bluuebunny/crossref_metadata_2025 huggingface dataset:
Endotoxin-induced bovine mastitis: Arachidonic acid metabolites in milk and plasma and effect of flunixin meglumine
Authors: Anderson K. L. , Kindahl H. , Smith A. R. , Davis L. E. , Gustafsson B. K.
Published: February 2025

Arachidonic acid metabolites (aam) were measured in milk and plasma during the course of acute endotoxin-induced mastitis in 12 lactating cows. Mastitis was induced by intramammary challenge exposure with 10 μg of Escherichia coli (026:B6) endotoxin. Endotoxin was injected into the teat cistern via the teat canal of a single randomly selected rear quarter of each cow. Concentrations of prostaglandin (pg) F2α and thromboxane (Tx) B2 in fat-free unextracted milk and of 15-keto-13,14-dihydro-pgf2α in plasma were measured by radioimmunoassay. Total production of aam in milk was determined by measuring quarter milk production. The aam were compared in 6 cows administered flunixin meglumine (1.1 mg/kg of body weight) and in 6 cows administered saline solution.

Concentrations of TxB2 in milk were significantly (P < 0.001) increased during the early course of acute mastitis in endotoxin-treated quarters of cows not administered flunixin meglumine. Peak concentrations of TxB2 in milk occurred at 8 hours after endotoxin inoculation. Flunixin meglumine treatment produced significant (P < 0.05) reductions in milk TxB2 and plasma 15-keto-13,14-dihydro-pgf2α concentrations. Concentrations of pgf2α, in milk and total pgf2α and TxB2 production per quarter per milking were not significantly influenced by endotoxin challenge or by flunixin meglumine treatment.
Hemodynamic effects of acute pneumonia experimentally induced in newborn calves inoculated with Pasteurella haemolytica
Authors: Alnoor S. A. , Slocombe R. F. , Derksen F. J. , Robinson Ν. E.
Published: February 2025

Hemodynamic responses to acute pneumonia and to hypoxia were investigated in 10 newborn calves. Experiments were performed on heparinized, anesthesized and ventilated calves. Control calves were inoculated intratracheally with bovine fetal serum. Pneumonia was induced in treated calves by intratracheal inoculation with Ρ haemolytica suspended in bovine fetal serum. Before inoculation (base line), at the time of inoculation (T = 0), and at 30-minute intervals for 3 hours, pulmonary arterial pressure (Ppa), systemic arterial pressure, cardiac output (co), arterial blood gases, pulmonary vascular resistance (pvr), and systemic vascular resistance were determined. At T = 0, calves in both groups became hypoxemic, alveolar-arterial O2 difference, pvr, and Ppa increased, and co and systemic vascular resistance remained unchanged. At subsequent measurement intervals, all values returned to base-line in control calves, whereas treated calves had progressive hypoxemia associated with a decrease in Ppa and pvr, with no change in co. Three hours after inoculation and after inhalation of 10% O2 in N2, pvr increased significantly in the control calves. In the treated group, hypoxia did not increase the resistance, compared with base-line and 3-hour values. The data indicate decreased Ppa during pneumonic pasteurellosis is because of a decrease in pvr and that pneumonia may attenuate the normal pulmonary hypoxic vasoconstrictor response.
Effect of furosemide administration on systemic circulation of ponies during severe exercise
Authors: Manohar Murli
Published: February 2025

Systemic distribution of blood flow was studied in 11 healthy adult grade ponies, using radionuclide-labeled microspheres (15 μm diameter) that were injected into the left ventricle. Measurements were made at rest, during severe exercise (se) without furosemide, as well as during se at 10 minutes and 120 minutes after furosemide administration (1.0 mg/kg, iv). During se, heart rate, cardiac output, mean aortic pressure, and whole body O2 consumption were 220 ± 4 beats/min, 720 ± 44 ml/min/kg, 169 ± 4 mm of Hg, and 126 ± 9 ml of O2/min/kg, respectively. With se performed after furosemide administration, mean aortic pressure decreased from prefurosemide se value (P < 0.05), but heart rate, cardiac output, and whole body O2 consumption remained similar to values during se without furosemide. During se, blood flow to cerebellar gray matter, pons, and medulla oblongata increased despite marked hypocapnia, but in other regions of the brain, blood flow was unchanged. As arterial O2 content increased by 58% with se, O2 delivery to all brain regions increased. With se, adrenal gland blood flow increased, but intense vasoconstriction in the kidneys, spleen, pancreas, small intestine, and colon caused blood flow to plummet. During se, blood flow in the diaphragm, gluteus medius, biceps femoris (muscles of propulsion), and triceps brachii muscles increased to a similar level, indicating that metabolic requirements of the diaphragm during exercise may not be less than those of other vigorously contracting muscles. With se, blood flow in the intercostal muscles also increased markedly, but it remained nearly half of that in the diaphragm (262 ± 23 ml/min/100 g), thereby indicating the dominant role played by the latter in respiration during exertion.

Significant modification(s) of the systemic circulatory response of ponies did not occur during exercise carried out at 10 and 120 minutes after furosemide administration. However, exercise performed 120 minutes after furosemide administration resulted in more intense vasoconstriction in kidneys and spleen.

