Objective—To determine the degree to which components
of the training program of 2-year-old
Thoroughbred racehorses influence their susceptibility
to fatigue injury of the third metacarpal bone
Animals—226 two-year-old Thoroughbred racehorses.
Procedure—Daily training information and health
reports on 2-year-old Thoroughbreds were compiled
from records provided from 5 commercial stables. For
each horse, data (exercise variables) were collected
that comprised distance jogged (approx speed of 5
m/s), galloped (approx 11 m/s), and breezed (approx
15 to 16 m/s) until a single instance of bucked shins
was reported. Data were coded for analysis using
cross-tabulation, graphic, and survival techniques.
Results—Of 226 horses, 56 had bucked shins, 9
completed the observation period without bucked
shins, and 161 were lost to follow-up. Distinct training
strategies were used at stables resulting in significantly
different survival profiles among stables. Mean
(± SD) allocation of exercise to breezing was 0.15 ±
0.13 miles/wk (maximum, 0.64 miles/wk), to galloping
was 4.47 ± 1.52 miles/wk (maximum, 9.56
miles/wk), and to jogging was 2.34 ± 1.70 miles/wk
(maximum, 8.53 miles/wk). Survival (ie, lack of
bucked shins during 1 year of monitoring) was found
to be significantly reduced by exercise allocation to
breezing, significantly increased by exercise allocation
to galloping, and uninfluenced by exercise allocation
to jogging. The log of the hazard ratio was
reduced by 4.2 ± 1.5/mile breezed and increased by
0.3 ± 0.1/mile galloped.
Conclusions and Clinical Relevance—Relationships
between different gaits and speeds in the training
regimen influence the incidence of bucked shins. To
reduce the incidence of bucked shins, trainers should
consider allocating more training effort to regular
short-distance breezing and less to long-distance galloping.
(Am J Vet Res 2000;61:602–608)
Objective—To evaluate stiffness and bone-pin interface
stress for a transcortical tapered-sleeve pin (TSP)
that incorporates bilateral tapered sleeves over a
Sample Population—14 third metacarpal bones
(MCIII) collected from adult horses of various breeds.
Procedure—Each MCIII was cut in half to provide 2
test specimens. Pins (conventional and TSP) of 3
diameters (6.35, 7.94, and 9.50 mm) were inserted in
specimens (3 specimens for each diameter and each
type of pin). The test fixture simulated a typical sidebar-
span skeletal fixation device for horses. Single
cycle load-deflection tests were performed. Cyclic
fatigue tests of TSP were performed to evaluate
fatigue characteristics and stress conditions at the
bone-pin interface. Maximum stress and strain were
calculated, and results were compared with existing
data on fatigue characteristics of bone.
Results—Significant increases in stiffness (loaddeflection)
and higher loads at yield point were
detected for the TSP (stiffness for conventional 9.50-
mm pins, 4,500 N/mm; stiffness for TSP, 19,988
N/mm). Results of cyclic tests revealed a close correlation
with existing data on fatigue characteristics.
Conclusions and Clinical Relevance—The TSP
described here is stiffer than conventional transcortical
pins, and stress across the bone-pin interface is
more evenly distributed. Use of this TSP should minimize
major problems encountered during external
fixation associated with the transcortical pin and
bone-pin interface (ie, bone necrosis, infection of the
pin track, pin loosening, and bone failure). ( Am J Vet
Objective—To report the outcome of surgical treatment
of comminuted fractures of the proximal phalanx
Procedure—Medical records and radiographs were
reviewed to obtain information regarding signalment,
fracture classification, and treatment. Follow-up information
was obtained by telephone conversation or
evaluation of production records.
Results—Thirty-eight horses had moderately comminuted
fractures of the proximal phalanx. Two horses were
euthanatized immediately. Fractures of the proximal phalanx
in 36 horses were repaired with open reduction and
internal fixation with a successful outcome in 33 (92%)
horses. Reconstruction of the fracture was performed in
most horses by use of a long curved incision, transection
of the collateral ligament of the metacarpophalangeal or
metatarsophalangeal joint, and open exposure of the
proximal articular surface of the proximal phalanx.
Twenty-six horses had severely comminuted fractures of
the proximal phalanx. Six horses were euthanatized
immediately. One horse was euthanatized after 9 days of
treatment with a cast alone. Severely comminuted fractures
of the proximal phalanx in 13 horses were treated
with an external skeletal fixation device, and fractures
healed in 8 of those horses. Six horses with severely
comminuted fractures of the proximal phalanx were
treated with transfixation pins incorporated into a fiberglass
cast, and fractures healed in 4 horses.
Conclusions and Clinical Relevance—Moderately
comminuted fractures of the proximal phalanx can be
successfully repaired; however, fractures that are too
severe to permit accurate reconstruction of the fragments
remain difficult to treat and horses have only a
fair prognosis for survival. (J Am Vet Med Assoc 2004;
Objective—To describe the pool-raft recovery system protocol and to evaluate the clinical outcome inhorses that underwent recovery from general anes-thesia using this system.
Animals—393 horses that underwent recovery fromgeneral anesthesia in the pool-raft system.
Procedure—Anesthetic records were examined fromhorses recovered from anesthesia in the pool-raft sys-tem between January 1984 and December 2000.Complete medical records of horses were examinedwhen available. Information regarding the anestheticand recovery period was recorded. Horses first recov-ered from general anesthesia in the pool-raft and,once awake, were transported to a recovery stall andlowered to the floor in a standing position.
Results—351 horses underwent 1 pool-raft recovery,and 42 horses underwent multiple pool-raft recover-ies. Most horses were recovered from general anes-thesia within the pool-raft system to safeguard repairof a major orthopedic injury. During 471 pool-raftrecoveries, 34 (7%) horses had complications withinthe recovery pool and 62 (13%) had complicationswithin the recovery stall. Deaths resulted from complete failure of internal fixation, pulmonary dysfunc-tion, or a combination of pulmonary dysfunction andfixation failure in 2% (10/471) of horses that under-went pool-raft recoveries.
Conclusions and Clinical Relevance—The pool-raftsystem is a good option for recovery from generalanesthesia. Although not a fail-safe system, itappears to decrease the complications of recoveringhorses in a high-risk category. Potential disadvan-tages of this system are added expense and man-power necessary in building, maintenance, andusage, as well as size limitations of the raft itself. (J Am Vet Med Assoc 2002;221:1014–1018)