bluuebunny/crossref_metadata_2025 huggingface dataset:
Normal motility of the cecum and right ventral colon in ponies
Authors: Ross Michael W. , Donawick William J. , Sellers Alvin F. , Lowe John E.
Published: February 2025

To study the normal motility of the cecum and right ventral colon (rvc) in 3 mature Shetland ponies, a 6-part, indwelling, intraluminal catheter system was used to measure intraluminal pressure changes. Three catheters were placed in the cecum at 10, 25, and 40 cm from the cecocolic orifice, and 3 catheters were placed in the rvc at 10,20, and 30 cm from the cecocolic orifice. Recordings were made during the interdigestive period beginning 2 weeks after surgical operation was done.

Frequent, low-amplitude peaks (0.35 ± 0.13 coordinated peaks/min) were seen involving the cecal body and caudal cecal base, which represented a haustra-to-haustra mixing pattern. Coordinated pressure peaks originated in the cecal body and progressed to the cranial cecal base (0.07 ± 0.01/min) or originated in the cranial cecal base and progressed to the cecal body (0.07 ± 0.04/min).

Associated with a loud rush of ingesta heard on transabdominal auscultation and progression of liquid ingesta confirmed with barium contrast radiography, there was a series of coordinated, progressive pressure peaks which originated in the cecal body, sequentially involved the cecal base, traversed the cecocolic orifice, and extended into the rvc (0.36 ± 0.05/min). It seemed that a pacemaker region existed in the cecal body and initiated the important aborally propagated progressive pattern responsible for the transit of ingesta from the cecum to the rvc. A separate mechanism for the transit of gas was not identified.

In the rvc, infrequent, nondirectional, low-amplitude segmental pressure peaks (0.12 ± 0.06/min), and aborally progressive coordinated pressure peaks originating at the beginning of the rvc (0.09 ± 0.02/min), occurred. An orally directed progressive pressure pattern, beginning aborally and progressing to the origin of the rvc (0.26 ± 0.05/min), confirmed the presence of retropulsion in the rvc.
Femoral venipuncture for collection of multiple blood samples in the nonanesthetized rat
Authors: Horton Michael L. , Olson Carl T. , Hobson David W.
Published: February 2025

A technique for blood collection via the femoral vein was developed for use in nonanesthetized rats. The technique was useful for single or serial blood collection. Volumes of 0.1 to 1 ml were collected for serum biochemical or venous blood gas determinations. The technique was effective, reproducible, did not require anesthesia, and was less stressful than other methods of blood collection in the rat.
Investigation of possible vaccine-induced epizootics of infectious bovine rhinotracheitis, using restriction endonuclease analysis of viral DNA
Authors: Whetstone C. A. , Wheeler J. G. , Reed D. E.
Published: February 2025

Viral DNA was extracted from each of 14 modified-live (ml) bovine herpesvirus 1 vaccines, representing all of the ml infectious bovine rhinotracheitis virus (ibrv) vaccines licensed by the US Department of Agriculture for use in cattle. Restriction endonucleases Pst I and Bgl II were used to establish restriction enzyme patterns for the vaccinal viruses. Viral DNA from isolates obtained from 6 field samples of ibrv (1 from Colorado, 1 from West Virginia, 3 from Wisconsin, 1 from South Dakota) were digested with restriction endonucleases, and patterns were compared to evaluate the role of vaccinal virus in these field epizootics of infectious bovine rhinotracheitis. Animals from which field samples were obtained had been vaccinated with ml ibrv vaccine before the epizootic of infectious bovine rhinotracheitis occurred in the herds. In 2 of the 6 field samples, DNA restriction endonuclease analyses patterns from the isolates were indistinguishable from the pattern for the vaccinal viruses used. In the remaining 4 field samples, DNA restriction endonuclease analyses patterns of the ibrv from isolates were different from those of the vaccinal viruses.
Clinical and pathologic changes in acute bovine aflatoxicosis: Rumen motility and tissue and fluid concentrations of aflatoxins B1 and M1
Authors: Cook W. O. , Richard J. L. , Osweiler G. D. , Trampel D. W.
Published: February 2025

Effects of aflatoxin on bovine rumen motility were determined by radiotelemetric techniques. Aflatoxin altered amplitude and/or frequency of rumen contractions in steers given dosages of 0.2, 0.4, 0.6, or 0.8 mg of aflatoxin/ kg of body weight. Effects of aflatoxin on rumen motility were dose dependent. An increase in elimination time of aflatoxin from rumen contents was observed in steers given the aflatoxin dosages of 0.4 to 0.8 mg/kg. The increase in elimination time of this toxin facilitates diagnostic capabilities for detecting bovine aflatoxicosis by obtaining rumen contents for analysis for aflatoxin. Aflatoxin was detected in rumen contents from steers at 2 hours after aflatoxin was administered. Thus, intraruminal metabolism of aflatoxin B1 to M1 may occur.
Feed aversion induced by intraruminal infusion with larkspur extract in cattle
Authors: Olsen J. D. , Ralphs M. H.
Published: February 2025

Twelve Hereford heifers were infused with larkspur extract (group 1, n = 4), lithium chloride solution (group 2, n = 4), or sodium chloride solution (group 3, n = 4). After 3 weeks of being fed basal ration (meadow grass hay), all heifers were offered a ration of alfalfa pellets (3,400 g) in a 2-phase, single-day feeding regimen. In phase 1, the amount eaten within 45 minutes was measured by weigh-back of uneaten pellets. In phase 2, cattle that ate > 150 g of pellets in phase 1 were offered the balance of uneaten pellets and were infused with their respective designated solution. Five pairings of pellet feedings and appropriate infusions were given at 2- or 3-day intervals to initially induce feed aversion. Heifers in groups 1 and 2 developed a strong aversion to pellets by the 5th feeding. Persistence of aversion was tested twice at weekly intervals. Infusion of cattle with larkspur extract or lithium chloride solution induced a persistent aversion to an otherwise palatable feed.
Fiber type composition of rostral and caudal portions of the digastric muscle in the dog
Authors: Bubb Wendy J. , Sims Michael H.
Published: February 2025

