bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of mechanical and pharmacologic manipulations on portal pressure, central venous pressure, and heart rate in dogs
Authors: Swalec Karen M. , Smeak Daniel D. , Brown John
Published: January 2024

Central venous pressure (cvp), portal pressure (pp), and heart rate (hr) were monitored in 6 female, sexually intact, middle-age Beagles during temporary portal vein obstruction, anesthetic recovery, abdominal bandaging, and propranolol administration. Intraoperative baseline pp was 7.3 mm of Hg (±1.7 SD). Portal pressure was significantly increased throughout portal vein occlusion, but returned to baseline values 2 minutes after release of the ligature. Central venous pressure was significantly decreased throughout portal vein occlusion, but did not differ significantly from baseline values 3 minutes after release of the portal vein ligature. Portal pressure increased significantly (8 ± 3.3 mm of Hg) over baseline values after application of an abdominal bandage; however, cvp did not change significantly. During postoperative monitoring, cvp and pp did not change significantly from respective 18-hour mean postoperative values in resting dogs. At 60 and 75 minutes after surgery, heart rate was significantly increased over the 18-hour mean. Portal pressure and cvp, respectively, were significantly increased over intraoperative baseline values in the first hour and the first 8 hours after surgery. Postoperative cvp and hr were significantly correlated. Individual measurements of pp in dogs that were abdominal pressing during barking or defecation were significantly increased (9 ± 3 mm of Hg) above measurements taken after cessation of abdominal press. Portal pressure measurements in standing dogs decreased 7.5 ± 2 mm of Hg, compared with measurements of the same dog in lateral recumbency. Central venous pressure was inaccurate in dogs performing abdominal press. Portal pressure did not decrease significantly from baseline after injection of propranolol (2 mg/kg, iv). Central venous pressure was significantly decreased at 2.5 and 3.0 hours after propranolol injection, and hr was significantly decreased from 1 to 3.5 hours after injection. Heart rate quickly returned to normal values if the dogs became excited. After propranolol administration, significant correlations were found between pp and hr, and between cvp and hr.
Quantitative evaluation of the remodeling response of the proximal sesamoid bones to training-related stimuli in Thoroughbreds
Authors: Young David R. , Nunamaker David M. , Markel Mark D.
Published: January 2024

Eight untrained 2-year-old Thoroughbred horses were used in a study of the remodeling response of the proximal sesamoid bone (psb) to training-related stimuli. Two horses each were assigned to 1 of 4 groups: group 1, untrained, pasture turnout (control); group 2, modified-classically trained, dirt track; group 3, classically trained, dirt track; and group 4, classically trained, wood chip track. Horses were given fluorochromic bone labels every 28 days during training. All horses were euthanatized after 5 months of training, and the proximal sesamoid bones (psb) were removed. A midsagittal section of bone 85- to 95- μm thick was prepared for histomorphometric analysis by use of computerized image analysis and epifluorescent microscopy. Porosity (percent), trabecular width (micrometer), extent of anisotropy (percent), mineralizing surface (percent), fractional mineralizing surface (percent), and mineral apposition rate (micrometers per day) were determined at 5 circular regions of each specimen. Region 1 was located within the apex of the psb, regions 2, 3, and 4 were subjacent to the subchondral plate, and region 5 was within the basilar articular margin. Data were pooled to allow comparison by training group and by region.

The psb from horses trained on dirt tracks (groups 2 and 3) had significantly (P < 0.05) lower porosities and greater trabecular width, compared with the control group. The psb from all training group specimens had significantly larger mineralizing surfaces than control group specimens. The fractional mineralizing surface revealed a rapid and vigorous response of the endosteal surface of the psb in horses trained on dirt tracks. When group data were pooled, region 2 was found to have the lowest porosity and greatest trabecular width of any region. Region 1 was found to have the highest porosity and lowest structural anisotropy of any region. Structural anisotropy of the cancellous bone was greatest at regions 2, 3, and 4.

The results of this study demonstrate a substantial stress adaptive remodeling response of the psb to training-related stimuli. Regional morphologic variations were found that presumably reflect the load history of the psb in vivo. Adaptive changes may allow the psb to withstand without failure large stresses generated during maximal exercise.
Pharmacokinetics and synovial fluid concentrations of cephapirin in calves with suppurative arthritis
Authors: Brown Murray P. , Gronwall Ronald R. , Pattio Nolton , Poulos Paul W. , Houston A. E.
Published: January 2024

Six calves with suppurative arthritis were given a single im injection of sodium cephapirin at a dosage of 10 mg/kg of body weight. Cephapirin concentrations were serially measured in serum and in normal and suppurative synovial fluid over a 24-hour period. Mean peak serum concentration was 6.33 μl/ml at 20 minutes after injection. The highest cephapirin concentrations in normal and suppurative synovial fluid were 1.68 and 1.96 μg/ml, respectively, 30 minutes after injection. Overall mean cephapirin concentration in normal synovial fluid for the first 4 hours (1.04 ± 0.612 μg/ml) was not significantly different from that in suppurative synovial fluid (0.88 ± 0.495 μg/ml; P > 0.05). Elimination half-life was 0.60 hours and clearance was 1,593 ml/h/kg.
Cardiopulmonary effects of a tiletamine-zolazepam combination in sheep
Authors: Lagutchik Michael S. , Januszkiewicz Adolph J. , Dodd Kenneth T. , Martin Dale G.
Published: January 2024

