bluuebunny/crossref_metadata_2025 huggingface dataset:
Usefulness of dobutamine stress tests for detection of cardiac abnormalities in dogs with experimentally induced early left ventricular dysfunction
Authors: Mc Entee Kathleen , Clercx Cécile , Soyeur Daniel , Amory Hélène , Michaux Charles , Flandre Thierry , Jonville Eva , Pynnaert Catherine , Miserque Nathalie , Henroteaux Marc
Published: December 2005

Objective—To determine whether dobutamine stress tests (DST) can be used to detect cardiac dysfunction in dogs with early left ventricular dysfunction (ELVD) induced by rapid right ventricular pacing (RRVP).

Animals—7 adult male Beagles.

Procedure—A pacemaker was surgically implanted in each dog at the level of the right ventricular apex. Electrocardiography, Doppler sphygmomanometry, and Doppler echocardiography were performed before and during a DST prior to activation of the pacemaker and every 3 to 4 days during the period of RRVP. Dobutamine stress tests were performed by infusing dobutamine at incremental dosages ranging from 12.5 to 42.5 µg/kg of body weight/min.

Results—Clinical signs of congestive heart failure were not observed during the pacing period. However, all dogs developed ELVD associated with significant changes in values for most Doppler echocardiographic variables obtained prior to DST. Adverse cardiac effects were not detected during DST. Most Doppler echocardiographic indices of cardiac function were significantly altered in response to dobutamine infusion during the pacing period, compared with prepacing values. However, a dobutamine-induced 2-fold increase in cardiac output was maintained.

Conclusions and Clinical Relevance—Dobutamine stress tests can be safely performed in dogs with experimentally induced ELVD. Dobutamine stress tests may be a sensitive, noninvasive diagnostic method, complementary to standard clinical examinations, for detection of early cardiac dysfunction in dogs asymptomatic for dilated cardiomyopathy. (Am J Vet Res2001;62:448–455)
Cardiovascular effects of romifidine in dogs
Authors: Pypendop Bruno H. , Verstegen John P.
Published: December 2005

Objective—To characterize the cardiovascular effects of romifidine at doses ranging from 5 to 100 µg/kg of body weight, IV.

Animals—25 clinically normal male Beagles.

Procedure—Romifidine was administered IV at a dose of 5, 10, 25, 50, or 100 µg/kg (n = 5/group). Heart rate, arterial pressure, central venous pressure, mean pulmonary arterial pressure, pulmonary capillary wedge pressure, body temperature, cardiac output, and PCV were measured immediately prior to and at selected times after romifidine administration. Cardiac index, stroke index, rate-pressure product, systemic and pulmonary vascular resistance indices, and left and right ventricular stroke work indices were calculated. Degree of sedation was assessed by an observer who was blinded to the dose administered.

Results—Romifidine induced a decrease in heart rate, pulmonary arterial pressure, rate-pressure product, cardiac index, and right ventricular stroke work index and an increase in central venous pressure, pulmonary capillary wedge pressure, and systemic vascular resistance index. In dogs given romifidine at a dose of 25, 50, or 100 µg/kg, an initial increase followed by a prolonged decrease in arterial pressure was observed. Arterial pressure immediately decreased in dogs given romifidine at a dose of 5 or 10 µg/kg.

Conclusion and Clinical Relevance—Results suggest that IV administration of romifidine induces dose-dependent cardiovascular changes in dogs. However, the 2 lowest doses (5 and 10 µg/kg) induced less cardiovascular depression, and doses ≥ 25 µg/kg induced similar cardiovascular changes, suggesting that there may be a ceiling on the cardiovascular effects of romifidine. (Am J Vet Res2001; 62:490–495)
Effect of centrally administered opioid receptor agonists on CSF and plasma oxytocin concentrations in dogs
Authors: Brown Dorothy C. , Perkowski Sandra Z. , Shofer Frances , Amico Janet A.
Published: December 2005

Objective—To measure oxytocin concentrations in
blood and CSF following central administration of opioid
agonists in dogs.

Animals—5 male dogs.

Procedure—In a crossover design, CSF and blood
were collected immediately before and 15 and 30
minutes after cisternal administration of D-Ala2,
MePhe4, Gly-ol-enkephalin (DAMGO, a µ-receptor
agonist); D-Pen, pCl-Phe4, D-Pen5-enkephalin (a δ-receptor agonist); U50488H (a κ-receptor agonist);
morphine; and saline (0.9% NaCl) solution.

Results—Plasma oxytocin concentration was significantly
increased 15 minutes after administration of
DAMGO and 30 minutes after administration of
U50488H, compared with concentrations obtained
after administration of saline solution. Concentration
of oxytocin in CSF was significantly decreased 30
minutes after administration of U50488H, compared
with concentration after administration of saline solution.

Conclusion and Clinical Relevance—Results suggest
that in male dogs, activation of centrally located
µ and κ receptors elicits an overall excitatory effect on
neurons that regulate peripheral release of oxytocin,
whereas activation of centrally located κ receptors
elicits an overall inhibitory effect on neurons that regulate
central release. These results are in contrast to
those reported for other species, in which opioids
have a pronounced inhibitory effect on release of oxytocin
from the neurohypophysis. (Am J Vet Res 2001;
62:496–499)
Infusion of a combination of propofol and medetomidine for long-term anesthesia in ponies
Authors: Bettschart-Wolfensberger Regula , Freeman Sarah L. , Jäggin-Schmucker Nicola , Clarke Kathleen W.
Published: December 2005

Objective—To determine the minimal infusion rate of propofol in combination with medetomidine for longterm anesthesia in ponies and the effects of atipamezole on recovery.

Animals—12 ponies.