The distribution of muscle fiber types in rostral and caudal portions of the musculus digastricus (digastric muscle) was studied in 6 dogs. Staining procedures which stain specifically for type IIM fibers, a fiber type found in other muscles supplied by the trigeminal nerve, were used. Rostral and caudal portions of the muscle were compared because the rostral portion is innervated by the trigeminal nerve, and the caudal portion is innervated by the facial nerve.

The musculus triceps brachii (triceps muscle), which contains fiber types I and IIA, and the musculus masseter (masseter muscle), which contains type IIM, were used as controls. Mean fiber diameters were calculated for each of the muscles. Both portions of the digastric muscle exhibited the same histochemical behavior, possessing types I and IIA myofibers. Neither portion contained type IIM fibers. Type I fibers in the masseter muscle were histochemically different from type I fibers in the other muscles studied. Type II fibers predominated in all 3 muscles, but there were significantly (P < 0.001) more type I fibers in the triceps muscle than in either portion of the digastric muscle or in the masseter muscle. Type II fibers were significantly larger than type I fibers in the caudal digastric (P < 0.01) and masseter (P < 0.05) muscles. There was no difference in the size of type I or type II fibers between any of the muscles studied (P > 0.20).
Immunoreactive protein antigens of Mycoplasma pulmonis in experimentally infected rats
Authors: Chang Jerjang , Pick James R.
Published: February 2025

Mycoplasma pulmonis was cultured in modified Hayflick's medium, washed in 0.25M NaCl, and solubilized by 2.5% sodium dodecyl sulfate. Protein antigens of M pulmonis separated by polyacrylamide-gel electrophoresis were blotted onto nitrocellulose strips. Specific-pathogen-free rats were inoculated intranasally with M pulmonis. The serum samples of these rats were obtained periodically and used to react with fractionated M pulmonis antigens which were fixed on the nitrocellulose strips. The antigen-antibody reactions were further recognized by 125I-labeled antiglobulin. Detection of immunoreactive antigens was obtained by autoradiography. Antibody response was not detected in serum obtained 7 days after rats were inoculated, and by 14 days, a slight response to several proteins was found. At 28 days after rats were inoculated, many immunoreactive antigens were detected. Generally, antibodies against antigens of moderate to low molecular weight appeared early in the infection, and antibodies against antigens of high molecular weight appeared late. Important immunoreactive antigens thus identified can readily be distinguished from more than 58 different M pulmonis antigens detectable by sodium dodecyl sulfate polyacrylamide-gel electrophoresis.

The humoral antibody response was measured by an enzyme-linked immunosorbent assay. The immunoglobulin G antibodies were initially detected at low level at 7 days after rats were inoculated. These humoral antibody responses reached maximum by 28 days. The increase in serum antibody titer corresponded with numbers of immunoreactive antigens detected by immunoradio-binding assay. The information gained by this investigation may improve our understanding of the antigenicity of M pulmonis and the immune response of rats exposed to M pulmonis.
Identification of a bovine enteric syncytial virus as a nongroup A rotavirus
Authors: Vonderfecht Steven L. , Eiden Joseph J. , Torres Alfonso , Miskuff Robin L. , Mebus Charles A. , Yolken Robert H.
Published: February 2025

An atypical or nongroup A rotavirus was identified in feces obtained from gnotobiotic calves in which fecal preparations originally derived during an epizootic of neonatal calf diarrhea had been serially passaged. The epizootic was previously reported to be caused by a noncharacterized viral agent that induced the formation of epithelial syncytia on small intestinal villi of experimentally infected calves. This bovine, nongroup A rotavirus was found to be antigenically related to a described atypical rotavirus of rats by immunofluorescence and by enzyme immunoassay. Complementary DNA derived from the atypical rat rotavirus cross hybridized with RNA obtained from the bovine virus, but not with RNA extracted from group A rotaviruses. Complementary DNA derived from SA-11 group A rotavirus cross hybridized with other group A rotavirus RNA, but not with RNA obtained from either the rat or bovine nongroup A isolates. Additionally, another similar, if not identical, bovine atypical rotavirus was identified in a second epizootic of neonatal calf diarrhea that occurred several hundred kilometers and 8 months apart from the original epizootic.
Immunologic profiles of cats with persistent, naturally acquired feline leukemia virus infection
Authors: Reimann Keith A. , Bull Robert W. , Crow Steven E. , Coffman Peggy , Raskin Rose E.
Published: February 2025

Several immunologic responses were measured in 13 healthy cats with naturally acquired, persistent feline leukemia virus (FeLV) viremia from 4 multiple-cat households and were compared with responses from 28 of their healthy, non-FeLV-viremic housemates. Significant differences (P = < 0.05) were not observed between results of FeLV-viremic and nonviremic cats for peripheral blood leukocyte or lymphocyte count, percentage of peripheral blood mononuclear cells able to form rosettes with guinea pig rbc or with antibody- and complement-coated sheep rbc, lymphocyte proliferative response to concanavalin A or pokeweed mitogen, or serum immunoglobulin G concentration. Seemingly, persistent FeLV viremia, when naturally acquired, may exist for some time without lymphopenia or a marked loss of mitogen-induced lymphocyte proliferation.
Progesterone secretion by the bovine fetoplacental unit and responsiveness of corpora lutea to steroidogenic stimuli at two stages of gestation
Authors: Pimentel S. M. , Pimentel C. A. , Weston P. G. , Hixon J. E. , Wagner W. C.
Published: February 2025

