bluuebunny/crossref_metadata_2025 huggingface dataset:
Technique for prolonged, minimally invasive monitoring of intragastric pH in ponies
Authors: Baker Simon J. , Gerring E. Lawrence
Published: January 2024

Intragastric pH monitoring was investigated in ponies. In cadaver stomachs, close contact with the mucosa led to high pH readings if nonweighted electrodes were used. However, pH recorded by weighted electrodes was markedly less affected by mucosal contact (P < 0.001). The latter were used for subsequent trials. In vivo, high correlations were found between pH recorded by weighted electrodes with or without a wire guard to prevent mucosal contact (correlation, r = 0.866; P < 0.001). Readings from each correlated well with those from simultaneous gastric aspirates (r = 0.774 and r = 0.807, respectively; P < 0.001 for both correlations). Plain electrodes recorded more highly variable (temporally heterogeneous) pH than did guarded electrodes. In vitro, trials using equine gastric fluid indicated that this resulted from greater responsiveness of the plain electrode. In vivo, episodes of nearly neutral pH were a common feature, and high pH correlated with intensely yellow-green, neutral fluid in the stomach (rank correlation, ρ = 0.626; P < 0.01). Concentration of bile acids did not correlate with pH or color score (ρ = −0.158 and ρ = 0.076, respectively). Causes of the episodes could include salivary influx, duodenogastric reflux, and variable gastric acid secretion. Pentagastrin infusion (0.6 μg/kg of body weight/h) reduced intragastric pH (P = 0.018), but episodes of neutrality still occurred. Experiments in fed ponies indicated possible existence of a stable pH gradient, from neutral dorsally to heterogeneous and more acidic ventrally. Care was required in the rational choice of summary variables for expression of monitored pH data. Of the frequency distributions of 3 summary variables assessed in this study (mean, median, and percentage of data > pH 4), only that of the mean approached normality. Thus, use of the mean may allow analysis by parametric statistical methods.

Intragastric pH monitoring was found to be a useful technique. Episodes of increased pH were often identified. These may represent episodic duodenogastric reflux.
Pulsatile secretion of luteinizing hormone and progesterone in mares during the estrous cycle and early pregnancy
Authors: Perkins Nigel Ross , Threlfall Walter Ronald , Ottobre Joseph Steven
Published: January 2024

Existence of ultradian variation in serum progesterone concentration and the relation between progesterone and luteinizing hormone (lh) secretory patterns were investigated in nonpregnant and pregnant mares. Blood samples were taken every 15 minutes for a 24-hour period on day 8 of the estrous cycle and day 18 of pregnancy, respectively. Progesterone and lh concentrations were determined by radioimmunoassay. Progesterone was secreted in pulsatile manner in nonpregnant and pregnant mares. Luteinizing hormone also was secreted in a pulsatile manner in both groups of mares. There was little temporal relation between lh and progesterone pulses in either pregnant or nonpregnant mares.
Pharmacokinetics of and serum thromboxane suppression by flunixin meglumine in healthy foals during the first month of life
Authors: Semrad Susan Diane , Sams Richard Alvin , Ashcraft Susan Marie
Published: January 2024

Age and species reportedly affect the pharmacokinetic variables of nonsteroidal anti-inflammatory drugs. We determined the effect of age on flunixin pharmacokinetic variables in foals during the first month of life. We also estimated the physiologic activity of the drug in neonatal foals by determining the effect of flunixin on thromboxane production during clotting of blood taken from the foals. Flunixin disposition and clearance were determined after iv administration of 1.1 mg of drug/kg of body weight to 5 healthy foals when they were 24 to 28 hours, 10 to 11 days, and 27 to 28 days old. The area under the curve (2,471 μg·min/ml), mean residence time (477 minutes), and zero-time intercept of the elimination phase (4,853 ng/ml) were significantly (P = 0.05) greater, the elimination half-life (339 minutes) and slope of the elimination phase (0.002 L/min) were significantly (P = 0.05) longer, and total body clearance (0.482 ml/min/kg) and zero-time intercept for the distribution phase (2,092 ng/ml) were significantly (P = 0.05) lower at 24 to 28 hours. At each age, a biexponential equation was best fitted to the plasma flunixin concentration from each foal. Thromboxane B2 production during clotting of blood was significantly (P = 0.05) suppressed for 12 hours after flunixin meglumine administration at all ages. Therefore, it appears that although age does alter the disposition and elimination of flunixin in neonatal foals, this effect may be of little consequence because the drug's physiologic activity in foals appears similar to that in mature horses.
Duration of QT interval in clinically normal dogs
Authors: Oguchi Yoko , Hamlin Robert L.
Published: January 2024

The QT interval is the period from onset of the QRS complex to the end of the T wave. The QT interval is useful for monitoring drug (eg, quinidine) and electrolyte (eg, calcium) effects on the heart. It depends principally on heart rate (hr), and the relationship between QT interval and hr has been expressed for human beings and for dogs. The purpose of the study reported here was to quantify that relationship for dogs and to assess whether body weight also influenced QT interval. The ecg was recorded from 17 dogs, ranging in weight between 7 and 25 kg. Dogs were anesthetized with fentanyl/droperidol/ketamine, and hr was accelerated by administration of graded doses of atropine. A significant relationship was not found between QT interval and body weight. Despite changes in hr during sinus arrhythmia, a significant relationship was not found between QT and RR intervals. The QT interval vs hr accelerated by atropine was analyzed for all dogs and for small (7 to 10 kg, n = 5), medium (10 to 20 kg, n = 7), and large dogs (20 to 25 kg, n = 5). Equations relating QT interval to mean hr were calculated for each group. Our data may serve as a baseline with which to compare QT intervals from dogs with heart disease and/or electrolyte imbalance.
Comparison of two ultralente insulin preparations with protamine zinc insulin in clinically normal cats
Authors: Broussard John D. , Peterson Mark E.
Published: January 2024

