bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of anatomic communications of the fetlock in cattle, using intra-articular latex injection and positive-contrast arthrography
Authors: Desrochers André , St-Jean Guy , Cash Walter C. , Hoskinson James J. , DeBowes Richard M
Published: January 2024

Objective

To evaluate the frequency and sites of communication between the lateral and medial synovial sacs of the metatarsophalangeal or metacarpophalangeal joints in cattle.

Animals

188 limbs were obtained from 55 fresh bovine cadavers submitted for necropsy because of problems unrelated to the fetlocks.

Procedure

In each ox, lateral or medial synovial sacs of each fetlock were randomly assigned. Joints were injected with a mixture of latex and barium sulfate. Communication between 2 joints was determined by presence of latex and contrast material in a joint adjacent to the injected joint by examining frozen sections and use of positive-contrast arthrography.

Results

Communication between the 2 synovial sacs existed in 186 of 188 (98.9%) specimens. The communication site between lateral and medial synovial sacs was located at the level of the proximal sesamoid bones, between the distal aspect of the interdigital band of the axial branch of the interosseus muscle and the metacarpal or metatarsal bone.

Conclusions and Clinical Relevance

Although communication between the lateral and medial synovial sacs did not exist in 2 specimens, the fetlock in cattle can be treated as 1 compartment. (Am J Vet Res 1997;58:710–712)
Distribution of technetium 99m-labeled red blood cells during isoflurane anesthesia in ferrets
Authors: Marini Robert P. , Callahan Ronald J. , Jackson Lynn R. , Jyawook Shireen , Esteves Maria I. , Fox James G. , Wilkinson Robert A. , Strauss H. William
Published: January 2024

Objective

To address the physiologic mechanism of isoflurane-associated reduction in hematologic variables in ferrets.

Animals

6 young adult female ferrets.

Procedure

Distribution of 99mTc-labeled autologous erythrocytes was measured by serial in vivo imaging. Data were recorded in 4 ferrets, using a gamma camera, immediately prior to anesthesia, 15 minutes after 2% isoflurane anesthesia in O2 via endotracheal tube, 1 minute prior to and throughout a 10-minute phenylephrine infusion, 20 and 40 minutes after termination of the phenylephrine infusion, and 45 minutes after termination of anesthesia. Blood indices were also measured at times that paralleled those for imaging. One ferret served as a conscious control (no anesthetic administration), and another as an isoflurane control (no phenylephrine administration).

Results

In ferrets under anesthesia, splenic radioactivity increased from baseline of 10.2 ± 2.0% to 38.4 ± 3.2% (mean ± SEM; P < 0.05) of the injected dose. Splenic radioactivity decreased to 13.4 ± 3.8% of the injected dose during phenylephrine infusion and to near baseline for the recovery image. Splenic radioactivity in the conscious control remained constant throughout the study, whereas that of the anesthetized control was persistently increased throughout administration of isoflurane. Percentage reduction of the 15-minute sample values, compared with baseline values for all hematologic indices, was: RBC count, 33% (P < 0.05); hemoglobin concentration, 34% (P < 0.05); hematocrit, 35% (P < 0.05); and plasma protein concentration, 20% (P < 0.05). All RBC variables returned to within 7 to 14% of baseline by 45 minutes after termination of anesthesia.

Conclusion

Isoflurane anesthesia causes splenic sequestration of RBC in ferrets that is partially reversed by phenylephrine infusion or termination of anesthesia. Thus, investigators and clinicians should be cautious when interpreting hematologic findings in isoflurane-anesthetized ferrets, and accordingly, fluid treatment and transfusion should be planned. (Am J Vet Res 1997;58:781–785)
Craniad migration of differing doses of new methylene blue injected into the epidural space after death of calves and juvenile pigs
Authors: Lopez Mandi J. , Johnson Rebecca , Hendrickson Dean A. , Kruse-Elliott Kris T.
Published: January 2024

Objective

To determine the relation between epidural injectate volume (ml/kg of body weight) and its craniad migration in calves and pigs.

Animals

23 neonatal calves and 26 feeder pigs.

Procedure

Animals were randomly assigned to receive different volumes of new methylene blue (NMB, 1.2 mg/ml in 0.9% saline solution). Injections were made into the sacrococcygeal intervertebral space in calves and the lumbosacral intervertebral space in pigs, immediately after euthanasia. Sagittal sections of the spine were made at necropsy, and craniad migration of NMB was determined and rounded to the nearest intervertebral space.

Results

In calves treated with 0.05, 0.1, or 0.15 ml of NMB/kg, mean ± SEM number of stained spinal segments was 5 ± 0.3, 8 ± 0.6, and 8 ± 0.6, respectively. Craniad migration of NMB was significantly greater for 0.15 and 0.1 ml/kg volumes versus 0.05 ml/kg. In pigs treated with 0.05, 0.1, 0.2, or 0.3 ml of NMB/kg, mean number of stained spinal segments was 8 ± 1.1, 8 ± 0.9, 10 ± 1.2, and 18 ± 2.0. Craniad dye migration was significantly greater in the 0.3 ml/kg group versus the 3 lower volume groups. Linear regression performed on both sets of data after logarithmic transformation of spaces migrated to correct for non-normality was significant (P < 0.05), and R2 values of 0.49 and 0.55 were obtained for calves and pigs, respectively.

Conclusions

There is a significant correlation between volume (ml/kg) of NMB injected in the epidural space and its craniad migration in calves and pigs.

