Objective—To determine the effect of manual
tongue protrusion on the dimensions of the hyoid
apparatus, nasopharynx, and oropharynx in anesthetized
Animals—5 adult horses.
Procedure—Horses were anesthetized and positioned
in sternal recumbency for 2 sequential computed
tomographic (CT) scans. Images were acquired
with the tongue in a natural position inside the mouth.
Then, the tongue was pulled rostrally and secured,
and a second CT scan was performed. Dorsoventral
length of the hyoid apparatus and angles of the
basisphenoid, basihyoid, and ceratohyoid were measured
on 3-dimensional reconstructed CT images.
Cross-sectional diameters and areas of the nasopharynx
and oropharynx were determined on reformatted
images in the transverse and longitudinal planes,
using osseous landmarks for consistency. Results
were tested between the 2 groups to determine significant
Results—We were unable to detect a significant
difference between any of the lengths or angles of
the hyoid apparatus measured with or without rostral
protrusion of the tongue. Similarly, nasopharyngeal
and oropharyngeal diameters and cross-sectional
areas were not significantly different with or
without rostral protrusion of the tongue.
Conclusions and Clinical Relevance—Tying the
tongue rostrally out of a horse's mouth did not influence
the position of the hyoid apparatus or dimensions
of the nasopharynx or oropharynx in anesthetized
horses. Currently, no data suggest that application
of a tongue-tie is effective for maintaining stability
and patency of the nasopharyngeal or orolaryngeal
airways in horses during races. (Am J Vet Res
Objective—To develop a method for arthrocentesis
of the temporomandibular joint in adult horses.
Animals—7 equine cadaver heads and 6 clinically
normal adult horses.
Procedure—Fluoroscopy, contrast radiography, and
computed tomography were used on cadaver specimens
to locate the temporomandibular joint, identify
externally palpable landmarks for joint access, guide
needle placement into the joint, and illustrate regional
anatomy. The arthrocentesis technique was performed
on 6 live healthy adult horses to determine
efficacy and safety of this procedure.
Results—Externally palpable structures were identified
as landmarks for temporomandibular arthrocentesis,
including the lateral border of the condylar
process of the mandible, the zygomatic process of
the temporal bone, and the lateral pericapsular fat
pad. Arthrocentesis was successful in all 6 joints in
the live horses, and no complications developed.
Conclusions and Clinical Relevance—The technique
identified will improve the ability to examine
and treat the temporomandibular joint in horses. (Am J Vet Res 2001;62:729–735).
Objective—To describe the vascular anatomy of the
palmar digital artery and its major branches in the
equine foot and to quantify the diameter of these vessels
by use of digital angiograms.
Sample Population—6 thoracic limbs obtained from
Procedure—Distal portions of each limb were perfused
with aerated Krebs-Henseleit solution. Digital
angiograms were acquired in standing and lateral
recumbent positions, following an intra-arterial injection
of iopamidol. Select vessels were measured on
radiographic views, and values were corrected for
Results—The palmar digital artery tapered from
2.28 mm at the coronary region to 1.61 mm at the
entrance to the solar canal, and the major arterial
branches ranged in diameter from 0.71 to 1.42 mm in
the standing position.
Conclusions and Clinical Relevance—Digital
angiography is useful for imaging small vessels, but
penumbra limits the image resolution of the
macrovasculature of the foot. The palmarodorsal projection
is more useful for evaluation of the terminal
arch and solar branches, but 2 projections are necessary
for a thorough examination of the foot. Image
magnification, position of horse, and vascular
response to contrast medium must be considered in
the quantitative assessment of vessel diameter.
Digital angiography may be performed in clinical
cases and research models for examination of vascular
perfusion of the distal portion of the limb. (Am J
Vet Res 2000;61:255–259)
Objective—To define the vertical position of the
patella in clinically normal large-breed dogs.
Sample Population—Cadavers of 13 clinically normal
Procedure—Both hind limbs were harvested with
intact stifle joints and mounted on a positioning device
that allowed full range of motion of the stifle joint.
