bluuebunny/crossref_metadata_2025 huggingface dataset:
Detection of free radicals in ischemic and reperfused canine gracilis muscle flaps by use of spin-trapping electron paramagnetic resonance spectroscopy
Authors: Brisson Brigitte A. , Miller Craig W. , Chen Guoman , McCutcheon L. Jill , Janzen Edward G.
Published: December 2005

Objective—To determine whether free radicals are produced in ischemic and reperfused canine skeletal muscle, whether free radicals can be detected from effluent blood by use of spin-trapping electron paramagnetic resonance (EPR) spectroscopy, and whether free radical-induced skeletal muscle damage is detectable by use of light microscopy.

Animals—6 healthy mixed-breed dogs.

Procedures—Dogs were anesthetized and both gracilis muscles were isolated, leaving only the major vascular pedicle intact. Ischemia was induced in 1 flap for 4 hours; the contralateral flap served as the control. Ischemic flaps were then reperfused for 15 minutes. α-Phenyl-N-tert-butylnitrone, a spin-trapping agent, was administered intravenously to each dog 1 hour prior to reperfusion. Following reperfusion, effluent blood samples from muscle flaps were obtained and processed for EPR spectroscopy. Muscle biopsy specimens were obtained for histologic evaluation, and dogs were euthanatized.

Results—Spin adducts were not detected in blood from control flaps. However, spin adducts were detected in all ischemic-reperfused muscle flaps. Principal signals identified were characteristic of oxygen- and carbon-centered radicals. Significantly more muscle damage was detected in ischemic-reperfused flaps, compared with control flaps.

Conclusions and Clinical Relevance—Free radicals may be an important component of injury induced by ischemia and reperfusion of canine skeletal muscle. Spin-trap adducts of free radicals can be detected in effluent blood of canine muscle flaps by use of spin-trapping EPR spectroscopy. Spin-trapping EPR spectroscopy may be useful for the study of antioxidants and free radical scavengers in attenuating ischemia and reperfusionmediated skeletal muscle damage. (Am J Vet Res2001;62:384–388)
Cytokeratins of the matrices of the chestnut (torus carpeus) and periople in horses with acute laminitis
Authors: Wattle Ove S.
Published: December 2005

Objectives—To determine whether there is a change in the expression of cytokeratins in the epidermal cells of the non-weight-bearing parts of the limb in horses with acute laminitis and thus determine whether the morphologic changes that develop in the periople and chestnut (torus carpeus) of horses early in acute laminitis are caused by inhibition of keratinocyte differentiation.

Animals—8 horses with acute laminitis.

Procedure—Tissue specimens were obtained from the chestnuts of all 8 horses and from the stratum externum of the hoof wall of 3 horses. Tissue specimens were obtained within 48 hours of the first clinical signs of laminitis. The cytokeratins were characterized by 1- and 2-dimensional gel electrophoresis, and the tissue distribution of the cytokeratins was studied by immunohistochemical staining.

Results—The biochemical findings indicated that the epidermal cells of tissues from horses affected by laminitis contained the same set of cytokeratins as corresponding tissues from clinically normal horses. Immunohistochemistry on sections from specimens of horses with laminitis versus clinically normal horses indicated a difference in the expression of cytokeratin in the basal cells in the matrix of the stratum externum of the hoof wall and in the matrix of the chestnut of horses with laminitis in which the most severe morphologic changes were observed.

Conclusions—Inhibition of keratinocyte differentiation, as observed by immunohistochemical changes, in cells in parts of the chestnut and periople may indirectly indicate that the observed epidermal changes in horses with laminitis are primary and are unaffected by weight-bearing. (Am J Vet Res2001;62:425–432)
Biomechanical properties of braided polyester tapes intended for use as intra-articular cranial cruciate ligament prostheses in dogs
Authors: de Rooster Hilde , Vangheluwe Lieven , van Bree Henri , Ledoux Marian , Van Langenhove Lieva
Published: December 2005

Objective—To determine the in vitro structural and material properties of braided, multifilament, nonabsorbable polyester tapes, used for intra-articular stabilization of cranial cruciate ligament- (CCL-) deficient stifle joints in dogs, and compare those with properties of multifilament polyamide tapes.

Sample Population—30 polyester tapes (width, 4 mm), 10 polyester tapes (width, 7 mm), and 30 polyamide tapes (width, 4 mm) were tested to failure. Cyclic loading experiments were also performed, using 3 polyester tapes of each width.

Procedure—Tapes were mounted in a tensile tester as single loops, simulating intra-operative conditions, and elongated to failure at 1,000 mm/min. Additionally, the behavior of polyester tapes was tested at different elongation rates. In a second series of experiments, biomechanical variables of the polyester tapes were measured after 25 sets of 2,000 cycles between physiologic force limits.

Results—Mean (± SD) ultimate loads of the 4-mm wide polyamide tapes, 4-mm wide polyester tapes, and 7-mm wide polyester tapes were 266.48 ± 13.19 301.78 ± 16.92, and 726.40 ± 37.74 N, respectively. Corresponding stiffnesses were 15.57 ± 0.49, 21.63 ± 2.19, and 34.85 ± 2.66 N/mm, respectively. Failure properties of polyester tapes were affected by previous cyclic loading.