The absorption kinetics and glycemic effects of 3 long-acting insulin preparations (protamine zinc beefpork insulin, ultralente beef-pork insulin, and ultralente human insulin) were evaluated in 9 healthy, adult, domestic shorthair cats (6 males, 3 females). A triple crossover study was performed, in which the serial serum concentrations of insulin and glucose were determined over a 24-hour period after SC administration of the 3 insulin preparations (dosage, 1.0 U/kg of body weight) at 3-week intervals. A control study was also performed in 4 of the cats by serially collecting samples for insulin and glucose determinations after administration of insulin diluent. After administration of protamine zinc insulin (pzi), mean (± sem) serum insulin concentration increased significantly (P < 0.05) above baseline, reached a peak value (484 ± 287 pmol/L) at 1 hour, and remained significantly (P < 0.05) higher than baseline at 24 hours. After administration of ultralente human insulin, the serum insulin curve was similar to that obtained after pzi administration, but mean serum insulin concentration took longer to peak (538 ± 177 pmol/L at 4 hours). After administration of ultralente beef-pork insulin, mean peak serum insulin concentration was lower (220 ± 54 pmol/L, not statistically significant) than that obtained after administration of pzi and ultralente human insulins; it then decreased to values statistically indistinguishable from baseline by 16 hours. The area under the serum insulin concentration curve for pzi (5,063 ±681 pmol • h/L) and ultralente human insulin (4,138 ± 439 pmol • h/L) was significantly (P < 0.05) larger than that for ultralente beef-pork insulin (2,378 ± 561 pmol • h/L). Serum glucose concentration decreased after administration of all 3 insulins, but the decrease was not different from that observed after diluent (control) administration. Results of this study indicate that differences may exist between absorption of pzi, ultralente human, and ultralente beef-pork insulins. Of the 2 ultralente insulin preparations, human insulin appears better absorbed than beef-pork insulin, but these findings need to be confirmed in cats with naturally acquired diabetes mellitus.
Modulation of Fc receptors for IgG on bovine polymorphonuclear neutrophils by interferon-γ through de novo RNA transcription and protein synthesis
Authors: Worku Mulumebet , Paape Max J. , Marquardt Warren W.
Published: January 2024

Polymorphonuclear neutrophils (pmn) from 4 cows were preincubated (30 minutes, 37 C) in either actinomycin D (100 μg/ml) or puromycin (10 μg/ ml), inhibitors of mRNA transcription and protein translation, or in medium 199. The pmn were incubated for a further 4.5 hours in medium containing 100 U of recombinant bovine interferon-γ (rbolfn-γ). The pmn were then incubated with bovine IgG1, IgG2, IgM, or aggregated IgG (algG; 4 C, 12 hours) for flow cytometric analysis, using fluoresceinated is-otype-specific antibody. The percentage of pmn binding the ligand and the logarithmic mean fluorescent channel (lmfc), an indicator of the amount of receptor (R) expression, were recorded. Competitive inhibition of ligand binding was measured by incubating pmn with fluoresceinated IgG2 in the presence or absence of 100-fold excess of IgG1, IgG2, and aIgG. Activation with rboIfn-γ induced a 4.5-fold increase in binding of IgG1 and a fivefold increase in lmfc for IgG2. These increases were inhibited by actinomycin D and puromycin. Percentage of pmn binding aIgG decreased after activation by rboIfn-γ. Interferon-γ treatment did not affect binding or lmfc of IgM. However, binding of IgM was reduced by treatment with actinomycin D. Binding of fluoresceinated IgG2 was inhibited by unlabeled IgG1, IgG2, and aIgG. Results indicate that bovine pmn Fc receptors (FcR) for IgG1 and IgG2 were rboIfn-γ inducible, that induction required de novo transcription and translation, that a heterogeneous population of FcR exist on bovine pmn, and that IgG1 and IgG2 share a common FcR. Further, bovine pmn are capable of gene activation and are responsive to changes in their environment, thus being amenable to modulation for effective pathogen destruction.
Safety, efficacy, and effects on copper metabolism of intrareticularly placed selenium boluses in beef heifer calves
Authors: Maas John , Peauroi John R. , Weber Dale W. , Adams Frank W.
Published: January 2024

Intrareticularly placed sustained-release selenium boluses were administered to 1 group of selenium-deficient heifer calves (n = 16), and a second group (n = 16) was left as nontreated controls. Age range for all calves was 83 to 156 days. These boluses release 3 mg of selenium each day, as sodium selenite. Measurements of blood selenium concentration, plasma copper concentration, hepatic copper concentration, and body weight were made over a 188-day study. The treated group of calves had significantly higher mean blood selenium concentration at posttreatment days 68 (P < 0.0001), 112 (P < 0.0001), and 188 (P < 0.005) than did the control group. Mean blood selenium concentration in the treated calves was > 0.10 μg/ml for 188 days. These boluses were observed to be clinically safe; signs of selenium toxicosis were not detected and untoward effects were not seen in the selenium-treated calves. There were no differences between control and treatment groups with respect to mean hepatic copper concentration or mean plasma copper concentration. There were no observed differences between the control and treatment groups with respect to weight gain during the study.
Concentration and molecular weight distribution of hyaluronate in synovial fluid from clinically normal horses and horses with diseased joints
Authors: Tulamo Riitta-Mari , Heiskanen Tiina , Salonen Matti
Published: January 2024

High molecular weight (mw) hyaluronate (ha) is an integral part of synovial fluid (sf), regulating many Important physiologic and pathophysiologic mechanisms. Many of its effects depend on, or are reflected in. the concentration and mw of ha. High-performance liquid chromatography was used to assess simultaneously the concentration and mw of ha in sf obtained from horses with various arthritides: acute traumatic arthritis; chronic traumatic arthritis, including degenerative joint disease (djd); and infectious arthritis. The size-exclusion column was calibrated, using appropriate ha concentration and mw standards, before the high-performance liquid chromatographic assays of the sf samples.