Lateral radiographic views were obtained with the stifle
joints positioned at each of 5 angles (148°, 130°,
113°, 96°, and 75°). Vertical position of the patella
through a range of motion was depicted on a graph of
mean stifle angle versus corresponding mean proximal
patellar position (PPP) and distal patellar position
(DPP) relative to the femoral trochlea for each dog.
Ratio of length of the patellar ligament to length of the
patella (L:P) was determined for each dog. Overall
mean, SD, and 95% confidence intervals for L:P were
calculated for all dogs.
Results—Evaluation of vertical position of the patella
through a range of motion revealed a nearly linear relationship
between joint angle and PPP and joint angle
and DPP. Evaluation of L:P results did not reveal significant
differences between limbs (left or right) or among
joint angles. Overall mean ± SD L:P for all dogs was
1.68 ± 0.18 (95% confidence interval, 1.33 to 2.03).
Conclusion and Clinical Relevance—The L:P
proved to be a repeatable measurement of vertical
patellar position, which is independent of stifle angles
from 75° to 148°. This measurement could be used as
a quantitative method for diagnosing patella alta and
patella baja in large-breed dogs. (Am J Vet Res
Objective—To study the effect of unilateral synovitis
in the distal intertarsal and tarsometatarsal joints on
locomotion, including the compensating effects within
and between limbs.
Animals—4 clinically normal horses.
Procedure—Gait analyses including kinematics, force
plate, and inverse dynamic analysis were performed
at the trot before lameness, after which synovitis was
induced by injecting endotoxin into the right distal
intertarsal and tarsometatarsal joints. Gait analyses
were repeated 24 to 30 hours later during lameness.
Differences between the stride variables during the 2
conditions (lame and sound) were identified.
Results—Tarsal joint range of motion, peak vertical
force, and vertical impulse were decreased during
lameness. Mechanical deficits included a decrease in
negative work performed by the tarsal extensors during
the early stance phase and a decrease in positive
work by the tarsal extensors during push off. No compensatory
changes in work were performed by other
joints within the lame hind limb during the stance
phase. Vertical impulse in the diagonal forelimb
decreased, but there were no significant changes in
forces or impulses in the ipsilateral forelimb or contralateral
Conclusions and Clinical Relevance—Results indicate
that horses are able to manage mild, unilateral
hind limb lameness by reducing the airborne phase of
the stride rather than by increased loading of the compensating
limbs. (Am J Vet Res 2003;64:1491–1495)
Objective—To evaluate the effects of nephrotomy on
renal function in clinically normal cats.
Animals—20 specific-pathogen-free, 9- to 11-month old
female mixed-breed cats.
Procedure—Serum chemistry analyses, CBC determinations,
urinalyses, microbiologic urine cultures,
renal ultrasonography, abdominal radiography, and
single-kidney and total glomerular filtration rate (GFR)
determinations by use of renal scintigraphy and measurements
of plasma disappearance of technetium
99m-diethylenetriaminepentaacetic acid were performed
before surgery and at 3, 12, 26, 52, and 78
weeks after surgery in 10 cats that underwent unilateral
nephrotomy and in 10 control cats that underwent
a sham surgical procedure.
Results—Two cats (1 from each group) did not complete
the study, and their data were eliminated from
analyses. Unilateral nephrotomy resulted in a 10% to
20% reduction in mean single-kidney GFR, compared
with that of nephrotomy contralateral control kidneys.
However, mean total GFR in nephrotomy-group cats
was not significantly different from that of shamgroup
cats. Over the 78 weeks of study, mean total
GFR declined 34% and 40% in nephrotomy- and
sham-group cats, respectively. Adverse events associated
with nephrotomy included persistent microscopic
hematuria, renal pelvis hyperechogenicity with
distant shadowing on ultrasonographic evaluation,
dilatation of renal pelves, and hydronephrosis.
Conclusions and Clinical Relevance—Nephrotomy
in normal functioning feline kidneys results in a modest
relative reduction in renal function, compared with
contralateral kidney controls, but has minimal effect
on total GFR when compared with sham-operated
control cats. However, any detrimental effects of
nephrotomy may be magnified in cats with diseased
kidneys, which may have little or no capacity for repair
or compensation. (Am J Vet Res 2005;66:1400–1407)