To evaluate the response of luteal cells to in vitro stimulation with luteinizing hormone (lh) or dibutyryl cyclic adenosine monophosphate (dbcAMP) and determine the secretion of progesterone by the fetoplacental unit, the corpora lutea were removed surgically in 10 cows (luteectomy) at 250 days (5 cows) or 270 days (5 cows) of gestation. During surgery, but before luteectomy, catheters were placed in the middle uterine artery and vein, carotid artery, and jugular vein. Blood samples were collected from all catheters just before luteectomy and at 8-hour intervals after luteectomy for 72 hours or until calving, whichever occurred first. Luteal tissue was prepared as a dispersed cell preparation and incubated with 0, 0.1, 1.0, 10, or 100 ng of lh/ml of medium or was incubated with 0, 0.5, or 2 mM dbcAMP. Synthesis of progesterone in response to lh by dispersed cells prepared from corpora lutea at 270 days was less (P < 0.01; analysis of variance) than that by similar preparations at 250 days because a dose-response relationship was not observed for incubations of luteal tissue with lh at 270 days of gestation. Progesterone synthesis in response to the addition of dbcAMP also was less (P < 0.01) at 270 than at 250 days of gestation. This difference in responsiveness to lh and dbcAMP between the 2 stages of gestation was not reflected by a significant difference between stages of gestation in systemic concentrations of progesterone before luteectomy. Mean concentrations of progesterone within the carotid artery and jugular vein decreased (P < 0.01; split-plot analysis) after removal of corpora lutea, and significant differences were not found between blood collection sites or between stages of gestation. Concentrations of progesterone within the uterine arterial and venous circulations decreased (P < 0.01) after luteectomy at both stages of gestation. After luteectomy at 250 days, venous plasma concentrations stabilized (1.1 to 1.9 ng/ml), whereas progesterone concentrations progressively decreased to < 0.5 ng/ml in the uterine artery at 250 days of gestation and in the uterine artery and vein after removal of corpora lutea at 270 days of gestation. This difference between the 2 stages of gestation (P < 0.01) indicated that the fetoplacental unit may have secreted progesterone at 250 days of gestation, but not at 270 days. A difference in progesterone synthesis and secretion between the 2 stages of gestation may explain why the interval between luteectomy and calving was longer for cows at 250 days of gestation than at 270 days of gestation (98 ± 18 hours vs 37 ± 14 hours; P < 0.05).
Echocardiographic characterization of dilatation cardiomyopathy in the English Cocker Spaniel
Authors: Gooding Jean P. , Robinson Wayne F. , Mews Geoffrey C.
Published: February 2025

The echocardiographic characterization of a dilatation cardiomyopathy in small-breed dogs is reported. Twelve clinically healthy adult English Cocker Spaniel dogs (between 2 and 9 years old and weighing 11.5 to 15.4 kg [mean 12.9 ± 1.00 kg]) from a kennel population with a history of cardiomyopathy were assessed, using M-mode echocardiography. The dogs were selected on ecg and/or radiographic evidence of ventricular enlargement. Nine dogs had R-wave amplitude in lead 11 of > 3.0 mV. Two dogs had an unusual right-axis deviation, the result of deep Q waves in the limb leads and deep S waves in chest leads CV6LL and CV6LU, indicating that there was right ventricular enlargement. All dogs had increased end-systolic dimensions (mean 3.0 ± 0.6 cm). End-diastolic dimensions were increased in 9 dogs (mean 4.0 ± 0.5 cm), and there was a decrease of left ventricular (lv) function as measured by fractional shortening in 8 dogs. Mean fractional shortening for the 12 dogs was 25.4 ± 5.7%. There was significant correlation between lv dimensions and age at echocardiographic assessment, indicating that lv dilatation was progressive. Three of the oldest dogs had severe dilatation of the lv, and in 2 of these, lv function was severely decreased. Left ventricular function in the 3rd dog, however, was within the acceptable range. Fractional shortening and thickness of the lv caudal wall and interventricular septum were significantly correlated (P < 0.01 for interventricular system and P < 0.05 for lv caudal wall).

R-Wave amplitude and lv mass and lv cross-sectional area calculated from the echocardiographic measurements correlated significantly in the 9 dogs in which R-wave amplitude exceeded 3.0 mV (P < 0.01 and P < 0.05, respectively).

The dilatation cardiomyopathy described differs from the idiopathic congestive cardiomyopathies of persons and of large- and giant-breed dogs in that it is generally benign. The course of the disease is variable and there is usually a long, clinically asymptomatic period, although affected animals may show early ecg abnormalities. However, progressive reduction in myocardial function eventually leads to congestive heart failure.
Evaluation of plasma and buffy coat ascorbic acid concentrations in dogs before and after a 24-hour fast
Authors: Lee Alice H. , Spano Joseph S. , Swaim Steven F. , McGuire John A. , Hughes Kim S.
Published: February 2025