Conclusions and Clinical Relevance—Polyester tapes of 4- or 7-mm widths should be able to resist forces resulting from weight bearing in dogs, suggesting that these tapes will be effective for stabilization of the stifle joint in dogs with a ruptured CCL. ( Am J Vet Res 2001;62:48–53)
Effects of anti-inflammatory drugs on lipopolysaccharide-challenged and -unchallenged equine synovial explants
Authors: Moses Valentine S. , Hardy Joanne , Bertone Alicia L. , Weisbrode Steven E.
Published: December 2005

Objective—To evaluate the effects of anti-inflammatory drugs on lipopolysaccharide (LPS)-challenged and -unchallenged equine synovial membrane in terms of production of prostaglandin E2(PGE2) and hyaluronan, viability, and histomorphologic characteristics.

Sample Population—Synovial membranes were collected from the carpal, tarsocrural, and femoropatellar joints of 6 adult horses.

Procedure—Synovial membranes from each horse were minced and pooled and explants were treated with one of the following: no drug (control), drug, LPS alone, or LPS and drug. Treatment drugs were phenylbutazone (PBZ), flunixin meglumine (FNX), ketoprofen (KET), carprofen (CRP), meloxicam (MEL), low-concentration methylprednisolone (METH), highconcentration METH, dimethyl sulfoxide (DMSO), or an experimental COX-2 inhibitor (dissolved in DMSO). Following 48 hours of culture, medium was assayed for PGE2and hyaluronan concentration. Synovial explants were assessed for viability and histomorphologic characteristics.

Results—For the LPS-challenged explants, PBZ, FNX, KTP, CRP, MEL, and low-concentration METH suppressed PGE2production, compared with LPS challenge alone. Only MEL suppressed PGE2production from LPS-challenged explants, compared with unchallenged explants. Synovial explants maintained > 90% viability and there was no significant difference in viability or hyaluronan production among explants. Histomorphologic scores were significantly decreased for explants treated with low-concentration METH or DMSO.

Conclusions and Clinical Relevance—PBZ, FNX, KTP, CRP, MEL, and low-concentration METH suppressed PGE2production in LPS-challenged explants. Meloxicam appeared to have more selective suppression of COX-2 activity. Histomorphologic scores suggest detrimental effects of METH, DMSO, and the experimental COX-2 inhibitor. Commonly used nonsteroidal anti-inflammatory drugs suppress induced synovial membrane PGE2production without detrimental effects on synovial membrane viability and function. (Am J Vet Res2001;62:54–60)
Effects of diazepam and flumazenil on minimum alveolar concentrations for dogs anesthetized with isoflurane or a combination of isoflurane and fentanyl
Authors: Hellyer Peter W. , Mama Khursheed R. , Shafford Heidi L. , Wagner Ann E. , Kollias-Baker Cynthia
Published: December 2005

Objective—To determine the effect of a constant-rate infusion of fentanyl on minimum alveolar concentration (MAC) of isoflurane and to determine the interaction between fentanyl and a benzodiazepine agonist (diazepam) and antagonist (flumazenil) in isoflurane-anesthetized dogs.

Animals—8 mixed-breed adult dogs.

Procedure—Dogs were anesthetized with isoflurane 3 times during a 6-week period. After a 30-minute equilibration period, each MAC determination was performed in triplicate, using standard techniques. Fentanyl was administered as a bolus (10 µg/kg of body weight, IV) that was followed by a constant infusion (0.3 µg/kg per min, IV) throughout the remainder of the experiment. After determining isoflurane-fentanyl MAC in triplicate, each dog received saline (0.9% NaCl) solution, diazepam, or flumazenil. After 30 minutes, MAC was determined again.

Results—Fentanyl significantly decreased isoflurane MAC (corrected to a barometric pressure of 760 mm Hg) from 1.80 ± 0.21 to 0.85 ± 0.14%, a reduction of 53%. Isoflurane-fentanyl-diazepam MAC (0.48 ± 0.29%) was significantly less than isoflurane-fentanylsaline MAC (0.79 ± 0.21%). Percentage reduction in isoflurane MAC was significantly greater for fentanyldiazepam (74%), compared with fentanyl-saline (54%) or fentanyl-flumazenil (61%). Mean fentanyl concentrations for the entire experiment were increased over time and were higher in the diazepam group than the saline or flumazenil groups.

Conclusion and Clinical Relevance—Fentanyl markedly decreased isoflurane MAC in dogs. Diazepam, but not flumazenil, further decreased isoflurane-fentanyl MAC. Our results indicate that diazepam enhances, whereas flumazenil does not affect, opioid-induced CNS depression and, possibly, analgesia in dogs. (Am J Vet Res2001;62:555–560)
Use of plasma clearance of iohexol for estimating glomerular filtration rate in cats
Authors: Miyamoto Kenji
Published: December 2005

Objective—To determine whether plasma clearance of iohexol (PCio) can be used to estimate glomerular filtration rate (GFR) in cats.

Animals—4 renal-intact and 6 partially nephrectomized adult cats.

Procedure—Plasma clearance of iohexol was determined after IV administration of iohexol; plasma concentrations of iodine were measured by use of a colorimetric assay. Results for PCio were compared with simultaneously obtained values for urinary clearance of creatinine (CCr).

Results—The colorimetric assay used to measure plasma iodine concentrations was extremely precise. Results of PCio for all cats, renal-intact cats, and partially nephrectomized cats were closely associated with results of CCr. Mean difference between CCr and PCio determined for all cats was 0.95 ml/min/kg, which was < 30% of mean CCr for renal-intact cats. Coefficients of variance for PCio (5%) and CCr (8%) in renal-intact cats were similar.

