bluuebunny/crossref_metadata_2025 huggingface dataset:
Virulence factors of Escherichia coli isolated from cows with acute mastitis
Authors: Sanchez-Carlo Vanessa , McDonald J. S. , Packer R. A.
Published: February 2025

A total of 184 Escherichia coli isolates recovered from cows with acute mastitis were examined for recognized pathogenic mechanisms and virulence factors commonly found in pathogenic groups of E coli. A modification of the Eng procedure (for detecting complement deficiencies in serum) was used to test for resistance to different animal sera. The Sereny test (for invasiveness), infant mouse test (for heat-stable enterotoxin), and Y-1 adrenal tumor cell assay (for heat-labile enterotoxin) were used. Hemagglutination tests, using rabbit, sheep, and guinea pig rbc, were done with and without added mannose.

All of the 184 isolates were serum resistant in all tested sera. None of the isolates was invasive. Only 1 isolate was positive for heat-stable enterotoxin and 2 cultures were positive for heat-labile enterotoxin. Multiple patterns of hemagglutination were observed. The majority of the isolates exhibited both mannose-sensitive and mannose-resistant hemagglutinins with guinea pig and rabbit rbc. A few strains were positive only in mannose-sensitive or mannose-resistant hemagglutination tests. A few strains were negative in all hemagglutination tests. Based on our results, E coli from cows with acute mastitis lack the virulence factors commonly observed in other E coli groups associated with disease. Serum resistance was the only characteristic that could be related to virulence.
Effect of dietary niacin supplementation on phlorhizin and 1,3-butanediol-induced ketonemia and hypoglycemia in steers
Authors: Dufva G. S. , Bartley E. E. , Nagaraja T. G. , Dayton A. D. , Frey R. A.
Published: February 2025

1,3-Butanediol and phlorhizin were used to induce ketonemia and hypoglycemia in steers. Oral administration of butanediol increased blood β-hydroxybutyrate (bhb) and plasma nonesterified fatty acids (nefa) and decreased serum glucose. Subcutaneous injections of phlorhizin, given in addition to butanediol orally, further increased nefa and bhb concentrations and decreased glucose. Dietary niacin supplementation of steers given phlorhizin and butane diol caused serum glucose concentration to increase and blood bhb and plasma nefa concentrations to decrease.
Mycoplasma hyopneumoniae infection in pigs immunosuppressed by thymectomy and treatment with antithymocyte serum
Authors: Tajima M. , Yagihashi T. , Nunoya T. , Takeuchi A. , Ohashi F.
Published: February 2025

The effect of immunosuppression on Mycoplasma hyopneumoniae infection was evaluated by comparing data from infected, thymectomized, and antithymocyte serum-treated pigs (group 1) with data from infected (group 2) and noninfected (group 3) healthy pigs. After groups 1 and 2 pigs were inoculated intranasally with M hyopneumoniae, mycoplasmas tended to multiply slightly more in the lungs and bronchial lymph nodes of group 1 pigs than that of group 2 pigs. Organisms were also isolated from the spleen of 1 of 3 group 1 pigs. Pneumonia developed in group 2 pigs and was characterized by massive peribronchial, peribronchiolar, and perivascular lymphoid hyperplasia and exudate consisting mainly of polymorphonuclear leukocytes in the alveoli and lumina of the bronchioles and bronchi. In group 1 pigs, perivascular and peribronchiolar cuffings by lymphocytes were less prominent, and the extent of intraluminal exudate was severe and widespread. Bronchial lymph nodes from group 2 pigs had marked hyperplasia of germinal centers and paracortical areas. In group 1 pigs, germinal centers were hyperplastic, whereas in the paracortical areas, depletion of lymphocytes was evident. Seemingly, cell-mediated immune mechanisms are important in the development of pneumonic lesions in enzootic pneumonia of pigs.
Distribution of innervation and circulation in porcine cervical trachea
Authors: Munoz Nilda M. , Cera Lee M. , Leff Alan R.
Published: February 2025

