Objective—To quantify geometric, inertial, and histomorphometric
properties at the mid-diaphyseal level
of left and right metacarpal bones (MCB) of racing
Sample Population—MCB from 7 racing Greyhounds
euthanatized for reasons unrelated to MCB
Procedures—Mid-diaphyseal transverse sections of
left and right MCB were stained with H&E or microradiographed.
Images of stained sections were digitized,
and cross-sectional area, cortical area, and maximum
and minimum area moments of inertia of each
bone were determined. Histomorphometric data
(osteonal density, osteonal birefringence, and
endosteal new lamellar bone thickness) were collected
in 4 quadrants (dorsal, palmar, lateral, medial).
Values were compared between limbs and among
bones and quadrants.
Results—Cross-sectional area, cortical area, and
maximum and minimum moments of inertia of left
MCB-IV and -V were significantly greater, compared
with contralateral bones. Overall osteonal densities in
the dorsal quadrants of left MCB were greater, compared
with lateral and medial quadrants. Also, percentage
of birefringent osteons was significantly
greater in the dorsal quadrant of left MCB-III, -IV, and
-V, compared with the palmar quadrant. Thickness of
new endosteal lamellar bone was not significantly
influenced by limb, bone, or quadrant.
Conclusions and Clinical Relevance—Increased
cortical thickness and geometric properties of left
MCB-IV and -V of Greyhounds, together with altered
turnover and orientation of osteons in the dorsal
quadrants of left MCB, are site-specific adaptive
responses associated with asymmetric cyclic loading
as a result of racing on circular tracks. Site-specific
adaptive remodeling may be important in the
etiopathogenesis of fatigue fractures in racing Greyhounds.
(Am J Vet Res 2001;62:787–793)
Objective—To evaluate effects of intra-articular and
extracapsular reconstruction of the cranial cruciate ligament
(CCL) on metabolism of articular cartilage as
reflected by concentrations of chondroitin sulfate epitopes
3B3 and 7D4 in synovial fluid.
Animals—13 adult dogs.
Procedure—Each dog underwent unilateral CCL transection
(CCLT). One month after CCLT, sham CCL
reconstruction (3 dogs), intra-articular CCL reconstruction
(5), or extracapsular CCL reconstruction (5)
was performed. Synovial fluid was collected by direct
arthrocentesis from CCLT and contralateral stifle
joints immediately before (time 0) and 1, 3, and 5
months after CCLT. Fluid was examined for concentrations
of 3B3 and 7D4 epitopes and total sulfated
glycosaminoglycan (GAG) content.
Results—Concentrations of 3B3, 7D4, and GAG,
3B3:GAG, or 7D4:GAG in CCLT joints did not differ significantly
among treatment groups nor in the ratios of
these variables in CCLT joints to contralateral joints at
3 months. In a longitudinal analysis, concentrations of
3B3 and 7D4, 3B3:GAG, and 7D4:GAG in CCLT joints
in all groups changed significantly with time, but we
did not detect time X group interactions.
Conclusion and Clinical Relevance—Transection
of CCL resulted in significant perturbation in articular
cartilage metabolism as reflected by alterations in
concentrations of 3B3 and 7D4 in synovial fluid. These
changes over time were not significantly influenced
by method of CCL reconstruction. We did not find evidence
that surgical stabilization of CCL-deficient joints
by intra-articular or extracapsular techniques had any
effect on preventing alterations in composition of synovial
fluid that have been associated with secondary
osteoarthritis. (Am J Vet Res 2001;62:581–587)
Objective—To test the effects of bone diameter and
eccentric loading on fatigue life of 2.7-mm-diameter
cortical bone screws used for locking a 6-mm-diameter
Sample Population—Eighteen 2.7-mm-diameter
cortical bone screws.
Procedure—A simulated bone model with aluminum
tubing and a 6-mm-diameter interlocking nail was
used to load screws in cyclic 3-point bending. Group
1 included 6 screws that were centrally loaded within
19-mm-diameter aluminum tubing. Group 2 included
6 screws that were centrally loaded within 31.8-mmdiameter
aluminum tubing. Group 3 included 6
screws that were eccentrically loaded (5.5 mm from
center) within 31.8-mm-diameter aluminum tubing.
The number of cycles until screw failure and the
mode of failure were recorded.
Results—An increase in the diameter of the aluminum
tubing from 19 to 31.8 mm resulted in a significant
decrease in the number of cycles to failure (mean ± SD,
761,215 ± 239,853 to 16,941 ± 2,829 cycles, respectively).
Within 31.8-mm tubing, the number of cycles of
failure of eccentrically loaded screws (43,068 ± 14,073
cycles) was significantly greater than that of centrally
loaded screws (16,941 ± 2,829 cycles).
Conclusions and Clinical Relevance—Within a
bone, locking screws are subjected to different loading
conditions depending on location (diaphyseal vs
metaphyseal). The fatigue life of a locking screw centrally
loaded in the metaphyseal region of bone may
be shorter than in the diaphysis. Eccentric loading of
the locking screw in the metaphysis may help to
improve its fatigue life. (Am J Vet Res 2003;64:569–573)
Objective—To compare synovial fluid biomarkers of
cartilage metabolism in joints with naturally acquired
or experimentally induced cranial cruciate ligament
(CCL) rupture and determine correlations with stage
and severity of disease in dogs.