Conclusion and Clinical Relevance—Plasma clearance of iohexol determined by use of a simple colorimetric assay provided an estimation of GFR in cats that was not significantly different from that provided by CCr. Moreover, PCio more reliably estimates renal function than BUN and plasma creatinine concentrations. Because determination of PCio is less labor intensive and invasive, compared with CCr, it may be easier to perform in a clinical setting. (Am J Vet Res2001;62:572–575)
Influence of an interdental full pin on stability of an acrylic external fixator for rostral mandibular fractures in dogs
Authors: Cook Wesley T. , Smith Mark M. , Markel Mark D. , Grant J. Wallace
Published: December 2005

Objective—To determine total stiffness and gap stiffness of an external fixation system in a canine mandibular fracture gap model incorporating a full interdental pin as the only point of rostral fixation in a bilateral type-I external fixator.

Sample Population—10 canine mandibles.

Procedure—Bilateral mandibular ostectomies were performed between premolars 3 and 4. A type-I external fixator incorporating a full interdental pin was placed to stabilize a 0.5-cm fracture gap. Four pin configurations (intact mandibular bodies with fixator; ostectomized mandibular bodies and complete fixator; ostectomized mandibular bodies with caudal pins of rostral fragment cut; ostectomized mandibular bodies with all pins of rostral fragment cut) were tested in dorsoventral bending 5 times on each mandible. The full interdental pin remained intact in all configurations. Total stiffness and gap stiffness were determined for each configuration on a materials testing machine.

Results—Total stiffness of intact mandibles was significantly greater than that of ostectomized mandibles, regardless of external fixator configuration. However, total stiffness and gap stiffness were not significantly different among different external fixator configurations applied to ostectomized mandibles.

Conclusion and Clinical Relevance—External fixator configurations with only the full interdental pin engaging the rostral fragment were as stiff as configurations that had 2 or 4 additional pins in the rostral fragment for the applied loads. External fixators for rostral mandibular fractures may be rigidly secured with rostral fragment implants applied extracortically, avoiding iatrogenic trauma to teeth and tooth roots. (Am J Vet Res2001;62:576–580)
In vitro characterization of FIV-pPPR, a pathogenic molecular clone of feline immunodeficiency virus, and two drug-resistant pol gene mutants
Authors: Stevenson M. A. McCrackin , McBroom Douglas G.
Published: December 2005

Objective—To compare in vitro replication kinetics
and nucleoside analog susceptibilities of a natural
feline immunodeficiency virus (FIV) isolate (FIV-Maxam),
a molecular clone of FIV (FIV-pPPR), and
two (-)-β-L-2',3'-dideoxy-3'-thiacytidine- (3TC-) resistant
mutants of FIV-pPPR.

Sample Population—Peripheral blood mononuclear
cells (PBMC) from 4 specific-pathogenfree cats.

Procedure—Two point mutations corresponding to
mutations of human immunodeficiency virus type 1
(HIV-1) were engineered into the highly conserved
YMDD motif of the reverse transcriptase- (RT-) encoding
region of the FIV-pPPR pol gene. Replication kinetics
and nucleoside analog susceptibilities of FIV-Maxam,
FIV-pPPR, and the 2 mutant viruses were
measured in vitro, using feline PBMC.

Results—Replication kinetics and nucleoside analog
susceptibilities were similar between FIV-Maxam and
FIV-pPPR. However, FIV-Maxam was significantly
more susceptible to 3TC. A methionine-to-valine
mutation at codon 183 (M183V) of the RT-encoding
region of the pol gene of FIV-pPPR conferred highlevel
phenotypic resistance to 3TC and cross-resistance
to the related compound (-)-β-L-2',3'-dideoxy-5-
fluoro-3'-thiacytidine.

Conclusion and Clinical Relevance—Similarities
between FIV-Maxam and FIV-pPPR suggest that
results of studies performed using FIV-pPPR will have
relevance to natural FIV infection in cats. In vitro evaluation
of nucleoside analog susceptibilities of FIV-Maxam
may help determine concentrations of nucleoside
analogs required for effective treatment of FIV-infected
cats.

Impact for Human Medicine—3TC resistance of
FIV-pPPR M183V was similar in magnitude to that of
HIV-1 M184V, a mutant described in infected humans
treated with 3TC. Thus, FIV-pPPR M183V may be a
useful model for studying the in vivo effects of 3TC
resistance on lentivirus pathogenesis. (Am J Vet Res
2001;62:588–594)
Amidolytic heparin activity and values for several hemostatic variables after repeated subcutaneous administration of high doses of a low molecular weight heparin in healthy dogs
Authors: Mischke Reinhard , Grebe Susanne , Jacobs Christina , Kietzmann Manfred
Published: December 2005

Objective—To determine effects of SC administration of repeated doses of a low molecular weight heparin (LMWH) in dogs.

Animals—5 healthy dogs.

Procedure—Each dog received 6 injections (each injection, 150 U of anti-factor-Xa [anti-FXa]/kg of body weight, SC) at 8-hour intervals. Blood samples were collected before and 2 hours after the first, second, third, and sixth injections to measure heparin activity, thrombin time, activated partial thromboplastin time (APTT), antithrombin activity, Hct, and platelet count.

Results—Heparin activity varied between 0.36 ± 0.10 and 0.77 ± 0.08 U of anti-FXa/ml (before and 2 hours after the third injection) and between 0.46 ± 0.11 and 0.82 ± 0.15 U of anti-FXa/ml (before and 2 hours after the sixth injection). Thrombin time and APTT were influenced only slightly. Platelet count, Hct, and antithrombin activity started to decrease significantly 2 hours after the second LMWH injection. Because of the increased consumption of antithrombin, antithrombin activity continuously decreased from 102.1 ± 6.3% before the study to 91.0 ± 3.0% at the end of the study.