The circulation and innervation to porcine cervical trachea were studied in 54 animals in situ. The antemortem response of porcine tracheal muscle was measured isometrically during selective injection of acetylcholine into the cranial thyroid arterial circulation. A predominantly unilateral (70.4%), rather than bilateral (3.7%), arterial circulation was identified; a cranial thyriod artery was not demonstrated in 25.9% of swine, suggesting dominant perfusion from the caudal thyroid circulation. After animals were killed, dye injection through the dominant cranial thyroid trunk demonstrated homogeneous perfusion of the muscle in all instances. In 20 of these animals, the distribution of parasympathetic innervation to porcine tracheal muscle was studied by selective electrical stimulation of the vagus nerves in situ. Tracheal smooth muscle response was measured isometrically, using settings (20 v, 20 Hz) causing maximal contractile force. Bilateral electrical stimulation caused active tracheal tension of 23.2 ± 1.9 g/cm. Unilateral stimulation of the left vagus nerve caused 17.8 ± 1.5 g/cm contraction, which was significantly greater than the response caused by selective stimulation of the right vagus nerve (12.1 ± 1,6 g/cm; P < 0.001). Innervation to porcine cervical trachea, although bilateral, is derived predominantly from the left vagus nerve; circulation is derived almost always from the left cranial thyroid artery.
Effects of aflatoxin M1 intake at physiologic levels on newborn dairy calves
Authors: van Dijk H. J. , O'Dell G. D. , Bodine A. B.
Published: February 2025

When aflatoxin-contaminated grain is consumed by dairy cows, aflatoxin M1 is excreted in the milk. Sixteen neonatal male Holstein calves were given milk which had been collected from cows given 5 to 6 mg of aflatoxin B1 each day. The calves were examined for possible detrimental effects of the mycotoxin at pseudophysiologic concentrations. Calves were allotted to 1 of 4 groups given different milk dietary aflatoxin M1 concentrations: group 1—given 0 μg of aflatoxin M1/L (undetectable); group 2—given 0.5 μg/L; group 3—given 1 μg/L; and group 4—given 2 μg/L. Whole milk equal to 8% of body weight was fed daily and adjusted each week to maintain this ratio. Water and a 15% crude protein complete calf starter ration were offered ad libitum for the 6-week feeding study. Weekly blood samples were collected via jugular venipuncture and analyzed for serum alkaline phosphatase and aspartate aminotransferase activities.

Daily means for milk dry matter intake (in kg) and complete ration intake (in kg) for the calf groups were as follows: 0.46 and 0.36 for group 1; 0.46 and 0.25 for group 2; 0.42 and 0.18 for group 3; and 0.49 and 0.40 for group 4. Significant differences in complete ration and total dry matter intake were noted. The average daily gains (in kg) and gains in height at withers (in cm) were 0.39 and 4.1 for group 1; 0.36 and 4.0 for group 2; 0.29 and 5.7 for group 3; and 0.42 and 5.1 for group 4. Differences in growth variables or in feed efficiency were not observed. Serum enzyme activities were not different for the 4 calf groups. At necropsy, gross abnormalities were not observed in specific organs (liver, heart, kidney, spleen, and adrenals), nor did weights of these organs differ between treatment, although a trend in increased weight of the spleen with toxin intake was observed. Calculated conversion of aflatoxin B1 ingested by cows to aflatoxin M1 produced was approximately 0.6%.
Normal values of the canine M-mode echocardiogram
Authors: Lombard Christophe W.
Published: February 2025

M-mode echocardiograms were recorded from 40 healthy dogs, awake and unsedated, in left, lateral recumbent position. Fifteen echocardiographic measurements were taken and correlated with body weights using linear regression equations. The left ventricular internal dimension in systole and diastole, the left ventricular wall thickness, the aortic root dimension, and the left atrial dimension had high correlation coefficients (r2), ranging from 0.756 to 0.619. The fractional shortening of the left ventricle in systole (39% ± 6%) and the left atrial to aortic root ratio (0.99 ± 0.10) were not linearly related to body weights and had constant values.
Electromyographic and urethral pressure profilometry: Assessment of urethral function before and after perineal urethrostomy in cats
Authors: Gregory C. R. , Holliday T. A. , Vasseur P. B. , Bruhl-Day R. A. G. A. , Parker H. R. , McNeal D.
Published: February 2025