To assess the effects on heart and lung function, a tiletamine-zolazepam (tz) anesthetic combination was evaluated in 10 Dorset-type ewes. Ewes were randomly allotted to 2 equal groups. Ewes of groups 1 and 2 were given a single bolus of tz (12 and 24 mg/kg of body weight, iv, respectively) at time zero. Hemodynamic, pulmonary, and ventilation variables were measured at 15-minute intervals to 120 minutes. Blood gas variables were evaluated at 5-minute intervals for the first 30 minutes, then at 15-minute intervals to 120 minutes. In all sheep, tz administration induced rapid, smooth induction, with gradual and unremarkable recovery. Anesthesia duration was not significantly different between groups (mean ± sd, 39 ± 5 and 40 ± 14 minutes for groups 1 and 2, respectively). Immediate drug effects included apnea, decreased mean arterial blood pressure, and arterial hypoxemia. Cardiac output was significantly decreased in both groups at all times after drug administration. Significant changes in group-1 ewes included increased pulmonary and systemic vascular resistances and decreased inspired minute ventilation, tidal volume, and respiratory airflow. Significant changes in group-2 ewes included increased systemic vascular resistance and decreased pulmonary arterial pressure, inspired minute ventilation, and respiratory airflow. Both drug dosages induced apneustic breathing patterns and caused significant changes in arterial and venous blood hemoglobin concentrations and pcv. Tiletamine-zolazepam is useful for intermediate-duration anesthesia in sheep. However, because of alterations in cardiopulmonary function, its use at the dosages evaluated by us is not recommended in studies, in which minimal effects on heart and lung function are required, or in sheep with compromised heart or lung function.
Evaluation of plate luting, using an in vivo ovine osteotomy model
Authors: Richardson Dean W. , Nunamaker David M.
Published: January 2024

Bilateral, midshaft metacarpal osteotomies were performed in 11 sheep and bilateral, midshaft radial osteotomies were performed in 7 sheep. The lesions were repaired with bone plates. One of each pair of plates was luted with polymethylmethacrylate and all screws were tightened uniformly with a torque screwdriver. Sheep were allowed unrestricted exercise after surgery. At 8 weeks, 10 of 11 sheep with metacarpal osteotomies were sound and both osteotomies were healing. Seven were lame on the limb with the unluted plate during the first 3 weeks; 4 were never lame on either limb. The screws of the unluted plates were significantly (P < 0.01) looser at 8 weeks than those in the luted plates. All of the sheep with radial osteotomies were lame in the limb with the unluted plate. Four of 7 sheep had overt loosening of the unluted plates. One sheep only had mild screw loosening with continued alignment of the osteotomy. Two of 7 sheep fractured the radius with the luted plate; these 2 sheep were lame in the limb with the unluted plate and were using the limb with the luted plate vigorously. Excluding the 2 sheep with fractures, all had substantially more screw loosening in the unluted plate. Histologically, there were no discernible differences in the vascularity or porosity of the bone under the luted vs the unluted plates. The only adverse consequence of the luting technique was introduction of a small amount of polymethylmethacrylate into the osteotomy gap in 5 bones.
Effects on aflatoxin M1 residues in milk by addition of hydrated sodium calcium aluminosilicate to aflatoxin-contaminated diets of dairy cows
Authors: Harvey Roger B. , Phillips Timothy D. , Ellis Jeffrey A. , Kubena Leon F. , Huff William E. , Petersen H. D.
Published: January 2024

Hydrated sodium calcium aluminosilicate (hscas), an anticaking agent for agricultural feeds, was added to aflatoxin (af)-contaminated diets of 3 lactating dairy cows and evaluated for its potential to reduce aflatoxin M1 (afm1) residues in milk. During phase I, cows were fed alternating diets that consisted of 200 μg of af/kg of feed for 7 days, 0.5% hscas plus 200 μg of af/kg of feed for 7 days, and feed with the hscas removed for a final 7 days. The afm1 milk concentrations from the intervals with hscas added to diets were compared with those times when hscas was absent. The presence of 0.5% hscas in feed containing 200 μg of af/kg reduced afm1 secretion into the milk by an average of 0.44 μg/L (from pretreatment of 1.85 μg/L to 1.41 μg/L with hscas, a 24% reduction). Following a 10-day period of noncontaminated feed consumption and no afm1 residues in the milk, phase II of the study was begun. The same experimental design as phase I was used, but the dosages of hscas and af were changed to 1.0% and 100 μg/kg of feed, respectively. The addition of 1.0% hscas in feed containing 100 μg of af/kg decreased afm1 content in the milk by an average of 0.40 μg/L (from a pretreatment of 0.91 μg/L to 0.51 μg/L when hscas was present, a 44% reduction). These findings suggest that hscas, a high-affinity sorbent compound for af in vitro, is capable of reducing the secretion of afm1 into milk.
Urine metabolite values in fed and nonfed clinically normal Beagles
Authors: Lulich Jody P. , Osborne Carl A. , Polzin David J. , Johnston Shirley D. , Parker Mary Lou
Published: January 2024

Twenty-four-hour excretion of urine metabolites was determined in 33 clinically normal Beagles during periods of consumption of a standard diet and when food was withheld. The goal was to determine normal canine values for urine analytes incriminated in the genesis of calcium oxalate uroliths.