Samples of blood were taken from 15 female and 15 male research laboratory Beagles before and after they were fasted for 24 hours. The mean buffy coat ascorbic acid concentration was significantly higher in dogs after they were fasted than that before they were fasted. In contrast, the mean plasma ascorbic acid concentration was significantly lower in dogs after they were fasted than that before they were fasted. The mean buffy coat ascorbic acid concentrations in blood samples of both fasted and nonfasted female Beagles was significantly greater than those of male Beagles, whereas the mean plasma concentrations of both fasted and nonfasted female Beagles was significantly lower than those of male Beagles. It was observed that whenever there was a decrease in plasma ascorbic acid concentration, there was an increase in buffy coat ascorbic acid concentration, regardless of fasting stress or sex difference.
Anthelmintic efficacy of febantel combined with praziquantel against Ancylostoma tubaeforme, Toxocara cati, and Taenia taeniaeformis in cats
Authors: Arther Robert G. , Cox Danny D.
Published: February 2025

Forty cats, each harboring 2 or 3 parasitic infections (Ancylostoma tubaeforme, Toxocara cati, and/or Taenia taeniaeformis), were used to titrate the anthelmintic efficacy of a paste containing 3.4% febantel and 0.34% praziquantel. The cats were allotted into 4 groups (10 cats/group). For 3 consecutive days, the cats were given febantel/praziquantel at 5/0.5 mg/kg/day, 10/1 mg/kg/day, 15/1.5 mg/kg/day, or a blank paste vehicle (control) at 0.29 g/kg of body weight. The recommended dosage of 10 mg of febantel and 1 mg of praziquantel/kg cleared ≥ 98% of the 3 helminth species.
Estimation of urinary flow rate in weanling and yearling horses
Authors: Glade Michael J.
Published: February 2025

In an attempt to validate the use of urinary creatinine concentration as an index of urinary flow rate, a series of timed quantitative urine collections were done on several groups of weanling and yearling ponies and Thoroughbreds. A total of 411 urine samples were generated by 19 ponies and 12 Thoroughbreds. Urinary flow rates and urinary creatinine concentrations were measured. When all the data were examined, urinary flow rates were independent of creatinine concentrations. However, for any given animal, daily urinary creatinine excretion was constant over several days, and urinary creatinine concentrations were related to urinary flow rates in a negative curvilinear fashion. Urinary flow rates in young horses can be estimated from urinary creatinine concentrations, but separate curves relating the 2 variables must first be derived for each animal.
Dexamethasone-induced attenuation of cardiopulmonary dysfunction in endotoxemic calves
Authors: Olson Neil C. , Brown Talmage T.
Published: February 2025

Effects of dexamethasone on pulmonary hemodynamics, pulmonary mechanics, and gas exchange were determined in anesthetized (pentobarbital sodium) and paralyzed (pancuronium bromide) calves (9.4 ± 0.4 weeks old) during 5 hours of endotoxemia. Escherichia coli endotoxin (055-B5) was infused iv at 20 μg/kg the 1st hour, followed by a continuous infusion at 10 μg/kg/hour for the following 4 hours. Dexamethasone (5 mg/kg) was given iv 18 hours and 1 hour before endotoxin administration, and was also administered iv (1 mg/kg/hr) during endotoxemia. Endotoxin induced large increases in pulmonary artery pressure, pulmonary vascular resistance, alveolar-arterial O2 gradient, alveolar dead-space ventilation, postmortem gravimetric lung weight of bloodless lung, albumin and total protein concentrations in bronchoalveolar lavage fluid, and the number of neutrophils recovered from bronchoalveolar lavage fluid. Endotoxin induced decreases in the cardiac index, dynamic lung compliance, and Pao2. Dexamethasone attenuated most of the cardiopulmonary responses induced by endotoxin, especially during the first 3 hours of endotoxemia. Dexamethasone blocked endotoxin-induced increases in bronchoalveolar lavage albumin, total protein, and neurophil content. Therefore, glucocorticoids modify endotoxin-induced pulmonary injury in calves, possibly by limiting mobilization of endogenous arachidonic acid.
Cardiac performance in cats after administration of xylazine or xylazine and glycopyrrolate: Echocardiographic evaluations
Authors: Dunkle Nancy , Moise N. Sydney , Scarlett-Kranz Janet , Short Charles E.
Published: February 2025

Cardiac performance was evaluted in 9 healthy cats sedated with xylazine. Each cat was evaluated echocardiographically before and after the administration of xylazine or xylazine and glycopyrrolate. Each cat was echocardiographically evaluated during manual restraint only (control value), after im administration of 0.55 mg of xylazine/kg of body weight, after im administration of 2.2 mg of xylazine/kg, and after im administration of 0.011 mg of glycopyrrolate/kg followed 10 minutes later by im administration of 2.2 mg of xylazine/kg. Echocardiographic indices of cardiac performance (fractional shortening, left ventricular wall amplitude, aortic amplitude, mitral valve E point septal separation) indicated a significant decrease (P < 0.05) in the left ventricular function and heart rate after the small (0.55 mg/kg) and large (2.2 mg/kg) dosages of xylazine. With the administration of glycopyrrolate, the bradycardia was minimized, but cardiac performance was not improved. After administration of glycopyrrolate, cardiac performance decreased, but the decrease was not significant when compared with the ventricular performance of the cats after administration of the large dosage of xylazine. Compared with control values, the reduction in left ventricular function values associated with administration of xylazine or xylazine and glycopyrrolate was independent of the heart rate. Therefore, the α-2 adrenergic agonist xylazine has a marked depressive effect on cardiac performance in the cat, and premedication with glycopyrrolate may not completely alleviate the undesirable bradycardia, but may actually be detrimental to the cardiovascular system.
Use of subcutaneously implanted chambers in calves for in vivo study of isolates of Moraxella bovis
Authors: Pugh George W. , Wilbur Linn A. , Beall Charles W.
Published: February 2025

Selected cultures of Moraxella bovis were studied in calves, using chambers fabricated from a semipermeable membrane supported and protected by perforated plastic golf balls. Plain balls, semipermeable membrane-covered balls, and balls that contained bags fabricated from semipermeable membranes were surgically implanted subcutaneously in calves at a site approximately 25 cm ventral to the paralumbar fossa and cranial to the prefemoral lymph node. After calves recovered from surgery, chambers were inoculated with different cultures of M bovis. Cultural examination of samples taken from inoculated chambers indicated that M bovis cultures were maintained within the chambers for variable times, depending on the characteristics of the culture inoculated. A smooth (piliated) culture dissociated into a rough (nonpiliated) culture after 4 wbeks of incubation within a chamber but none of the rough cultures became smooth.