Urethral pressure and electromyographic profiles were recorded in 10 healthy adult male cats before and after perineal urethrostomy. There was a significant decrease (P = 0 at 1 week after surgery, P = 0.002 at 3 weeks after surgery) in the mean maximum urethral pressure profile with associated loss of periurethral striated muscle activity.
Greater sensitivity of caprine synovial membrane cells to human interferon-alpha than human or bovine cells
Authors: Yilma Tilahun , Breeze Roger G. , Leib Steven R.
Published: February 2025

The sensitivity of caprine synovial membrane cells to the antiviral effects of natural and recombinant DNA-derived human interferons (HuIFN) was compared with that of human foreskin fibroblast (FS7), ovine choroid plexus, and bovine turbinate cells. Caprine cells were found to be more sensitive (P < 0.01) to natural HuIFN-α than human, ovine, and bovine cells. The sensitivity of caprine cells to recombinant DNA-derived HuIFN-α was equivalent to that of ovine cells, but greater than human or bovine cells. The sensitivity of caprine cells to natural and recombinant DNA-derived HuIFN-β was equivalent to human cells, but less than that of ovine cells.
Action of epinephrine on the function of the teat sphincter in the lactating cow
Authors: Vandeputte-Van Messom Georgette , Burvenich Christian , Peeters Georges
Published: February 2025

Under continuous iv infusion of oxytocin, milk leakage was elicited in 6 lactating cows with full udders by induction of a vacuum (−30 cm of water) around 1 mammary papilla (teat) with a plethysmography apparatus. The volumes of milk loss were measured every minute.

Epinephrine injected either into the jugular vein (20, 100, and 500 μg) or into the external pudic artery (1.5, 7.5, and 37.5 μg) induced an increase in milk leakage in 5 cows. This effect could be antagonized by the β-blocking agent sotalol hydrochloride (0.5 to 4 mg) injected into the external pudic artery. In 1 cow, however, epinephrine given intra-arterially exerted a biphasic effect, small doses inducing stimulation, and large doses evoking inhibition of milk loss. The stimulating effects were blocked by sotalol (2 mg). The inhibiting effects were antagonized by the α-blocking agent prazosin (2 mg).
Correction of organophosphate-induced neuromuscular blockade by diphenhydramine
Authors: Clemmons R. M. , Meyer D. J. , Sundlof S. F. , Rappaport J. J. , Fossler M. E. , Hubbell J. , Dorsey-Lee M. R.
Published: February 2025

Dogs exposed to topical organophosphate (fenthion) developed decreased plasma and muscle cholinesterase activities. After 2 doses were applied (1 week between doses), plasma concentrations declined 80% and muscle cholinesterase activity was reduced by 56%. Decremental responses to repetitive nerve stimulation developed after fenthion administration. Diphenhydramine, but not placebo, corrected the electrical abnormalities caused by organophosphate application, but without altering plasma or muscle cholinesterase activity. Control dogs housed in the same kennel demonstrated a slight decrease (18%) of plasma cholinesterase, which indicates that there may be potential cross contamination. Diphenydramine may be effective in treating organophosphate-induced neuromuscular weakness which is refractory to other forms of therapy.
In vitro propagation of canine distemper virus: Establishment of persistent infection in Vero cells
Authors: Metzler Alfred E. , Krakowka Steven , Axthelm Michael K. , Gorham John R.
Published: February 2025

Primary cultures of bovine fibroblast (bf) and canine brain cells, persistently infected with virulent R252-canine distemper virus (cdv), were cocultured with African green monkey (Vero) cells. Transfer of persistent cdv from bf to Vero cells varied inversely with the in vitro passage level (age) of the cdv-infected bf cells. Successful transfer of cdv to Vero cells was signaled by the transient appearance of viral syncytia, rapid spread of viral antigen to all Vero cells in the culture, and by recovery of cell-free Vero-infectious virus in culture fluids. With time, viral cytopathic effects in Vero cells containing cdv disappeared, and the infected lines could not be distinguished from noninfected control Vero cells, except by immunoassay for viral antigen.
Aromatic-dependent Salmonella dublin as a parenteral modified live vaccine for calves
Authors: Smith Bradford P. , Reina-Guerra Mario , Stocker Bruce A. D. , Hoiseth Susan K. , Johnson Eugene
Published: February 2025