It is concluded that during se in ponies, blood flow was diverted away from kidneys and splanchnic viscera; the latter responded homogeneously to the stress of exercise. Brain-O2 supply was increased in all regions during exercise in ponies. Furosemide administration in ponies failed to modify the overall circulatory response to se, although the increment in mean aortic pressure was attenuated.
Effect of zearalenone on the fertility of virgin dairy heifers
Authors: Weaver Gary A. , Kurtz Harold J. , Behrens Jerome C. , Robison Thomas S. , Seguin Bradley E. , Bates Fern Y. , Mirocha Chester J.
Published: February 2025

Eighteen cycling, virgin, Holstein heifers daily were given 250 mg of 99% purified zearalenone in a gelatin capsule orally, and 18 controls were given an empty gelatin capsule once a day. The study lasted through 1 nonbreeding estrous cycle and the next 2 consecutive estrous cycles during which the 36 heifers were bred, using artificial insemination. Serum concentrations of progesterone and complete blood cell counts were determined throughout the study.

The treated and control heifers had conception rates of 62% and 87%, respectively. There was no effect (P < 0.05) on the serum concentration of progesterone or the complete blood cell counts. Three heifers, bred but not pregnant by the end of the study, were euthanatized and necropsied. The treated heifer did not have any zearalenone-attributable lesions, and there was no effect seen in the bone marrow smears.

The remaining 33 heifers were sold as a herd, and the 31 pregnant heifers calved normally. There was no effect (P < 0.05) on the sex ratio of the offspring, which were all clinically healthy.

Zearalenone did lower the conception rate of the treated heifers (P < 0.065).
Outer membrane protein antigens of Moraxella bovis
Authors: Ostle A. G. , Rosenbusch R. F.
Published: February 2025

Outer membranes were isolated from bovine isolates and type strains of Moraxella bovis, M phenylpyruvica, M lacunata, and M ovis by sodium N lauroyl sarcosinate extraction and differential centrifugation. Analysis of outer membranes from these organisms by sodium dodecyl sulfate-polyacrylamide-gel electrophoresis revealed that all M bovis isolates shared a common polypeptide pattern that was readily distinguishable from other Moraxella spp. Nine major outer membrane protein bands were identified by sodium dodecyl sulfate-polyacrylamide-gel electrophoresis analysis of M bovis. Immunoblotting of protein antigens of M bovis revealed several outer membrane proteins that seemed to be common antigens of all M bovis isolates.
Electromyographic and urethral pressure evaluations: Assessment of urethral function in female and ovariohysterectomized female cats
Authors: Gregory C. R. , Willits N. H.
Published: February 2025

Urethral pressure and electromyographic evaluations were performed in 10 healthy, intact female cats and in 10 healthy, ovariohysterectomized (ovh) female cats. Mean maximum urethral closure pressure was 71.4 ± 25 cm of water for intact cats and 77.5 ± 31.3 cm of water for ovh cats. Mean maximum pressure of the proximal 60% of the urethral pressure profile length was 39.2 ± 7.4 cm of water for intact cats and 32.1 ± 11.6 cm of water for ovh cats. Mean maximum pressure of the distal 40% of the urethral pressure profile length was 76.2 ± 27.4 cm of water in intact cats and 80.5 ± 32.9 cm of water in ovh cats. Significant differences between intact and ovh cats were not found in mean maximum urethral closure pressure, proximal urethral sphincter pressure, or distal urethral sphincter pressure.
Echocardiography, electrocardiography, and radiography of cats with dilatation cardiomyopathy, hypertrophic cardiomyopathy, and hyperthyroidism
Authors: Moise N. Sydney , Dietze Amy E. , Mezza Lawrence E. , Strickland Daniel , Erb Hollis N. , Edwards N. Joel
Published: February 2025

The echocardiographic, ecg, and radiographic findings of sequentially examined cats with dilatation cardiomyopathy (dcm, n = 7), hypertrophic cardiomyopathy (hcm, n = 8), and hyperthyroidism (ht, n = 20) were compared with those of healthy control cats (n = 11). Cats with dcm were easily differentiated from healthy cats by echocardiography and from cats with hcm and ht by a dilated left ventricle at end-diastole with a mean ± sd of 2.20 ± 0.36 cm, reduced fractional shortening (2.9% ± 3.7%), reduced aortic amplitude (0.07 ± 0.05 cm), reduced left ventricular wall amplitude (0.09 ± 0.09 cm), and increased E-point septal separation (0.83 ± 0.29 cm). The cats with hcm were most consistently recognized echocardiographically by increased left ventricular wall thickness at end-diastole (0.75 ± 0.12 cm). Some cats with ht had abnormal echocardiograms with left ventricular wall hypertrophy. These cats could usually be differentiated from the cats with hcm because of normal or increased ventricular wall amplitude, aortic amplitude, or percentage of thickening of the left ventricular wall and interventricular septum. Left atrial enlargement (left atrial diameter > 1.57 cm or left atrium/aorta > 1.75) was commonly detected by the echocardiogram in cats with dcm, hcm, or ht. The echocardiogram was helpful in differentiating the type of cardiomyopathy (dcm, hcm, or ht) when plain thoracic radiographs indicated that cardiomegaly existed. The ecg may have indicated incorrectly that there was left ventricular enlargement in some cats with ht, and it did not indicate consistently that left ventricular enlargement existed when present in cats with dcm or hcm. The ecg was a poor indicator of left atrial enlargement in all cats.
Echocardiographic, electrocardiographic, and radiographic detection of cardiomegaly in hyperthyroid cats
Authors: Moise N. Sydney , Dietze Amy E.
Published: February 2025

Hyperthyroid cats were examined by electrocardiography, radiography, and echocardiography for the presence of cardiomegaly. These examinations were performed at the time of the initial diagnosis of hyperthyroidism and repeated during the course of antithyroid medication and after thyroidectomy was done. If the hyperthyroid cats had cardiomegaly, reduction in cardiac size was detected once the euthyroid state was reestablished. This decrease in size was appreciated electrocardiographically and radiographically. The echocardiogram demonstrated a decrease in left atrial size. A consistent decrease in left ventricular wall thickness was not observed by the echocardiogram, although 2 cats did have resolution of free wall hypertrophy.
In vitro transformation of lymphocytes from blood and milk of cows with subclinical paratuberculosis
Authors: Elsken Lawrence A. , Nonnecke Brian J.
Published: February 2025

Lymphocytes from blood or milk of 12 cows were evaluated in vitro for the lymphocyte's capability to proliferate in response to mitogens (phytohemagglutinin-A, concanavalin A, and pokeweed mitogen) and to an antigen prepared from Mycobacterium paratuberculosis (purified protein derivative, ppd-j). Responses of 4 control cows were compared with those of 4 cows subclinically infected with M paratuberculosis and with 4 apparently noninfected herdmates.