Procedure—Ponies were sedated with medetomidine (7 µg/kg of body weight, IV). Ten minutes later, anesthesia was induced with propofol (2 mg/kg, IV). Anesthesia was maintained for 4 hours, using an infusion of medetomidine (3.5 µg/kg per hour, IV) and propofol at a rate sufficient to prevent ponies from moving after electrical stimulation. Arterial blood pressures and blood gas analysis, heart rates, and respiratory rates were monitored. For recovery, 6 ponies were given atipamezole (60 µg/kg, IV). Induction and recovery were scored.

Results—Minimal propofol infusion rates ranged from 0.06 to 0.1 mg/kg per min. Mean arterial blood pressure was stable (range, 74 to 86 mm Hg), and heart rate (34 to 51 beats/min) had minimal variations. Variable breathing patterns were observed. Mean Pao2(range, 116 to 146 mm Hg) and mean Paco2(range, 48 to 51 mm Hg) did not change significantly with time, but hypoxemia was evident in some ponies (minimal Pao2, 47 mm Hg). Recovery was fast and uneventful with and without atipamezole (completed in 20.2 and 20.9 minutes, respectively).

Conclusion and Clinical Relevance—Infusion of a combination of medetomidine and propofol was suitable for prolonged anesthesia in ponies. Recovery was rapid and uneventful. A combination of propofol and medetomidine may prove suitable for long-term anesthesia in horses. Monitoring of blood gases is essential because of potential hypoxemia. (Am J Vet Res2001;62:500–507)
Generation of reactive oxygen species by equine spermatozoa
Authors: Ball Barry A. , Vo Anthony T. , Baumber Julie
Published: December 2005

Objective—To characterize generation of reactive oxygen species (ROS) by equine spermatozoa.

Sample Population—Multiple semen samples collected from 9 stallions.

Procedure—Equine spermatozoa were separated from seminal plasma on a discontinuous polyvinylpyrrolidone (PVP)-coated silica gradient and resuspended in a modified Tyrode albumin-lactate-pyruvate medium. Amount of hydrogen peroxide (H2O2) generated was assayed by use of a 1-step fluorometric assay, using 10-acetyl-3,7-dihydroxyphenoxazine as a probe for detection of H2O2in a microplate assay format. Concentration of H2O2was determined by use of a fluorescence microplate reader.

Results—Amount of H2O2generated increased significantly with time and spermatozoa concentration for live and flash-frozen spermatozoa, and amount of H2O2generated was significantly greater for flash-frozen than for live spermatozoa. Addition of the reduced form of nicotinamide adenine dinucleotide phosphate (NADPH) significantly increased generation of H2O2by live and flash-frozen spermatozoa. Addition of a calcium ionophore also significantly increased the amount of H2O2generated by live spermatozoa but did not have an effect on amount of H2O2generated by flash-frozen spermatozoa. Abnormal equine spermatozoa generated significantly greater amounts of H2O2than did normal spermatozoa.

Conclusion and Clinical Relevance—Equine spermatozoa generate ROS in vitro, possibly via a NADPH-oxidase reaction. Spermatozoa damaged during flash-freezing or morphologically abnormal spermatozoa generated significantly greater amounts of ROS than did live or morphologically normal spermatozoa. Damaged and abnormal spermatozoa generate greater amounts of ROS that may contribute to reduced fertility or problems related to semen preservation. (Am J Vet Res2001;62:508–515)
Clinical signs, evaluation of bronchoalveolar lavage fluid, and assessment of pulmonary function in horses with inflammatory respiratory disease
Authors: Couëtil Laurent L. , Rosenthal Frank S. , DeNicola Dennis B. , Chilcoat Clayton D.
Published: December 2005

Objective—To evaluate the association among clinical signs, results of cytologic evaluation of bronchoalveolar lavage (BAL) fluid, and measures of pulmonary function in horses with inflammatory respiratory disease.

Animals—9 healthy horses, 5 horses with inflammatory airway disease (IAD), and 9 horses with chronic obstructive pulmonary disease (COPD).

Procedure—Clinical examination, lung function tests, and BAL were performed on each horse.

Results—Standard lung mechanics of horses with exacerbated COPD differed significantly from those of healthy horses; however, there were few differences among horses with IAD, horses with COPD during remission, and healthy horses. Most variables for forced expiration (FE) in horses with COPD or IAD differed significantly from those for healthy horses. Results of clinical examination had low to moderate sensitivity and predictive values for a diagnosis of COPD (range, 67 to 80%). Results of FE tests had high sensitivity, specificity, and predictive values for a diagnosis of COPD (79 to 100%), and results of standard lung mechanics tests had low sensitivity and predictive values (22 to 69%). Percentage of neutrophils in BAL fluid was highly sensitive (100%) but moderately specific (64%) for a diagnosis of COPD.

Conclusion and Clinical Relevance—Clinical examination is moderately accurate for establishing a diagnosis of COPD. Forced expiration tests can specifically detect early signs of airway obstruction in horses with COPD and IAD that may otherwise be inapparent. Cytologic evaluation of BAL fluid allows early detection of inflammatory respiratory disease, but it is not specific for COPD. (Am J Vet Res2001;62: 538–546)
Effects of sodium citrate, low molecular weight heparin, and prostaglandin E1 on aggregation, fibrinogen binding, and enumeration of equine platelets
Authors: Kingston Janene K. , Bayly Warwick M. , Sellon Debra C. , Meyers Kenneth M. , Wardrop K. Jane
Published: December 2005

Objective—To investigate the effects of sodium citrate, low molecular weight heparin (LMWH), and prostaglandin E1(PGE1) on aggregation, fibrinogen binding, and enumeration of equine platelets. Sample Population—Blood samples obtained from 4 Thoroughbreds.

