Objective—To investigate the effect of laser shock
peening on the fatigue life and surface characteristics
of 3.5-mm-diameter cortical bone screws.
Sample Population—32 stainless steel, 3.5-mm-diameter
cortical bone screws.
Procedure—Screws were randomly assigned to an
untreated control group or 2 power-density treatment
groups, 6 gigawatts (GW)/cm2 and 8.5 GW/cm2, for laser
shock peening. Number of cycles to failure and findings
on scanning electron microscopy-assisted morphometric
evaluation, including the mode of failure, surface
debris, surface damage, and thread deformation, were
compared between control and treated screws.
Results—The 6 GW/cm2 treated screws had a significant
(11%) improvement in fatigue life, compared
with untreated control screws. The 8.5 GW/cm2 treated
screws had a significant (20%) decrease in fatigue
life, compared with control screws. A mild but significant
increase in thread deformation was evident in all
treated screws, compared with control screws. The
8.5 GW/cm2 treated screws had significantly more
surface irregularities (elevations and pits), compared
with control or 6 GW/cm2 treated screws.
Conclusions and Clinical Relevance—A modest positive
increase in fatigue strength was produced by this
design of laser shock peening on the midshaft of cortical
bone screws. High laser shock peening power densities
were detrimental, decreasing screw fatigue strength
probably resulting from structural damage. Greater
fatigue life of cortical bone screws can be generated
with laser shock peening and could reduce screw breakage
as a cause of implant failure; however, future studies
will be necessary to address biocompatibility, alternative
cleaning techniques, alterations in screw strength
and pullout characteristics, and effects on susceptibility
to corrosion. ( Am J Vet Res 2004;65:972–976)
Objective—To evaluate use of kinetic gait analysis for detection, quantification, and differentiation of hind limb lameness and spinal ataxia in horses.
Design—Prospective clinical study.
Procedures—Kinetic gait analysis with a force plate was performed for 12 clinically normal horses, 12 horses with hind limb lameness, and 12 horses with spinal ataxia. Kinetic variables were compared among groups, correlated to subjective grading, and used to build predictive models to assess the accuracy of discrimination.
Results—Subsets of kinetic variables were characteristically altered in ataxic and lame gaits. Ataxic horses had significantly increased lateral force peak and variation in vertical force peaks in both hind limbs. Lame horses had significantly decreased vertical force peak and increased variation in vertical force peaks only in the lame hind limb. These variables were used to differentiate between spinal ataxia and hind limb lameness with excellent accuracy. There were significant correlations between a subset of kinetic variables and subjective lameness and neurologic grades.
Conclusions and Clinical Relevance—Kinetic gait variables, specifically lateral force peak and the variation in vertical force, can be used to support the differential diagnosis between spinal ataxia and hind limb lameness in horses. Kinetic gait analysis may also be applied for quantification of equine hind limb gait abnormalities as well as confirming lack of lameness and ataxia in soundness examinations.
Objective—To determine survival rate and athletic ability after nonsurgical or surgical treatment of cleft palate in horses.
Design—Retrospective case series.
Animals—55 horses with cleft palate.
Procedures—13 of the 55 horses died or were euthanized without treatment and were not included in all analyses. Medical records were reviewed for signalment, history, method of diagnosis, soft or hard palate involvement, type of surgical procedure performed, postoperative complications, and survival to hospital discharge. Information on athletic ability was acquired from race records and follow-up conversations with owners, trainers, or referring veterinarians.
Results—The predominant reason for initial evaluation was milk or feed in the nostrils (60%). The diagnosis was confirmed by means of videoendoscopy of the upper portion of the airway in all cases. Most cases involved the soft palate only (92.7%). Twenty-six of the 55 (47.3%) horses underwent surgical repair, and 12 of these had dehiscence at the caudal edge of the soft palate. Among potential racehorses, 14 of 33 had surgery. Of these, 12 of 14 survived to discharge and 2 horses raced. Among potential racehorses, 10 of 33 were discharged without surgery and 2 of these raced. Among nonracehorses, 12 of 22 underwent surgery and 11 survived to discharge. All horses that were discharged and for which follow-up information was available survived to 2 years of age or older without ill thrift despite dehiscence at the caudal edge of the soft palate and continued mild nasal discharge.