Clinical Relevance

Results provide a basis for determination of volume of injectate to be given to reach a minimal desired level and should be a useful baseline for future investigations of epidural drug administration. (Am J Vet Res 1997;58:786–790)
Comparative pharmacokinetics of caffeine and three metabolites in clinically normal horses and donkeys
Authors: Peck K. , Mealey K. L. , Matthews N. S. , Taylor T. S.
Published: January 2024

Objective

To determine whether clearance of capacity-limited drugs in horses differs from that in donkeys by comparing the serum disposition of caffeine and its metabolites, theophylline, theobromine, and paraxanthine after IV administration of caffeine to horses and donkeys.

Animals

4 healthy horses and 5 healthy donkeys.

Procedure

Blood samples were collected from each animal at time 0. (before) and 5,10, 15, 20, 30, and 45 minutes, and 1, 2, 3, 4, 6, 8, 12, 24, 30, 36, 48, 54, 60, 72, and 96 hours after IV administration of a bolus of caffeine. Serum was analyzed in triplicate by high-performance liquid chromatography to determine caffeine, theophylline, theobromine, and paraxanthine concentrations. The serum concentration-time curves for each animal were analyzed separately to estimate model-independent pharmacokinetic variables.

Results

Mean pharmacokinetic values for caffeine, theophylline, and paraxanthine did not differ significantly in horses, compared with donkeys. Mean peak serum concentration of theobromine was significantly higher in donkeys, compared with horses.

Conclusion

Clearance of the capacity-limited drug caffeine does not appear to differ in horses, compared with donkeys.

Clinical Relevance

For some drugs that undergo hepatic metabolism, the dose and dose interval used for horses may be appropriate for use in donkeys. (Am J Vet Res 1997;58:881–884)
Cardiorespiratory and metabolic effects of walking, standing, and standing with a splint during the recuperative period from maximal exercise in horses
Authors: Hubbell J. A. E. , Hinchcliff K. W. , Muir W. W. , Robertson J. T. , Sams R. A. , Schmall L. M.
Published: January 2024

Objective

To determine the effects of walking, standing, or standing with a splint on 1 forelimb on rate of recuperation of horses after a brief, intense bout of exercise.

Animals

6 adult Thoroughbreds (435 to 542 kg).

Procedure

Horses were preconditioned by exercise on a treadmill to establish a uniform level of fitness. Once fit, the treadmill speed causing each horse to exercise at 120% of its maximal oxygen consumption was determined and was used in simulated races at 14-day intervals. Horses were instrumented for collection of arterial and mixed venous blood samples for measurement of acid-base status, concentrations of metabolites, and cardiopulmonary indices. The horses were exercised at a speed inducing 120% of their maximal oxygen consumption until fatigued or for a maximum of 2 minutes. Three recuperative interventions were evaluated: walking at 1.8 m/s for 30 minutes, then standing for the remainder of the 90-minute trial; standing stationary for 90 minutes; and standing stationary for 90 minutes with a splint on the right forelimb.

Results

Walking significantly increased cardiac output during the recuperative phase and hastened recovery of normal acid-base status and return of blood lactate concentration to baseline values.

Conclusion

Limiting movement of horses during the recuperative period delays recovery from maximal exercise. Most measured indices returned to baseline by 60 minutes after exercise. All measured cardiopulmonary indices returned to baseline values by 90 minutes after exercise.

Clinical Relevance

Horses that are not allowed to walk during recuperation from exercise may have a prolonged recovery period. (Am J Vet Res 1997;58:1003–1009)
Effects of acute endotoxemia on serum somatotropin and insulin-like growth factor I concentrations in prepubertal gilts
Authors: Hevener William , Almond Glen W. , Armstrong Jeff D. , Richards R. Gregg
Published: January 2024

Objective

To evaluate effects of endotoxemia on serum somatotropin (ST) and insulin-like growth factor I (IGF-I) concentrations in finishing pigs.

Animals

Eight female pigs (98 ± 2 kg) randomly assigned to IV administration (time 0) of saline solution (n = 4) or Escherichia coli lipopolysaccharide (LPS; 5 μg/kg of body weight; n = 4).

Procedure

Serum ST concentration was determined in serum samples obtained at 20-minute intervals for 6 hours after treatment. Serum IGF-I concentration was determined in samples collected at 1-hour intervals for 6 hours and at 12, 15, 18, 24, 48, 72, and 96 hours after treatment.

Results

One distinct pulse of ST (peak 10.5 ± 0.5 ng/ml) was observed at 40 minutes in each pig after administration of LPS. Control pigs had 2.25 ± 0.48 ST pulses during the 6 hours of frequent sample collection; however, magnitude of the ST pulses was similar between gilts given LPS and control gilts. A temporal association between ST pulses and saline administration was not evident. Serum IGF-I concentration was similar between gilts of the LPS and control groups prior to treatment. The IGF-I concentration was lower (P < 0.01) in gilts of the LPS group (44 ± 5 ng/ml) than in gilts of the control group (157 ± 4 ng/ml) at 24 hours. The difference in IGF-I concentrations between groups was evident for 96 hours.

Conclusions

Immediate release of ST was attributed to stress associated with acute endotoxemia and stimulation of the pituitary gland; immune stimulation by LPS may have contributed to the changes in IGF-I concentration. Because feed consumption was similar between the 2 groups of pigs, suppression of IGF-I concentration for 96 hours after administration of LPS was attributable to factors in addition to transient feed restriction. Thus, acute endotoxemia altered the positive association between ST and IGF-I, and provided evidence for a potential mechanism of impaired growth in endotoxemic animals. (Am J Vet Res 1997;58:1010–1013)
Cardiopulmonary and anesthetic effects of propofol in wild turkeys
Authors: Schumacher Juergen , Citino Scott B. , Hernandez Kelly , Hutt Julie , Dixon Brandon
Published: January 2024

Objective

To determine safety, anesthetic variables, and cardiopulmonary effects of IV infusion of propofol for induction and maintenance of anesthesia in wild turkeys.