A virulent Salmonella dublin isolate was made histidine-requiring (his−) to allow recognition. The his− derivative, SL1367 (still calf-virulent), was then given by transduction and mutation, a transposon-generated non-reverting aromatic biosynthesis (aro) defect; this defect caused loss of virulence for the mouse. The his− aro− derivative strain, SL1438, was effective as a live vaccine in mice.

Twenty male Holstein calves were divided into 4 groups. Groups I, II, and III were vaccinated IM at 2 weeks and at 3 weeks of age with aromatic-dependent (aro−) S dublin strain SL1438.

Groups I and III received freshly prepared vaccine and group II received lyophilized vaccine. Serious adverse reactions to the vaccination were not seen. After vaccination, the mean maximum increase in rectal temperature was 1.8 C in group I and III calves and 0.6 C in group II calves. Fewer group II calves developed diarrhea (1 of 5) or positive blood cultures (0 of 5) after vaccination compared with group I and III calves (6 of 10 and 5 of 10, respectively). Postvaccination diarrhea was mild and of short duration, Group IV was comprised of 5 nonvaccinated calves.

At 5 weeks of age, all calves were challenge exposed orally. Group I, II, and IV calves were challenge exposed with 1011 virulent S dublin SL1367. Group III was challenge exposed with 1011 virulent S typhimurium UCD 108-11. Subsequently, fever and diarrhea (lasting 1 to 3 days), but no deaths, were observed in the vaccinated calves. Four of the 5 nonvaccinated (group IV) calves died (P < 0.001) within 8 days after challenge exposure.

Aro− S dublin SL 1438 did not cause serious adverse effects and provided protection against oral challenge exposure with either virulent S dublin or S typhimurium.
Identification of canine lymphocyte subpopulations by immunofluorescence assay
Authors: Koyama Hiroyuki , Sakurai Yoshinori , Kajikawa Osamu , Saito Hiroshi
Published: February 2025

Experiments were performed to identify subpopulations of lymphocytes in lymphoid tissues of dogs. Anti-canine thymocyte serum (ats) and anti-canine brain-associated T-cell antigen (abat) were obtained by immunization of rabbits with canine thymocytes and canine brain tissue homogenate, respectively. The ats and abat antisera were absorbed using canine rbc, liver powder, and bone marrow cells. Part of the abat antiserum was further absorbed using canine thymocytes (abat-t antiserum). The ats, abat, abat-t, and antiasialo GM1 antisera were used for identification of lymphocyte subpopulations by means of indirect immunofluorescent antibody (fa) techniques. For bone marrow-derived lymphocytes, surface immunoglobulin (SIg) was measured by direct fa using fluorescein isothiocyanate-conjugated rabbit anti-dog immunoglobulin G antiserum. The specificites of the various antisera were proven by treatment of the lymphocytes by means of nylon wool columns or rosette-forming techniques followed by treatment with antisera and rabbit complement. Results indicated that ats reacted with T-lymphocytes, and abat antiserum reacted with T-lymphocytes, with abat-t-positive cells, and with antiasialo GM 1-positive cells The abat-t and asialo GM1 antisera reacted with the same cell populations, but did not react with ats-positive cells and abat-positive cells.