Blood lymphocytes or milk lymphocytes from control cows had no detectable responses to ppd-j. Blood lymphocytes from infected cows had significant (P < 0.05) responses to ppd-j, but milk lymphocytes from these cows did not. Conversely, milk lymphocytes from apparently noninfected herdmate cows had significant (P < 0.05) responses to ppd-j, but blood lymphocytes from these cows did not.

There were no significant differences in the responses of blood lymphocytes from control, noninfected, or infected cows to the mitogens. However, milk lymphocytes from infected cows had significantly (P < 0.05) lower responses than did lymphocytes from the milk of control or noninfected cows to all mitogens. The decreased responsiveness of milk lymphocytes from cows subclinically infected with M paratuberculosis may indicate that immunocompetency of the mammary gland was altered.
Comparison of the results of card, Rivanol, complement-fixation, and milk ring tests with the isolation rate of Brucella abortus from cattle
Authors: Huber Jan D. , Nicoletti Paul
Published: February 2025

Specimens from 4,553 cows were examined by card, Rivanol, and complement-fixation (cf) tests and bacterio-logic culture. A ring test was performed on milk from 1,003 of these cows. The isolation rate of Brucella abortus correlated directly with antibody titers, and the field strain predominated in adult-vaccinated cows when the Rivanol test titer was > +100 and the cf test titer was > 4 + 40. The cf test had the best balance of sensitivity and specificity in adult-vaccinated cows. The false-negative rate for the Rivanol and cf tests was higher in nonadult-vaccinated cows.
Endometriosis: Clinical and pathologic findings in 70 rhesus monkeys
Authors: Fanton John W. , Hubbard Gene B. , Wood David H.
Published: February 2025

Endometriosis was histologically confirmed in 70 female rhesus monkeys (Macaca mulatto). Severity of endometriosis was staged as minimal (14% of the monkeys), moderate (20%), or massive (66%). Clinical examination indicated masses in the abdomen and/or pelvic cavity palpable abdominally (64% of the monkeys) or rectally (93%), constipation (29%), anorexia (39%), irregular menses (17%), and radiographic evidence of abdominal soft tissue masses (38%). Pathologic findings were of intra-abdominal endometrial cyst formation (73% of the monkeys), and adhesions involving the ureters (51%), colon (66%), urinary bladder (50%), or ovaries (81%). Metastatic growth of endometrial tissue was found in 4 (6%) of the monkeys.
Effects of microbial and host variables on the interaction of rotavirus and Escherichia coli infections in gnotobiotic calves
Authors: Runnels Paul L. , Moon Harley W. , Matthews Peter J. , Whipp Shannon C. , Woode Gerald N.
Published: February 2025

Naturally occurring mixed infections with Escherichia coli and rotavirus have been associated with fatal diarrhea of calves about 1 week old. Experiments were designed to reproduce this syndrome in gnotobiotic calves. Clinical, microbiological, and pathologic data were used to assess severity of disease and mechanisms of the interaction between the 2 infections. An initial study involved 5- to 8-day-old gnotobiotic calves inoculated with a strain of enterotoxigenic E coli (etec) and a strain of rotavirus. Calves were observed for 2 days after they were inoculated; fatal diarrhea was not produced.

In later studies, variables were tested to identify those that might contribute to fatal diarrhea. Variables which did not result in fatal or severe diarrhea or which did not cause disease that was more severe in dually inoculated calves than that in monoinoculated calves were (i) increasing feed to 2 times base line, (ii) increasing dose of etec to 10 times base line, (iii) inoculating calves when they were 2 days old, (iv) using a strain of E coli that causes colisepticemia, and (v) using a different strain of rotavirus. When the observation period was extended from 2 days to 6 days after calves were inoculated, severe, watery, fatal diarrhea occurred in 6 of 12 calves by 32 to 72 hours after dual inoculation was given. Fatal diarrhea was associated with intensive colonization by the etec in the caudal half of the small intestine. Microscopic lesions were similar between dually inoculated and rotavirus-monoinoculated calves, except there was more severe atrophy of ileal villi of dually inoculated calves. Fatal diarrhea, intensive bacterial colonization, and severe villus atrophy in dually infected calves indicated that there was synergistic interaction of the 2 infections. Inherent (presumably genetic) variation among calves may account for the inconsistent demonstration of the synergistic interaction.
Dermatopathology and immunity in experimental Psoroptes ovis (Acari: Psoroptidae) infestation of naive and previously exposed Hereford cattle
Authors: Stromberg Paul C. , Fisher William F.
Published: February 2025