Animals

10 healthy, adult wild turkeys.

Procedure

Anesthesia was induced by IV administration of propofol (5 mg/kg of body weight) over 20 seconds and was maintained for 30 minutes by constant IV infusion of propofol at a rate of 0.5 mg/kg/min. Heart and respiratory rates, arterial blood pressures, and arterial blood gas tensions were obtained prior to propofol administration (baseline values) and again at 1, 2, 3, 4, 5, 10, 15, 20, 25, and 30 minutes after induction of anesthesia. All birds were intubated immediately after induction of anesthesia, and end-tidal CO2 concentration was determined at the same time intervals. Supplemental oxygen was not provided.

Results

Apnea was observed for 10 to 30 seconds after propofol administration, which induced a decrease in heart rate; however, the changes were not significant. Compared with baseline values, respiratory rate was significantly decreased at 4 minutes after administration of propofol and thereafter. Systolic, mean, and diastolic pressures decreased over the infusion period, but the changes were not significant. Mean arterial blood pressure decreased by 30% after 15 minutes of anesthesia; end-tidal CO2 concentration increased from baseline values after 30 minutes; PO2 was significantly decreased at 5 minutes after induction and thereafter; PCO2 was significantly (P< 0.05) increased after 15 minutes of anesthesia; and arterial oxygen saturation was significantly (P < 0.05) decreased at the end of anesthesia. Two male turkeys developed severe transient hypoxemia, 1 at 5 and the other at 15 minutes after induction. Time to standing after discontinuation of propofol infusion was 11 ± 6 minutes. Recovery was smooth and unremarkable.

Conclusion

Propofol is an effective agent for IV induction and maintenance of anesthesia in wild turkeys, and is useful for short procedures or where the use of inhalational agents is contraindicated. (Am J Vet Res 1997;58:1014–1017)
Safety and efficacy of a mutagen-attenuated Rift Valley fever virus vaccine in cattle
Authors: Morrill J. C. , Mebus C. A. , Peters C. J.
Published: January 2024

Objective

To examine safety and efficacy of a mutagen-attenuated Rift Valley fever virus (RVFV) vaccine (RVF MP-12) in cattle.

Animals

38 pregnant cows, 14 steers, and 10 lactating dairy cows.

Procedure

Pregnant cows in their third, fifth, or eighth month of gestation were vaccinated (1 ml of RVF MP-12 containing 5 log10 plaque-forming units [PFU] of virus) and were monitored daily through parturition for signs of disease, viremia, and immunologic response. Additionally, 10 vaccinated pregnant cows were challenge inoculated with virulent RVFV at postvaccination day (PVD) 30 and were monitored daily for untoward effects. Ten unvaccinated pregnant cows also were challenge inoculated with virulent RVFV and served as challenge controls. Vaccinated lactating dairy cows were monitored for viremia and virus shedding in the milk through PVD 14. Yearling steers were vaccinated to assess their immunologic response to various doses of vaccine and were challenge inoculated with virulent RVFV at PVD 28 to assess protection.

Results

10 of 38 (26.3%) cows vaccinated during pregnancy developed transient postvaccination viremia titer ≥ 2.5 log10 PFU/ml of serum. All vaccinated cows delivered live, healthy calves that were RVFV seronegative at birth, but which quickly acquired colostral antibodies. Vaccinated cows and their fetuses were protected when challenge exposed with virulent RVFV at PVD 30, whereas unvaccinated pregnant cows inoculated with RVFV became febrile and viremic, and aborted. Vaccine virus was unsuccessfully sought from milk of lactating dairy cows after vaccination, suggesting that shedding of vaccine virus through milk should not be a concern. Steers, inoculated with tenfold escalating vaccine doses, beginning with 1.0 log10 PFU, were protected against virulent RVFV challenge exposure.

Conclusions

RVF MP-12 may be safe and efficacious for use in pregnant or lactating bovids, and a minimal dose of vaccine may provide suitable protection against viremia. (Am J Vet Res 1997;58:1104–1109)
Safety of a mutagen-attenuated Rift Valley fever virus vaccine in fetal and neonatal bovids
Authors: Morrill J. C. , Mebus C. A. , Peters C. J.
Published: January 2024

Objective

To examine effects of in utero inoculation with a mutagen-attenuated Rift Valley fever virus (RVFV) vaccine (RVF MP-12) on fetal bovids and to assess the safety and efficacy of calfhood vaccination with RVF MP-12.

Animals

18 pregnant Hereford and Hereford-type cows in the third or fifth month of gestation, their progeny, and 25 calves from cows immunized with RVF MP-12 during pregnancy.

Procedure

Bovine fetuses were inoculated, via laparotomy, with 1 ml of RVF MP-12 containing 5 log10 plaque-forming units (PFU) of virus. Blood was obtained from newborn calves prior to their ingestion of colostrum. Immune-naive calves and calves born to RVF MP-12-vaccinated dams, ranging in age from 2 to 45 days, were vaccinated with RVF MP-12, and some were later challenge exposed with 1 ml of 5.7 log10 PFU of virulent RVFV strain ZH-501. Cows were monitored for viremia and antibody responses and for hematologic and serum biochemical alterations through parturition or abortion.