The technique offers a method to study the in vivo variations in a series of cultures or strains of microorganisms under the influence of the same host factors. The selective permeability of the chamber may be controlled by using membranes of different porosities to control the flow of entering or exiting dialysate.
Restriction endonuclease analysis of various strains of Mycobacterium paratuberculosis isolated from cattle
Authors: Collins Desmond M. , de Lisle Geoffrey W.
Published: February 2025

Deoxyribonucleic acid (dna) preparations from 3 reference strains of Mycobacterium paratuberculosis and from 23 isolates of M paratuberculosis obtained from cattle in New Zealand were characterized by restriction endonuclease analysis, using the enzymes BstE II, Pvu II, and Bcl I. Patterns of dna fragments for strain 18 (one of the reference strains) differed markedly from patterns of other strains, indicating genetic differences between strain 18 and the other strains of M paratuberculosis evaluated. The other 2 reference strains (TMC 1613 and Weybridge strain 316) and all but 1 of the isolates from cattle had identical patterns with the 3 enzymes. These 2 reference strains differed from each other in their dependence on exogenous mycobactin, but this was not reflected in their restriction patterns. The single variant isolate from cattle had patterns identical to those of the other isolates, using Pvu II and Bcl I, and had only 1 fragment line difference with BstE II. Although close genetic homogeneity of cattle strains of M paratuberculosis prevented development of a typing system on the basis of restriction endonuclease analysis, the results provided a basis for genomic comparison with other closely related organisms.
Effect of suramin on serum viral replication in feline leukemia virus-infected pet cats
Authors: Cogan D. C. , Cotter S. M. , Kitchen L. W.
Published: February 2025

Suramin treatments were administered (iv) to 2 healthy adult cats infected with naturally acquired feline leukemia virus. Serum viral infectivity—as assessed by focus induction by the method of Fischinger, using serial serum samples titrated on clone 81 cells—ceased transiently in both cats during treatment with suramin, but returned to significantly high levels approximately 14 days after treatment was stopped. Both cats tested positive for FeLV internal antigens in peripheral blood cells and serum before, during, and after treatment. Both cats tested negative for antibody to feline oncornavirus membrane antigen before, during, and after treatment. The major adverse effects of suramin in the 2 cats were transient vomiting and anorexia.
Chromatographic separation and characterization of Pasteurella Haemolytica Cytotoxin
Authors: Mosier Derek A. , Lessley Bruce A. , Confer Anthony W. , Antone Susan M. , Gentry Martha J.
Published: February 2025

Biochemical and immunologic properties of the cytotoxin (leukotoxin) produced by Pasteurella haemolytica were examined. Crude, bacteria-free supernatants from logarithmic phase P haemolytica were fractionated, using a series of column chromatographic techniques. Sequential anion exchange chromatography, gel-filtration chromatography, and chromatofocusing resulted in a cytotoxic substance (cytotoxin-C) of approximately 160 kilodaltons (kD), as determined by use of gel-filtration chromatography. Polyacrylamide-gel electrophoresis of cytotoxin-C yielded 3 protein bands with relative mobilites of 0.37, 0.42, and 0.63. On the basis of immunoblotting with a cytotoxin-neutralizing bovine immunoglobulin for antigen detection, the 2 low-mobility bands shared a strong region of immunogenicity. Using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, principal protein constituents of cytotoxin-C were found at 160, 66, 57, and 23 kD. Using immunoblotting with cytotoxin-neutralizing immunoglobulin, strong, distinct reactions with the 66-and 57-kD bands were detected. Immunization of rabbits and mice with cytotoxin-C resulted in sera that reacted strongly with cytotoxin-C in enzyme-linked immunosorbent assays and immunodiffusion assays. The major immunogenic proteins also were detected by use of immunoblotting with anticytotoxin-C sera from rabbits and mice. Postinoculation rabbit sera neutralized crude cytotoxin.
Transmission of Anaplasma marginale Theiler by males of Dermacentor andersoni Stiles fed on an Idaho field-infected, chronic carrier cow
Authors: Zaugg Jerry L. , Stiller David , Coan Michael E. , Lincoln Stuart D.
Published: February 2025

The role of ticks and carrier cattle in epizootics of bovine anaplasmosis was further clarified by demonstrating unequivocally, for the first time, that male ticks fed on a chronic carrier cow naturally infected with Anaplasma marginale can transmit this parasite intrastadially and biologically when subsequently fed on susceptible cattle. These data indicate that field epizootics of acute anaplasmosis may be initiated by males of tick vector species that feed on carrier cattle and subsequently transfer to susceptible cattle.
Experimentally induced thiamine deficiency in Beagle dogs: Pathologic changes of the central nervous system
Authors: Read Deryck H. , Harrington Daniel D.
Published: February 2025

Brain and spinal cord were examined in twenty-two 2- to 5-month-old Beagle dogs fed a purified thiamine-deficient ration for 84 ± 42 (range, 32 to 134) days. Eleven dogs were used as principals, 6 were pair-fed controls, and 5 were controls fed ad libitum. Thiamine at 300 μg/kg of body weight was administered im to control groups once a week.