Conclusion and Clinical Relevance—Heparin plasma activity was only slightly higher than that recommended for LMWH treatment of humans, and none of the dogs had signs of increased bleeding. Thus, administration of heparin in accordance with this dosing regimen can be recommended for use in clinical studies. The screening tests investigated were not suitable for use in monitoring LMWH treatment of dogs. Assays that use chromogenic substrates are necessary to reliably monitor LMWH plasma concentrations in dogs. (Am J Vet Res2001;62:595–598)
Relationship between mean body surface temperature measured by use of infrared thermography and ambient temperature in clinically normal pigs and pigs inoculated with Actinobacillus pleuropneumoniae
Authors: Loughmiller Joseph A. , Spire Mark F. , Dritz Steve S. , Fenwick Bradley W. , Hosni Mohammad H. , Hogge Steven B.
Published: December 2005

Objective—To determine the relationship between ambient temperature and mean body surface temperature (MBST) measured by use of infrared thermography (IRT) and to evaluate the ability of IRT to detect febrile responses in pigs following inoculation withActinobacillus pleuropneumoniae.

Animals—28 crossbred barrows.

Procedures—Pigs (n = 4) were subjected to ambient temperatures ranging from 10 to 32 C in an environmental chamber. Infrared thermographs were obtained, and regression analysis was used to determine the relationship between ambient temperature and MBST. The remaining pigs were assigned to groups in an unbalanced randomized complete block design (6A pleuropneumoniae-inoculated febrile pigs [increase in rectal temperature ≥ 1.67 C], 6A pleuropneumoniae-inoculated nonfebrile pigs [increase in rectal temperature < 1.67 C], and 12 noninoculated pigs). Infrared thermographs and rectal temperatures were obtained for the period from 2 hours before to 18 hours after inoculation, and results were analyzed by use of repeated-measures ANOVA.

Results—A significant linear relationship was observed between ambient temperature and MBST (slope, 0.40 C). For inoculated febrile pigs, a treatment X method interaction was evident for rectal temperature and MBST, whereas inoculated nonfebrile pigs only had increased rectal temperatures, compared with noninoculated pigs. A method X time interaction resulted from the longer interval after inoculation until detection of an increase in MBST by use of IRT.

Conclusions and Clinical Relevance—Infrared thermography can be adjusted to account for ambient temperature and used to detect changes in MBST and radiant heat production attributable to a febrile response in pigs. (Am J Vet Res2001;62:676–681)
Intranasal vaccination of rabbits with Pasteurella multocida A:3 outer membranes that express iron-regulated proteins
Authors: Confer Anthony W. , Suckow Mark A. , Montelongo Marie , Dabo S. Mady , Miloscio Lawrence J. , Gillespie Arden J. , Meredith Glacia L.
Published: December 2005

Objective—To determine efficacy of intranasal vaccination of rabbits withPasteurella multocidaA:3 outer membrane proteins (OMP) expressing iron-regulated OMP (IROMP) in conferring protection against experimental challenge exposure.

Animals—52 male New Zealand White rabbits.

Procedure— Rabbits were vaccinated intranasally on days 0, 7, and 14; some vaccines included cholera toxin (CT) as an adjuvant. Concentrations of intranasal IgA and serum IgG antibodies againstP multocidaOMP were determined. In experiment A, rabbits were vaccinated with either phospate-buffered saline solution (PBSS), PBSS-CT, OMP-CT, or IROMP-CT, challenge-exposed intranasally on day 16, and euthanatized and necropsied on day 28. Rabbits were also vaccinated with OMP or IROMP without CT and were not challenge-exposed. In experiment B, rabbits were vaccinated with PBSS, PBSS-CT, IROMP, or IROMP-CT. On day 17, rabbits were challenge-exposed intranasally .Nasal bacteria and antibodies were determined on day 24.

Results—In experiment A, OMP-CT vaccination stimulated mucosal and systemic antibody responses to the bacterium and enhanced resistance against challenge exposure. Intranasal bacterial counts were not significantly reduced. Vaccination with IROMP-CT stimulated mucosal and systemic antibodies, enhanced resistance to challenge exposure, and significantly reduced nasal bacterial counts. In experiment B, natural infection was detected in several rabbits at challenge exposure; however, IROMP-CT-vaccinated rabbits had significantly higher serum and nasal antibody responses, compared with other rabbitsIROMP-CT-vaccinated rabbits had significantly lower nasal bacterial counts compared to control rabbits.

Conclusions and Clinical Relevance—Intranasal vaccination of rabbits withP multocidaouter membranes containing IROMP and CT stimulated immunity against experimental pneumonic pasteurellosis. (Am J Vet Res2001;62:697–703)
Evaluation of polymyxin B in an ex vivo model of endotoxemia in horses
Authors: Parviainen Anna K. , Barton Michelle H. , Norton Natalie N.
Published: December 2005

Objective— To evaluate effects of polymyxin B sulfate (PMB) on response of horses to endotoxin, using an ex vivo model.

Animals—8 healthy horses.