Naive and previously exposed young Hereford cattle were infested with Psoroptes ovis and maintained in stanchions for 7 weeks. Skin biopsy samples were examined at 1, 2, 5, and 7 weeks after infestation was induced, compared with those from noninfested control calves, and correlated with changes in the mite populations and development of dermatitis Gross and microscopic appearance of lesions were qualitatively simlar in both groups of infested calves. The lesions occurred early in the previously exposed calves, but progressed slowly, whereas lesions in the naive calves appeared later, but were rapidly progressive. The basic histopathologic pattern was chronic exudative superficial perivascular dermatitis compatible with allergy. The mite populations on the naive calves revealed exponential growth and high fecundity, and reached high population densities, whereas mite populations on previously exposed calves had low growth rates and low fecundity and reached population densities 100 to 1,000 times less than those on naive calves. Seemingly, there was a hypersensitivity to mite antigens. The hypersensitivity response may have been a mechanism by which humoral immunity was delivered to the mite microenvironment and may have contributed to acquired resistance by controlling mite populations. The mechanism of population control seems to be related partially to decreased fecundity of female P ovis.
Dobutamine-induced augmentation of cardiac output does not enhance respiratory gas exchange in anesthetized recumbent healthy horses
Authors: Swanson Clifford R. , Muir William W.
Published: February 2025

The influence of pharmacologic enhancement of cardiac output on the alveolar-to-arterial oxygen tension (difference (P[A-a]O2), physiologic right-to-left shunt fraction (Q̇s/Q̇t), and physiologic dead space-to-tidal volume ratio (VD/VT) was studied in halothane-anesthetized horses in left lateral, right lateral, and dorsal recumbencies. Adult horses were anesthetized, using xylazine (2.2 mg/kg, im), guaifenesin (50 mg/kg, iv), thiamylal (4.4 mg/kg, iv), and halothane (1.5% to 2% inspired) in 100% O2. Mechanical ventilation was controlled to maintain arterial eucapnia (PaCO2) 35 to 45 mm of Hg) for a period lasting at least 1 hour. Dobutamine was administered at dosages of 1, 3, and 5 μg/kg/min, iv, on a randomized basis. The P(A-a)O2, Q̇s/Q̇t, and VD/VT were calculated during equilibration and after each dobutamine infusion was given. The P(A-a)O2 and Q̇s/Q̇t were significantly (P < 0.05) greater and Vq/Vt tended to be greater in horses in dorsal recumbency, compared with those values in horses in left lateral or right lateral recumbency. Cardiac output was similar in all horses, regardless of body position (recumbency). The qualitative relationships between horses in the 3 recumbent positions were not altered by dobutamine. Cardiac output was significantly (P < 0.05) increased by 3 or 5 μg of dobutamine/kg/min in all horses, whereas P(A-a)O2, Q̇s/Q̇t, and VD/VT were not significantly altered by dobutamine. The results of the present study failed to substantiate pur clinical observations of decreased P(A-a)O2 and Q̇s/Q̇t in anesthetized compromised horses given dobutamine.
Effects of isobutyl-2-cyanoacrylate on bone healing
Authors: Hampel Nancy L. , Pijanowski Gerald J. , Johnson Richard G.
Published: February 2025

An in vivo evaluation of isobutyl-2-cyanoacrylate as an osseous adhesive was performed to determine its effect on bone healing. Oblique cortical fractures were induced at the tibial-fibular junctions of adult rabbits. Forty-eight fractures were repaired by the use of isobutyl-2-cyanoacrylate and a full cerclage wire. The opposite control frac-ture was repaired with a full cerclage wire only. One hundred percent of the glued fractures were not united through the glue interface, although normal periosteal new bone formation (secondary bone healing) took place around the glue. One hundred percent of the nonglued fractures healed by secondary bone union. Reactions were not seen in the bone or soft tissue adjacent to the adhesive material.
Efficacy of injectable ivermectin against natural infections of Stephanurus dentatus in swine
Authors: Becker H. Neil
Published: February 2025

Ivermectin (300 μg/kg of body weight) was given to swine subcutaneously in the neck to test its efficacy against the kidney worm, Stephanurus dentatus. Two separate field trials were conducted using 146 swine (40 males and 106 females). Urine was obtained before and after treatment and was examined for presence of S dentatus eggs. Stephanurus dentatus eggs were quantitated in positive samples. All treated swine positive for S dentatus eggs in the pretreatment urine samples (n = 54) were negative by 14 to 21 days after treatment with ivermectin. Adverse reactions caused by ivermectin injection were not noticed.
Research needs and priorities for avian internal parasites in the United States
Authors: _ _
Published: February 2025

The importance of parasitic infections to the poultry industry has been well documented. The introduction of large scale confinement rearing techniques have decreased the variety of parasitic diseases, but have increased vheir frequency and economic impact. Coccidiosis and helminthiasis are the two most important parasitic diseases, although diseases such as histoplasmosis and leukocytozoonosis have the potential to become serious in certain geographic areas.

Much of the research effort has been directed at the development of new anticoccidial drugs. However, drug resistance is an increasing problem, and there is a need to develop vaccines, at least for the control of coccidiosis. A better understanding of the biologic aspects of parasitic infections, including the host response, would allow for coordinated control programs involving diagnosis, management, treatment, and immunization. Specific recommendations are made for research objectives with immediate and long-range application.
Toxic and protective constituents in pet foods
Authors: Mumma Ralph O. , Rashid Kamal A. , Shane Barbara S. , Scarlett-Kranz Janet M. , Hotchkiss Joseph H. , Eckerlin Richard H. , Maylin George A. , Lee Chang Y. , Rutzke Michael , Gutenmann Walter H. , Bache Carl A. , Lisk Donald J.
Published: February 2025