Results

Surviving in utero-vaccinated calves were healthy, with no noticeable defects. Except for 1 vaccine-inoculated fetus that died on postinoculation day 21, all in utero-vaccinated fetuses had serum neutralizing antibody titer ≥ 1:20 at the time of delivery. All dams of in utero-vaccinated fetuses also developed neutralizing antibody titer. Calves born to cows vaccinated during gestation did not have antibody at birth, and all but 1 quickly acquired colostral antibody. Postparturient inoculation of immune-naive calves and calves with colostral antibodies resulted in no untoward effects, and all calves with detectable neutralizing antibodies were protected against virulent virus challenge exposure.

Conclusions

Fetal death and abortion would be rare even if fetuses were exposed to RVF MP-12. The trauma and complications associated with in utero inoculation do not make this a practical method of immunization. RVF MP-12 was safe, immunogenic, and protective in calves as young as 2 days of age. (Am J Vet Res 1997;58:1110–1114)
Evaluation of aspartate transaminase activity and β-hydroxybutyrate concentration in blood as tests for prediction of left displaced abomasum in dairy cows
Authors: Geishauser Thomas , Habil  , Leslie Ken , Duffield Todd , Edge Victoria
Published: January 2024

Objectives

To evaluate aspartate transaminase (AST) activity and β-hydroxybutyrate (BHB) concentration in blood obtained during the first or second postpartum (PP) week as tests for prediction of subsequent left displaced abomasum (LDA) diagnosis in dairy cows.

Animals

36 cows with LDA tested at a mean 3 PP days, which was 7 to 22 days prior to LDA diagnosis (25, 75% quantiles), and 28 cows with LDA tested at 10 PP days, which was 5 to 18 days prior to LDA diagnosis, were matched to 3 controls per case by herd and calving date. Data were available from a large field study.

Procedure

Odds ratio, sensitivity, specificity, and likelihood ratio were determined for various AST and BHB cutoff values.

Results

AST, using cutoff values between 100 and 180 U/L, and BHB, using cutoff values between 1,000 and 1,600 μmol/L, were significantly associated with subsequent LDA diagnosis. When cutoff values were increased, odds ratio and likelihood ratio increased; however, sensitivity decreased and specificity increased.

Conclusion and Clinical Relevance

AST activity and BHB concentration in blood obtained during the first or second PP week might be useful as predictors of subsequent LDA diagnosis. (Am J Vet Res 1997;58:1216–1220)
Effects of high-dose gentamicin sulfate on neuromuscular blockade in halothane-anesthetized horses
Authors: Hague Brent A. , Martinez Elizabeth A. , Hartsfield Sandee M.
Published: January 2024

Objective

To evaluate effects of a single high dose of gentamicin on neuromuscular function in horses anesthetized with halothane.

Animals

6 healthy adult horses.

Procedure

Halothane-anesthetized horses were positioned in left lateral recumbency, and the right hind limb was immobilized in a reusable fiberglass cast fixed to a steel frame. The hoof was attached to a force transducer, and resting tension of 0.93 ± 0.16 kg was maintained. A supramaximal train-of-four stimulus of 2 Hz for a duration of 0.25 millisecond was applied to the superficial peroneal nerve every 20 seconds by a square-wave stimulator. The force of the evoked digital extensor tension was recorded to determine first muscle twitch tension, compared with the baseline value (T1%) and the ratio of the force of the fourth twitch to the first twitch (T4/T1). Data were recorded at 5, 10, 15, 30, and 60 minutes after IV administration of vehicle or gentamicin (6 mg/kg of body weight).

Results

There was a significant (P = 0.04) treatment-time interaction for the effect of gentamicin on T1%; T1% associated with vehicle decreased from 100% to 92% during the 60- minute study period, but no decrease was associated with gentamicin. For T4/T1, there was no significant effect of treatment or time or treatment-time interaction between gentamicin and vehicle.

Conclusions

Gentamicin did not cause a decrease in initial muscular strength, nor did it impair the muscles’ ability to sustain strength.

Clinical Relevance

A single high dose of gentamicin does not cause significant neuromuscular blockade when administered alone to healthy horses anesthetized with halothane. (Am J Vet Res 1997;58:1324–1326)
Room temperature storage and cryopreservation of canine platelet concentrates
Authors: Allyson Kay , Abrams-Ogg Anthony C. G. , Johnstone Ian B.
Published: January 2024

Objective

To determine whether in vitro viability and function, and microbiological sterility, of canine platelet concentrates (PC) could be retained during storage at 20 to 24 C (room temperature [RT]) for up to 7 days and cryopreservation for 6 months.

Animals

14 mature dogs.

Procedure

PC prepared by centrifugation of fresh blood were stored for 7 days at RT with continuous agitation. An aliquot of each was cryopreserved with 6% dimethyl sulfoxide at −74 C for 6 months. Fresh PC (day 0) were tested by microbial culture and measurement of platelet count, mean platelet volume, pH, glucose and lactate concentrations, lactate dehydrogenase activity, response to hypotonic stress, and aggregation. Tests were also performed on PC stored at RT on days 3, 5, and 7, and on the cryopreserved aliquots after thawing.

Results

After 7 days at RT, microbial growth was not evident, and decrease in platelet number was not significant. On the basis of pH and glucose and lactate concentrations, metabolic activity was maintained throughout RT storage. On the basis of mean platelet volume and lactate dehydrogenase activity, platelet swelling and membrane damage had occurred. Aggregatory responses decreased during RT storage, and platelets recovered poorly from hypotonic stress. After cryopreservation for 6 months, microbial growth was not evident, but platelet numbers were significantly decreased. Mean platelet volume and lactate dehydrogenase activity were significantly greater, compared with values for day-0 PC. Crypreserved platelets aggregated poorly and did not respond to hypotonic stress.