Sample Population—Blood samples obtained from 4 Thoroughbreds.

Procedure—Blood was collected into syringes in the ratio of 9 parts blood:1 part anticoagulant. Anticoagulants used were sodium citrate, LMWH, sodium citrate and LMWH, or 300 nMPGE1/ml of anticoagulant. Platelet aggregation in response to ADP, collagen, and PGE1was assessed, using optical aggregometry. Platelet activation was evaluated, using flow cytometry, to detect binding of fluorescein- conjugated anti-human fibrinogen antibody. Plasma concentration of ionized calcium was measured, using an ion-selective electrode.

Results—Number of platelets (mean ± SEM) in samples containing LMWH (109.5 ± 11.3 × 103cells/µl) was significantly less than the number in samples containing sodium citrate (187.3 ± 30.3 × 103cells/µl). Increasing concentrations of sodium citrate resulted in reductions in platelet aggregation and plasma concentration of ionized calcium. Addition of PGE1prior to addition of an agonist inhibited platelet aggregation in a concentration-dependent manner, whereas addition of PGE14 minutes after addition of ADP resulted in partial reversal of aggregation and fibrinogen binding.

Conclusion and Clinical Relevance—A high concentration of sodium citrate in blood samples decreases plasma concentration of ionized calcium, resulting in reduced platelet aggregation and fibrinogen binding. Platelets tend to clump in samples collected into LMWH, precluding its use as an anticoagulant. Platelet aggregation and fibrinogen binding can be reversed by PGE1, which may result in underestimation of platelet activation. (Am J Vet Res2001; 62:547–554)
Evaluation of a nonradioactive colorimetric assay for analysis of lymphocyte proliferation in healthy cats
Authors: Saker Korinn E. , Kalnitsky Joan , Gogal Robert M. , Ward Daniel L.
Published: December 2005

Objective—To compare results of a nonradioactive
colorimetric microplate assay with results of a traditional
radioactive proliferation assay for determination
of its use as a reliable and accurate alternative
method for determination of proliferative activity of
feline lymphocytes.

Sample Population—Blood samples from 10 clinically
normal domestic shorthair cats.

Procedure—Double-density gradient separation was
used to isolate mononuclear cells. Isolated cells were
stimulated with various concentrations of concanavalin
A (Con-A) and cultured for 72 hours.
Lymphocyte proliferation was measured by radioactive
([3H]thymidine) and nonradioactive (colorimetric)
techniques. Immunophenotypic analysis with felinespecific
CD4+ and CD8+ monoclonal antibody was performed,
using flow cytometry.

Results—Mononuclear cells were successfully isolated
(97 to 99% purity and viability) from blood samples.
A similar dose-dependent proliferative response
to Con-A stimulation was measured with [3H]thymidine
incorporation and the colorimetric assay. For
both techniques, concentrations of 0.1 and 1.0 µg of
Con-A/ml were submitogenic, and 100 µg/ml was
toxic to cultured cells. For both techniques, maximal
proliferation was observed with 5 µg of Con-A/ml.

Conclusion and Clinical Relevance—These results
indicate that the nonradioactive colorimetric technique
is a reliable and accurate method for measuring
proliferative activity of feline lymphocytes. Clinically,
this assay can be used as part of a screening process
to determine immunocompetence of at-risk cats and
to evaluate treatments for cats with immune-mediated
or T-cell-dependent diseases. (Am J Vet Res 2001;
62:567–571)
Comparison of fermentation of selected fructooligosaccharides and other fiber substrates by canine colonic microflora
Authors: Vickers Robert J. , Sunvold Gregory D. , Kelley Russell L. , Reinhart Gregory A.
Published: December 2005

Objective—To compare fermentation characteristics of fructooligosaccharides (FOS) and other fiber substrates that are commonly found in canine diets.

Sample Population—Fecal samples from 3 adult dogs.

Procedure—The ability of fiber substrates to be used in microbial fermentation reactions was assessed by use of an in vitro fermentation system. Dogs were fed a commercially available food, and feces were collected for use as the microbial inoculum. Substrates used were beet pulp, cellulose, soy fiber, mannanoligosaccharides (MOS), FOS, and 4 inulin products (inulin 1, 2, 3, and 4). Each substrate was incubated anaerobically with fecal inoculum and growth media for 6, 12, and 24 hours, and production of short-chain fatty acids (SCFA) was measured.

Results—Total production of SCFA was higher for fermentation of the 4 inulin products and FOS, whereas fermentation of beet pulp, MOS, and soy fiber resulted in moderate concentrations of SCFA. Fermentation of cellulose produced the lowest concentrations of total SCFA without detection of butyrate or lactate. Butyrate production was greatest for fermentation of the 4 inulin products and FOS. Total lactate production was greatest for FOS and inulin 4. As expected, production of SCFA increased for all substrates as fermentation time increased.

Conclusion and Clinical Relevance—Canine fecal microflora ferment FOS-containing substrates in a similar manner, with little fermentation of cellulosebased carbohydrates. Furthermore, results of an in vitro fermentation system indicate that fiber type affects the metabolic activity of microorganisms, thus influencing the amount and nature of the end products of fermentation. (Am J Vet Res2001;62: 609–615)
Impact of doramectin treatment at the time of feedlot entry on the productivity of yearling steers with natural nematode infections
Authors: MacGregor D. Scott , Yoder Darwin R. , Rew Robert S.
Published: December 2005

Objective—To measure the reduction in fecal nematode
egg counts and productivity impact of treatment
of yearling steers with doramectin at entry into the
feedlot, compared with control steers treated only
with fenthion.