Lesions occurred in 2 topographic patterns in the brain of 8 of the principals. In pattern I, only the caudal colliculi were involved. In pattern II, the suprasplenial gyri of the cerebral cortex and the claustra, caudal colliculi, cerebellar nodulus, and medial vestibular nuclei were commonly involved. In both patterns I and II, gray matter was primarily involved, and in bilateral structures, the 2 sides were affected. Lesions were not limited to a given cerebral lamina or layer of the cerebellum, whereas sulcal areas were relatively spared, and the cingulate gyri were completely spared. Microscopic appearance of the lesions varied greatly among locations and individual principals. Collectively, regressive and reparative changes indicated that there was a progressive process which began with spongiosis and ended with tissue necrosis. These included hydropic vacuolation of the neuropil and myelin sheaths followed by demyelination, neuronal cell body necrosis, hypertrophy and hyperplasia of endothelial cells, necrosis of glia, neutrophil infiltration, disintegration of neuropil, and, finally, accumulation of lipid-containing phagocytes. Axonal degeneration was variable. Neuronal necrosis in the brain stem was characterized by acute swelling and lysis and by shrinkage of the cell body in cerebral and cerebellar cortex and basal ganglia.
Antidotal effect of vitamin K1 against warfarin-induced anticoagulation in horses
Authors: Byars T. D. , Greene C. E. , Kemp D. T.
Published: February 2025

Warfarin-induced anticoagulation and reversal of the induced anticoagulation by vitamin K1 were evaluated in 4 mature horses. Each horse was given warfarin iv until the prothrombin (pt) time was prolonged by approximately 1.5 times the predosing base-line value. In experiment 1, we evaluated the time required for pt to return to the predosing value (pt reversal time) after warfarin administration was discontinued. Between each experiment, a 1-week rest period was allowed. In experiment 2, two doses of vitamin K1 (100 mg/dose) were administered im 6 hours apart, and the pt was monitored hourly for 24 hours. In experiments 3 and 4, the horses were dosed with warfarin as in experiment 1, and the pt reversal time was evaluated after administration of 300- and 500-mg doses of vitamin K1 im, respectively. In experiment 5, one horse was eliminated from the study, 1 horse was given 300 mg of vitamin K1 iv, and 2 horses were given 300 mg of vitamin K1 subcutaneously (sc); the reversal times were evaluated in the 3 horses given vitamin K1. Therapeutic response time was designated as the time required for the mean pt time of treated horses to reach the midpoint between the longest mean pt time achieved during anticoagulation and the mean base-line pt time.

The therapeutic response time, without supportive therapy, after discontinuation of warfarin administration was 30 hours, and there was a pt reversal time of approximately 5 days from the last dose of warfarin. The 100-mg dose of vitamin K1 shortened the therapeutic response time to 12 hours and the pt reversal time to 24 hours. Intramuscular administration of 300 or 500 mg of vitamin K1 resulted in therapeutic response times of 15 hours and 6 hours, respectively, and pt reversal times of 24 hours each. Administration of vitamin K1 iv or sc resulted in therapeutic response times of 2 hours and 5 hours, respectively, and pt reversal times of 24 hours each. One horse given vitamin K1 developed an adverse drug reaction characterized by transient restlessness, tachypnea, tachycardia, and sweating.

Results of this preliminary study indicated that an antidotal regimen for warfarin-induced anticoagulation in the horse may be sc administration of 300 to 500 mg of vitamin K1 every 4 to 6 hours, until pt times return to an expected base-line value, and then daily monitoring of the base-line stability for 3 to 4 days.
Experimentally induced Brucella abortus infection in pregnant goats
Authors: Meador Vincent P. , Deyoe Billy L.
Published: February 2025

Pregnant goats in midgestation (7 to 16 weeks) were conjunctivally exposed to Brucella abortus strain 2308 to evaluate their applicability as an animal model for bovine brucellosis. Brucellae were isolated from uterine fluid and/or placental specimens of 10 of 12 does at parturition. Six of the 10 infected does delivered dead fetuses and 1 of the 10 delivered live, premature twins. Dead fetuses typically contained brucellae in multiple tissues, whereas brucellae generally were not isolated at birth from live kids. After parturition, B abortus was excreted in the milk and uterine fluids of the infected does. At necropsy (6 weeks after parturition), organisms in the doe were primarily in the uterus and in the lymph nodes that drained the mammary glands, uterus, and head. Brucella abortus was most often isolated from the cranial lymph nodes of neonates that had remained with their dam for 6 weeks after parturition. Serum anti-Brucella antibody concentrations were determined by use of standard tube agglutination, mercaptoethanol agglutination, Rivanol plate tests, card tests, complement fixation, hemolysis-in-gel tests, and an enzyme-linked immunosorbent assay. Serologic responses were detected 2 to 3 weeks after exposure and remained detectable until parturition. Antibody titers increased after parturition in does shedding B abortus at parturition. Anti-Brucella antibody was not detected in neonates before colostrum intake. The neonate’s postcolostral titers were similar to those in the dam at the time of parturition. Milk anti-Brucella antibody was detected in milk (milk ring test) from infected and noninfected mammary glands. Results of the study indicated that goats are susceptible to a bovine pathogenic strain of B abortus and should be a suitable animal model for the study of bovine brucellosis.
Vaccination of cattle against ringworm caused by Trichophyton verrucosum
Authors: Gudding Roar , Naess Bjørn
Published: February 2025