Calibration of the column disclosed that the maximal limit for mw estimation of ha was around 3 million. In control joints, mw of ha ranged from 2 to 3 × 106 (mean 2.5 × 106) and did not differ significantly from mw of ha in sf from horses with acute or chronic traumatic arthritis (mean 2 × 106; range 1.5 to 3 × 106). Interestingly, a small amount of ha of moderately high mw (approx 1 to 1.5 × 106) was detected in chromatograms of sf from infected joints. This degree of polymerization of sf ha was significantly (P < 0.01) lower, compared with that for control joints.

There was no difference in mean (± sd) concentration of ha between control joints and joints with acute or chronic traumatic arthritis (0.33 ± 0.12 g/L vs 0.18 ± 0.03 g/L. or 0.23 ± 0.12 g/L.), indicating that sf ha concentration probably should not be used as a diagnostic marker for the condition. However, the sf ha concentration was significantly (P < 0.01) lower in joints with infectious arthritis (0.07 ± 0.03 g/L) and in the joints with radiographic evidence of djd (0.12 ± 0.01 g/L), compared with control joints.
Effect of ergovaline, lolinc, and dopamine antagonists on rat pituitary cell prolactin release in vitro
Authors: Strickland James R. , Cross Dee L. , Birrenkott Glenn P. , Grimes Larry W.
Published: January 2024

Cultured rat pituitary cells were studied to: determine the effects of ergovaline and loline on in vitro prolactin release; delineate the agonistic activity of these alkaloids at the D2 dopamine receptor, using 2 selective D2 dopamine receptor antagonists; and compare the efficacy of 2 dopamine receptor antagonists in reversing effects of the treatments on in vitro prolactin secretion. Ergovaline reduced in vitro prolactin release by at least 40% (P < 0.05) at concentrations of 10−4, 10−6, and 10−8M However, loline reduced (P < 0.05) prolactin release only at the highest concentration, 10−4 M. Two standard dopamine agonists, dopamine and α-ergocryptine, were used to verify that the inhibitory control mechanisms of in vitro prolactin release were intact. Both compounds reduced prolactin release by at least 40% for concentrations of 10−4, 10−6, or 10−8M. Selective D2 dopamine receptor antagonists (10−6M), domperidone and sulpiride, reversed (P < 0.05) the effect of loline on in vitro prolactin release. However, only domperidone (10−6M) was able to reverse (P < 0.05) the effect of ergovaline and only at the lowest ergovaline concentration (10−8M). Domperidone was more effective (P < 0.05) in reversing the prolactinsuppressing effect of α-ergocryptine than was sulpiride. The dose-response curve for domperidone (cubic fit, P < 0.0001) indicated a threshold concentration (10−7M) for reversal of a-ergocryptine's (10−8M) effect on prolactin release. However, at similar concentration of sulpiride (quadratic fit, P < 0.007), a threshold level was not obtained. These data indicate that ergovaline and loline may act as D2 dopamine receptor agonists. Additionally, domperidone seems to be a more potent drug for reversal of the alkaloids’ hypoprolactinemic effect in vitro than does sulpiride.
Isolation and partial polypeptide characterization of bovine neutrophil plasma membranes
Authors: Salgar Shashikumar K. , Paape Max J. , Alston-Mills Brenda
Published: January 2024

The neutrophil plasma membrane has a major role in migration, phagocytosis, and destruction of microorganisms. Neutrophils isolated from blood and mammary secretions were homogenized, and the plasma membrane fraction was isolated on discontinuous sucrose gradient (20, 32, and 50%). Purity of plasma membrane preparation was determined by use of marker enzyme analysis. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (sds-page) of the membrane proteins was performed under reducing conditions for polypeptide characterization. The membrane proteins were also labeled with 125I externally, using 1,3,4,6-tetrachloro-3α-6α-diphenylgly-couril, and proteins were separated by sds-page and autoradiographed.

Compared with whole cell homogenate, the plasma membrane fraction obtained at the 20/32% interface was enriched for the marker enzymes, 5′-nucleotidase (16-fold), alkaline phosphatase (5.5-fold), and total phosphatase (26-fold). The membrane fraction had minimal specific activity for β-glucuronidase (0.4-fold), compared with whole cell homogenate. Plasma membrane protein yield was about 500 μg/ 109 bovine blood neutrophils. The sds-page of plasma membrane proteins revealed 25 protein bands, of which 13 were major bands. There were 3 distinct bands (18, 36, and 65 kd) in the plasma membrane-enriched fraction (20/32 interface) that were not seen in other fractions (30/50% and pellet). Further, 125I-labeling identified 5 distinct protein bands (205, 140, 65, 35, and 30 kd). Blood and mammary neutrophils had similar polypeptide patterns, except that 36- and 65-kd bands were more prominent for blood neutrophils than for mammary neutrophils.
Hemorheologic alterations induced by incremental treadmill exercise in Thoroughbreds
Authors: Geor Raymond J. , Weiss Douglas J. , Smith Clark M.
Published: January 2024