Animals—6,096 crossbred yearling steers with a
mean (± SD) body weight of 377.0 (± 37) kg.

Procedure—Steers were implanted with zeranol and
alternately separated to fill each of 24 pens. Groups of
steers within 12 matched pairs of pens were randomly
allocated to treatment with doramectin or no treatment
with doramectin for internal nematodes. Fecal
samples were collected from approximately every
twentieth steer from each pen at day 0 and at reimplant
(approx day 60). Each steer was weighed on day
0 and at reimplant and then mean body weights of
steers per pen were determined at 120 to140 days
after trial initiation.

Results—Treatment steers had a significantly lower
fecal egg count at reimplant than control steers.
Treatment steers had a significantly greater mean
daily gain during the study, significantly greater feed
consumption, significantly lower feed-to-gain ratio,
and significantly better quality carcass grades at
slaughter.

Conclusion and Clinical Relevance—Under the
conditions of our trial, there was a significant fecal
egg count reduction response to doramectin treatment,
which resulted in significantly improved productivity.
Results of economic analysis of return on
investment indicated that even with low egg counts
in heavy body weight cattle, nematode egg count
reduction with doramectin significantly improved
returns. (Am J Vet Res 2001;62:622–624)
Assessment of a point-of-care instrument for identification of primary hemostatic disorders in dogs
Authors: Callan Mary Beth , Giger Urs
Published: December 2005

Objective—To assess a point-of-care instrument for identification of primary hemostatic disorders in dogs.

Animals—29 healthy dogs and 23 nonanemic dogs with primary hemostatic disorders (thrombocytopenia, n = 6; thrombopathia, 6; von Willebrand disease [vWD], 11).

Procedure—Citrated blood was obtained and closure times (CT) were determined by measuring the time required for occlusion of an aperture by a platelet plug within the point-of-care instrument. Reference ranges for CT were established, and CT were determined for dogs with primary hemostatic disorders.

Results—CT measured with adenosine diphosphate as the platelet agonist (ADP-CT) ranged from 52 to 86 seconds for healthy dogs (mean ± 2 SD, 67 ± 7.8 seconds; median, 65 seconds), and CT measured with epinephrine as the agonist (EPI-CT), from 97 to 225 seconds (151 ± 38 seconds; 148 seconds). In thrombocytopenic dogs, ADP- and EPI-CT were prolonged (> 165 and > 264 seconds, respectively). Five of 6 dogs with thrombopathia had prolonged ADP-CT, whereas EPI-CT was prolonged in all 6 dogs. In all dogs with vWD, ADP-CT was prolonged; EPI-CT was prolonged in 10 of these dogs. Sensitivity and specificity for ADP-CT were 95.7 and 100%, respectively, and positive and negative predictive values, 100 and 96.7%, respectively, whereas for EPI-CT, these values were 95.7 and 82.8%, respectively, and 81.5 and 96%, respectively.

Conclusions and Clinical Relevance—The point-ofcare instrument allowed quick assessment of primary hemostasis in nonanemic dogs. Use of this instrument may be helpful for making decisions regarding management of dogs with primary hemostatic disorders. (Am J Vet Res2001;62:652–658)
Effects of enrofloxacin and ciprofloxacin hydrochloride on canine and equine chondrocytes in culture
Authors: Egerbacher Monika , Edinger Johannes , Tschulenk Waltraud
Published: December 2005

Objective—To study chondrotoxic effects of enrofloxacin (ENR) and ciprofloxacin hydrochloride (CFX) on canine and equine articular chondrocytes in culture and to compare the effects with that of cultivation in Mg2+-free medium.

Sample Population—Chondrocytes from articular cartilage of 4- and 6 -month old dogs and 2- to 4- year-old horses.

Procedure—Chondrocytes were cultivated with 10, 40, 80, and 160 μg of CFX/ml, 10, 50, 100, and 150 μg of ENR/ml, or in Mg2+-free medium. A live-to-dead test was performed to test cytotoxic effects. Morphologic changes were evaluated by electron microscopy. An attachment assay was used to test the ability of chondrocytes to adhere to collagen type- II coated-chamber slides in the presence of CFX and with Mg2+-free medium.

Results—Chondrocytes cultivated in quinolone-supplemented medium or Mg2+-free medium had a decreased ability to adhere to culture dishes. Cell shape and the actin and vimentin cytoskeleton changed in a concentration-dependent manner. These effects were not species-specific and developed with both quinolones. On day 1 of culture, adhesion of chondrocytes to collagen type II was reduced to 70 and 45% of control values in the CFX treatment and Mg2+-free treatment groups, respectively. On day 5 of culture, adhesion of chondrocytes was reduced to 45 and 40% of control values in the CFX treatment and Mg2+-free treatment groups, respectively.

Conclusion and Clinical Relevance—In vitro, chondrotoxic effects of quinolones appear to be the result of irregular integrin signaling and subsequent cellular changes. Drug concentrations leading to morphologic changes in vitro may be achieved in articular cartilage in vivo. (Am J Vet Res2001;62:704–708)
Arthrocentesis of the temporomandibular joint in adult horses
Authors: Rosenstein Diana S. , Bullock Matthew F. , Ocello Peter J. , Clayton Hilary M.
Published: December 2005

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 Res2001;62:729–735).
Bovine papillomavirus DNA in neoplastic and nonneoplastic tissues obtained from horses with and without sarcoids in the western United States
Authors: Carr Elizabeth A. , Théon Alain P. , Madewell Bruce R. , Griffey Stephen M. , Hitchcock Margaret E.
Published: December 2005

Objective—To determine the incidence of bovine
papillomavirus (BPV) type 1 or 2 in sarcoids and other
samples of cutaneous tissues collected from horses
in the western United States.