Procedure—In a crossover design, 3 doses of PMB (100, 1,000, and 10,000 U/kg of body weight) and physiologic saline solution (control) were evaluated. Prior to and for 24 hours after administration of PMB, blood samples were collected into heparinized tubes for use in 2 assays. For the endotoxin-induced tumor necrosis factor (TNF) assay, blood samples were incubated (37 C for 4 h) with 1 ng ofEscherichia coliorSalmonellaTyphimurium endotoxin/ml of blood. Plasma was harvested and assayed. For the residual endotoxin activity assay, plasma was collected into sterile endotoxin-free borosilicate tubes, diluted 1:10 with pyrogen-free water, and incubated for 10 minutes at 70 C.Escherichia coliendotoxin (0.1 or 1 ng/ml of plasma) was added to the thawed samples prior to performing the limulus ameobocyte lysate assay. Serum creatinine concentrations were monitored for 1 week.

Results—Compared with baseline values, PMB caused a significant dose- and time- dependent decrease in endotoxin-induced TNF activity. Compared with baseline values, residual endotoxin activity was significantly reduced after administration of 10,000 U of PMB/kg. Compared with baseline values, 1,000 and 5,000 U of PMB/kg should inhibit 75% of endotoxin-induced TNF activity for 3 and 12 hours, respectively. Serum creatinine concentrations remained within the reference range.

Conclusion and Clinical Relevance—Results of the study suggest that PMB is a safe, effective inhibitor of endotoxin-induced inflammation in healthy horses. (Am J Vet Res2001; 62:72–76)
Comparison of bending modulus and yield strength between outer stratum medium and stratum medium zona alba in equine hooves
Authors: Wagner Ilka P. , Hood David M. , Hogan Harry A.
Published: December 2005

Objective—To determine whether the bending modulus and yield strength of the outer stratum medium (SM) differed from those of the SM zona alba (SMZA) and to what degree they differed. In addition, a comparison was made among our values and values reported elsewhere.

Sample Population—10 normal equine feet.

Procedure—A 3-point bending technique was used to determine the bending modulus and yield strength of the outer SM and SMZA. Efforts were made to minimize biological and technical factors that could influence the bending modulus.

Results—Bending modulus of the outer SM was (mean ± SD) 187.6 ± 41.3 MPa, whereas mean value for the SMZA was 98.2 ± 36.8 MPa. Mean yield strength was 19.4 ± 2.6 MPa for the outer SM and 5.6 ± 1.7 MPa for the SMZA. Values for bending modulus and yield strength differed significantly between the outer SM and SMZA. Significant differences were not detected when the outer SM was loaded in bending from the outer or inner surface.

Conclusions and Clinical Relevance—Potentially, the SMZA could serve as a mechanical buffer zone between the rigid hoof wall and bone and laminar tissues. This buffer zone potentially assists the feet of horses in transmitting a load through the tissues and prevents the most susceptible tissues from becoming damaged. More consistency among tissue selection, preparation, and testing protocols must be attained before an accurate 3-dimensional finite-element model of an equine foot can be constructed. (Am J Vet Res2001;62:745–751)
Evaluation of dual energy x-ray absorptiometry for in situ measurement of bone mineral density of equine metacarpi
Authors: McClure Scott R. , Glickman Lawrence T. , Glickman Nita W. , Weaver Connie M.
Published: December 2005

Objective—To determine the accuracy and precision of dual energy x-ray absorptiometry (DEXA) for measuring bone mineral density in horses in situ.

Sample Population—12 randomly selected forelimbs from 12 horses.

Procedure—Metacarpi were scanned in 2 planes and DEXA measurements obtained for 6 regions of interest (ROI). Each ROI was isolated and bone density measured by Archimedes' principle. Linear regression analysis was used to determine the correlation between the 2 measurements at each ROI. An additional metacarpus was measured 10 times to determine the coefficient of variation for both techniques.

Results—Dual energy x-ray absorptiometry and bone density were significantly associated at multiple ROI. The addition of age, weight, and soft tissue or bone thickness improved these associations. Repeated measurements had a low coefficient of variation.

Conclusions and Clinical Relevance—Dual energy x-ray absorptiometry can be used to accurately and precisely measure the bone density in the equine metacarpus. Dual energy x-ray absorptiometry appears suitable for serial in vivo measurement of bone density of the equine metacarpus. Dual energy x-ray absorptiometry may be used for studies to evaluate the effects of diet or drugs on bone density or density changes from bone remodeling that develop prior to stress fractures. (Am J Vet Res2001; 62:752–756)
Basic three-dimensional kinematics of the vertebral column of horses trotting on a treadmill
Authors: Faber Marjan , Johnston Christopher , Schamhardt Henk , Weeren René van , Roepstorff Lars , Barneveld Ab
Published: December 2005

Objective—To determine movements of the vertebral
column of horses during normal locomotion.

Animals—5 young Dutch Warmblood horses that did
not have signs of back problems or lameness.

Procedure—Kinematics of 8 vertebrae (T6, T10, T13,
T17, L1, L3, L5, and S3) and both tuber coxae were
determined, using bone-fixated markers. Measurements
were recorded when the horses were trotting
on a treadmill at a constant speed of 4.0 m/s.

Results—Flexion-extension and axial rotation were
characterized by a double sinusoidal pattern of motion
during 1 stride cycle, whereas lateral bending was
characterized by 1 peak and 1 trough. Ranges of
motion for all vertebrae were: flexion-extension, 2.8o
to 4.9o; lateral bending, 1.9° to 3.6°; axial rotation, 4.6°
to 5.8°, except for T10 and T13, where the amount of
axial rotation decreased to 3.1° and 3.3°, respectively.