During periods when dogs consumed food, dairy urinary excretion of calcium, uric acid, sodium, potassium, magnesium, ammonium, and hydrogen ions were significantly (P = 0.0004, 0.0038, 0.001, 0.0001, 0.0004, 0.0001, and 0.024, respectively) higher than when food was withheld. Urinary excretion of phosphorus, oxalate, and citrate were not significantly different between samples obtained during periods of food consumption and when food was withheld. Male dogs excreted significantly higher quantities of urine oxalate than females during fed (P = 0.003) and nonfed (P = 0.003) conditions. When food was withheld, urinary uric acid excretion was significantly higher in males than females (P = 0.01). Females excreted significantly more urine calcium than males when food was withheld (P = 0.003). Our results indicated that dietary conditions influence the quantity of sodium, potassium, calcium, magnesium, and uric acid excreted in the urine of clinically normal dogs; therefore, dietary conditions should be considered when measuring the concentration of these analytes in urine.
Static thoracic compliance as a measurement of pulmonary function in dogs
Authors: King Lesley G. , Drobatz Kenneth J. , Hendricks Joan C.
Published: January 2024

Thoracic compliance measurements by use of readily available equipment were determined to be practical and safe in dogs. Twenty healthy dogs (age 1 to 16 years, weight 2.3 to 49.5 kg) were anesthetized for routine procedures such as dentistry or neutering. The animals were first hyperventilated to reduce pulmonary atelectasis, to check for leakage at the endotracheal tube cuff, and to induce mild hypocarbia, thus minimizing voluntary respiratory efforts. Total thoracic compliance measurements were calculated as the difference between exhaled volumes at static inspiratory pressures of 15 and 20 cm of H2O, divided by the pressure difference, and expressed as a function of body weight. The procedure was easy, took 5 to 10 minutes, and caused no recognizable ill effects in any of the dogs studied. Mean total thoracic compliance was 42.25 ± 32 ml/cm of H2O. There was a significant correlation with weight, but no significant relationship was seen between compliance and age, or gender. The mean weight-adjusted total thoracic compliance was 1.85 ± 0.56 ml/cm of H2O/kg. In studies in a small group of dogs with documented respiratory tract disease, 4 of 7 had a mean compliance > 2 sd below the normal range. Thus, this test may become part of the routine workup of any animal being anesthetized for procedures such as bronchoscopy to evaluate respiratory tract disease. Routine monitoring of animals on ventilators could provide early warning of complications such as pneumonia, pleural effusion, or pulmonary edema.
Effects of a highly concentrated hypertonic saline-dextran volume expander on cardiopulmonary function in anesthetized normovolemic horses
Authors: Moon Paula F. , Snyder Jack R. , Haskins Steve C. , Perron Paul R. , Kramer George C.
Published: January 2024

Conventional fluid resuscitation is unsatisfactory in a small percentage of equine emergency surgical cases because the large volumes of fluids required cannot be given rapidly enough to adequately stabilize the horse. In anesthetized horses, the volume expansion and cardiopulmonary effects of a small volume of highly concentrated hypertonic saline-dextran solution were evaluated as an alternative initial fluid choice. Seven halothane-anesthetized, laterally recumbent, spontaneously ventilating, normovolemic horses were treated with a 25% NaCl-24% dextran 70 solution (hsd) at a dosage of 1.0 ml/kg of body weight, iv, infused over 10 minutes, and the effects were measured for 120 minutes after infusion. Plasma volume expansion was rapid and significant (from 36.6 ± 4.6 ml/kg to 44.9 ± 4.8 ml/kg), and remained significantly expanded for the duration of the experiment. Packed cell volume, total blood hemoglobin, and plasma protein concentrations significantly decreased, confirming rapid and sustained volume expansion with hemodilution. Cardiac index and stroke index immediately increased and remained high for the entire study (from 69.6 ± 15.3 ml/min/kg to 106.6 ± 28.4 ml/min/kg, and from 1.88 ± 0.49 ml/beat/kg to 2.50 ± 0.72 ml/beat/kg, respectively). Systemic vascular resistance significantly decreased immediately after hsd infusion and remained decreased for the duration of the study (from 1.41 ± 0.45 mm of Hg/ml/min/kg to 0.88 ± 0.22 mm of Hg/ml/min/kg). Arterial and venous blood oxygen content decreased significantly because of hemodilution, but actual oxygen transport transiently increased at the 10-minute measurement before returning toward baseline. Plasma osmolality and sodium significantly increased and remained high for the entire 120 minutes (from 293 ± 2 osm/L to 326 ± 9 mosm/L, and from 142.8 ± 3.3 mM/L to 159.0 ± 6.2 mM/L, respectively). Urine output increased in 5 of 7 horses within minutes of hsd infusion, but the mean increase was not statistically significant.

Three horses developed transiently severe, clinically apparent intravascular hemolysis and hemoglobinuria. One horse developed multiple single premature ventricular contractions during the infusion with no persistent ecg changes after infusion. The potential benefit of using hsd as a rapid volume expander in anesthetized horses was documented because infusion of 1 ml of hsd/kg rapidly increased plasma volume by approximately 8 ml/kg. Substantial side effects developed in these normovolemic horses, however, and this solution requires further investigation before it can be recommended in hemodynamically unstable horses.
Characterization of encephalomyocarditis virus isolated from aborted swine fetuses
Authors: Kim H. S. , Christianson W. T. , Joo H. S.
Published: January 2024