Conclusions and Clinical Relevance—Horses with cleft palate had a higher survival rate than previously reported.
Objective—To evaluate anesthetic effects of 4 drug
combinations used for total intravenous anesthesia of
horses undergoing surgical removal of an abdominal
Animals—32 healthy cryptorchid horses.
Procedure—Horses were sedated with xylazine and
butorphanol and were randomly assigned to 1 of 4
groups: induction of anesthesia with ketamine and
diazepam and maintenance with bolus administration
of ketamine and xylazine (KD/KX); induction and maintenance
of anesthesia with bolus administration of
tiletamine-zolazepam, ketamine, and detomidine
(TKD); induction and maintenance of anesthesia with
continuous infusion of xylazine, guaifenesin, and ketamine;
and induction and maintenance of anesthesia
with continuous infusion of guaifenesin and thiopental.
Horses that moved 3 consecutive times in
response to surgical stimulation or for which surgery
time was > 60 minutes were administered an inhalant
anesthetic, and data from these horses were excluded
Results—Quality of induction was not significantly
different among groups. Muscle relaxation and analgesia
scores were lowest for horses given KD/KX, but
significant differences among groups were not
detected. Horses anesthetized with TKD had a significantly
greater number of attempts to stand, compared
with the other groups, and mean quality of
recovery from anesthesia for horses in the TKD group
was significantly worse than for the other groups.
Anesthesia, surgery, and recovery times were not significantly
different among groups.
Conclusions and Clinical Relevance—Results suggest
that all 4 drug combinations can be used to
induce short-term anesthesia for abdominal cryptorchidectomy
in horses. However, horses receiving
TKD had a poorer recovery from anesthesia, often
requiring assistance to stand. (J Am Vet Med Assoc
Objective—To determine the anesthetic, cardiorespiratory,
and metabolic effects of 4 IV anesthetic regimens
in Thoroughbred horses recuperating from a
brief period of maximal exercise.
Animals—6 adult Thoroughbreds.
Procedure—Horses were preconditioned by exercising
them on a treadmill. Each horse ran 4 simulated
races, with a minimum of 14 days between races.
Races were run at a treadmill speed that caused horses
to exercise at 120% of their maximal oxygen consumption.
Horses ran until fatigued or for a maximum
of 2 minutes. Two minutes after exercise, horses
received a combination of xylazine hydrochloride (2.2
mg/kg of body weight) and acepromazine maleate
(0.04 mg/kg) IV. Five minutes after exercise, horses
received 1 of the following 4 IV anesthetic regimens:
ketamine hydrochloride (2.2 mg/kg); ketamine (2.2
mg/kg) and diazepam (0.1 mg/kg); tiletamine
hydrochloride-zolazepam hydrochloride (1 mg/kg); and
guaifenesin (50 mg/kg) and thiopental sodium (5
mg/kg). Treatments were randomized. Cardiopulmonary
indices were measured, and samples of
blood were collected before and at specific times for
90 minutes after each race.
Results—Each regimen induced lateral recumbency.
The quality of induction and anesthesia after ketamine
administration was significantly worse than after
other regimens, and the duration of anesthesia was
significantly shorter. Time to lateral recumbency was
significantly longer after ketamine or guaifenesinthiopental
administration than after ketaminediazepam
or tiletamine-zolazepam administration.
Arterial blood pressures after guaifenesin-thiopental
administration were significantly lower than after the
Conclusions and Clinical Relevance—Anesthesia
can be safely induced in sedated horses immediately
after maximal exercise. Ketamine-diazepam and tiletamine-
zolazepam induced good quality anesthesia
with acceptable perturbations in cardiopulmonary and
metabolic indices. Ketamine alone and guaifenesinthiopental
regimens are not recommended. (Am J Vet