Hemorheologic alterations induced by incremental treadmill exercise were examined in 5 Thoroughbreds. Blood viscosity; pcv; rbc filterability, density gradient profile, and shape; serum and rbc electrolyte concentrations; and plasma total solids and lactate concentrations were measured before exercise, at treadmill speeds of 9 and 13 m/s, and 10 minutes after exercise. Exercise was associated with significant (P < 0.05) increases in pcv, blood viscosity, and plasma total solids concentration. After adjustment of pcv to 40% by adding or removing each horse's own plasma, blood viscosity remained significantly greater in the sample obtained at 13 m/s, compared with that in samples taken at rest. Filterability of rbc was significantly decreased at 13 m/s, compared with values from other sampling times. During exercise, a significantly greater proportion of the rbc were less dense and were found in the upper layers of the rbc density gradient profile, compared with resting values. This change was associated with a significant increase in rbc mean cell volume. Rapid increases in serum sodium and potassium concentrations during exercise were accompanied by significant increases in rbc potassium and chloride concentrations. This study revealed a consistent pattern of hemorheologic alterations associated with exercise in Thoroughbreds, suggesting that multiple hemorheologic tests are needed to adequately define these complex alterations during exercise in horses.
Morphologic characteristics of equine endometrium classified as Kenney categories I, II, and III, using light and scanning electron microscopy
Authors: Ferreira-Dias Graça , Nequin Lynn G. , King Sheryl S.
Published: January 2024

Pathologic changes in the endometrium of mares may be rated according to Kenney's method of classification. Category I endometrium contains healthy tissue with no or few widely scattered pathologic changes. At the opposite end, severe widespread pathologic changes are associated with category III.

Uterine biopsy specimens were collected aseptically from 16 mares during the estrous and diestrous stages of the cycle. Pathologic changes were evaluated, using light microscopy, and endometrium was classified as Kenney's category I, II, or III.

Endometrial tissue of category I (n = 5 mares in estrus; n = 3 in diestrus); category II (n = 3 in estrus; n = 4 in diestrus), and category III (n = 4 in estrus; n = 4 in diestrus) were processed for scanning electron microscopy (sem). All specimens were fixed immediately after biopsy because it was found that numerous bleb-like projections were formed when fixation was delayed.

Category I endometrium had normal glands, and fibrotic tissue was not observed by light microscopy. Scanning electron microscopy revealed numerous hexagonally shaped cells that were covered with many microvilli. Ciliated cells also were observed, and they contained long healthy cilia. Category II endometrium had 2 to 4 nests surrounded by collagen fibers. Of the 4 specimens, 3 had moderate leukocyte infiltration (59 ± 14.8 wbc/4 high-power fields [450 × ]). Scanning electron microscopy revealed some inflammatory changes with slight swelling of the cell surface. Several cells in category II endometrium lacked microvilli, but they were interdispersed among many healthy hexagonal cells. Many nests were seen in category III tissue, and 2 specimens had severe infiltration of wbc (232,264 cells/4 fields). These 2 specimens appeared to be swollen when examined by sem. Degenerative changes were more extensive in category III endometrium. Large areas lacked microvilli, and some areas had complete loss of the cell boundaries. Numerous holes and ulcer-like formations also were observed on the surface of this type of endometrium.

Morphometric analysis, of the ciliated cell population indicated no significant difference in the quantity of cells in normal tissue during estrus vs diestrus. Category III tissue had significantly (P < 0.05) more surface damage than did tissue of the other 2 categories.

In conclusion, the degree of surface damage observed, using sem, paralleled the number of fibrotic nests that were seen by light microscopy. The amount of surface swelling was related to the amount of inflammatory infiltration observed by light microscopy.
Seroepidemiologic survey of Borrelia burgdorferi exposure of daily cattle in Wisconsin
Authors: Ji Benxiu , Collins Michael T.
Published: January 2024

An ELISA, using purified flagellin of Borrelia burgdorferi as the solid-phase antigen, was used to measure antibody concentrations to B burgdorferi in dairy cattle in Wisconsin. Serum obtained from 5,060 cows in 160 randomly selected herds in the state were tested. Serum from an additional 2,600 cattle in Barron County, Wis, a county with a high annual incidence of B burgdorferi infections in human beings, was also tested. Only 7% of the cows that were tested, but 66% of the herds that were tested, were seropositive for B burgdorferi. Sixteen percent of the herds had a prevalence of ≥ 15% seropositive cows, whereas 50% of the herds had a prevalence of 1 to 14% seropositive cows. Seropositive herds were concentrated in the west-central part of Wisconsin. An association existed between the geographic location of seropositive herds and counties in which B burgdorferi infection of human beings was acquired (P< 0.05) as well as the geographic location of seropositive herds and the geographic distribution of Ixodes scapularis (P < 0.05). Barron County, in which B burgdorferi infection is endemic, had a significantly (P< 0.05) higher percentage of seropositive cows (17%) than did the state of Wisconsin (7%).
Porcine respiratory coronavirus-mediated interference against influenza virus replication in the respiratory tract of feeder pigs
Authors: Van Reeth K. , Pensaert M. B.
Published: January 2024

Effect of prior porcine respiratory coronavirus (PRCV) infection on replication of H1N1-influenza virus in the respiratory tract of swine was studied. In an initial experiment, 3 groups of 5 feeder pigs were studied. Pigs of 2 groups were inoculated sequentially with PRCV, followed by H1N1-influenza virus at 2- and 3-day intervals. Pigs of the other group were inoculated with H1N1-influenza virus only. Pigs were monitored clinically and examined for nasal excretion of influenza virus. In the singly influenza virus-inoculated group, 83% of nasal swab specimens were influenza virus-positive over a period of 6 days after inoculation. In the dually virus-inoculated groups, only 27% (2-day interval) and 53% (3-day interval) of nasal swab specimens were virus-positive over the same postinoculation period. However, clinical signs of infection in these dually inoculated pigs were more severe than those in the singly influenza virus-inoculated pigs. There were no significant differences in antibody responses against influenza virus among the 3 groups of pigs.