An analytical survey of mutagens, nitrosamines, polychlorinated biphenyls, toxic elements, and γ-emission, as well as the toxicologically protective constituents zinc, selenium, and vitamin C, in 48 pet foods was conducted. Aside from high concentrations of fluoride and iodide in some samples and the expectedly higher concentrations of mercury and selenium in certain cat foods containing fish, the samples were notably free of the other toxic constituents. Direct-acting and promutagens and nitrosamines were not detectable in any of the samples, γ-Emission was very low in all of the foods. Polychlorinated biphenyls were only detected in one cat food.
Percutaneous infection of nymphal Dermacentor andersoni with Anaplasma marginale
Authors: Kocan Katherine M. , Wickwire Kathie B. , Hair Jakie A. , Ewing S. A. , Barron Selwyn J.
Published: February 2025

Newly replete nymphal Dermacentor andersoni (principals) were percutaneously exposed to Anaplasma marginale by injection of either intact or lysed infected bovine erythrocytes. Control nymphs were fed on calves with anaplasmosis. The subsequently molted adults were examined for infection by light microscopy, and companion ticks were tested for infectivity by allowing them to feed on susceptible calves. When they fed as adults, both control ticks and percutaneously inoculated principals transmitted A marginale to susceptible calves. Prepatent periods in calves varied according to the method by which nymphs were infected. Colonies of A marginale were found in all ticks that acquired infection by feeding, but colonies were not observed in any ticks exposed percutaneously. The possible developmental cycle of A marginale in artificially infected ticks is discussed.
Evaluation of decoquinate, lasalocid, and monensin against experimentally induced sarcocystosis in calves
Authors: Foreyt William J.
Published: February 2025

Effects of decoquinate, lasalocid, and monensin against experimentally induced sarcocystosis (Sarcocystis bovicanis) were evaluated in 12 calves, 3 of which were inoculated, nontreated controls. Three additional calves were noninoculated, nontreated controls. Drugs were administered in the feed (33 mg/kg of feed) of the treated calves (3 calves/group) for 87 days. Eight of the 12 inoculated calves died from acute sarcocystosis during the experiment (the 3 inoculated, nontreated controls, the 3 calves given decoquinate, and 2 of the 3 calves given lasalocid). Large numbers of sarcocysts were found in tissues from inoculated calves that survived in the experiment (1 of the 3 calves given lasalocid and the 3 calves given monensin). Although large numbers of sarcocysts developed in the muscles of monensin-treated calves, monensin may have an ameliorating effect on acute sarcocystosis.
Strongylid parasites of horses: Experimental ecology of the free-living stages on the canadian prairie
Authors: Polley Lydden
Published: February 2025

Each month for a 1-year period (October through September), equine fecal masses containing eggs of strongylid nematodes were placed outdoors on small grass plots in Saskatchewan, Canada. Thereafter, feces and grass from the plots were sampled after intervals of 1 week or longer, and the strongylid eggs and larvae recovered were counted. These observations were made over a 2-year period. Development of eggs to infective larvae occurred in all experiments, except those established in October, December, and January. Infective larvae from experiments set up in April through September survived that winter. During the summer, there was a gradual build up of infective larvae in the fecal masses, which reached a peak in August and September and then decreased into the winter. These results are discussed in the context of the control of strongylid parasites of horses on the Canadian prairie and in other areas of the world with a similar climate and similar horse management practices.
Isolation of leptospires from the genital tracts of Iowa cows
Authors: Ellis William A. , Thiermann Alex B.
Published: February 2025

Leptospira interrogans serovar hardjo was recovered from 5 of 11 nonpregnant cows chosen at random from an Iowa slaughterhouse. Isolations were made from the kidney in each instance, the genital tract of 3 cows: uterus from 1 cow, oviduct of another, and oviduct and uterus of a 3rd cow.
Pharmacokinetics of metronidazole given to horses by intravenous and oral routes
Authors: Sweeney R. W. , Sweeney C. R. , Soma L. R. , Woodward C. B. , Charlton C. A.
Published: February 2025

Serum and peritoneal fluid concentrations of metronidazole were determined in 6 healthy adult horses given the drug (25 mg/kg) by iv or oral routes.

The disposition of metronidazole in horses given the drug by the iv route conformed to a 2-compartment model with a distribution half-life of 0.16 hours, an elimination half-life of 2.9 hours, and a body clearance of 0.40 ± 0.05 L/kg/hr. The oral absorption half-life was 0.40 hours, and the bioavailability, 85.0 ± 18.6%. Peritoneal fluid concentrations were approximately equal to serum concentrations at all times, regardless of the route of administration.

On the basis of reported minimal inhibitory concentrations for anaerobic bacteria, a dosage of 15 to 25 mg/kg given orally 4 times daily was recommended.
Pharmacokinetics and body fluid and endometrial concentrations of cefoxitin in mares
Authors: Brown Murray P. , Gronwall Ronald R. , Houston A. E.
Published: February 2025

Four healthy adult mares were each given a single injection of sodium cefoxitin (20 mg/kg of body weight, iv), and serum cefoxitin concentrations were measured serially during a 6-hour period. The mean elimination rate constant was 1.08/hour and the elimination half-life was 0.82 hour. The apparent volume of distribution (at steady state) and the clearance of the drug were estimated at 0.12 L/kg and 259 ml/hr/kg, respectively. Each mare and 2 additional mares were then given 4 consecutive im injections of sodium cefoxitin (400 mg/ml) at a dosage of 20 mg/kg. Cefoxitin concentrations in serum, synovial fluid, peritoneal fluid, csf, urine, and endometrium were measured serially. After im administration, the highest mean serum concentration was 23.1 μg/ml 30 minutes after the 2nd injection. The highest mean synovial concentration was 11.4 μg/ml 1 hour after the 4th injection. The highest mean peritoneal concentration was 10.4 μg/ml 2 hours after the 4th injection. The highest mean endometrial concentration was 4.5 μg/g 4 hours after the 4th injection. Mean urine concentrations reached 11,645 μg/ml. Cefoxitin did not readily penetrate the csf. Bpavailability of cefoxitin given im was 65% to 89% (mean ± sem = 77% ± 5.9%). One of the 6 mares developed acute laminitis during the im experiment.
Effect of cimetidine on aspirin-induced gastric hemorrhage in dogs
Authors: Boulay James P. , Lipowitz Alan J. , Klausner Jeffrey S.
Published: February 2025