Characteristics of 2 encephalomyocarditis virus (emcv) isolates (MN-25 and MN-30) recovered from aborted swine fetuses were examined along with 2 other swine isolates (NVSL-MDV and NVSL-PR) and a reference ATCC strain (VR-129). All 5 emcv isolates were found to be serologically related by cross testing, using serum neutralization and fluorescent antibody assays. Hemagglutination (ha) properties of the 5 isolates were compared, using 5 diluents. The MN-25 and NVSL-MDV strains had ha activity with guinea pig rbc in all 5 diluents, whereas MN-30, NVSL-PR, and VR-129 had ha activity only in KCl-borate buffer. The ha ability with rbc of various animal species was examined, using KCl-borate diluent. All virus isolates had high ha titer (1:512 to 1:2,048) with guinea pig, rat, and horse rbc and lower ha titer (1:16 to 1:64) with sheep rbc. The MN-25 and NVSL-MDV isolates agglutinated dog rbc, whereas MN-30, NVSL-PR, and VR-129 strains did not. Viral replication was evident in 8 of 10 cell lines tested, although infectivity titers of each virus varied by cell line used. Plaque-forming ability was similar for all 5 isolates, but plaque size was different by virus and cell culture used. Virus isolates were found to be stable after being heated at 56 C and subjected to a wide range of pH. A viral polypeptide pattern difference for all 5 isolates was not found by use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis. It was concluded that MN-25 and MN-30 are serologically related and have similar viral characteristics as those of previous emcv isolates and the reference ATCC strain, although differences in ha ability could be observed.
Effect of whole-body potassium depletion on plasma, erythrocyte, and middle gluteal muscle potassium concentration of healthy, adult horses
Authors: Johnson Philip J. , Goetz Thomas E. , Foreman Jonathan H. , Vogel Raymond S. , Hoffmann Walter E. , Baker Gordon J.
Published: January 2024

The effects of whole-body potassium depletion induced by food deprivation on plasma, erythrocyte, and middle gluteal muscle K concentrations was quantified in 16 healthy, adult horses before, during, and at the end of a 7-day period of food deprivation during which water and sodium chloride were available ad libitum. Potassium concentrations were determined by atomic absorption spectroscopy.

Plasma K concentration remained constant (3.49 ± 0.09 mM K/L of plasma; mean ± sem) throughout the study. Erythrocyte potassium concentration decreased from 93.10 ± 1.94 mM K/L of erythrocytes on day 0 to 88.63 ± 2.39 mM K/L of erythrocytes on day 2 (decrease of 4.8%; P < 0.05) and thereafter did not change. The K concentration of the middle gluteal muscle decreased from 91.06 ± 2.96 μM K/g of muscle (wet weight) to 79.61 ± 2.09 μM K/g of muscle (decrease of 12.6%; P < 0.05) on day 4 and decreased further on day 7 to 73.62 ± 1.85 μM K/g of muscle (decrease of 19.2%; P < 0.05). There was no correlation between the plasma and erythrocyte K concentrations (r = −0.066), the erythrocyte and middle gluteal muscle K concentrations (r = 0.167), or the plasma and middle gluteal muscle potassium concentrations (r = −0.018). The water content of the middle gluteal muscle remained constant (73.23 ± 0.36%) throughout the study.

Erythrocyte membrane potential did not change (−99.26 ± 0.87 mV) during the study, whereas the magnitude of the membrane potential of the middle gluteal muscle decreased from −105.84 ± 1.67 mV on day 0 to −100.93 ± 2.10 mV on day 7 (P < 0.05).
Modulation of function of bovine polymorphonuclear leukocytes and lymphocytes by high temperature in vitro and in vivo
Authors: Elvinger Francois , Hansen Peter J. , Natzke Roger P.
Published: January 2024

Function of polymorphonuclear leukocytes (pmnl) and proliferation of lymphocytes after stimulation with mitogens were evaluated in vitro at incubation temperatures of 38.5 and 42 C, and after in vivo heat stress of lactating Holstein cows. Cytochrome-c reduction and random migration of pmnl were reduced when cells were preincubated or incubated at 42 C, but high incubation temperature had little or no effect on phagocytosis and killing of Escherichia coli. Proliferation of lymphocytes was reduced when cells were incubated for 60 hours at 42 C after stimulation with phytohemagglutinin, poke-weed mitogen, or concanavalin A. After stimulation with phytohemagglutinin, lymphocytes were most sensitive to high temperature during the first 24 hours of the 60-hour culture period. High incubation temperature had little effect on viability of cells. In vivo heat stress had no significant effect on responses of pmnl in vitro, but the decrease in proliferation of lymphocytes in vitro at high temperature was less when cells were obtained from heat-stressed cows. Total leukocyte counts in blood and somatic cell counts in milk were higher in heat-stressed cows. Results indicate that: exposure to high temperature in vitro can depress responses of pmnl and lymphocytes; apparent adaptive mechanisms induced by in vivo heat stress provide protection from effects of high temperature seen in vitro; and evidence could not be found to support the hypothesis that reduction in immune function is the basis for increases in the incidence of mastitis during the summer.
Epizootiology of helminth parasitism in a beef cow/calf herd in Minnesota
Authors: Stromberg Bert E. , Schlotthauer John C. , Haggard Dale L. , Vatthauer Richard J. , Hanke Harley , Myers Gil H.
Published: January 2024

To test the effect of a parasite control program for cattle, 2 groups of similar composition were grazed on separate, but equivalent, improved pastures. Cattle in 1 group were treated with fenbendazole at 5.0 mg/kg of body weight at the time they were turned out on pasture in the spring and again at midsummer, when the cattle were moved to a new pasture. The control group was not treated. Parasite egg counts were significantly (P < 0.04) lower in the treated group. Trichostrongyle-type eggs were the most prevalent throughout the year, except in the month of May, when Strongyloides papillosus eggs were predominant. The number of worms recovered from tracer calves was lower for those on pastures where the treated group grazed than for those on the control group's pasture. The most consistently recovered parasite was Ostertagia ostertagi, and hypobiosis was observed.
Relationships between prevalence of Leptospira interrogans in cattle, and regional, climatic, and seasonal factors
Authors: Miller David A. , Wilson Mark A. , Beran George W.
Published: January 2024