Conclusion and Clinical Relevance—During locomotion,
3 types of rotations are evident in the thoracolumbar
vertebrae. Regional differences are
observed in the shape and timing of the rotations.
These differences are related to actions of the limbs.
The method described here for direct measurement
of vertebral column motion provides insights into the
complex movements of the thoracolumbar portion of
the vertebral column in trotting horses. Information
on normal kinematics is a prerequisite for a better
understanding of abnormal function of the vertebral
column in horses. (Am J Vet Res 2001;62:757–764)
Pharmacokinetics of imipramine in narcoleptic horses
Authors: Peck Kenneth E. , Hines Melissa T. , Mealey Katrina L. , Mealey Robert H.
Published: December 2005

Objective—To validate use of high-performance liquid chromatography (HPLC) in determining imipramine concentrations in equine serum and to determine pharmacokinetics of imipramine in narcoleptic horses.

Animals—5 horses with adult-onset narcolepsy.

Procedure—Blood samples were collected before (time 0) and 3, 5, 10, 15, 20, 30, and 45 minutes and 1, 2, 3, 4, 6, 8, 12, and 24 hours after IV administration of imipramine hydrochloride (2 or 4 mg/kg of body weight). Serum was analyzed, using HPLC, to determine imipramine concentration. The serum concentration-versus-time curve for each horse was analyzed separately to estimate pharmacokinetic values.

Results—Adverse effects (muscle fasciculations, tachycardia, hyperresponsiveness to sound, and hemolysis) were detected in most horses when serum imipramine concentrations were high, and these effects were most severe in horses receiving 4 mg of imipramine/kg. Residual adverse effects were not apparent. Value (mean ± SD) for area under the curve was 3.9 ± 0.7 h × μg/ml, whereas volume of distribution was 584 ± 161.7 ml/kg, total body clearance was 522 ± 102 ml/kg/h, and mean residence time was 1.8 ± 0.6 hours. One horse had signs of narcolepsy 6 and 12 hours after imipramine administration; corrresponding serum imipramine concentrations were less than the therapeutic range.

Conclusions and Clinical Relevance—Potentially serious adverse effects may be seen in horses administered doses of imipramine that exceed a dosage of 2 mg/kg. Total body clearance of imipramine in horses is slower than that in humans; thus, the interval between subsequent doses should be longer in horses. (Am J Vet Res2001;62:783–786)
Site-specific adaptive remodeling of Greyhound metacarpal cortical bone subjected to asymmetrical cyclic loading
Authors: Johnson Kenneth A. , Skinner Gerry A. , Muir Peter
Published: December 2005

Objective—To quantify geometric, inertial, and histomorphometric properties at the mid-diaphyseal level of left and right metacarpal bones (MCB) of racing Greyhounds.

Sample Population—MCB from 7 racing Greyhounds euthanatized for reasons unrelated to MCB abnormalities.

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 Res2001;62:787–793)
Development of an ex vivo model to study adherence of Mannheimia haemolytica serovar 1 to mucosal tissues of the respiratory tract of cattle
Authors: Clarke Jean M. , Morton Rebecca J. , Clarke Cyril R. , Fulton Robert W. , Saliki Jeremiah T.
Published: December 2005

Objective—To develop and validate an ex vivo model for study of adherence ofMannheimia haemolytica(formerlyPasteurella haemolytica) to respiratory tract mucosa of cattle and to use this model to confirm adherence ofM haemolyticaserovar 1 (Mh1) to several relevant respiratory mucosal surfaces.

Sample Population—Excised nasal, nasopharyngeal, turbinate, and tonsillar mucosal tissue from the bovine upper respiratory tract.

Procedure—Mh1 was radiolabeled by use of tritiated leucine. Various concentrations of labeled bacteria were incubated with bovine upper respiratory tract tissues for various times. Tissue was washed to remove nonadherent bacteria, and percentage of bacteria adhered (percentage of adherence) was estimated using radioactivity. Using an optimal inoculum concentration and incubation time, percentage of Mh1 adherence was compared on nasal, nasopharyngeal, turbinate, and tonsillar mucosal tissue, and adherence to nasopharyngeal tissue was confirmed by scanning and transmission electron microscopy.

Results—The optimal Mh1 inoculum concentration was 1 × 107colony forming units/ml and incubation time was 3 hours. Percentage of adherence of Mh1 to nasopharyngeal tissue was greater than adherence to other tissue types.

Conclusions and Clinical Relevance—The ex vivo model maintained the functional and structural integrity of bovine upper respiratory tract mucosa, as confirmed by light and electron microscopy. Electron microscopy revealed participation of epithelial cell cilia and surface mucus in adherence of Mh1 to nasopharyngeal tissue. Adherence of Mh1 was confirmed in repeated assays, indicating that this organism adheres to upper respiratory tract mucosa of cattle. (Am J Vet Res2001;62:805–811)
Estimation of genetic population variables for six radiographic criteria of hip dysplasia in a colony of Labrador Retrievers
Authors: Ohlerth Stefanie , Lang Johann , Busato André , Gaillard Claude
Published: December 2005

Objective—To estimate genetic population variables for 6 radiographic criteria of canine hip dysplasia (CHD).

Animals—664 full- and half-siblings from a colony of Labrador Retrievers.

Procedure—Heritability estimates and genetic correlations were calculated for 6 radiographic criteria of CHD. Two evaluation protocols were compared: the grade of the most severely affected hip joint and the sum of the scores for both hip joints. The predictive performance of estimated breeding values was also evaluated.