In a second experiment, 2 groups of pigs were studied. One group of pigs was inoculated sequentially with PRCV, followed by H1N1-influenza virus 2 days later; the other group was inoculated with H1N1-influenza virus only. Pigs of both groups were serially euthanatized on postinoculation days (pid) 1, 2, 3, and 4 (after influenza virus). At necropsy, influenza virus titer and immunofluorescence in lung tissue were determined and gross lung lesions were recorded. Influenza virus titer in the dually inoculated pigs (pid 1 and 2) was at least 100-fold reduced, compared with that in the corresponding singly inocu lated pigs, and fluorescence was either not detected (pid 1) or was scant (pid 2). Differences in influenza virus replication between pigs of dually and singly inoculated groups became gradually less pronounced at pid 3 and 4. Lung lesions in the dually virus-inoculated pigs were distinctly more severe than those in the corresponding singly virus-inoculated pigs, and became progressively more pronounced as time after influenza virus inoculation progressed.

These results indicate that PRCV infection may induce factors in the lungs that markedly interfere with replication and virus production during a subsequent influenza virus infection. On the other hand, clinical signs of infection and lung lesions were enhanced in the dually virus-inoculated pigs. It is believed that early nonspecific defense mechanisms in the lungs may have a role in the host antiviral response, as well as in development of lesions.
Acute effects of perineural administration of sodium hyaluronate on palmar digital neurectomy sites in horses
Authors: Murray Rachel C. , Gaughan Earl M. , DeBowes Richard M. , Mosier Derek A. , Hoskinson James J.
Published: January 2024

Biaxial palmar digital neurectomy of all limbs was performed on 6 mixed-breed castrated adult male horses, using a standard guillotine method. Using a Teflon catheter, 20 mg (2 ml) of sodium hyaluronate (group 1), 2 ml of phosphate-buffered saline solution (group 2), or catheter placement with no infusion (group 3) was applied to 4 (group 1) or 2 (groups 2 and 3) of 8 incisions/horse. Treatments were administered after closure of the neurectomy incision, and the catheter was removed. Horses were evaluated daily for 1 week, then weekly over a 9- week period for evidence of lameness, swelling, and ultrasonographic changes. On week 9, horses were euthanatized and neurectomy sites were removed en bloc for histologic evaluation of axonal regrowth, inflammation, and fibrosis. Neither lameness nor sign of painful neuroma was observed clinically in any of the horses. Neurectomy eliminated cutaneous heel sensation in all limbs for the duration of the study. Swelling was evident at all neurectomy sites. There were no significant differences between treatment sites for measurement of pastern circumference or ultrasonographic evaluation of incisional swelling. Foci of ultrasonographic hyperechogenicity increased over time, but there was no significant difference in hyperechogenicity between treatment groups. Histologic evidence of neuroma formation was observed at all sites. Morphometric assessment of neuroma cross-sectional areas revealed no significant difference between the groups, as did subjective histologic assessment of neuroma density and fibrous tissue content. We conclude that there are no clinical, ultrasonographic, or histologic effects on neuroma formation and fibrosis at sites of palmar digital neurectomy associated with a single perineural administration of sodium hyaluronate or phosphate-buffered saline solution.
Functional and structural changes of porcine alveolar macrophages induced by sublytic doses of a heat-labile, hemolytic, cytotoxic substance produced by Actinobacillus pleuropneumoniae
Authors: Tarigan S. , Slocombe R. F. , Browning G. F. , Kimpton W.
Published: January 2024

Alterations in the size and functions of porcine alveolar macrophages exposed to sublytic amounts of heat-labile, hemolytic cytotoxin produced by Actinobacillus pleuropneumoniae (App) serotype 1, strain HS54 into the culture medium were studied in vitro. Alveolar macrophages were sensitive to the cytotoxin; treatment of the macrophages with low concentrations of cytotoxin (0.016 hemolytic unit) resulted in severe, irreversible cell swelling. However, high doses of cytotoxin (2.0 hemolytic units) were required to cause substantial cell death, as indicated by the influx of propidium iodide into and release of lactate dehydrogenase from cells. Macrophages exposed to low, sublytic doses of cytotoxin failed to migrate toward chemoattractant, were unable to attach to glass, and failed to phagocytize optimally opsonized erythrocytes. Macrophages already attached to glass surfaces detached when exposed to sublytic doses of cytotoxin. The swelling and impairment of functions of alveolar macrophages observed in this study could not be attributed to endotoxic effects, because heat treatment of the cytotoxin preparation for 60 minutes at 60 C resulted in complete loss of cytotoxicity. We conclude that sublytic doses of heat-labile, hemolytic cytotoxic substances produced by App depress alveolar macrophage function at concentrations likely to develop in association with acute pulmonary infection with App. The Apx (A pleuropneumoniae Rtx toxins) exotoxins secreted by the bacteria into culture medium were considered responsible for the toxic activity of the cytotoxin preparation. The Apx of the App field strain used in this study were likely to be similar to those of serotype -1 reference strain (S4707). Analysis by use of DNA-DNA hybridization indicated that genomic DNA of the field strain contained sequences similar to those encoding structural protein of ApxI (apxIA) and ApxII (apxIIA) of the serotype - 1 reference strain. Therefore, Apx produced by the field strain of App used in this study are likely to be of similar pathogenic importance worldwide.
Effect of phenylephrine on hemodynamics and splenic dimensions in horses
Authors: Hardy Joanne , Bednarski Richard M. , Biller David S.
Published: January 2024