Efficacy of cimetidine in the prevention of aspirin-induced gastric hemorrhage was evaluated, using 4 groups of 6 dogs given: Group 1—controls; group 2—7.5 mg of cimetidine/kg of body weight every 8 hours; group 3—7.5 mg of cimetidine/kg every 8 hours and 35 mg of nonbuffered aspirin/kg every 8 hours; and group 4—35 mg of nonbuffered aspirin/kg every 8 hours. All medication was given orally for 10 days at the time of feeding a commercial dry food. The gastric mucosa was evaluated endoscopically before treatment, on treatment day 5, and 36 hours after the final treatment. The dogs were given halothane inhalation anesthesia and were evaluated, using a grading system. Total 24-hour fecal hemoglobin (Hb) concentration was measured, using a quantitative fluorometric analysis for Hb-derived porphyrins.

Control dogs and dogs given cimetidine only had no endoscopically visible gastric lesions and no increase in fecal Hb concentration. All dogs given aspirin or aspirin and cimetidine had a similar marked increase in endoscopically visible gastric hemorrhage and marked increases in fecal Hb concentration; however, there was no significant (P = 0.48) difference between the 2 groups. Seemingly, cimetidine given at an oral dosage of 7.5 mg/ kg every 8 hours was not effective in preventing aspirin-induced gastric hemorrhage in clinically normal dogs.
Interrelationships among liposoluble vitamins in ruminants
Authors: Hidiroglou M. , Williams C. J.
Published: February 2025

Plasma concentrations of vitamins A and E were examined in sheep, and a transitory decrease was observed after a single massive dose of vitamin D3 (5 × 106 IU) was administered orally or parenterally. Administration of a large dose of vitamin E to sheep decreased plasma retinol concentrations within 72 hours, but thereafter, the plasma retinol concentrations returned to near baseline values. Oral administration of a single pharmacologic dose of dl-α-tocopherol (5 g) to sheep caused a slow increase of this vitamin in the blood plasma. In cattle, a single im administration of 3 liposoluble vitamins (A, D3, and E) at acceptable concentrations had no detectable influence on plasma α-tocopherol concentrations with the sampling intervals used. Plasma concentrations of α-tocopherol in these cattle showed a marked seasonal pattern; the concentrations increased from January to a peak in July, with a subsequent decrease in the fall. Also reported are estimates of inter- and intraindividual variation in plasma liposoluble vitamin concentrations.
Density-gradient sedimentation of feline bone marrow cells with polyvinyl-pyrrolidone-coated silica gel
Authors: Stiff Mary I. , Kociba Gary J. , Olsen Richard G.
Published: February 2025

Feline bone marrow cells were separated based on their density distribution in a continuous polyvinyl-pyrrolidone-coated silica gel density gradient. Morphologic identification of cytocentrifuged preparations at specific densities revealed a progressive increase in density with maturation of the cells within the granulocytic and erythroid series. Segmented eosinophils peaked at 1.084 g/ml, monocytes at 1.07 g/ml, and lymphocytes spanned the density of 1.068 to 1.084 g/ml. Bone marrow samples from 6 healthy specific-pathogen-free cats were separated by the continuous polyvinyl-pyrrolidone-coated silica gel gradient and were studied for progenitor colony formation in methylcellulose. Erythroid colony formation was greatest at a density of 1.084 g/ml and also appeared in cells from g cats at a lighter density of 1.016 to 1.05 g ml. Colony formation in the granulocytic series revealed progenitors throughout the gradient with enrichment at 1.055 g/ml.
Neutralization of African swine fever virus by sera from African swine fever-resistant pigs
Authors: Gonzalvo F. Ruiz , Caballero C. , Martinez J. , Carnero M.E.
Published: February 2025

Sera from African swine fever-resistant pigs with infection-inhibitory activity decreased virus replication in infected porcine huffy coat cultures. This same effect was observed even after virus was adsorbed. The infection-inhibition was not reversed by removing the immune serum from the assay cultures. Reduction of African swine fever virus replication by immune sera was demonstrated by fluorescent focus assay on MS cell line cultures. Virus-neutralization tests showed a persistent fraction of nonneutralized virus, which was not demonstrable by infection-inhibition tests. One hypothesis for explaining this difference is proposed.
Mortality in swine herds endemically infected with Haemophilus pleuropneumoniae: Effect of immunization with cross-reacting lipopolysaccharide core antigens of Escherichia coli
Authors: Fenwick B. W. , Osburn B. I. , Cullor J. S. , Henry S. C. , Olander H. I.
Published: February 2025