On the basis of serologic test results and isolation of leptospires from mature cattle, distribution and prevalence of Leptospira interrogans serovars and genotypes were compared by state and region of the United States. Relationships between isolation rate and month of sample collection, mean regional temperature, and mean regional precipitation were examined. Isolation rate and seroprevalence were significantly (P < 0.001) higher for southeastern, south central, and Pacific coastal regions than for other regions of the United States. Isolates of genotypes hardjo-bovis A and kennewicki A and B, and of serovar grippotyphosa appeared to be randomly distributed. Genotype hardjo-bovis B isolates came from a southern area of the country that extends from Georgia to New Mexico. To the authors’ knowledge, this is the first recorded isolation of serovar hardjo from Hawaii. Although significant relationship was not documented between isolation rate and month or season of the year, seroprevalence for summer, fall, and winter was significantly (P < 0.001) higher than that for spring. Regional isolation rate was related more to mean temperature (r = 0.83; P < 0.05) than to mean precipitation amount (r = 0.34; P > 0.50).
Effect of Pasteurella haemolytica saline capsular extract on bovine pulmonary endothelial cells
Authors: Kumar Sarmishtha , Breider Mike A. , Corstvet Richard E. , Maddux Jeanne L.
Published: January 2024

The purpose of this in vitro study was to determine whether Pasteurella haemolytica capsular extract (ce) damages bovine pulmonary endothelial cells (ec) directly or through neutrophil-mediated mechanisms. Chromium 51-labeled ec were treated with the following variables: ce (1, 10, and 100 ng of protein/ml), ce and bovine neutrophils (106 cells/well), and ce and polymyxin B (500 U/ml). Although only minimal damage to ec occurred by 5 hours after treatment, by 22 hours after treatment, the 10-ng and 100-ng ce dose produced severe damage to ec, as indicated by 51Cr release, cellular detachment, and loss of monolayer confluency. The component in the ce that was toxic to the ec was lipopolysaccharide, evidenced by effective neutralization of the toxic effect with polymyxin B. Neutrophils inhibited the ce-mediated ec toxicity and were activated, as indicated by shape change and adhesion to ec monolayers. We concluded that the lipopolysaccharide component of ce causes direct damage to ec, which can be attenuated by neutrophils and polymyxin B.
In vitro and in vivo 2′,5′-oligoadenylate synthetase activity induced by recombinant DNA-derived bovine interferon αI1 in bovine alveolar macrophages and blood mononuclear cells
Authors: Holland Sheryl P. , Fulton Robert W. , Short Everett C. , Wyckoff John H. , Fox J. C.
Published: January 2024

Biological responses to recombinant dna-derived bovine interferon α (rBoifn-αI1) by bovine alveolar macrophages were examined by measuring viral yield reduction and 2′,5′-oligoadenylate synthetase (2′,5′-oas) production by ifn-treated cells. In vitro ifn pretreatment of alveolar macrophages reduced viral yield in cultures challenged exposed with parainfluenza-3 virus, compared with control cultures. In vitro treatment of alveolar macrophages with ifn also resulted in increased 2′,5′-oas activity. The 2′,5′-oas activity was measured in alveolar macrophages and blood mononuclear leukocytes of calves injected im with 3.6 × 106 U of rBoifn-αI1/kg of body weight. The ifn action was monitored by measuring 2′,5′-oas activity of blood mononuclear leukocytes beginning 6 days before and ending 24 hours after ifn treatment. The 2′,5′-oas activity in the blood mononuclear leukocytes sharply increased 24 hours after ifn treatment, indicating response to ifn. The alveolar macrophages collected from the same calves 24 hours after ifn administration also had increased 2′,5′-oas activity, compared with alveolar macrophages from the same calves collected 6 days before treatment. Increased 2′,5′-oas activity indicates: a possible mechanism of ifn action in cattle that may be responsible for viral yield reduction; potential use of high enzyme activity as a marker for ifn induction; and potential use of 2′,5′-oas activity as a marker for determining effects of ifn on bovine macrophages and other cells of the bovine immune system.
Resistance to fecal shedding of salmonellae in pigs and chickens vaccinated with an aromatic-dependent mutant of Salmonella typhimurium
Authors: Lumsden J. S. , Wilkie B. N. , Clarke R. C.
Published: January 2024

The purpose of this study was to evaluate the effectiveness of an aromatic-dependent mutant of Salmonella typhimurium as a parenteral vaccine for prevention of fecal shedding of Salmonella spp. Pigs and chickens were vaccinated im, with 1 × 109 and 1 × 108 organisms, respectively, followed by a second identical vaccination 2 weeks later. Salmonella organisms were not detected by analysis of fecal or cloacal swab specimens from any animal after vaccination. Deleterious side effects were not noticed after vaccination. Pigs were challenge-inoculated po with 1 × 1012 virulent S typhimurium 1 week after the second vaccination. Chickens were challenge-inoculated po with 3 × 108 organisms of either S enteritidis or the virulent parent strain of S typhimurium 3 weeks after the second vaccination. Vaccinated pigs shed Salmonella spp significantly less frequently than did nonvaccinated pigs. Vaccinated chickens challenge-inoculated with either S enteritidis or S typhimurium also shed Salmonella less frequently than the corresponding nonvaccinated control birds; however, the difference was not significant.
Pharmacokinetic properties of enrofloxacin in rabbits
Authors: Broome R. L. , Brooks D. L. , Babish J. G. , Copeland D. D. , Conzelman G. M.
Published: January 2024