Conclusions

Platelet viability and microbiological sterility are retained in canine PC stored for 7 days at RT, but platelet function progressively decreases and day-7 platelets are substantially damaged. Crypreservation of PC results in considerable damage, compared with that of PC stored at RT.

Clinical Relevance

Similar to human PC, canine PC stored at RT for up to 5 days can be recommended for treatment. (Am J Vet Res 1997;58:1338–1347)
Comparison of radiography, magnetic resonance imaging, and surgical findings in dogs with elbow dysplasia
Authors: Snaps F. R. , Balligand M. H. , Saunders J. H. , Park R. D. , Dondelinger R. F.
Published: January 2024

Objective

To describe the magnetic resonance imaging (MRI) appearance of medial coronoid process and humeral condyle lesions in dysplastic cubital joints and to compare survey radiography and MRI for evaluation of fragmented medial coronoid process (FMCP) and lesions of the medial aspect of the humeral condyle (MAHC).

Animals

18 dogs with elbow dysplasia.

Procedure

Radiography of 22 cubital joints was performed. The 22 joints then underwent MRI. The scans were evaluated with regard to the shape and signal of the coronoid process; articular cartilage change, subchondral bone disruption of the MAHC. Surgical findings were used as the standard to calculate accuracy, sensitivity, specificity, and positive- and negative-predictive values for specific diagnosis of FMCP (free fragment) and lesions of the MAHC.

Results

At surgery, 31.8% of the joints had FMCP (free), 36.4% had nondisplaced unmineralized coronoid process, and 27.2% had nondisplaced mineralized coronoid process. Eleven joints had lesions of the MAHC, and wear lesions were observed in 41 % of the joints. On radiography, FMCP (free) was visualized in 9% of the joints and lesions of the MAHC were observed in 23%. MRI had the highest accuracy (95.5%), sensitivity (100%), and negative-predictive value (100%) for detection of FMCP (free), and had accuracy (91 %), sensitivity (87.5%), specificity (92.5%), and positive (87.5%)- and negative (92.5%)- predictive values for detection of nondisplaced unmineralized coronoid process.

Conclusions and Clinical relevance

Compared with radiography, MRI was useful for detection of nondisplaced unmineralized coronoid process; images consistently correlated with surgical findings. The technique is accurate and especially useful when radiographic findings are inconclusive. (Am J Vet Res 1997;58:1367–1370)
Infection of bone marrow macrophages by equine infectious anemia virus
Authors: Swardson C. J. , Lichtenstein D. L. , Wang S. , Montelaro R. C. , Kociba G. J.
Published: January 2024

Objective

To characterize infection of bone marrow-derived macrophages (BMDM) with equine infectious anemia virus (EIAV) by determining virus production, effects on viability, and induction of cytokines.

Sample Population

BMDM obtained from bone marrow of 6 clinically normal adult horses.

Procedure

BMDM were infected with EIAV at a multiplicity of infection of 8. Cell viability, percentage of cells with detectable viral protein, reverse transcriptase activity, and concentrations of infective virus (focus-forming units/ml), interleukin 6, and tumor necrosis factor-α were measured in culture supernatant samples obtained at various days after infection.

Results

Cell viability was decreased on day 4 and was maximally decreased on day 8. The number of cells with detectable viral protein and supernatant reverse transcriptase activity increased significantly on day 4 and increased until day 6. Virus concentration (focus-forming units per milliliter) peaked on day 4 after infection and was constant thereafter. Infection with EIAV caused significant induction of interleukin 6 production by BMDM. The maximal difference was seen on day 4 after infection. Control and infected BMDM produced only negligible amounts of tumor necrosis factor-α.

Conclusions

BMDM are useful, as a cell population, to study the effects of infection with EIAV, including cell death and induction of interleukin 6 but not tumor necrosis factor-α production. (Am J Vet Res 1997;58:1402–1407)
Comparison of pulsed-field gel electrophoresis and phage typing for discriminating poultry strains of Staphylococcus aureus
Authors: Shimizu Akira , Kawano Junichi , Yamamoto Chikage , Kakutani Osamu , Fujita Manabu
Published: January 2024

Objective

To compare pulsed-field gel electrophoresis (PFGE) patterns of Staphylococcus aureus from chickens in England, Belgium, Bulgaria, Argentina, and Japan, to assess the value of PFGE for discriminating strains, and to compare results obtained by PFGE with those obtained by biotyping and phage typing.

Sample Population

78 S aureus isolates from diseased and healthy chickens.

Procedure

Chromosomal DNA of S aureus was digested with restriction endonuclease Sma l, and fragments were separated by PFGE in 1 % agarose gel.

Results

All 78 strains from 5 countries were classified as poultry ecovar according to a previously established biotyping system. Chromosomal DNA was cut by Sma l into 18 to 23 fragments ranging from about 3 to 685 kb. Seventy-eight strains produced 15 types, arbitrarily designated A to O, and 45 subtypes. Some differences were observed in PFGE patterns among countries. However, 10 fragments (333, 190, 110, 63, 55, 42, 34, 19, 10, and 3 kb) were highly conserved and were shared by almost all (> 78%) of the strains examined. The PFGE patterns were compared with those obtained by phage typing. All 29 strains belonging to avian phage-group II produced type A and 19 subtypes. Of the 15 strains belonging to phage-group I, 11 produced 8 types (B to H, O) and 5 subtypes that were different from those of type A.