Animals—55 horses with sarcoids and 12 horses
without sarcoids.

Procedure—Tissue samples (tumor and normal skin
from horses with sarcoids and normal skin, papillomas,
and nonsarcoid cutaneous neoplasms from
horses without sarcoids) were collected. Tissue samples
were analyzed for BPV-1 or -2 DNA, using a polymerase
chain reaction (PCR) and restriction fragment
length polymorphism. The PCR products from 7 sarcoid-
affected horses were sequenced to evaluate percentage
homology with expected sequences for BPV-1 or -2.

Results—Most (94/96, 98%) sarcoids contained BPV
DNA. Sixty-two percent of the tumors examined had
restriction enzyme patterns consistent with BPV-2.
Thirty-one of 49 (63%) samples of normal skin
obtained from horses with sarcoids contained BPV
DNA. All samples subsequently sequenced had
100% homology with the expected sequences for the
specific viral type. All tissues from healthy horses,
nonsarcoid neoplasms, and papillomas were negative
for BPV DNA.

Conclusions and Clinical Relevance—Bovine papillomaviral
DNA was detected in essentially all sarcoids
examined. There appears to be regional variation in
the prevalence of viral types in these tumors. The fact
that we detected viral DNA in normal skin samples
from horses with sarcoids suggests the possibility of
a latent viral phase. Viral latency may be 1 explanation
for the high rate of recurrence following surgical excision
of sarcoids. (Am J Vet Res 2001;62:741–744)
Comparison of heartworm extract-induced shock and endotoxin-induced shock in dogs by determination of serum tumor necrosis factor concentrations
Authors: Kitoh Katsuya , Katoh Hiroko , Kitagawa Hitoshi , Sasaki Yoshihide
Published: December 2005

Objective—To compare the mechanisms of heartworm (HW) extract-induced shock and endotoxininduced shock in dogs by determination of serum tumor necrosis factor (TNF) concentrations.

Animals—11 mixed-breed dogs (7 without and 4 with HW infections).

Procedure—Eight dogs were treated with 2 ml of HW extract IV, and 3 dogs were given endotoxin (Escherichia colilipopolysaccharide [LPS]) at 40 or 400 μg/kg of body weight, IV. Changes in clinical and hematologic findings and serum TNF concentrations were examined from before treatment to 120 minutes after treatment in dogs given HW extract or from before treatment to 180 minutes after treatment in dogs given LPS. Tumor necrosis factor concentration was determined by cytotoxic assay, using WEHI-164 murine sarcoma cells, and plasma endotoxin concentration was determined in 2 dogs treated with HW extract, using the endotoxin-specific chromogenic test.

Results—Eight dogs developed shock 3 to 16 minutes after HW extract treatment. Rectal temperature did not change during examination. Serum TNF concentration was detected at a low concentration only 60 and 120 minutes after HW extract treatment, and plasma endotoxin was not detected during examination. In dogs treated with LPS, rectal temperature increased to > 40 C in 2 of 3 dogs, and serum TNF concentration began to increase 30 minutes after LPS treatment, reaching a maximum concentration by 60 minutes.

Conclusions—The cause and mechanism of HW extract-induced shock may be different from those of endotoxin-induced shock, because TNF, which was a pivotal mediator in endotoxin-induced shock, increased minimally in serum of dogs treated with HW extract. (Am J Vet Res2001;62:765–769)
Pharmacodynamics and pharmacokinetics of ketoprofen enantiomers in sheep
Authors: Arifah Abdul K. , Landoni Maria F. , Frean Stephen P. , Lees Peter
Published: December 2005

Objective—To establish pharmacokinetic and pharmacodynamic
properties of a racemic mixture and
individual R(–) and S(+) enantiomeric forms of ketoprofen
(KTP) in sheep and determine pharmacodynamic
variables of KTP by pharmacokinetic-pharmacodynamic
modeling.

Animals—8 female Dorset crossbred sheep.

Procedure—A tissue cage model of inflammation
was used. Carrageenan was administered into tissue
cages. Time course of cyclooxygenase (COX)-2 inhibition
was determined in vivo by measurement of exudate
prostaglandin E2 (PGE2) concentrations. Time
course of COX-1 inhibition was determined ex vivo by
measurement of serum thromboxane B2 (TXB2) concentrations.
In addition, plasma concentration-time
course and penetration of KTP enantiomers into
inflammatory exudate and transudate (noninflamed
tissue cage fluid) were investigated. Four treatments
were compared: placebo, racemic mixture (rac-KTP [3
mg/kg of body weight, IV]), S(+) KTP (1.5 mg/kg,
IV),and R(–) KTP (1.5 mg/kg, IV).

Results—Both KTP enantiomers had elimination halflife
and mean residence time measurements that
were short and volume of the central compartment
and steady state volume of distribution that were low.
Clearance was rapid, particularly for R(–) KTP.
Elimination of both enantiomers from exudate was >
10 times slower than from plasma. Both rac-KTP and
the individual enantiomers significantly inhibited
serum TXB2 concentrations for 12 hours. Rac-KTP and
S(+) KTP, but not R(–) KTP, also significantly inhibited
PGE2 synthesis in exudate for 12 hours.

Conclusions and Clinical Relevance—Inhibition of
serum TXB2 concentration and exudate PGE2 synthesis
for similar time courses after S(+) KTP administration
indicates that it is a nonselective inhibitor of COX
in sheep. ( Am J Vet Res 2001;62:77–86)
Role of histamine in heartworm extract-induced shock in dogs
Authors: Kitoh Katsuya , Katoh Hiroko , Kitagawa Hitoshi , Nagase Masayuki , Sasaki Nobuo , Sasaki Yoshihide
Published: December 2005

Objective—To determine whether heartworm (HW) extract-induced shock in dogs is consistent with anaphylactic shock by examining the role of histamine.