Pharmacologically induced splenic contraction might be useful during certain medical or surgical procedures in horses. The effects of phenylephrine, an α1-adrenergic receptor agonist, on hemodynamic function and splenic dimensions were examined in 6 healthy adult horses. Phenylephrine infusion (1, 3, or 6 μg/kg of body weight/min for 15 minutes) resulted in a dose-related increase in mean pulmonary artery pressure; right atrial pressure; systolic, mean, and diastolic arterial pressures; and packed cell volume (P = 0.0001). Concurrent decreases in heart rate and specific cardiac output (P = 0.0001) were detected, but stroke volume did not vary significantly. The rate pressure product was increased only at the highest phenylephrine dosage (P = 0.012). Bradycardia was observed at all dosages during drug infusion, and second - degree atrioventricular block was detected in 88 % of horses during infusion. Phenylephrine administration caused dose - dependent splenic contraction, as detected by ultrasonographic measurements of splenic area and thickness (P = 0.0001).At the 3- and 6-μg/kg/min infusion rates, splenic area was reduced to 28 and 17 % of baseline measurement, respectively. Splenic dimensions had returned to baseline values by 35 minutes after the end of infusion. Infusion of phenylephrine at a dosage of 3 μg/kg/min for 15 minutes can be used to induce splenic contraction in horses.
Potential for oxytetracycline administration by three routes to cause milk residues in lactating cows, as detected by radioimmunoassay (Charm II) and high-performance liquid chromatography test methods
Authors: Anderson Kevin L. , Moats William A. , Rushing John E. , Wesen Donald P. , Papich Mark G.
Published: January 2024

Milk antimicrobial residues are a serious concern for the dairy industry. Residues of the tetracycline family of antimicrobials have been reported in market milk by investigators, using radioimmunoassay and microbial receptor technology (hereafter referred to as the Charm II test). In response to these reports, an investigation was conducted to determine the potential of 3 extra-label routes of oxytetracycline (otc) administration to cause milk residues above the Food and Drug Administration safe value of 30 parts per billion (ppb). Lactating Holstein cows were administered otc once by use of 1 of 3 routes: iv at 16.5 mg/kg of body weight (n = 6); im at 11 mg/kg (n = 6); and intrauterine (iu) at 2 g in 500 ml of saline solution/cow (n = 6). Duplicate milk samples were collected at the milking prior to drug administration and for the next 13 milkings at 12-hour intervals. Concentrations of otc in milk samples were analyzed by use of the Charm II test for tetracyclines (lmit of otc detection, approx 5 ppb) and were compared with concentrations determined by use of a high-performance lquid chromatography (hplc) method (lower lmit of otc quantitation, approx 2 ppb).

The potential for milk otc residues above the Food and Drug Administration safe value of 30 ppb after treatment was considerably greater for the iv and im routes, compared with the iu route. Mean peak otc concentrations in milk at the first milking after treatment for the hplc and Charm II tests were approximately 3,700 to 4,200 ppb for the iv route, 2,200 to 2,600 ppb for the im route, and 186 to 192 ppb for the iu route, respectively.

Pharmacokinetic analysis, based on milk otc concentrations, indicated that the area under the curve (auc) and milk maximal concentration (Cmax) differed significantly (P < 0.001) among routes of administration. The auc was similar for iv and im administrations; values for both were greater than the auc for iu administration. The Cmax was greatest for iv, intermediate for im, and least for iu administration. There were significant (P ≤ 0.01) differences in auc between assay methods (Charm II vs hplc) for the iv route. Concentrations of otc in milk determined by the Charm II test were often greater than those determined by hplc.

Administration of otc to lactating cows via these routes is extra-label drug use. Failure to withhold the product from early milkings of cows administered otc by the iv or im route should be considered a potential cause of otc residues in market milk. Milk from nearly all cows contained otc (< 30 ppb), the Food and Drug Administration safe level, by 120 hours after otc administration. Use of appropriate withholding times and antibiotic residue testing is indicated to avoid otc residues.
Right atrial bypass model in the dog
Authors: Breen Peter H. , Isserles Schlomo A.
Published: January 2024