Conclusions

Genomic DNA fingerprinting by PFGE is an effective technique for discriminating poultry S aureus strains and appears to be a useful method for subtyping strains of avian phage groups or the poultry-specific ecovar. (Am J Vet Res 1997;58:1412–1416)
Effect of low-dose atropine administration on dobutamine dose requirement in horses anesthetized with detomidine and halothane
Authors: Weil Ann B. , Keegan Robert D. , Greene Stephen A.
Published: January 2024

Objective

To determine whether a low dose of atropine is associated with decreased requirement for cardiovascular supportive treatment in horses given detomidine prior to maintenance of general anesthesia with halothane.

Animals

3 groups of 10 healthy horses.

Procedure

Detomidine (20 μg/kg of body weight, IM) was administered to all 30 horses. Then, 10 horses received atropine (0.006 mg/kg, IV) 1 hour after detomidine administration, 10 horses received atropine (0.012 mg/kg, IM) at the time of detomidine administration, and 10 horses served as a control group. Heart rate was measured prior to detomidine administration and at fixed intervals throughout anesthesia. The dobutamine infusion rate necessary to maintain mean arterial blood pressure between 70 and 80 mm of Hg was recorded. Systemic blood pressures, end-tidal halothane, end-tidal CO2, and arterial blood gas tensions were measured at fixed intervals.

Results

Mean heart rate was higher among horses receiving atropine IV or IM, compared with that in control horses. Horses that received atropine IV had higher systemic arterial blood pressure and required a lower dobutamine infusion rate than did horses of the other groups.

Conclusion

Detomidine-treated, halothane-anesthetized horses given atropine IV required less dobutamine, compared with horses receiving or not receiving atropine IM. Complications, such as colic and dysrhythmias, from use of higher doses of atropine, were not observed at this lower dose of atropine.

Clinical Relevance

IV administration of a low dose of atropine prior to induction of general anesthesia may result in improved blood pressure in horses that have received detomidine before anesthesia with halothane. (Am J Vet Res 1997;58:1436–1439)
Effects of medetomidine on serum insulin and plasma glucose concentrations in clinically normal dogs
Authors: Burton Shelley A. , Lemke Kip A. , Ihle Sherri L. , Mackenzie Allan L.
Published: January 2024

Objective

To determine the effects of medetomidine, administered IV, on serum insulin and plasma glucose concentrations in clinically normal dogs.

Animals

6 healthy adult Beagles.

Procedure

Dogs were randomly assigned to each of 3 treatments in a prospective cross-over study design. Serum insulin and plasma glucose concentrations were determined before and 20, 40, 60, 120, 180, 240, 300, 360, 420, and 480 minutes after IV administration of 0.9% NaCI solution (control) or medetomidine (10 or 20 μg/kg of body weight).

Results

Mean serum insulin concentration decreased after medetomidine administration and was significantly (P ≤ 0.05) lower than control values 20, 40, 60, and 120 minutes after drug administration. Mean plasma glucose concentration tended to increase after medetomidine administration, but did not differ significantly from control values.

Conclusions

In dogs, IV administration of medetomidine at dosages of 10 and 20 μg/kg transiently decreases serum insulin concentration, but plasma glucose concentration remains within the normal physiologic range.

Clinical Relevance

Medetomidine can be given at low, preanesthetic dosages without significantly altering plasma glucose concentration in clinically normal dogs. (Am J Vet Res 1997;58:1440–1442)
Exercise capacity in young and old mares
Authors: McKeever Kenneth Harrington , Malinowski Karyn
Published: January 2024

Objective

To test the hypothesis that, compared with unfit young horses, unfit older horses have lower aerobic capacity and reduction in other indices of exercise capacity.

Animals

6 young (mean ± SEM, 5.3 ± 0.8 years and 445 ± 13 kg) and 6 aged (22.0 ± 0.4 years and 473 ± 18 kg) healthy Standardbred and Thoroughbred mares.

Procedures

The mares, accustomed to running on a treadmill, were tested by use of an incremental exercise test. None of the mares had received exercise training for at least 4 months prior to the study. During testing, mares ran up a fixed 6% grade, starting at a speed of 4 m/s, with 1 m/s increase every 60 seconds (omitting 5 m/s) until they reached fatigue. Maximal oxygen uptake (VO2max) was measured by use of an open-flow calorimeter. Venous blood samples (10 ml) were collected during the last 10 seconds of each step and were used to measure blood lactate concentration and PCV. Calculated performance indices included velocity at VO2max, maximal velocity, and velocity at lactate concentration of 4 mmol/L; work rate (watts) at those velocities also was determined.

Results

There were differences (P < 0.05) between old and young mares for maximal run velocity attained during the test (8.7 ± 0.5 versus 10.8 ± 0.5 m/s, respectively), VO2max (89.4 ± 4.3 versus 117.3 ± 9.5 ml/kg of body weight/min, respectively), and velocity at VO2max (8.0 ± 0.4 versus 9.8 ± 0.7 m/s, respectively). Also, velocity required to reach blood lactate concentration of 4 mmol/L was lower (P < 0.05) in old (7.5 ± 0.4 m/s), compared with young (10.2 ± 0.7 m/s), mares.

Conclusion

Older mares have substantially (−24%) lower maximal aerobic capacity than do young mares.

Clinical Relevance

Many horses participate in athletic activities into their late teens and some do so beyond the age of 20 years; thus, the need exists to explore ways to adjust training programs for older horses. (Am J Vet Res 1997;58:1468–1472)
Cardiorespiratory effects of sevoflurane, isoflurane, and halothane anesthesia in horses
Authors: Grosenbaugh D. A. , Muir W. W.
Published: January 2024

Objective

To determine and compare cardiorespiratory and recovery effects of sevoflurane, isoflurane, and halothane in horses.

Animals

8 clinically normal horses (4 mares, 4 geldings), 5 to 12 years old.