Lymphocytes from 21 clinically normal mixed-breed dogs and from 2 Beagle dogs were identified by various antisera. For mixed-breed dogs, the positive percentages of peripheral blood lymphocytes with respect to SIg, ats, abat, and abat-t were 36.3 ± 3.2%, 52.7 ± 3.5%, 56.1 ± 3.6%, and 2.4 ± 0.3%, respectively; in the spleens, the positive percentages were 44.8 ± 3.8%, 39.6 ± 2.8%, 42.6 ± 2.6%, and 1.9 ± 0.5%, respectively; and in the lymph nodes, 39.0 ± 2.7%, 49.4 ± 3.6%, 52.1 ± 3.9%, and 1.6 ± 0.5%, respectively. In the peripheral blood lymphocytes of Beagle dogs, the positive percentages were 16.3 ± 1.3%, 73.3 ± 0.8%, 76.5 ± 1.0%, and 2.5 ± 0% with respect to surface SIg, ats, abat, and abat-t, respectively.
An aspirin-prednisolone combination to modify postadulticide lung disease in heartworm-infected dogs
Authors: Rawlings Clarence A. , Keith James C. , Losonsky John M. , McCall John M.
Published: February 2025

A combination of aspirin and prednisolone was used in an attempt to modify the pulmonary disease produced by thiacetarsamide treatment of heartworm-infected dogs. Results of 6 heartworm-infected dogs treated with prednisolone (1 mg/kg, daily for 4 weeks) and aspirin (10 mg/ kg, daily for 4 weeks) after thiacetarsamide treatment were compared with previously published results of 3 groups of dogs (6 dogs/group). One of these 3 groups was a nontreated control group, another was treated with prednisolone, and the 3rd was treated with aspirin. All dogs each with 9 adult heartworms transplanted were treated with a 2-day, twice-a-day treatment of thiacetarsamide (1 mg/kg) 4 weeks after the transplant. Thoracic radiographs were taken before and at 1, 2, and 3 weeks after thiacetarsamide treatment to evaluate lung disease. Pulmonary arteriography was performed before and 3.5 weeks after thiacetarsamide treatment to evaluate pulmonary blood flow.

After treatment, radiographs of the aspirin-prednisolone group were similar radiographs the prednisolone group, both with a marked attenuation of the parenchymal disease, as compared with the non-treated group. Addition of aspirin to prednisolone prevented the blood flow obstruction and intraluminal filling defects that were present in the groups not receiving aspirin. Sixteen of 54 transplanted heartworms survived thiacetarsamide treatment in both prednisolone-treated groups, in contrast to complete elimination of heartworms in the nontreated group. Aspirin may be considered for treatment of any heartworm-infected dog that does not have hemotypsis, but postthiacetarsamide use of prednisolone should be restricted to the dog that develops severe lung disease after the heartworms have been killed.
Effect of the caprine variant of Mycoplasma mycoides subsp mycoides on endothelium, monocytes, and complement of guinea pig, calf, sheep, and goat serum
Authors: Rosendal S.
Published: February 2025

The caprine variant of Mycoplasma mycoides subsp mycoides causes septicemia with coagulopathy in goats. Pathogenetic mechanisms that might explain the coagulopathy, the ability of the Mycoplasma to persist in the blood, and its specificity for goats were studied.

Severe endothelial damage was seen by electron microscopy of goat aorta tissue exposed in vitro to 107 colony-forming units of mycoplasmas. The Mycoplasma did not damage 51Cr-labeled adherent cells from peripheral blood of goats. The hemolytic complement titer was reduced by 94%, 50%, 50%, and 25% in guinea pig, calf, sheep, and goat serum, respectively, 30 minutes after treatment with 8 × 109 colony-forming units of the Mycoplasma. Freshly prepared serum from these animal species killed the Mycoplasma. Heat-inactivated serum was not mycoplasmacidal. Complement from these 4 animal species was activated by the Mycoplasma through the classical pathway, because ethyleneglycoltetraacetic acid precipitation of serum Ca2+ inhibited activation. Proof that the classical pathway was functional in goats was not conclusive because Ca2+ supplementation of ethyleneglycoltetraacetic acid-treated serum did not restore complement activity.