Results—The overall prevalence of CHD (Fédération Cynologique Internationale grades C, D, and E) was 29.6%. Median age at radiographic examination was 377 days. Heritability for the total CHD grade, Norberg angle (NA), coverage of the femoral head (COV), craniodorsal acetabular rim (ACR), subchondral bone sclerosis (SUBCH), shape of the femoral head and neck (FHN), and osteoarthritic changes at the insertion site of the joint capsule (JC) was estimated as follows: 0.44, 0.43, 0.46, 0.37, 0.32, 0.21, and 0.05, respectively. Heritability estimates were slightly higher for the sum of the scores for both hip joints. If NA and COV were included as fixed effects in the model for the dependent variables ACR, SUBCH, FHN, and JC , then heritability of these traits significantly decreased (0.08 to 0.15). High scores of NA and COV lead to a significant increase of the scores of the remaining criteria.

Conclusions and Clinical Relevance—Canine hip dysplasia is heritable to a moderate degree. Signs of subluxation revealed the highest heritability estimates. The criteria ACR, SUBCH, FHN, and JC were strongly influenced by NA and COV. (Am J Vet Res2001;62:846–852)
Fluorophotometric determination of aqueous humor flow rate in clinically normal dogs
Authors: Ward Daniel A. , Cawrse Margaret A. , Hendrix Diane V. H.
Published: December 2005

Objective—To determine aqueous humor flow rate in clinically normal dogs, using fluorophotometry.

Animals—20 clinically normal Beagles.

Procedure—A study was performed on 5 dogs to establish an optimal protocol for fluorophotometric determination of aqueous humor flow rate. This protocol then was used to measure aqueous humor flow rate in 15 dogs. Corneas were loaded with fluorescein by topical application, and corneal and aqueous humor fluorescein concentrations were measured 5, 6.5, and 8 hours after application. Concentration-versus- time plots were generated, and slopes and ratios of the fluorescein concentration in the cornea and aqueous humor from these graphs were used to calculate flow rates. Calculations were performed by use of automated software provided with the fluorophotometer and by manual computation, and the 2 calculation methods were compared.

Results—The protocol established for the 5 dogs resulted in semilogarithmic and parallel decay of corneal and aqueous humor concentrations. Manually calculated mean ± SD aqueous humor flow rates for left, right, and both eyes were 5.58 ± 2.42, 4.86 ± 2.49, and 5.22 ± 1.87 μl/min, respectively, whereas corresponding flow rates calculated by use of the automated software were 4.54 ± 3.08, 4.54 ± 3.10, and 4.54 ± 2.57 μl/min, respectively. Values for the left eye were significantly different between the 2 computation methods.

Conclusions and Clinical Relevance—Aqueous humor flow rates can be determined in dogs, using fluorophotometry. This technique can be used to assess pathologic states and medical and surgical treatments that alter aqueous humor dynamics. (Am J Vet Res2001;62:853–858)
Molecular epidemiologic features and antimicrobial susceptibility profiles of various ribotypes of Pseudomonas aeruginosa isolated from humans and ruminants
Authors: Rivas Ariel L. , Bodis Mary , Bruce James L. , Anderson Kevin L. , Klein Renate F. , González Rubén N. , Quimby Fred W. , Batt Carl A. , Lein Donald H.
Published: December 2005

Objectives—To assess automated ribotyping for characterization ofPseudomonas aeruginosaisolates and to identify their type prevalence and geographic distribution.

Sample Population—39 human and 56 ruminantP aeruginosaisolates.

Procedures—Isolates were identified by use of bacteriologic techniques and automatedPvuII-based ribotyping. Susceptibility to antimicrobials was tested in vitro. Data were analyzed for index of discrimination; prevalence ratio; geographic distribution of ribotypes found only in humans, only in cows, or only in goats (single-host ribotypes); and geographic distribution of ribotypes found in humans and ruminants (multihost ribotypes).

Results—All isolates were typeable (45 ribotypes, 35 single-host ribotypes). Ribotyping index of discrimination was 0.976. More isolates (45.3%) than expected yielded multihost ribotypes (22% of all ribotypes). Although 8.6% of single-host ribotypes were found in 4 or more isolates, 60% of multihost ribotypes were found in 4 or more isolates. Ninety percent of multihost ribotypes were isolated from different geographic areas, whereas 3.0% of singlehost ribotypes were isolated from different geographic areas. All ruminant isolates were susceptible to gentamicin and polymyxin B. In contrast, antibiogram profiles differed for human isolates from different geographic areas. Susceptibility to antimicrobials differentiated 6 isolates not distinguished by ribotyping.

Conclusions and Clinical Relevance—Automated ribotyping withPvuII discriminated more isolates than in vitro antimicrobial susceptibility. In combination, both tests provided more information than either test alone. Given the greater prevalence and geographic distribution of multihost ribotypes, immunocompromised humans and lactating ruminants may have a greater risk for disease if exposed to multihostPaeruginosaribotypes, compared with single-host ribotypes. (Am J Vet Res2001;62:864–870)
Effect of a leukocyte-depleting filter in an extracorporeal circuit used for low-flow ischemia and reperfusion of equine jejunum
Authors: Hoogmoed Linda M. Van , Snyder Jack R. , Nieto Jorge G. , Harmon Faye A. , Timmerma Brenna L.
Published: December 2005

Objective—To determine effect of leukocyte depletion on hematologic, morphologic, and metabolic variables of equine jejunum after induction of arterial lowflow ischemia and reperfusion by use of an extracorporeal circuit.

Animals—14 healthy adult horses.