Procedure

Inhalation anesthesia was maintained for 90 minutes with sevoflurane, isoflurane, or halothane. Anesthesia depth was maintained at 1.5 minimum alveolar concentration of halothane, isoflurane, and sevoflurane, then was reduced at 30 and 60 minutes. A surgical plane of anesthesia was reinduced by administration of ketamine or thiopental or by increasing the fractional inspired concentration of sevoflurane. Cardiovascular and pulmonary variables were recorded and compared among inhalation anesthetics. Recovery was monitored, and subjective assessment of recovery quality was performed.

Results

Hemodynamic and pulmonary indices during sevoflurane anesthesia were similar to those of isoflurane. Cardiac output and systemic arterial pressure decreased less during sevoflurane and isoflurane anesthesia than during halothane anesthesia. After 90 minutes, cardiac output was greater for sevoflurane and isoflurane, respectively, compared with halothane. Mean arterial pressure was similar for all thre anesthetic agents. Respiratory rate for sevoflurane and isoflurane was less than that for halothane. This apparent respiratory depression correlated with greater increase in Paco2 and decreased pH when sevoflurane and isoflurane were compared with halothane. Recovery from sevoflurane anesthesia was qualitatively similar and superior to recovery from isoflurane and halothane, respectively. Time to standing did not differ significantly between sevoflurane and isoflurane, but was shorter than halothane.

Conclusions

Sevoflurane induced cardiorespiratory effects that were comparable to those of isoflurane and halothane. Cardiac output was greater and respiratory rate was less than that for halothane at 1.5 MAC. Sevoflurane anesthesia was characterized by good control of anesthesia depth during induction, maintenance, and recovery. Recovery time after sevoflurane anesthesia was comparable to that for isoflurane, and recovery was smooth and controlled in a manner consistent with recovery from halothane. (Am J Vet Res 1998;59:101–106)
Survival analysis of risk factors associated with the occurrence of lameness in a Michigan horse population
Authors: Ross Whitney A. , Kaneene John B. , Gardiner Joseph C.
Published: January 2024

Objective

To evaluate the associations of operation and individual animal-level risk factors with occurrence of lameness in the Michigan horse population.

Sample Population

3,925 horses monitored from 138 randomly selected Michigan operations for a total of 814,753 horse-days.

Procedure

All horses monitored < 60 days were eliminated from the source population. From the remaining horses, a prospective unmatched case-control study population was generated that included all cases and a random sample of noncases. Analysis of risk factors associated with occurrence of lameness was conducted, using Cox's proportional hazards regression model.

Results

Horses in larger operations, compared with horses in the first operation size quartile, were associated with decreased risk of lameness (2nd quartile [Qj: hazard ratio [HR] = 0.57; 95% confidence interval [CI]: 0.36, 0.91; 3rd Q: HR = 0.74; 95% CI: 0.49, 1.13; 4th Q: HR = 0.46; 95% CI: 0.28, 0.76). Compared with mares, stallions (HR = 1.90; 95% CI: 1.17, 3.07) and geldings (HR = 1.46; 95% CI: 1.02, 2.09) were at increased risk of lameness. Compared with horses used for breeding purposes only, those participating in exercise or performance-related activities including racing (HR = 4.70; 95% CI: 1.70, 13.03) and showing (HR = 2.80; 95% CI: 1.07, 7.28) also were at increased risk of lameness.

Conclusions

Comparison of these results with those conducted using multivariable logistic regression strengthens the argument that there is decreased risk of lameness for horses in larger operations and increased risk of lameness for active horses. Additionally, results of this analysis suggested that stallions and geldings are at increased risk of lameness, compared with mares.

Clinical Relevance

Lameness prevention strategies in the horse industry should focus principally on horses participating in exercise or performance-related activities, including racing and showing, on male horses, and on horses stabled in smaller operations. (Am J Vet Res 1998;59:23–29)
Molecular cloning and cartilage gene expression of equine stromelysin 1 (matrix metalloproteinase 3)
Authors: Balkman Cheryl E. , Nixon Alan J.
Published: January 2024

Objective

To clone and determine molecular structure of equine stromelysin 1 (matrix metalloproteinase 3) and examine stromelysin expression in articular cartilage.

Samples and Procedure

Total RNA was harvested from equine arthritic cartilage specimens and was used for reverse transcription and polymerase chain reaction amplification to develop overlapping complementary DNA (cDNA) clones. Four cDNA sequences were ligated into plasmid (pGEM3Z) constructs and subcloned into bacterial expression vectors, and sequence was determined by automated dye terminator sequencing. Stromelysin mRNA expression was assessed in normal and arthritic cartilage and synovium by northern blotting. Interleukin 1 (IL-1) regulation of stromelysin transcriptional activity in articular chondrocytes cultured in the presence of 0, 20, and 50 ng of IL-1α/ml was assessed by northern blotting of total RNA isolated from the cell layer and probed with 32P-labeled stromelysin cDNA.

Results

4 overlapping clones provided the full-length cDNA sequence of equine stromelysin, including portions of untranslated 5′ and 3′ regions, and the entire translated portion coding for the stromelysin prepropeptide. The coding region of 1,431 base pairs was well conserved between species, with 86, 83, and 78% sequence homology to that of human, rabbit, and mouse stromelysin, respectively. Predicted amino-acid (AA) sequence data indicated highly conserved features. Comparison of the equine AA sequence revealed 89, 88, and 84% homology to the AA structure in human, rabbit, and mouse stromelysin, respectively. Minimal stromelysin mRNA expression was evident in normal cartilage and synovium, and increased expression was evident in arthritic cartilage. Marked dose-dependent up-regulation of stromelysin transcriptional activity was evident in chondrocyte cultures exposed to 20 and 50 ng of IL-1/ml.