Endothelial damage and complement activation may explain the coagulopathy. The function that complement activation may have in the inflammatory response of this disease is not known. Difference in susceptibility of calves, sheep, and goats to M mycoides septicemia cannot be explained by species variation in complement mycoplasmacidal activity.
Rapid screening and confirmation for drugs and metabolites in racing animals by tandem mass spectrometry
Authors: Brotherton Harry O. , Yost Richard A.
Published: February 2025

A screening and confirmation procedure for drugs and metabolites in the blood serum and urine of racing animals was developed. Equine blood serum was spiked with low concentrations of several drugs of interest. Canine blood serum and urine were collected following oral doses of diethylcarbamazine, procaine, and phenylbutazone. Serum, urine, and extracts of each were analyzed, using a triple quadrupole mass spectrometer. Simultaneous screening of up to 50 drugs was possible in a single sample, in < 2 minutes. Detection limits for most compounds were in the ng/ml to μg/ml range, using 1-μl samples. This procedure provided fast, sensitive screening for selected drugs and metabolites in blood serum and urine.
Quantitation of bovine immunoglobulin G2 antibodies binding Staphylococcus aureus, using a murine monoclonal antibody
Authors: Mathison B. A. , Kelley K. W. , Davis W. C.
Published: February 2025

A murine monoclonal antibody specific for bovine immunoglobulin (Ig) G2 was used to develop an enzyme-linked immunosorbent assay (elisa) to measure serum antibodies against the bovine pathogen Staphylococcus aureus. Anion exchange chromatography was used to prepare IgG2 from serum taken from a mastitic cow infected with S aureus. Specific-IgG2 antibodies binding S aureus were purified with an affinity column, using a heat-killed, low protein A strain of S aureus (M-10). Purified antibodies did not contain IgG1 or IgM and were composed of greater than 95% heavy and light chains determined on the basis of polyacrylamide gel electrophoresis. Purified IgG2 anti-S aureus antibody was used as a reference in an elisa that (i) could detect 5.0 ng of IgG2, (ii) was specific for IgG2 antibodies binding S aureus, (iii) was precise within and among different assays, (iv) yielded 112% recovery of the purified standard, and (v) when diluted in nonspecific IgG2, generated a curve that was parallel to the standard when a sample was serially diluted. A field study with cows having elevated California mastitis test scores showed evidence of infection with S aureus, as judged by a 59% increase (P < 0.01) in IgG2 S aureus-specific antibodies and a 25% increase (P < 0.05) in total IgG2 antibodies. There were no differences in IgG1 concentrations in plasma. Using indirect immunofluorescence, we also confirmed that bovine polymorphonuclear cells bound IgG2 preferentially over IgG1 or IgM. Measurement of antigen-specific IgG2 antibodies may therefore be useful as an index of specific antibody immunity to mastitis-causing organisms.
Controlled field trial on the anthelmintic effectiveness of the morantel sustained-release bolus in grazing calves
Authors: Presson B. L. , Yazwinski T. A. , Greenway T. , Pote L. , Newby T.
Published: February 2025

The direct and indirect anthelmintic efficacies of the morantel sustained-release bolus given to calves were assessed in a 154-day controlled field trial. A permanent calf pasture (divided into 2 lots) and naturally parasitized calves were used. The medicated calves were given the bolus at the time they were placed on the pastures. Control calves did not receive anthelmintic therapy. The effectiveness of the bolus to control parasitic gastroenteritis was determined by monitoring various parasitologic determinants.

The treated calves had significantly (P < 0.01) reduced numbers of fecal nematode eggs for every posttreatment sampling period when compared with the control calves. Tracer calves, used periodically during the study to indicate pasture larval infectivities, had equivalent worm burdens at the beginning of the trial (treated vs control pasture). Tracer calves, added later in the study to the lot with treated calves, harbored 83% to 94% fewer nematodes than did their counterparts in the lot with the controls. Plasma pepsinogen concentrations, reflective of abomasal worm burden size and/or activity, were significantly higher (P < 0.01) in the control than in the treated calves from day 54 until trial termination. At trial termination, the treated calves weighed an average of 27.8 kg more and harbored 80.9% fewer nematodes than the control calves.
Identification of common antigens in ribosome-rich extracts from Fusobacterium necrophorum
Authors: Berg J. N. , Evans J. W.
Published: February 2025

Ribosome-rich extracts (rre) were prepared by differential and ultracentrifugation from 25 bovine and 6 ovine isolates of Fusobacterium necrophorum (fn) including both biotypes A and B. A pooled rabbit antiserum was prepared against whole-cell and sonicated whole-cell bacterins of F necrophorum isolate fn 3080, and a 2nd pooled rabbit antiserum was prepared against a rre of fn 3080. The rre of the 25 bovine isolates were tested against the fn 3080 whole-cell antiserum, using Ouchterlony double-immunodiffusion procedures. One to 3 precipitin lines were observed with the 25 isolates. The individual bovine isolates were found to have lines of identity with 5 to 21 of the other 24 isolates.