The pharmacokinetic properties of the fluoroquinolone antimicrobial enrofloxacina were studied in New Zealand White rabbits. Four rabbits were each given enrofloxacin as a single 5 mg/kg of body weight dosage by iv, sc, and oral routes over 4 weeks. Serum antimicrobial concentrations were determined for 24 hours after dosing. Compartmental modeling of the iv administration indicated that a 2-compartment open model best described the disposition of enrofloxacin in rabbits. Serum enrofloxacin concentrations after sc and oral dosing were best described by a 1- and 2-compartment model, respectively. Overall elimination half-lives for iv, sc, and oral routes of administration were 2.5, 1.71, and 2.41 hours, respectively. The half-life of absorption for oral dosing was 26 times the half-life of absorption after sc dosing (7.73 hours vs 0.3 hour). The observed time to maximal serum concentration was 0.9 hour after sc dosing and 2.3 hours after oral administration. The observed serum concentrations at these times were 2.07 and 0.452 μg/ml, respectively. Mean residence times were 1.55 hours for iv injections, 1.46 hours for sc dosing, and 8.46 hours for oral administration. Enrofloxacin was widely distributed in the rabbit as suggested by the volume of distribution value of 2.12 L/kg calculated from the iv study. The volume of distribution at steady-state was estimated at 0.93 L/kg. Compared with iv administration, bioavailability was 77% after sc dosing and 61% for gastrointestinal absorption. Estimates of predicted average steady-state serum concentrations were 0.359, 0.254, and 0.226 μg/ml for iv, sc, and oral administration, respectively. On the basis of maintaining enrofloxacin serum concentrations at 4 times the minimal inhibitory concentration90 for Pasteurella multocida, oral dosing resulted in the longest maximal time interval between doses of 15.4 hours vs 9.9 hours and 7.4 hours for iv and sc injections, respectively. Because enrofloxacin is widely dispersed in the rabbit's body, it is estimated from the data in this study that in vivo inhibitory concentrations of enrofloxacin for Pasteurella multocida may be maintained at oral dosage regimens equivalent to 5 mg/kg (q 12 h).
Detection of anti-equine neutrophil antibody by use of flow cytometry
Authors: Jain Nemi C. , Stott J. L. , Vegad J. L. , Dhawedkar R. G.
Published: January 2024

Flow cytometric and conventional fluorescence microscopic methods were compared to detect heterologous (rabbit) neutrophil antibody bound to equine neutrophils. Unfixed and paraformaldehyde-fixed neutrophils were treated with normal rabbit serum or various dilutions of an antineutrophil serum. The cells were then reacted with fluorescein conjugates of goat anti-rabbit IgG, staphylococcal protein A, and streptococcal protein G. Antibody binding was evaluated by use of fluorescence microscopy and flow cytometry. Unfixed neutrophils treated with normal rabbit serum did not fluoresce, whereas many of the fixed neutrophils had distinct cytoplasmic and some membranous (nonspecific) fluorescence. Unfixed cells treated with the antiserum had localized areas (capping) of intense membrane fluorescence, whereas fixed cells had bright uniform membranous fluorescence. The intensity of specific fluorescence varied with the antiserum dilution and the conjugate. On flow cytometry, over 80% of unfixed cells treated with antiserum dilutions up to 1:1,024, 1:2,048, and 1:256 fluoresced, respectively, with anti-IgG, protein-G, and protein-A conjugates. Fixed cells generally had similar percentages of fluorescent cells, but at a higher (1-step) antiserum dilution. It was concluded that flow cytometry is more sensitive than conventional fluorescence microscopy to detect antibodies associated with equine neutrophils.
Efficacy of ivermectin chewable tablets and two new ivermectin tablet formulations against Dirofilaria immitis larvae in dogs
Authors: Paul Allan J. , Todd Kenneth S. , Acre Kenneth E. , Plue Raymond E. , Wallace Dennis H. , French Richard A. , Wallig Matthew A.
Published: January 2024

One hundred four heartworm-free Beagles < 1 year old were studied to determine the efficacy of ivermectin chewable tablets and of 2 other ivermectin tablet formulations against heartworm larvae. At 30 days after sc inoculation of dogs with infective Dirofilaria immitis larvae, all ivermectin formulations were given orally at dosage of 6 μg/kg of body weight. The ivermectin chewable tablets also were given orally at dosage of 2 and 6 μg/kg at 30 and 45 days, respectively, after injection of larvae. Replicates of 6 or 8 dogs in each study were formed on the basis of gender and body weight and, within replicates, were randomly allocated to treatment groups. At 30 days after injection of larvae, the additional dogs (in replicates of 8) were assigned to the control group and to the group given ivermectin chewable tablets at dosage of 6 μg/kg. All dogs were housed individually. Necropsy was performed approximately 5 or 6 months after larvae were administered.

In both trials, all control dogs had heartworms at necropsy (Univerity of Illinois—geometric mean, 35.0; Florida—geometric mean, 26.1). In both trials, the ivermectin chewable tablet (6 μg/kg) and both tablet formulations (6 μg/kg) given at 30 days after larval injection, and the chewable formulation (6 μg/kg) given at 45 days after larval injection were 100% effective (P < 0.01) in preventing development of induced infection with D immitis. Of 8 dogs at the University of Illinois that were given ivermectin chewable tablets (2 μg/kg) at 30 days after larval injection, 6 had heartworms (geometric mean, 2.25; efficacy, 93.6%; P < 0.01) and 5 of 7 dogs treated similarly in Florida had heartworms (geometric mean, 4.4; efficacy, 83.3%; P < 0.05).