Animals—6 mixed-breed dogs (3 without and 3 with HW infections) and 4 specific pathogen-free (SPF) Beagles.

Procedure—Four experiments were performed as follows: 1) 6 mixed-breed dogs were treated IV with 2 ml of HW extract, and plasma histamine concentrations were determined; 2) 4 SPF dogs were treated IV with 2 ml of HW extract and examined for shock; 3) sera from 6 dogs of experiment 1 and from 4 SPF dogs of experiment 2 that were obtained before HW extract treatment were tested for heterologous passive cutaneous anaphylaxis (PCA), using rabbits during a sensitization period of 48 to 72 hours; and 4) mast cell degranulation by HW extract was tested, using rat mesentery and canine cultured mast cells.

Results—Experiment 1: 6 dogs developed shock, and plasma histamine concentrations increased significantly from 0.3 ± 0.2 (mean ± SD) ng/ml before HW extract treatment to 44.6 ± 68.9 ng/ml at the onset of shock; experiment 2: all SPF dogs developed shock and had an increase in plasma histamine concentrations; experiment 3: sera from mixed-breed dogs without HW infection and from SPF dogs had negative PCA reactions; experiment 4: HW extract degranulated rat mesentery mast cells and released histamine directly from canine mast cells.

Conclusions and Clinical Relevance—Results of our study indicate that an unknown mast cell-degranulating substances contained in HW extract may degranulate mast cells directly, consequently releasing histamine that may participate in the onset of shock in HW extract-induced shock in dogs. (Am J Vet Res2001;62:770–774)
Blood oxygen binding in calves with naturally occurring diarrhea
Authors: Cambier Carole , Clerbaux Thierry , Moreaux Benoít , Detry Bruno , Beerens Dominique , Frans Albert , Gustin Pascal
Published: December 2005

Objective—To assess blood oxygen binding in calves with diarrhea.

Animals—22 dairy and 26 double-muscled calves with diarrhea, 31 healthy dairy calves and 37 healthy double-muscled calves.

Procedure—Severity of disease, including the ability of affected calves to stand, was evaluated. Hydration and signs of depression were scored. Venous and arterial blood samples were collected, and 2,3-diphosphoglycerate, ATP, chloride, inorganic phosphate, lactate, pyruvate, total protein, albumin, and hemoglobin concentrations, and Hct, pH, Pco2, and Po2were determined. Oxygen equilibrium curves (OEC) were constructed under standard conditions, and oxygen extraction ratios were calculated.

Results—Recumbent calves of both breed-types were more dehydrated and had more severe signs of depression than ambulatory affected calves. In both breed-types, hemoglobin oxygen affinity was increased in calves with diarrhea, compared with healthy calves, as indicated by a decrease in standard partial oxygen pressure (P50). Diarrhea induced hypocapnia and hypothermia in the most severely affected calves, which counteracted the acidosisinduced right shift in arterial and venous OEC. Arterial and venous P50 were significantly less in doublemuscled calves with diarrhea than healthy calves, whereas P50 for affected dairy calves were similar to those of healthy calves. Except in the most severely affected dairy calves, oxygen extraction ratio was significantly less in calves with diarrhea, compared with healthy calves.

Conclusions and Clinical Relevance—Release of oxygen from blood may be impaired in calves with diarrhea, depending on the effect of the disease on certain blood biochemical variables. (Am J Vet Res2001;62:799–804).
Myofibroblasts in the accessory ligament (distal check ligament) and the deep digital flexor tendon of foals
Authors: Hartzel Dina K. , Arnoczky Steven P. , Kilfoyle S. Jean , Stick John A.
Published: December 2005

Objective—To demonstrate myofibroblasts in the accessory ligament of the deep digital flexor tendon (ie, distal check ligament) and deep digital flexor tendon of clinically normal foals.

Sample Population—Tissue specimens from 25 foals that were necropsied for reasons unrelated to this study and unrelated to musculoskeletal disease.

Procedure—The distal check ligament and deep digital flexor tendon of both forelimbs were examined histologically. Myofibroblasts were identified by immunohistochemical staining specific for alphasmooth muscle actin (α-SMA).

Results—Most of the cells in the distal check ligament and deep digital flexor tendon of all foals stained positive for α-SMA.

Conclusion and Clinical Relevance—Myofibroblasts made up most of the cells in the distal check ligament and deep digital flexor tendon of clinically normal foals. These cells have contractile ability and therefore, may play a role in flexure contracture of these tendons. The ability of tetracycline to chelate calcium or decrease the expression of the contractile protein α-smooth muscle actin could inhibit the myofibroblasts' ability to contract, thus providing a rationale for tetracycline administration as a treatment of distal interphalangeal joint flexor deformity in foals. (Am J Vet Res2001;62:823–827)
Metabolic and structural abnormalities in dogs with early left ventricular dysfunction induced by incessant tachycardia
Authors: Mc Entee Kathleen , Flandre Thierry , Dessy Cécile , Desmecht Daniel , Clercx Cécile , Balligand Marc , Michaux Charles , Jonville Eva , Miserque Nathalie , Henroteaux Marc , Keene Bruce
Published: December 2005

Objective—To assess morphologic and metabolic abnormalities in dogs with early left ventricular dysfunction (ELVD) induced by rapid right ventricular pacing (RRVP).

Animals—7 Beagles.

Procedure—Plasma carnitine concentrations were measured before and after development of ELVD induced by RRVP. At the same times, transvenous endomyocardial biopsy was performed, and specimens were submitted for determination of myocardial carnitine concentrations and histologic, morphometric, and ultrastructural examination.