The 25 bovine isolates and the 6 ovine isolates were then compared, using the fn 3080 rre antiserum. One to 3 precipitin lines were observed for the 31 isolates with the rre antiserum, and lines of identity were observed between all 31 of the isolates. These results indicated that common antigens are present in the rre from a wide variety of F necrophorum isolates including both A and B biotypes.
Equine herpesvirus type 2: Cell-virus relationship during persistent cell-associated viremia
Authors: Gleeson L. J. , Coggins L.
Published: February 2025

Some aspects of the biology of equine herpesvirus type 2 (ehv-2) were investigated by examination of the persistent cell-associated viremia stage of the infection. The ehv-2 infection of leukocytes was latent, because free virus was not retrieved without first cultivating harvested leukocytes in vitro. A virus infective center (ic) assay was developed to enumerate latently infected cells in the leukocyte population. This assay proved to be simple and reproducible and revealed a linear relationship between c plaques formed and the number of cells inoculated, except where large numbers of cells (> 4 × 106) were inoculated per 10 cm2 dish. This reduction at high cell densities of ic/106 cells inoculated was dependent on cells obtained from an ehv-2-infected horse. There was considerable variation in the numbers of ic/106 leukocytes harvested from different horses, but little variation in the harvests from the same horse at different times. There seemed to be a direct relationship between serum-neutralization titers and ic numbers. Transfer of viable infected leukocytes to 2 fetuses failed to establish ehv-2 infection. Infection of equine fetal kidney cells with ehv-2 virus failed to produce detectable Fc receptors on the cell surface.
Electrophysiologic studies of the facial reflexes of the dog
Authors: Whalen L. R.
Published: February 2025

Reflexes associated with the trigeminal and facial nerves were investigated electromyographically in 14 barbiturate-anesthetized dogs. Using subcutaneous needle electrodes, electrical stimulation of the infraorbital, frontal, and zygomaticofacial branches of the trigeminal nerve produced reflex contractions of the ipsilateral orbicularis oculi muscle. Cutaneous and subcutaneous electrical stimulation of the internal auricular branches of the facial nerve also produced reflex contractions of the ipsilateral orbicularis oculi muscle. After sectioning of this branch between the vagus and facial nerves, electrical stimulation of the proximal portion of the auricular branch of the vagus nerve produced reflex contractions of the ipsilateral orbicularis oculi muscle. After sectioning of the auricular branch of the vagus nerve; electrical stimulation of the proximal portion of the caudal and middle internal auricular nerves did not produce reflex contractions of the ipsilateral orbicularis oculi muscle. Subcutaneous electrical stimulation of the palpebral nerve produced reflex contractions and direct-evoked muscle activity of the orbicularis oculi muscle. Subcutaneous electrical stimulation of the infraorbital and middle mental nerves produced reflex contractions of the rostral belly of the digastricus muscle.
Aqueous outflow in the Beagle: Unconventional outflow, using different-sized microspheres
Authors: Samuelson Don A. , Gum Glenwood G. , Gelatt Kirk N. , Barrie Kathleen P.
Published: February 2025

Normal drainage of aqueous humor from the anterior chamber of the canine eye occurred through the angular aqueous plexus and uveoscleral route. In order to understand more clearly, uveoscleral outflow with regard to larger sized tracer particles and the possible influence that varying intraocular pressure (iop) may have on them, microspheres of 3 sizes, 0.5, 1.0, and 3.0 μm, were perfused at 3 different iop (20, 50, and 75 mm of Hg) for 3 different times (30, 60, and 90 minutes). Presence of spheres was detected by light microscopy and scanning electron microscopy, and verified by transmission electron microscopy.