Drug-related adverse reactions were not observed in either trial.
An ultrasonographic off-set system for examination of equine tendons and ligaments
Authors: Wood A. K. W. , Newell W. H. , Borg R. P.
Published: January 2024

In a dorsal plane, an improved ultrasonographic off-set system was used to obtain serial ultrasonographic images with enhanced anatomic and pathologic detail of the tendons, ligaments, and associated structures of the limbs of 100 horses. The off-set provided good acoustic coupling between a linear array ultrasonographic transducer and the horse's skin. A water-soluble gel contained within the off-set had acoustic properties similar to those of mammalian soft tissues.
Cutaneous laser-Doppler velocimetry in nine animal species
Authors: Manning Thomas O. , Monteiro-Riviere Nancy A. , Bristol David G. , Riviere J. Edmond
Published: January 2024

The assessment of cutaneous microcirculation by laser-Doppler velocimetry (ldv) has been primarily limited to human studies. The purpose of this investigation was to establish normal values in various species and anatomic sites for blood flow, velocity, and volume as determined by ldv. Microcirculation was measured with a laser-Doppler velocimeter in 54 animals, 6 healthy animals from each of 9 species. The standard sites used were the buttocks, convex surface of the ear, metacarpal pad, humeroscapular junction, thoracolumbar junction, ventral portion of the abdomen, dorsal metacarpus (hooved animals), and ventral surface of the tail (horse). Significant differences in blood flow, velocity, and volume were measured between species and sites within species. The ventral portion of the abdomen consistently had the highest relative blood flow across all species except the monkey. Measurements in the canine metacarpal pad had a high sd, possibly indicating the stratum corneum and epidermis to be too thick for ldv. Our findings provide baseline data in several species, with application of ldv in comparative dermatologic research.
Effects of dietary fiber supplementation on glycemic control in dogs with alloxan-induced diabetes mellitus
Authors: Nelson R. W. , Ihle S. L. , Lewis L. D. , Salisbury S. K. , Miller T. , Bergdall V. , Bottoms G. D.
Published: January 2024

The effect of a high insoluble-fiber (if) diet containing 15% cellulose in dry matter, high soluble-fiber (sf) diet containing 15% pectin in dry matter, and low-fiber (lf) diet on glycemic control in 6 dogs with alloxan-induced insulin-dependent diabetes mellitus was evaluated. Each diet contained > 50% digestible carbohydrate in dry matter. A crossover study was used with each dog randomly assigned to a predetermined diet sequence. Each dog was fed each diet for 56 days. Caloric intake was adjusted weekly as needed to maintain each dog within 1.5 kg of its body weight measured prior to induction of diabetes mellitus. All dogs were given pork lente insulin and half of their daily caloric intake at 12-hour intervals.

Mean (± sem) daily caloric intake was significantly (P < 0.05) less when dogs consumed the if diet vs the sf and lf diets (66 ± 3 kcal/kg, 81 ± 5 kcal/kg, and 79 ± 4 kcal/kg, respectively). Serum alkaline phosphatase activity was significantly (P < 0.05) higher when dogs consumed the lf diet vs the if and sf diets (182 ± 37 IU/L, 131 ± 24 IU/L, and 143 ± 24 IU/L, respectively). Mean postprandial plasma glucose concentration measured every 2 hours for 24 hours, beginning at the time of the morning insulin injection, was significantly (P < 0.05) lower at most blood sampling times in dogs fed if and sf diets, compared with dogs fed the lf diet. As a result, 24-hour mean plasma concentration of glucose (if, 165 ± 17 mg/dl; sf, 169 ± 19 mg/dl; lf, 218 ± 29 mg/dl), 24-hour mean plasma-glucose fluctuation (if, 49 ± 2 mg/dl; sf, 47 ± 4 mg/dl; lf, 63 ± 7 mg/dl), and 24-hour urine-glucose excretion (if, 31 ± 10 g/d; sf, 42 ± 16 g/d; lf, 67 ± 13 g/d) were significantly (P < 0.05) lower in dogs fed if and sf diets, compared with dogs fed the lf diet. These variables were not significantly different between dogs fed if and sf diets. Mean glycosylated hemoglobin concentration also was significantly (P < 0.05) lower when dogs consumed the if diet, compared with the lf diet (4.3 ± 0.4% vs 5.2 ± 0.4%, respectively).

In dogs with alloxan-induced insulin-dependent diabetes mellitus, consumption of diets containing 15% cellulose or 15% pectin and > 50% digestible carbohydrate on a dry-matter basis resulted in improvement in glycemic control, compared with consumption of a diet containing > 50% digestible complex carbohydrate without added fiber.
Prevalence of autoantibodies to thyroglobulin, thyroxine, or triiodothyronine and relationship of autoantibodies and serum concentrations of iodothyronines in dogs
Authors: Thacker Eileen L. , Refsal Kent R. , Bull Robert W.
Published: January 2024

Assays were developed to detect and measure autoantibodies (aa) to thyroglobulin (Tg) and to the thyroid hormones, thyroxine (T4) and triiodothyronine (T3). An elisa to detect aa to Tg was developed, using purified canine Tg as the antigen and goat anti-canine IgG conjugated with alkaline phosphatase as the second antibody. A highly charged agarose electrophoresis assay was used for determination of aa to T4 and T3. Sera from dogs (n = 119) with clinical signs consistent with hypothyroidism were tested for aa to Tg, T4, and T3. Autoantibodies to at least 1 of the 3 thyroid antigens were detected in 58 of the 119 (48.7%) sera tested. Autoantibodies to Tg were detected more frequently in samples with low serum concentrations of thyroid hormones than in samples with normal concentrations. The presence of aa to T4, T3, or both was not significantly associated with low thyroid hormone concentrations, but this lack of association may have been attributable to binding of aa in the measurement of thyroid hormones by radioimmunoassay.
Characterization of a feline T-cell-specific monoclonal antibody reactive with a CD5-like molecule
Authors: Ackley Christopher D. , Cooper Max D.
Published: January 2024