A live-trichophyton vaccine against ringworm in cattle which was based on an attenuated strain of Trichophyton verrucosum was tested in controlled challenge-exposure experiments and in field trials. On the basis of data involving approximately 400,000 vaccinated animals over a 5-year period, it was concluded that trichophytosis in cattle can be controlled by immunoprophylaxis. Side effects associated with the vaccination occur infrequently.
Prekallikrein deficiency in a family of miniature horses
Authors: Turrentine Mark A. , Sculley Paul W. , Green Eleanor M. , Johnson Gary S.
Published: February 2025

Two sibling miniature horses, a male and a female, had a normal 1-stage prothrombin time and a prolonged activated-partial thromboplastin time (aptt). The addition of as little as 5% of a normal equine plasma pool to the plasma samples of both horses shortened their prolonged aptt to within normal limits. Coagulation factor analysis revealed deficiencies in factor XII (12 and 13 U/dl, control population 77 to 128 U/dl), when determined with a feline factor XII-deficient plasma substrate, but normal concentrations (119 and 96 U/dl) when a human factor XII-deficient plasma substrate was used. Deficiencies of another factor, prekallikrein, were detected with a human prekallikrein-deficient plasma substrate (16 and 6 U/dl, control population 70 to 173 U/dl). Other intrinsic coagulation factors were present in normal concentrations. The aptt was measured with plasma from the 2 horses after various incubation periods (1 to 15 minutes) with a contact activator before the addition of Ca ions. With incubation times of ≥ 10 minutes, the aptt of both horses were essentially the same as that of the normal equine plasma pool. Several family members of the 2 prekallikrein-deficient miniature horses appeared to be heterozygous carriers of the prekallikrein deficiency.
Methylprednisolone and gentamicin effects on hepatosplanchnic blood flow and carbohydrate metabolism in endotoxemic Yucatan miniature pigs
Authors: Fettman Martin J. , Hand Michael S. , Chandrasena Lal G. , Cleek James L. , Mason Ruth A. , Brooks Patricia A. , Phillips Robert W.
Published: February 2025

Conjoint therapy of a glucocorticoid and aminoglycoside antibiotic have been recommended for septic shock. These studies examined the hemodynamic and metabolic effects of methylprednisolone sodium succinate (mpss) with and without gentamicin sulfate in a nonanesthetized model of nonseptic endotoxemia in Yucatan miniature pigs. Methylprednisolone sodium succinate alone had no effect on endotoxin-induced systemic hypotension. Endotoxemic pigs treated with mpss in combination with gentamicin sulfate had lower mean arterial pressures than did mpss-treated and nontreated endotoxemic pigs. Methylprednisolone sodium succinate alone and with gentamicin sulfate improved portal and hepatic venous blood flows moderately. Net hepatic lactate extraction, glucose production, and whole body [6-3H]glucose-derived rates of glucose appearance were also improved, but [6-3H]glucose-derived rates of glucose disappearance and blood lactate concentrations were increased, leading to no improvement in plasma glucose concentration. Pancreatic insulin secretion was higher in treated groups, which may have contributed to greater glucose utilization rates. Hepatic oxygen extraction efficiency was not affected by treatment, but increased in all groups to maintain hepatic oxygenation at base-line values. Although a calcium-antagonistic activity of gentamicin has been reported to synergize with endotoxin, thereby adversely affecting cardiovascular function, such effects did not complicate the metabolic response to steroid in the present studies.
Effect of fasting on thyroxine, 3,5,3'-triiodothyronine, and cortisol concentrations in serum of dogs
Authors: Reimers Thomas J. , McGarrity Michael S. , Strickland Daniel
Published: February 2025

The present study was designed to compare basal and stimulated concentrations of 3,5,3'-triiodothyronine (T3), thyroxine (T4), and cortisol in serum of dogs fasted 12 or 18 hours (to represent overnight fasting) or 24 or 36 hours (to represent prolonged inappetence) with those of dogs that were not fasted. Twenty-five adult Beagle bitches were allotted to 5 experimental fasting groups (0, 12, 18, 24, and 36 hours). Blood samples for hormonal analyses were obtained 4, 3, 2, and 1 hour before food was removed; at the time of food removal; 1 hour after food was removed; and every 2 hours during experimental fasting until 0800 hours on the day fasting ended. Dogs were injected with 5 IU of thyrotropin, iv, and 2.2 IU of adrenocorticotropin/kg, im, to evaluate thyroidal and adrenocortical endocrine reserves. Additional blood samples were collected 0.5, 1, 2, 3, and 4 hours after injections were given. Serum concentrations of T3, T4, and cortisol were determined by validated radioimmunoassays. Body weights and ages of the dogs and food consumption during a 2-hour preliminary feeding period before dogs were fasted did not differ among fasting groups. Length of fasting did not affect serum concentrations of T3 or T4 in dogs at 12, 18, 24, or 36 hours after food was removed. Mean serum concentrations of cortisol in dogs fasted 12 or 24 hours were lower than those in dogs that were not fasted. Serum concentrations of the hormones after thyrotropin and adrenocorticotropin were injected were not affected by fasting. We conclude that basal (ie, resting) concentrations of T3, T4, and cortisol in serum of dogs were not affected by fasting for 36 hours. Fasting also did not affect thyroidal and adrenocortical reserves of these hormones.
Radiologic study of the canine urethra
Authors: Poogird W. , Wood A. K. W.
Published: February 2025