Results—In 4 dogs in which baseline plasma total carnitine concentration was normal, RRVP induced a decrease in myocardial total and free carnitine concentrations and an increase in myocardial esterified carnitine concentration. In 3 dogs in which baseline plasma total carnitine concentration was low, plasma and myocardial carnitine concentrations were unchanged after pacing. Structural changes associated with pacing included perinuclear vacuolization in 3 dogs. Morphometric analyses indicated there was a decrease in myofiber cross-sectional diameter and area following pacing. Electron microscopy revealed changes in myofibrils and mitochondria following pacing.

Conclusions and Clinical Relevance—Results indicated that moderate to severe alterations in myocyte cytoarchitecture are present in dogs with ELVD induced by RRVP and that in dogs with normal plasma carnitine concentrations, myocardial carnitine deficiency may be a biochemical marker of ELVD. Results also indicated that transvenous endomyocardial biopsy can be used to evaluate biochemical and structural myocardial changes in dogs with cardiac disease. (Am J Vet Res2001;62:889–894)
Characterization of Pasteurellaspp isolated from healthy domestic pack goats and evaluation of the effects of a commercial Pasteurella vaccine
Authors: Ward Alton C. S. , Weiser Glen C. , DeLong Walter J. , Frank Glynn H.
Published: December 2005

Objective—To characterizePasteurellaspp isolated from healthy pack goats and evaluate the effects of administration of a commercialPasteurellavaccine.

Animals—45 goats.

Procedure—Pharyngeal swab specimens and blood samples were collected on day 0 before vaccination with aPasteurella(Mannheimia) haemolyticaserotype A1 bacterin. Samples were also collected from 17 goats on days 21 and 35. IsolatedPasteurellaspp were assigned to biovariant groups on the basis of results of biochemical utilization tests and serotyped. Serum antibody titers were determined.

Results—Multiple strains ofPasteurellaspp were isolated from swab specimens and assigned to 30 nonhemolytic and 14 β-hemolytic biovariant groups. The most common biovariant isolated was nonhemolyticP trehalosibelonging to group 2. This strain was isolated from 41 goats. NonhemolyticP haemolyticastrains were isolated from 31 goats, whereas β-hemolytic strains ofP trehalosiandP haemolyticawere isolated from 8 and 35 goats, respectively. Vaccination with the A1 serotype did not affect the proportion of goats from which we isolated each biovariant group or the number of biovariant groups isolated.

Conclusion and Clinical Relevance—Multiple strains ofP haemolyticaandP trehalosibelonging to nonhemolytic and β-hemolytic biovariant groups were isolated from the pharynx of healthy domestic pack goats. Because hemolytic activity correlates with leukotoxin production, β-hemolytic strains may have a greater potential to cause disease in naive populations of wild ruminants. However, vaccination with an A1 serotype bacterin did not decrease the proportion of culture-positive goats. (Am J Vet Res2002;63:119–123)
Effects of management, feeding, and treatment on clinical and biochemical variables in cattle with displaced abomasum
Authors: Stengärde Lena U. , Pehrson Bo G.
Published: December 2005

Objective—To determine effects of management, feeding, and treatment on clinical and biochemical variables in cows with displaced abomasum (DA).

Animals—374 cows that received 470 treatments for DA.

Procedure—Blood and milk samples were obtained from 139 affected cows for analysis; for all cows, clinical data, management, feeding, and treatments were evaluated.

Results—Multiparous cows were more predisposed to DA than primiparous cows were, and Swedish Friesians were more predisposed than Swedish Red and Whites were. Eighty percent of cows had leftsided DA, and 20% had right-sided DA. In > 50% of affected cows, clinical signs appeared just before calving to 2 weeks after calving. Incidence of twin calves and periparturient diseases was significantly higher in affected cows than in the overall Swedish cow population. Content of neutral detergent fiber in the silage was low in herds with DA. Feeding a total mixed ration was a risk factor for DA. Treatment by surgical methods gave a significantly higher recovery rate than nonsurgical methods.

Conclusion and Clinical Relevance—Displaced abomasum is a periparturient nutritional disease. Feeding roughage with low neutral detergent content is a more important causative factor than the amount of concentrates fed at the time of calving. The basic principle for prevention of DA is to maintain good ruminal filling before and at calving. The amount of high-quality roughage fed before and at calving should be kept to a minimum. By changing routines for periparturient feeding, it should be possible to reduce the incidence of DA. (Am J Vet Res2002;63:137–142)
Evaluation of splanchnic oxygen extraction ratio as an index of portal vein pressure in dogs
Authors: MacPhail Catriona M. , Monnet Eric , Gaynor James S.
Published: December 2005

Objective—To determine changes in splanchnic oxygen extraction ratio during experimentally induced portal hypertension in dogs.

Animals—6 clinically normal dogs.

Procedure—Standard midline laparotomy and median sternotomy were performed in anesthetized dogs. Baseline measurements of arterial blood pressure, aortic blood flow, portal vein blood flow, and portal vein pressure were acquired, and arterial, venous, and portal vein blood samples were obtained to determine systemic and splanchnic oxygen extraction ratios. The portal vein was gradually occluded until a pressure of 18 cm of H2O was reached; this pressure was maintained for 30 minutes, and measurements and collection of blood samples were repeated.

Results—Portal vein blood flow decreased significantly from 457 ± 136 ml/min before to 266 ± 83 ml/min after induction of portal hypertension. Oxygen content in the portal vein significantly decreased from 12.3 ± 1.85 to 8.2 ± 2.31%, and splanchnic oxygen extraction ratio significantly increased from 15.8 ± 6.2 to 37.4 ± 10.9% during portal hypertension. There was a significant inverse correlation between portal vein blood flow and splanchnic oxygen extraction ratio at baseline and during portal hypertension.