The 43 monoclonal antibody raised against feline T cells was found to react with a single-chain glycoprotein of Mr 72,000 that is present on most thymocytes, 60% of lymph node cells, 20% of splenocytes, and 45% of blood mononuclear cells. All CD4+ and CD8+ T cells were found to express the 43-reactive determinant, as did a small subpopulation of CD4-/CD8-/AgM- lymphocytes in the periphery. The 43-reactive determinant was not detected on B cells, macrophages, or other types of blood cells. The 43 antigen was phosphorylated in resting and activated T cells. Its expression was upregulated by stimulation with phorbol myristate acetate and with phytohemagglutinin. When added to concanavalin A-stimulated T-cell cultures in low concentrations, the 43 antibody was found to augment mitogenesis. The data indicate that this antibody may identify a CD5 homologue on feline T cells.
Prophylactic effect of monensin sodium against experimentally induced paratuberculosis in mice
Authors: Brumbaugh Gordon W. , Frelier Paul F. , Roussel Allen J. , Thomson T. D.
Published: January 2024

Monensin sodium (0, 15, or 30 mg/kg of complete feed) was fed ad libitum for 1 week to female mice (strain C57BL6/J) that were genetically susceptible to infection with Mycobacterium paratuberculosis. Ten mice in each of the 3 groups were inoculated intraperitoneally with M paratuberculosis (109 organisms). Sterile saline solution was injected intraperitoneally into 10 other mice in each group. Rations were continued for 50 days, then mice were euthanatized, and body weight, splenic weight, and hepatic weight for each mouse were recorded. Ratios of body weight to splenic weight and of body weight to hepatic weight were calculated for each mouse. Hepatic granulomas in 50 light microscopic fields were counted, and presence of acid-fast organisms in those granulomas was recorded. Infected mice given monensin had higher body weight and fewer hepatic granulomas than did mice not given monensin. Although hepatic granulomas were fewer in these mice, they contained acid-fast organisms. Effects of 15 mg of monensin and those of 30 mg of monensin/kg of complete feed were not different.
Susceptibility to onion-induced hemolysis in dogs with hereditary high erythrocyte reduced glutathione and potassium concentrations
Authors: Yamoto Osamu , Maede Yoshimitsu
Published: January 2024

The hemolytic effect of onion consumption in dogs with hereditary high erythrocyte reduced glutathione and potassium concentrations (designated HK dogs) was compared with that in clinically normal dogs. Twelve hours after oral administration of boiled onions (200 g/dog), hemoglobin concentration decreased to 84.4% of the initial value in hk dogs; it decreased only to 90.5% in clinically normal dogs. At 24 hours, methemoglobin concentration was significantly (P< 0.05) higher in HK dogs than in clinically normal dogs. The concentration of erythrocyte oxidized glutathione increased about fivefold at 10 hours in HK dogs, whereas it did not change during the experimental period in clinically normal dogs. In addition, at 12 hours, the proportion of erythrocytes containing Heinz bodies increased to 24.4% in hk dogs, but increased only to 1.2% in clinically normal dogs. Thus, results indicated that HK dogs were more susceptible to the oxidant action of onions than were clinically normal dogs.
Effects of an extract of Gingko biloba on bromethalin-induced cerebral lipid peroxidation and edema in rats
Authors: Dorman David C. , Côté Louise Marie , Buck William B.
Published: January 2024

The effects of administration of a commercially available extract of Gingko biloba (egb) on bromethalin-induced brain lipid peroxidation and cerebral edema in adult male Sprague-Dawley rats was determined. Gingko biloba extract was given (100 mg/kg) by gavage immediately after bromethalin (1.0 mg/kg) administration. Rats were euthanatized at 24 hours after dosing. Brain lipid peroxidation was determined by measurement of brain malonaldehyde-thiobarbituric acid chromophore (mda-tba) concentration, brain sodium concentration, and brain water content.

Treatment of bromethalin-dosed rats (10/group) with egb was associated with a statistically significant (P < 0.05) decrease in clinical sign severity, compared with bromethalin-dosed saline solution-treated rats. All rats given bromethalin and saline solution developed clinical signs of toxicosis including CNS depression, hind limb weakness, ataxia, paralysis, and coma. Some rats given bromethalin and egb developed clinical signs, however, none developed hind limb paralysis. The brain mda-tba concentration (2.4 ± 0.5 Δ mda-tba concentration/mg of protein), percentage of water in brain tissue (80.3 ± 0.30%), and brain sodium concentration (6.68 ± 0.21 mg/g of dry weight) were significantly increased in rats given bromethalin and saline solution, compared with control rats given saline solution (1.0 ± 0.1 Δ mda-tba concentration/mg of protein; 78.1 ± 0.33% water in brain tissue; 4.83 ± 0.30 mg of brain Na+/g of dry weight) and rats given bromethalin and egb (1.6 ± 0.2 Δ mda-tba concentration/mg of protein; 79.3 ± 0.31% water in brain tissue; 5.37 ± 0.34 mg of brain Na+/g of dry weight). The mda-tba concentration (1.2 ± 0.2 Δ mda-tba concentration/mg of protein), percentage of water in brain tissue (78.7 ± 0.40%), and brain sodium concentration (4.93 ± 0.26 mg/g of dry weight) increased slightly in control rats given egb.