Procedure—A segment of jejunum was surgically removed and maintained in an isolated circuit for 3 hours (control group), arterial flow was reduced to 20% of baseline for 40 minutes followed by 1 hour of reperfusion (low-flow group), or leukocyte depletion was filter-induced, and low-flow ischemia and reperfusion were conducted as in the low-flow control group (filter-treated group). Various metabolic, hemodynamic, and histomorphologic variables were evaluated, including effects of electrical field stimulation and L-N-nitro-arginine-methyl-ester (L-NAME) on contractile activity.

Results—The extracorporeal circuit appeared to maintain the jejunum within physiologic limits for an extended period. Low-flow ischemia with reperfusion induced significant differences in various measurements, compared with control specimens. Significant differences were not detected between the low-flow and filter-treated groups. Myeloperoxidase activity was greater in the low-flow group than the control group, whereas a difference was not detected between control and filter-treated groups.

Conclusions and Clinical Relevance—The extracorporeal circuit maintained intestine for 3 hours in a physiologic state and may be used for simulation of tissue injury. Leukocyte depletion generally did not attenuate the effects of low-flow ischemia and reperfusion on equine small intestine. (Am J Vet Res2001;62:87–96)
Morphometric and anatomic study of the hind limb of a dog
Authors: Shahar Ron , Milgram Joshua
Published: December 2005

Objective—To obtain the anatomic and morphometric
data required for biomechanical analysis of the
hind limb in dogs.

Animals—A healthy adult mixed-breed 23-kg male
dog.

Procedure—Following euthanasia of the dog, all
muscles of the right hind limb were identified and
meticulously removed. Physiologic cross-sectional
areas (PCSA) and architectural indices (AI) were calculated.
The coordinates for the origin and insertion
of each muscle were determined, using orthogonal
right-handed coordinate systems embedded in the
pelvis, femur, and tibia.

Results—PCSA and AI were calculated for 29 muscles,
and coordinates for the origins and insertions of
these muscles were determined.

Conclusions—Results provide the morphometric
and anatomic data necessary for 3-dimensional biomechanical
studies of the hind limb in dogs. ( Am J
Vet Res 2001;62:928–933)
Selenium status of cats in four regions of the world and comparison with reported incidence of hyperthyroidism in cats in those regions
Authors: Foster Darren J. , Thoday Keith L. , Arthur John R. , Nicol Fergus , Beatty Julia A. , Svendsen Carl K. , Labuc Robert , McConnell Mary , Sharp Margaret , Thomas Jan B. , Beckett Geoffery J.
Published: December 2005

Objective—To assess selenium (Se) status of cats in
4 regions of the world and to compare results for Se
status with reported incidence of hyperthyroidism in
cats in those regions.

Animals—50 cats (30 from 2 regions with an allegedly
high incidence of hyperthyroidism and 20 from 2 regions
in which the disease is less commonly reported).

Procedure—Hematologic samples (heparinized
whole blood, plasma, and RBC fractions) were
obtained from 43 healthy euthyroid cats and 7 hyperthyroid
cats. Plasma concentration of Se and activity
of glutathione peroxidase (GPX) in whole blood and
plasma were determined.

Results—Plasma concentration of Se and GPX activity
in whole blood or plasma did not differ significantly
among cats from the 4 regions. However, cats had
a plasma concentration of Se that was approximately
10 times the concentration reported in rats and
humans. The GPX activity in whole blood or plasma in
cats generally was higher than values reported in rats
or humans.

Conclusions and Clinical Relevance—Cats have
higher Se concentrations in plasma, compared with
values for other species. However, Se status alone
does not appear to affect the incidence of hyperthyroidism
in cats. High Se concentrations may have
implications for health of cats if such concentrations
are influenced by the amount of that micronutrient
included in diets. (Am J Vet Res 2001;62:934–937)
Use of a monovalent leptospiral vaccine to prevent renal colonization and urinary shedding in cattle exposed to Leptospira borgpetersenii serovar hardjo
Authors: Bolin Carole A. , Alt David P.
Published: December 2005

Objective—To determine whether a monovalentLeptospira borgpeterseniiserovar hardjo (type hardjobovis) vaccine commercially available in Australia, New Zealand, Ireland, and the United Kingdom would protect cattle from renal colonization and urinary shedding when exposed to a US strain ofLeptospira borgpeterseniiserovar hardjo.

Animals—24 Hereford heifers that lacked detectable antibodies against serovar hardjo.

Procedure—Heifers received 2 doses, 4 weeks apart, of the commercial hardjo vaccine (n = 8) or a monovalent US reference hardjo vaccine (8) or were not vaccinated (controls; 8). Heifers were challenged 16 weeks later by intraperitoneal inoculation or conjunctival instillation. Serum antibody titers were measured weekly, and urine samples were examined for leptospires. Heifers were euthanatized 11 to 14 weeks after challenge, and kidney tissue was examined for evidence of colonization.

Results—All 8 heifers vaccinated with the reference vaccine were found to be shedding leptospires in their urine and had evidence of renal colonization. All 4 control heifers challenged by conjunctival instillation and 2 of 4 control heifers challenged by intraperitoneal inoculation shed leptospires in their urine, and all 8 had evidence of renal colonization. In contrast, leptospires were not detected in the urine or tissues of any of the 8 heifers that received the commercial hardjo vaccine. Heifers that received the commercial hardjo vaccine had significantly higher antibody titers than did heifers that received the reference vaccine.

Conclusions and Clinical Relevance—Results suggest that cattle that received 2 doses of the commercial hardjo vaccine were protected against renal colonization and urinary shedding when challenged withL borgpeterseniiserovar hardjo strain 203 four months after vaccination. (Am J Vet Res2001;62:995–1000)