Conclusions

Stromelysin DNA sequence in horses is similar to that in people and rodents. Constitutive stromelysin message amounts in normal cartilage and synovium are low, but considerably increased in arthritic cartilage and in chondrocytes exposed to IL-1. (Am J Vet Res 1998;59:30–36)
Expression of adhesion molecules on neutrophils of periparturient cows and neonatal calves
Authors: Lee Eun-kyung , Kehrli Marcus E.
Published: January 2024

Objective

To determine expression of the β2-integrin (CD18) family of adhesion molecules and L-selectin (CD62L) on neutrophils from periparturient cows and calves.

Animals

8 periparturient Holstein cows and 9 Holstein calves.

Procedure

Constitutive CD18 and CD62L expression on neutrophils was determined by flow cytometry, using specific monoclonal antibodies. Platelet-activating factor was used to activate neutrophils in vitro to measure down-regulation of CD62L and up-regulation of CD18 on activated neutrophils.

Results

Mean values for constitutive and platelet-activating factor-stimulated CD18 expression on neutrophils from cows and calves were highest at parturition, then decreased during the first 24 hours after parturition on calf neutrophils, whereas CD62L expression decreased markedly by 9 to 24 hours after parturition on cow and calf neutrophils. Constitutive amounts of CD18 and CD62L on cow neutrophils returned to prepartum values by day 3 after parturition. Amounts of CD18 expression on calves’ neutrophils recovered by 1 week of age, but did not reach original birth values, whereas CD62L expression exceeded birth values by day 3 after parturition. Cows had leukocytosis (neutrophilia), with a doubling of circulating neutrophils 9 hours after calving that was inversely correlated with CD62L expression on neutrophils.

Conclusions and Clinical Relevance

Low amounts of CD62L and CD18 on calf neutrophils and of CD62L on neutrophils from cows for several days after parturition may result in impaired inflammatory response. Low CD62L expression may contribute to increased susceptibility to disease. (Am J Vet Res 1998;59:37–43)
Disposition of cyproheptadine in cats after intravenous or oral administration of a single dose
Authors: Norris Carol R. , Boothe Dawn M. , Esparza Teri , Gray Connie , Ragsdale Michelle
Published: January 2024

Objective

To determine disposition of cyproheptadine hydrochloride in cats after intravenous or oral administration of a single dose.

Animals

6 healthy cats.

Procedure

A randomized crossover design was used, and each cat was studied after intravenous (2 mg) and oral (8 mg) administration of cyproheptadine. Blood samples were collected at fixed time intervals after drug administration, and serum cyproheptadine concentration was determined by means of polarized immunofluorescence.

Results

Mean (± SD) residence time was significantly longer after oral (823 ± 191 minutes) than after intravenous (339 ±217 minutes) administration, but no significant differences were detected between other pharmacokinetic parameters after oral and intravenous administration. Mean ± SD oral bioavailability was 1.01 ± 0.36. Mean elimination half-life after oral administration was 12.8 ± 9.9 hours. Peak extrapolated cyproheptadine concentration was 669 ± 206 ng/ml. Only 1 cat developed adverse effects (transient vocalization).

Conclusions

Cyproheptadine appeared to be well tolerated in cats and had high bioavailability after oral administration. The mean elimination half-life of 12 hours indicated that approximately 2.5 days must elapse to achieve steady-state concentrations of cyproheptadine after oral administration of multiple doses. A 12-hour dosing interval is acceptable, but an 8-hour interval may be indicated for some cats.

Clinical Relevance

On the basis of pharmacokinetic parameters determined in this study, the oral form of cyproheptadine appears to be suitable for use in clinical trials to treat anorexia in cats. Its half-life is compatible with once or twice daily dosing. (Am J Vet Res 1998;59:79–81)
Safety, immunogenicity, and efficacy of an inactivated avian polyomavirus vaccine
Authors: Ritchie Branson W. , Latimer Kenneth S. , Leonard Joan , Pesti Denise , Campagnoli Raymond , Lukert Phil D.
Published: January 2024

Objective

To determine safety, immunogenicity, and efficacy of an inactivated avian polyomavirus vaccine in nonbudgerigar psittacine birds that varied in age, species, and immunologic status.

Animals

Safety of the vaccine was evaluated in 1,823 psittacines representing more than 80 species. Immunogenicity was evaluated in 285 birds (260 of various Psittaciformes species, 25 chickens). Efficacy was evaluated in 104 birds (78 of various Psittaciformes species, 26 chickens).

Procedures

Safety was evaluated by vaccinating birds that were determined to be seronegative or seropositive (titer > 1:10) prior to vaccination. Birds were then evaluated for clinically detectable systemic or local reactions for 2 months to 2 years. Immunogenicity was evaluated by testing for virus-neutralizing antibodies, vaccinating each bird twice, and then testing for a significant change in antibody titer. Efficacy was evaluated by vaccinating birds, followed in 2 to 4 weeks by intramuscular or intravenous challenge exposure. After challenge exposure, protection was evaluated by attempting to recover virus from tissues or by observing birds for clinical signs of disease and testing for a significant change in titer.

Conclusions

Avian polyomavirus vaccine is safe, immunogenic, and efficacious for use in multiple species of mature and immature psittacines.

Clinical Relevance

Until now, prevention of polyomavirus infection in psittacine birds could only be accomplished through strict isolation to reduce potential exposure to the virus. The USDA-registered inactivated avian polyomavirus vaccine can safely be used to protect vaccinates from infection and control spread of this virus in flocks. (Am J Vet Res 1998,59:143–148)