The benefit of increased immunity to cross-reacting lipopolysaccharide core antigens of gram-negative bacteria induced by vaccination with an Rc mutant of Escherichia coli 0111:B4 (strain J5) was evaluated in commercial swine herds endemically infected with Haemophilus pleuropneumoniae. Weanling pigs were vaccinated im with E coli J5 (group 1) before the expected time of H pleuropneumoniae infection. Clinical signs, antibiotic treatment frequency, mortality, growth performance (days to market weight), and serologic responses of the pigs were monitored for approximately 5 months after vaccination. The results were compared with those of pigs vaccinated im with a commercial H pleuropneumoniae bacterin (group 2) and with those of nonvaccinated control pigs of the same age (group 3). The treatment frequency and growth performance were similar in the 3 groups. However, vaccination with E coli J5 or with the H pleuropneumoniae bacterin lowered mortality, compared with mortality in the controls. Serum titers against E coli J5 increased after vaccination with the E coli J5 bacterin, but were not increased by vaccination with the H pleuropneumoniae. In contrast, serum titer to E coli J5 increased in all treatment groups as a result of H pleuropneumoniae infection or exposure. The protection against lethal H pleuropneumoniae infections in swine that was provided by vaccination with the E coli J5 and the H pleuropneumoniae bacterin appeared to be immunologically distinct on the basis of serologic analysis, indicating the possibility of different mechanisms of protection.
Antiviral effectiveness of butylated hydroxytoluene against pseudorabies (Aujeszky's disease) virus in cell culture, mice, and swine
Authors: Pirtle Eugene C. , Sacks Jerome M. , Nachman Ronald J.
Published: February 2025

Butylated hydroxytoluene (bht) was evaluated for antiviral effectiveness on pseudorabies virus (prv) in cell culture, mice, and swine. When relatively small amounts of bht were mixed with prv and incubated at 37 C for 30 or 60 minutes before inoculation into cell cultures, the cell cultures did not become infected with virus. The prv was not infectious when the virus was treated with bht and then inoculated intraperitoneally into mice, but was infectious when bht and prv were inoculated simultaneously or when bht was inoculated either 30 or 60 minutes before prv. Swine fed bht-medicated feed for 10 days before they were intranasally exposed with virulent prv did not have overt signs of pseudorabies, had a lower concentration of prv in nasal mucus than did control swine, and had acceptable blood enzyme and cholesterol concentrations during the experiment. The bht was detected in tissues of 2 swine after they were fed bht-medicated feed for 10 days, and higher concentrations of bht were detected in tissues of 3 swine given bht feed for 29 days.
Study of porcine postweaning diarrhea involving K88(−) hemolytic Escherichia coli
Authors: Hoblet K. H. , Kohler E. M. , Saif L. J. , Theil K. W. , Ingalls W. L.
Published: February 2025

The onset of fecal shedding, serogroup involvement, and association of hemolytic Escherichia coli with the postweaning diarrhea syndrome were studied in swine. The only E coli O antigen, detected by slide agglutination with the antisera used, was 0157; K antigens were not detected. The ligated intestinal loop test (lilt) was used for enterotoxigenicity testing. All 0157 serogroup isolates (n = 9) were hemolytic, and 89% (8 of 9) were lilt positive. Of all hemolytic isolates tested, 59% (10 of 17) were lilt positive. Twenty-seven nonhemolytic isolates were tested for enterotoxigenicity; of these, 45% (12) were lilt positive. The onset of postweaning diarrhea coincided with the modal onset of hemolytic E coli shedding at postweaning day 7. At postweaning day 7, hemolytic E coli shedding was concurrently associated with diarrhea (P < 0.0005), whereas later during the postweaning period, this was not the situation.
Prevalence of Histophilus ovis and Actinobacillus seminis in the genital tract of sheep
Authors: Walker Richard L. , LeaMaster Brad R.
Published: February 2025

Histophilus ovis and Actinobacillus seminis were isolated from the preputial cavity of 6-month-old rams and the vagina of 6-month-old ewes at a substantially higher rate than that in mature (> 2 years old) rams and ewes. These organisms appeared to be a transitory component of the ovine genital flora, the prevalence of which was associated with age regardless of gender.

Additional evaluation of the recoverability of H ovis and A seminis from the preputial cavity of rams from birth to 1 year of age indicated that the isolation rate from rams and predominance of the organisms in the preputial cavity differed greatly over this age period. These organisms were not recoverable until ram lambs were 12 weeks of age and were most prevalent at 20 weeks of age, after which recoverability of H ovis and A seminis from the preputial cavity steadily decreased, continuing through the time of the last evaluation at 1 year of age. The time period with which these organisms can be isolated from the preputial cavity is closely correlated with the time period when epididymitis associated with these organisms develops, and may be an important factor in the pathogenesis of epididymitis.
Responses of horses vaccinated with avirulent modified-live equine arteritis virus propagated in the E. Derm (NBL-6) cell line to nasal inoculation with virulent virus
Authors: McCollum William H.
Published: February 2025

Nineteen horses with no prior experience with equine arteritis virus (eav) were inoculated im with an avirulent live-virus vaccine against equine viral arteritis; the vaccinal virus had been passaged serially 131 times in primary cell cultures of equine kidney, 111 times in primary cell cultures of rabbit kidney, and 16 times in an equine dermis cell line (eav HK-131/RK-111/ED-16). Three or 4 of the vaccinated horses each, along with appropriate nonvaccinated controls, were inoculated nasally with virulent eav at each of months 3, 6, 9, 12, 18, and 24 after they were vaccinated. The following was concluded:

(1)

Vaccination did not induce clinical signs of disease in any horse and, thus, seemed safe for use in the field.

(2)

All vaccinated horses (n = 19) developed serum-neutralizing antibodies to eav.

(3)

Fourteen of the vaccinated horses were completely protected from clinical arteritis when exposed to large doses of virulent eav. Four were partially protected, and one had little or no protection. Six of 13 nonvaccinated horses died of acute arteritis, and the remaining 7 horses experienced severe signs of disease, but survived the infection.