In gas exchange studies addressing the storage and transport of CO2 in dogs, a model in which cardiac output (t) can be precisely controlled and measured would be beneficial. We identified problems with described extracorporeal circuits and implemented right atrial bypass (rab) in dogs. In 6 anesthetized (chloralose and urethane), heparinized dogs (mean ± sd, 24 ± 4 kg) with open thorax, cannulas were inserted in both vena cavas to drain venous blood return to a reservoir (anaerobic bag or bubble oxygenator). A roller pump then drove blood through a heat exchanger back to the right atrial appendage. After 1.8 ± 1.4 hour of rab, physiologic variables remained within reference limits for dogs (t, 1.5 ± 0.3 L/min; blood pressure, 92 ± 25 mm of Hg; arterial PCO2, 35 ± 4 mm of Hg; PCO2, 513 ± 39 mm of Hg; pH, 7.39 ± 0.08; and tissue CO2 production, 126 ± 56 ml/min). To permit study of gas exchange, venous return (and thus, t) and venous PCO2 and PCO2 could be accurately regulated and measured over a wide range. Maintenance of native pulsatile lung perfusion and cardiogenic oscillations minimizes mismatching of pulmonary ventilation and perfusion and facilitates studies addressing pulmonary gas exchange. This rab model is designed so that investigators can establish the preparation in a few hours.
Comparison of the holding power of 3.5-mm cortical versus 4.0-mm cancellous orthopedic screws in the pelvis of immature dogs (cadavers)
Authors: Sardinas Juan C. , Kraus Karl H. , Sisson Richard D.
Published: January 2024

A 3.5-mm cortical orthopedic screw was compared with a 4.0-mm cancellous screw for maximal load to failure in the pelvis of immature dogs. The pelvis from young cadavers (7 to 13 months old) was divided into hemipelves and used for testing of the 2 screw types. Two sites in each hemipelvis were used, mid-shaft of the ilium and mid-sacrum, including the wing of the ilium. The screws were extracted, and maximal load to failure and mode of failure were recorded. Maximal load to failure per millimeter of engaged thread was calculated. In either pelvic site, the 4.0-mm cancellous screw required a significantly (P < 0.05) higher pullout force per millimeter of engaged screw threads than did the 3.5-mm cortical bone screw.
Magnetic resonance arthrography of the scapulohumeral joint in dogs, using gadopentetate dimeglumine
Authors: van Bree Henri , Van Ryssen Bernadette , Degryse Hendrik , Ramon Frank
Published: January 2024

Six scapulohumeral joints (3 normal joints and 3 joints with radiographic evidence of osteochondrosis) underwent conventional magnetic resonance (mr) imaging and mr scapulohumeral arthrography to evaluate delineation of the articular cartilage. The mr arthrography was performed, using 5 ml of 500 μM gadopentetate dimeglumine (Gd-dtpa) as a contrast medium. Delineation of normal articular cartilage and cartilage defects was less accurate after intra-articular administration of Gd-dtpa. Therefore, it was concluded that mr arthrography with Gd-dtpa is unrewarding for evaluation of osteochondrosis lesions.
Comparison of the sensitivity of the caudal fold skin test and a commercial γ-interferon assay for diagnosis of bovine tuberculosis
Authors: Whipple Diana L. , Bolin Carole A. , Davis Arthur J. , Jamagin Jerald L. , Johnson Dorothy C. , Nabors Richard S. , Payeur Janet B. , Saari Dennis A. , Wilson Arach J. , Wolf Mary M.
Published: January 2024

A study to determine and compare the sensitivity of the caudal fold tuberculin test (cft) and a commercial γ-interferon (γ-ifn) assay for diagnosis of bovine tuberculosis was conducted. A dairy herd with approximately a third of the cattle infected with Mycobacterium bovis was chosen for this study. All cattle from this herd were slaughtered, and tissue specimens for bacteriologic culturing and histologic examination were collected. Results of the cft and γ-ifn assay were compared with results of bacteriologic culturing and histologic examination to determine test sensitivity. Results were analyzed, using each of the following 4 standards to classify cattle as infected: positive test result by bacteriologic culturing only; histologic examination only; bacteriologic culturing and histologic examination; and bacteriologic culturing or histologic examination. Sensitivity of the cft ranged from 80.4 to 84.4%, depending on the standard of comparison. Sensitivity of the γ-ifn assay ranged from 55.4 to 97.1%, depending on the standard of comparison and on the method of interpretation. The cft was significantly (P < 0.001) more sensitive than the γ-ifn assay for diagnosis of bovine tuberculosis when the γ-ifn assay was conducted and interpreted as instructed by the manufacturer. Maximum overall sensitivity was achieved when results of the cft and γ-ifn assay were interpreted in parallel.
Effect of selenium supplementation on colostral IgG concentration in cows grazing selenium-deficient pastures and on postsuckle serum IgG concentration in their calves
Authors: Swecker William S. , Thatcher Craig D. , Eversole Dan E. , Blodgett Dennis J. , Schurig Gerhardt G.
Published: January 2024

Effects of selenium (Se) deficiency and supplementation on production of colostral immunoglobulins by beef cows and transfer of antigen-specific and nonspecific immunoglobulins to their calves were examined. Eighty beef cows, with marginal to deficient Se status (blood Se concentration, 50 μg/L), were allotted by breed and age to 1 of 4 Se treatment groups (n = 20/group): no supplemental Se; parenteral administration of 0.1 mg of Se and 1 mg of vitamin E/kg of body weight; ad libitum consumption of 120 mg of Se/kg of salt-mineral mix (smm); and parenteral administration of 0.1 mg of Se and 1 mg of vitamin E/kg plus ad libitum consumption of 120 mg of Se/kg of smm. All cows were inoculated IM with lysozyme. Cows consumed Se-deficient pastures or hay (21 to 62 μg/kg) during the study that began at mid-gestation and ended at postpartum hour 24. Although the concentration of specific lysozyme antibodies was not affected, cows given 120 mg of Se/kg of smm (treatments 3 and 4) had higher colostral IgG concentration (P < 0.002) than did Se-deficient cows (treatments 1 and 2). Calves from cows in treatments 3 and 4 had higher postsuckle serum concentrations of IgG (P < 0.01) than did calves from cows in treatments 1 and 2. Colostral IgM and calf serum IgM concentrations did not differ among treatments.
Detection of pseudorabies viral DNA in tonsillar epithelial cells of latently infected pigs
Authors: Brown Talmage T. , Shin Kwang Ok , Fuller Frederick J.
Published: January 2024

