treadmill, this movement decreased when walking over ground after administration of xylazine (P<0.05). Furthermore, centre of pressure and path length indices changed significantly in horses following administration of xylazine (P<0.05).


CONCLUSIONS
This study examined one breed of horse (Arabian), all of similar height and weight. Accelerometers were attached to skin, not bone; no correction was made for artefacts from skin displacement. The sedative drug effect is of certain duration, limiting the data collection period.


CONCLUSIONS
Administration of xylazine induced a dose-dependent ataxia in horses and resulted in significant changes of gait parameters, pelvic accelerations, and stabilographic variables, some of which changed in a dose-dependent fashion. Some of the altered gait parameters in this model were probably a result of overall slowing down of the stride cycle secondary to the sedative effect. Continued efforts to discover and evaluate quantifiable gait parameters that are susceptible to change following development of clinical neurological disease in horses is warranted.
College of Veterinary and Biomedical Sciences, Colorado State University, Fort Collins, USA.
Y S
YS
Nout-Lomas
Equine Research Center, Department of Animal and Veterinary Sciences, California State Polytechnic University Pomona, USA.
K M
KM
Page
Department of Kinesiology, California State University San Marcos, USA.
H G
HG
Kang
College of Veterinary and Biomedical Sciences, Colorado State University, Fort Collins, USA.
M E
ME
Aanstoos
Equine Research Center, Department of Animal and Veterinary Sciences, California State Polytechnic University Pomona, USA.
H M
HM
Greene
D061725:Accelerometry / Q000662:veterinary; D000818:Animals; D001259:Ataxia / Q000139:chemically induced / Q000662:veterinary*; D005684:Gait / Q000187:drug effects*; D006736:Horses; D014991:Xylazine / Q000494:pharmacology*
D014991:Xylazine
accelerometer; force plate; horse; kinematic; kinetic; neurology; treadmill