(4)

All horses (n = 32), whether vaccinated or not, became infected when inoculated nasally with virulent eav. Virus was recovered from 17 of the 19 vaccinated horses, and all 19 had a secondary humoral immune response. The duration and severity of thermal reaction and persistence of virus were more transitory in vaccinated horses than in the nonvaccinated controls.

(5)

Protection afforded by this vaccine can persist for at least 24 months, the maximal time after horses were vaccinated that immunity was challenged in the present study.

(6)

The more pronounced clinical and virologic responses which were seen among horses given the vaccine eav HK-131/RK-111/ED-16 and subsequently inoculated with virulent eav, when compared with the responses in horses given the vaccine eav HK-131/RK-80 or HK-131/RK-111, indicated that vaccine eav HK-131/RK-111/ED-16 had become more attenuated as a result of the further serial passage in the equine dermis cell line.
Immunohistochemical staining patterns of canine eyes affected with chronic superficial keratitis
Authors: Eichenbaum J. D. , Lavach J. D. , Gould D. H. , Severin G. A. , Paulsen M. E. , Jones R. L.
Published: February 2025

Fourteen limbal biopsy specimens from 11 dogs with chronic superficial keratitis (csk) were examined histologically and immunohistochemically. Ten of the 14 specimens had corneal epithelial hyperplasia and/or atrophy. Eleven of the 14 specimens had thickened epithelial basement membranes. Each specimen had cellular infiltration and lamellar disruption of the stroma.

An avidin-biotin immunoperoxidase complex stain was used to detect immunoglobulin (Ig) deposition. Twelve of the 14 specimens stained positive for Ig. The staining pattern was consistent and characterized by diffuse deposition of stain in the superficial conjunctival stroma near the limbus. Four of the 12 Ig-positive specimens also stained positive in the superficial corneal stroma with 1 of these 4 also staining positive along the epithelial cell basement membrane.

The diffuse pattern of stain deposition and the absence of staining of specific epithelial structures indicated that csk is not a classical autoimmune disease similar to any disease in the pemphigus group or similar to systemic lupus erythematosus. Although the results may implicate csk as an immune-mediated disease, nonspecific factors could not be ruled out.
Immunotoxic effects of T-2 toxin on cell-mediated immunity to listeriosis in mice: Comparison with cyclophosphamide
Authors: Cornier Donald E. , Ziprin Richard L.
Published: February 2025

Immunotoxic effects of T-2 toxin and cyclophosphamide on cell-mediated resistance were evaluated in mice exposed to Listeria monocytogenes infection. Mice were inoculated intraperitoneally with 4.0 × 105 (ld50) or 4.0 × 104 (nonlethal) L monocytogenes and were treated with 4.0 mg of T-2 toxin/kg of body weight or 180 mg of cyclophosphamide/kg. The immunosuppressive effect of the toxin and cyclophosphamide was indicated by the rapid growth of Listeria and significant (P < 0.005) increases in mortality because of listeriosis. Necrosis and depletion of lymphoid tissue, lymphopenia, and significant (P < 0.005) decreases in the influx and number of lymphocytes and macrophages occurred in Listeria-elicited peritoneal exudates and at sites of infection in the liver and spleen of the toxin- and cyclophosphamide-treated mice. Immunotoxic effects of T-2 toxin and cyclophosphamide were comparable and attributed primarily to the depletion of T lymphocytes and the subsequent failure of surviving immunologically committed T cells and T-cell dependent immune-activated macrophages to clear the host of bacteria.
Effects of estrone infusion on secretion of F series prostaglandins and on function of the corpus luteum during late gestation in cattle
Authors: Pimentel C. A. , Vijayakumar R. , Weston P. G. , Pimentel S. M. , Wagner W. C. , Hixon J. E.
Published: February 2025

Catheters were surgically implanted in the carotid artery, jugular vein, and middle uterine vein of 8 cows at 245 days of gestation. Four cows were given 4 mg of estrone/hour via continuous jugular infusion from 0800 hours on day 246 of gestation through 0800 hours on day 250 of gestation; the remaining 4 cows (controls) were given the vehicle for estrone at 10 ml/hour for the same period. Blood samples were collected from the carotid artery every 3 hours during the infusion. Samples were collected hourly from the middle uterine vein from 0 through 8, 54 through 66, and 112 through 120 hours of the infusion periods. After completion of the infusion, corpora lutea were enucleated and blood samples were collected from the carotid artery and uterine vein at hourly intervals for an additional 8 hours. Dispersed cell preparations of the corpora lutea were incubated with and without luteinizing hormone (lh) or dibutyryl cyclic adenosine monophosphate (dbcAMP).

Circulating concentrations of unconjugated and conjugated estrone and estradiol-17β were higher (P < 0.05) in the group infused with estrone than in the vehicle-infused group. Mean and base-line concentrations of F series prostaglandins (pgf) for each blood collection period tended to increase (P < 0.10) during infusion with estrone, but not during infusion with vehicle. After luteectomy, mean and base-line concentrations of pgf also tended (P < 0.10) to be greater in the estrone-infused cows than in the control cows, but a surge in pgf concentrations due to removal of the ovarian source of progesterone did not develop. Long intervals (14 to 16 days) between enucleation of corpora lutea and calving and a more rapid (P < 0.05) rate of decrease in progesterone concentrations in the systemic arterial circulation than in the uterine venous circulation after luteectomy indicated that the placenta may have secreted progesterone during the course of the study.

Corpus luteum weight and systemic and luteal concentrations of progesterone were not affected by infusions with estrone. Although the addition of lh or dbcAMP did increase the synthesis rate of progesterone by incubated luteal cells from 2 cows in each group, the response of luteal cells to lh or dbcAMP was not different between the groups. Secretory pulses of pgf were detected, but estrone treatment did not affect their frequency.