The Rice strain of pseudorabies virus (prv) was intranasally instilled in pigs that were seronegative to prv. Cells were scraped or brushed from tonsillar surfaces biweekly until pigs were euthanatized at either 10 or 16 weeks after infection. The dna extracted from tonsillar cells or parenchyma were subjected to polymerase chain reaction analysis, using either a single set of oligonucleotide primers or nested primers from the prv gII glycoprotein gene. Pigs became seropositive to prv by 3 weeks after infection. The virus was isolated from the trigeminal ganglia and tonsils of pigs that were euthanatized or died 1 to 2 weeks after infection, but not from pigs that were euthanatized 10 or 16 weeks after infection. The prv gene products were consistently detected in trigeminal ganglia and tonsils of all pigs at 1, 10, and 16 weeks after infection, and sporadically in the nasal mucosa, lymph nodes, and lungs of pigs that were euthanatized or died during the first 2 weeks after infection. Cells collected biweekly from tonsillar surfaces were mostly nucleated, squamous epithelial cells with fewer lymphocytes and neutrophils. Polymerase chain reaction analysis of dna extracted from these cells revealed prv dna in a large proportion of the samples when sufficient cells were collected to provide 1 μg of extracted dna for use in the reaction mixtures.

A second group of pigs had prv strain 4892 intranasally instilled. The virus was isolated from tonsillar swab specimens until 3 weeks after infection. Tonsillar brushing specimens were collected biweekly until 14 weeks after infection. Some brushing specimens contained all nucleated, squamous epithelial cells, whereas other specimens contained a mixture of epithelial cells and up to 15% neutrophils, lymphocytes, and small mononuclear cells. Results of polymerase chain reaction analysis of dna extracted from tonsillar cells collected 5,11, and 14 weeks after infection were consistently positive for prv gene products. Intact cells collected from tonsillar surfaces were placed in polymerase chain reaction mixtures with nested oligonucleotide primers from the prv gII glycoprotein gene and were subjected to multiple amplification cycles. Afterward, the specificity of the amplified prv gene products was determined by hybridization procedures, using a virus-specific oligonucleotide probe. Most nucleated, squamous epithelial cells stained positive for prv dna, suggesting that these cells were the primary source of prv gene products in tonsillar brushing specimens.
Comparison of methods for measurement of enzootic pneumonia lesions in pigs
Authors: Davies Peter R. , Bahnson Peter B. , Grass Julie J. , Marsh William E. , Dial Gary D.
Published: January 2024

A rapid subjective method for estimating the extent of gross pneumonia lesions in slaughtered pigs was compared with dissection of lungs in 51 slaughtered pigs. After standardization for prevalence in the regional industry, regression analysis indicated that the subjective method was highly predictive of the extent of pneumonic lesions (R2· = 0.88). Part of the error with the subjective method was attributed to approximations used for the relative proportions of lung lobes, which result in overestimation of the affected tissue by approximately 20%. Retrospective analysis of data from a slaughter monitoring program revealed strong associations (R2, 0.54 to 0.91) between prevalence, mean, median, and maximal lung scores in groups of pigs. Maximal lung score was biased by sample size, but prevalence and mean or median lung scores could be used to describe pneumonia severity in groups of pigs. Our results indicate that error in measurement of the extent of pneumonic tissue in slaughtered pigs is unimportant if the time of onset, clinical severity, and duration of disease are not quantified.
Ultrastructural study of the uptake of ferritin by M cells in the follicle-associated epithelium in the small and large intestines of pigs
Authors: Liebier Elisabeth M. , Lemke Christine , Pohlenz Joachim F.
Published: January 2024

Uptake of ferritin by M cells in follicle-associated epithelium at various sites in the small and large intestines was examined in 4 healthy 5-week-old pigs by use of electron microscopy. A 2.5% solution of ferritin in saline was injected into ligated loops of the jejunum and ileum containing aggregations of lymphoid follicles (Peyer's patches), as well as into intestinal loops containing lymphoglandular complexes at the ileocecal junction, in the central colonic flexure, and in the rectum. As negative control, saline solution was injected into loops at identical localizations. After an exposure period of 2 hours, uptake of ferritin by M cells, but not by enteroabsorptive cells of the small and large intestines, was observed. Numbers of M cells with ferritin and total M cells were counted and the percentage was calculated. Total number of M cells was highest in lymphoglandular complexes in the rectum and lowest on domes of the ileal Peyer's patch. High numbers of M cells with ferritin were found on domes of the jejunal Peyer's patch, and in lymphoglandular complexes at the ileocecal entrance and in the rectum. Only a few M cells on domes of the ileal Peyer's patch and in lymphoglandular complexes in the central colonic flexure contained ferritin. The percentage of M cells with internalized ferritin was similar on domes of the ileal Peyer's patch, and in lymphoglandular complexes at the ileocecal junction and in the rectum. It was higher on domes of the jejunal Peyer s patches and lower in lymphoglandular complexes of the central colonic flexure. Ferritin was found in the apical tubulovesicular system, multivesicular bodies, and a few vacuoles in the central area of M cells. Ferritin was exocytosed into the lateral intercellular spaces next to M cells. Uptake of ferritin by intraepithelial cells in the follicle-associated epithelium could not be documented, but ferritin was present in vesicles of subepithelial macrophages.