Animals—95 dogs with ruptured CCL, 8 dogs with
experimentally ruptured CCL, and 24 healthy dogs.
Procedure—Synovial fluid was assayed for chondroitin
sulfate neo-epitopes 3B3(–) and 7D4 and glycosaminoglycan
(GAG) concentration. Results were
correlated with demographic data, duration of lameness,
radiographic osteoarthritis score, and intra-articular
Results—The 7D4 concentrations and 7D4:GAG in
synovial fluid from joints with naturally acquired
CCL rupture and experimental CCL transection
were similar and significantly greater than values
for healthy control joints. The 3B3(–) concentrations
in the CCL-deficient groups were not significantly
different, although only values in the naturally
acquired CCL rupture group were significantly
greater than those in the healthy control group.
Within the naturally acquired CCL rupture group
there was a significant correlation between 3B3(–)
and 7D4 concentrations. However, there were no
significant correlations between biomarker concentrations
and continuous demographic or diseaserelated
variables or differences in biomarker concentrations
with different categories of disease.
Conclusion and Clinical Relevance—Synovial fluid
biomarker concentrations were significantly
increased in joints with secondary osteoarthritis associated
with naturally acquired or experimental CCL
rupture; however, lack of apparently simple relationships
with demographic variables or stage or severity
of disease limits their clinical usefulness. (Am J Vet
Objective—To determine the accuracy of sow culling classifications reported by lay personnel on commercial swine farms.
Design—Retrospective cohort study.
Animals—A convenience sample of 923 sows from 8 conventional, farrow-to-wean farms that followed standard operating procedures.
Procedures—Sows were examined at slaughter, and lesions were recorded. Individual production records were reviewed to determine the farm-reported reason for culling the sows, and criteria were developed to assess the accuracy of recorded culling classifications.
Results—For 209 of the 923 (23%) sows, the farm-reported culling classification was judged to be inaccurate. The culling code was considered to be inaccurate for 62 of 322 (19%) sows reportedly culled because of old age, 48 of 172 (28%) sows reportedly culled because of failure to conceive, 31 of 90 (34%) sows reportedly culled because of poor body condition, and 23 of 73 (32%) sows reportedly culled because of poor farrowing productivity.
Conclusions and Clinical Relevance—Results suggested that for commercial swine farms, farm-reported culling code classifications were frequently inaccurate. This degree of inaccuracy may cause severe limitations for studies that rely on farm-reported assessments of clinical conditions.
Objective—To evaluate and compare bone modeling and remodeling in fractured and non-fractured central tarsal bones (CTBs) of racing Greyhounds.
Sample—Paired cadaveric tarsi from 6 euthanized racing Greyhounds with right CTB fractures and 6 racing Greyhounds with other nontarsal injuries.
Procedures—CTBs were dissected and fractured CTBs were reconstructed. Central tarsal bones were evaluated through standard and nonscreen high-detail radiography, computed tomography, and histologic examination. The bone mineral density (BMD) was calculated adjacent to fracture planes and as a gradient on sagittal computed tomographic images. Sagittal and transverse plane sections of bone were obtained and submitted for subjective histologic assessment. Linear mixed-effects models were used to compare findings.
Results—Fractured right CTBs had greater BMD in the dorsal and midbody regions of the sagittal plane sections than did nonfractured CTBs. The BMD ratios from bone adjacent to the dorsal slab fracture planes were not different between fractured and nonfractured right CTBs.
Conclusions and Clinical Relevance—Findings supported the existence of site-specific bone adaptation in CTBs of Greyhounds, with modeling and remodeling patterns that were unique to fractured right CTBs. The dorsal and midbody regions of fractured bones had greater BMD, and fractures occurred through these zones of increased BMD.
OBJECTIVE To evaluate the outcome for cats with benign ureteral obstructions treated by means of ureteral stenting and to compare the outcome for these cats with outcome for a historical cohort of cats treated by means of ureterotomy only.
DESIGN Prospective study with historical cohort.
ANIMALS 62 client-owned cats with benign ureteral obstructions, including 26 cats treated with ureteral stenting and 36 cats previously treated with ureterotomy.
PROCEDURES Data were recorded prospectively (ureteral stent cases) or collected retrospectively from the medical records (ureterotomy cases), and results were compared.
RESULTS Cats treated with ureteral stents had significantly greater decreases in BUN and serum creatinine concentrations 1 day after surgery and at hospital discharge, compared with values for cats that underwent ureterotomy. Six cats in the ureteral stent group developed abdominal effusion after surgery, and cats in this group were significantly more likely to develop abdominal effusion when a ureterotomy was performed than when it was not. Cats that developed abdominal effusion after surgery were significantly less likely to survive to hospital discharge. Cats that underwent ureteral stenting were significantly more likely to have resolution of azotemia prior to hospital discharge than were cats that underwent ureterotomy alone.
CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that cats with benign ureteral obstructions treated with ureteral stenting were more likely to have resolution of azotemia prior to hospital discharge, compared with cats undergoing ureterotomy alone. Results of ureteral stenting were encouraging, but further investigation is warranted.