Conclusion and Clinical Relevance—An increase in splanchnic oxygen extraction ratio is evident with partial attenuation of the portal vein and the concurrent decrease in portal vein blood flow. Correlation of oxygen extraction ratio with portal vein blood flow may be a more important indicator for determination of an endpoint to prevent congestion and ischemia of the gastrointestinal tract and pancreas during ligation of portosystemic shunts. (Am J Vet Res2002;63:15–18)
Effects of aerosolized feedyard dust that contains natural endotoxins on adult sheep
Authors: Purdy Charles W. , Straus David C. , Chirase Norbert , Parker David B. , Ayers J. R. , Hoover Mark D.
Published: December 2005

Objective—To determine the clinical, clinicopathologic, and histologic effects of aerosolized feedyard dust that contains natural endotoxins on adult sheep.

Animals—Eighteen 3-year-old Saint Croix sheep.

Procedure—A prospective randomized controlled study was conducted. There were 2 treatment groups (dust-endotoxin group, n = 9; control group, 9). Aerosolized feedyard dust was provided continuously during a 4-hour period for each application (once in week 1, 3 times in week 2, and 7 times in week 3) to sheep in a semiairtight tent. All sheep were euthanatized and necropsied 8 hours after the treatment group received the last dust treatment. Variables measured before and after each dust treatment were rectal temperature, total WBC count, and concentrations of fibrinogen and haptoglobin.

Results—Mean amount of dust administered during each treatment was 451 g/4 h. Filter collection indicated 51 mg of dust/m3and 7,423 ng of endotoxin. Mean rectal temperature at 8 hours (40.4 C) and mean WBC counts 12 and 24 hours after dust treatment were significantly higher for the treated group than the means of the respective variables for the control group. Similar responses were observed with repeated dust-endotoxin treatments; however, with each subsequent treatment, there was a diminished response. Sheep in the treatment group had generalized alveolar septal thickening and hypercellularity.

Conclusion and Clinical Relevance—Feedyard dust induced a temporary febrile response and leukocytosis in sheep in the treatment group. Exposure to dust that contains endotoxins may be a stressor preceding acute infectious respiratory tract disease of marketed sheep. (Am J Vet Res2002;63:28–35)
Evaluation of stability over time for measures of heart-rate variability in overtly healthy Doberman Pinschers
Authors: Calvert Clay A. , Wall Michelle
Published: December 2005

Objective—To determine whether results of analysis of heart-rate variability (HRV) in overtly healthy Doberman Pinschers remain stable over time.

Animals—24 overtly healthy client-owned Doberman Pinschers.

Procedure—The HRV was analyzed in time- and frequency- domains from 24-hour ambulatory electrocardiographic (Holter) monitor recordings. Activity during paired tests (tests 1 and 2) was similar (17 dogs) or nearly identical (7). Holter recordings and HRV analyses of those 17 dogs were repeated at a mean ± SD of 65 ± 50 weeks (median, 51 weeks; range, 10 to 177 weeks), whereas it was repeated for the other 7 dogs at 3 to 9 weeks (mean, 7.3 ± 2.1 weeks).

Results—Differences between test 1 and test 2 were not significantly different, except for 24-hour means of the normal beat-to-normal beat (NN) intervals in all 5-minute segments. Strongest correlations were for SD of all NN intervals and root mean square successive difference between adjacent NN intervals of the time-domain analyses and total power, verylow frequency power, and high-frequency power of the frequency-domain analyses. When activity during tests 1 and 2 in 7 dogs was stringently controlled, the differences were not significantly different, and correlation factors for the 24-hour HRV analyses exceeded 0.83.

Conclusion and Clinical Relevance—Variables from sequential HRV analyses in overtly healthy Doberman Pinschers with normal echocardiograms are moderately stable when physical activity is not stringently controlled and extremely stable for at least 3 to 9 weeks when physical activity is stringently controlled. (Am J Vet Res2002;63:53–59)
Effects of florfenicol injection on the meat characteristics of the cervical muscles in cattle
Authors: Hawkins Larry L. , Perino Louis J. , Kennedy George , Dikeman Michael , Cole Dana
Published: December 2005

Objective—To determine the effects of florfenicol
injection on the meat characteristics of the cervical
muscles in cattle.

Animals—100 steers (mean weight, 380 kg).

Procedure—In 50 calves, florfenicol (25 ml, twice)
was injected into the cervical muscles of 1 side of the
neck, and saline (0.9% NaCl) solution (25 ml, twice)
was injected into the cervical muscles of the other
side of the neck. In the remaining 50 calves, florfenicol
was injected into the cervical muscles of 1 side of
the neck, and nothing was injected into the cervical
muscles of the other side of the neck. Animals were
slaughtered 132 days later, and samples of the cervical
muscles were submitted for histologic evaluation
and measurement of shear forces.

Results—2 injection sites used in the present study
had extensive lesions, and both of these were sites
where florfenicol had been injected. However, histologic
scores for the florfenicol injection sites were not
significantly different from scores for the contralateral
saline solution injection sites and uninjected control
sites. In addition, shear force values were not significantly
different between sites in which florfenicol had
been injected and the contralateral sites.

Conclusion and Clinical Relevance—Results suggest
that few reactions should be expected with
injection of florfenicol into the cervical muscles in
steers and that reactions that do occur will consist
mainly of fibrosis and infiltration of adipose tissue.
However, shear force values, a measure of tenderness
of the meat, should not be affected. (Am J Vet
Res 2002;63:64–68)