The structure and function of the canine urethra were studied during retrograde and voiding urethrography in 9 male and 8 female dogs. The lumen of the prostatic portion of the urethra was variable in diameter. During retrograde urethrography, the lumen was narrow with streaks of contrast medium outlining mucosal folds, but during voiding, it was dilitated and a spindle-shaped seminal hillock was detected. Retrograde urethrography revealed other regions of the urethra of males and females had a smooth radiographic outline. During voiding urethrography, characteristic identical urethral contractions were observed in the caudal portion of the pelvic urethra (male) and in the caudal half of the urethra (female). Contractions were progressive, occurred where striated muscle was present in the urethral wall, and resulted in an intermittent flow of urine from the urethra. In the male, contractions had a rate of 2.02 ± 0.23 contraction/s and 1.65 ± 0.53 in the females. Contractions may have a role in the controlled voiding of small volumes of urine necessary for the repeated marking of territory, in the passage of the ejaculate along the male urethra during copulation, and in the clearance of any residual urine from the urethra at the completion of micturition.
Ketoconazole-induced changes in selected canine hormone concentrations
Authors: Willard M. D. , Nachreiner R. , McDonald R. , Roudebush P.
Published: February 2025

The effects of administering ketoconazole at a high dosage (30 mg/kg of body weight/day) and at a low dosage (10 mg/kg/day) on steroidogenesis in the dog were compared. Ketoconazole significantly suppressed basal plasma cortisol concentrations (P = 0.001), cortisol responsiveness to ACTH (P = 0.002 to 0.005), and serum testosterone concentrations (P = 0.0005). The data indicated a rebound effect after ketoconazole treatment was stopped and that testosterone suppression was being overridden at lower ketoconazole doses. Plasma 17-α-hydroxyprogesterone concentrations (P = 0.0005) and serum progesterone concentrations (P = 0.014 to 0.003) were significantly increased during ketoconazole treatment. Aldosterone, 11-desoxycortisol, and 17-β-estradiol concentrations did not change significantly during ketoconazole treatment.
Use of sodium deoxycholate to extract cell wall components of virulent Mycobacterium bovis
Authors: Hall Michael R. , Thoen Charles O.
Published: February 2025

Mycobacterium bovis ATCC No. 19210 was grown on Middlebrook 7H-10 medium with pyruvate. Cells were harvested, and extracts were prepared, using 2% sodium deoxycholate (doc) and 0.003M EDTA (in 0.1M Tris-HCl, 0.15M NaCl with 0.02% sodium azide [pH 8.4]). Phenylmethylsulfonyl fluoride was added, and the cells were extracted for 48 hours at 4 C. Cells were removed by centrifugation at 10,000 × g for 30 minutes. The supernatant was filter sterilized and separated into 2 fractions (peak A and peak B) by size-exclusion chromatography. The nonfractionated doc extract and doc peak A elicited delayed-type hypersensitivity responses at each of the protein concentrations tested (0.5, 1.5, and 4.5 μg) in M bovis-sensitized guinea pigs; responses were not detected, using doc peak B. Significant differences were detected for each of the antigens when enzyme-linked immunosorbent assay values were compared, using sera from cattle before and 10 months after they were exposed to M bovis (P < 0.01).
Dome epithelial M cells dissociated from rabbit gut-associated lymphoid tissues
Authors: Roy Michael J. , Ruiz Antonio
Published: February 2025

Dome and dome epithelial cells were selectively dissociated from gut-associated lymphoid tissues of rabbits. Sequential tissue washes in dithiothreitol, EDTA, and collagenase removed the dome epithelium, without disrupting the follicles or villi, and provided a cell suspension containing 74 ± 6% lymphocytes, 9 ± 4% columnar epithelial cells, 10 ± 7% tingible-body macrophages, and 4 ± 2% M cells (follicle-associated epithelial cells). The last mentioned cells were characterized by transmission electron microscopy as large (20 to 55 μm diameter) cuboidal, round, or oval cells with eccentric nuclei and thin membranous processes surrounding empty vacuoles. The M cells were occasionally joined together by tight junctions. Histochemical and immunocytochemical analyses of M cells with the light microscope showed that they were devoid of immunoglobulins and negative for T-cell antigen and secretory component and had no detectable alkaline phosphatase or endogenous peroxidase activity. The M cells had few vacuoles with faint acid phosphatase activity; nonspecific neutral esterase was abundant. Possible uses for dome and dome epithelial cells are discussed.
Teratogenic effect of acetohydroxamic acid in clinically normal Beagles
Authors: Bailie Norma C. , Osborne Carl A. , Leininger Joel R. , Fletcher Thomas F. , Johnston Shirley D. , Ogburn Phillip N. , Griffith Donald P.
Published: February 2025

Acetohydroxamic acid (aha), a potent urease inhibitor used for treatment of infection-induced struvite urolithiasis, was teratogenic after administration of 25 mg of aha/kg of body weight/day orally to 5 clinically normal Beagles from the onset of proestrus until parturition.

Thirty pups exposed to aha in utero developed anomalies of the skeletal system, heart, and ventral midline. Cardiac anomalies included atrial septal defects (20%), ventricular septal defects (3%), and atrial and ventricular septal defects (3%). Skeletal anomalies included coccygeal hemivertebrae and fused coccygeal vertebrae (50%), supernumerary vertebrae (67%), supernumerary ribs (50%), duplicated sternebrae (3%), and lumbar hemivertebrae (3%). Defects of the ventral midline of the abdominal wall occurred in 20% of aha-exposed pups. Other abnormalities included retarded growth, high neonatal mortality, and a decreased number of circulating rbc, compared with those in 30 control pups born to 5 Beagles given a placebo.

Adverse effects of aha in pregnant Beagles were limited to morphologic alterations (Howell-Jolly bodies, spherocytes, and target cells) in a small number of circulating rbc. Slight neutrophilic leukocytosis and monocytosis occurred between 0 and 30 days of pregnancy in dogs given aha, compared with those in controls. Seemingly, aha did not influence fertility, conception rate, or length of gestation.