By 30 minutes of perfusion, all 3 sphere sizes thoroughly infiltrated the anterior uveal trabecular meshwork. At normotensive pressure (20 mm of Hg), spheres of each size penetrated the outer anterior extension of the ciliary musculature and entered the supraciliary space. Only 0.5- and 1.0-μm spheres moved posteriorly into the suprachoridal space. At hypertensive pressures, movement of the tracer particles increased markedly toward the posterior uveal trabecular meshwork. However, 3.0- and 1.0-μm spheres did not enter the supraciliary space and suprachoroidal space, respectively. Spheres also entered the iris, mostly at its root. They remained comparably sparse at different perfusion times and iop. The present study supported evidence for uveoscleral outflow (vs uveovortex) in the dog and indicated that passage of materials through this pathway may be influenced by iop when these substances are within a critical size range.
Demonstration of rabies viral antigen in paraffin tissue sections: Comparison of the immunofluorescence technique with the unlabeled antibody enzyme method
Authors: Palmer Dieter G. , Ossent Peter , Suter Maja M. , Ferrari Elena
Published: February 2025

The immunofluorescence technique and the peroxidase-antiperoxidase method were used to demonstrate rabies antigen in a retrospective study on formalin-fixed, paraffin-embedded brain tissues from 34 naturally infected wild and domestic animals. Rabies was confirmed with immunofluorescent staining on fresh brain tissue at the time of necropsy of the animals. There was a perfect correlation (serial sections from a given brain area were always positive by both methods), but the peroxidase-antiperoxidase technique was preferred, since no trypsin digestion was required.

Twenty six of the 34 animals were immunohistochemically positive and had encephalitis, and in 21 of these 26, the hematoxylin and eosin-stained sections contained detectable intracytoplasmic inclusion bodies in at least 1 brain area. Of the remaining 8 animals (with no inflammatory lesions), 7 were positive for rabies antigen and 2 had no inclusion bodies.

Rabies antigen was apparent in 62% of the brain areas in which inclusion bodies were not found in the corresponding hematoxylin and eosin stained sections. Thus, together with the inclusion body positive areas, which were all immunohistochemically positive, it was possible to diagnose rabies in a total 84% of the areas examined.

Both techniques greatly facilitate the diagnosis of rabies and may be a reliable help to the diagnostic pathologist when only formalin-fixed tissues are available. However, the methods should not be considered substitutes for the immunofluorescence technique and the mouse inoculation test with fresh brain tissue.
Anesthetic potency of nitrous oxide in young swine (Sus scrofa)
Authors: Tranquilli W. J. , Thurmon J. C. , Benson G. J.
Published: February 2025

Determination of nitrous oxide (N2O) potency was accomplished by extrapolation using the concepts of minimum alveolar concentration (mac) and additivity among inhalation anesthetics.

Halothane and isoflurane anesthetic requirement (alveolar concentration) necessary to achieve mac in 9 pigs decreased with each successive increase in the percentage of inspired N2O (25%, 50%, 75%). Halothane and isoflurane mac was determined to be 0.94 ± 0.03 and 1.75 ± 0.01 volumes percent, respectively. Halothane and isoflurane requirements decreased to 0.74 ± 0.02, 0.66 ± 0.02, and 0.58 ± 0.02; and to 1.56 ± 0.02, 1.38 ± 0.02, and 1.08 ± 0.03 volumes percent with 25%, 50%, and 75% N2O, respectively. The line of best fit derived from regression analysis of the combined data (isoflurane and halothane mac values) had a correlation coefficient of 0.987 and an X intercept equivalent to 195% N2O. The potency of N2O in pigs was similar to that of other domesticated mammals and reduced halothane and isoflurane anesthetic requirements by approximately 50% of the reduction observed in human beings.
Quantitation of uveoscleral outflow in normotensive and glaucomatous Beagles by 3H-labeled dextran
Authors: Barrie Kathleen P. , Gum Glenwood G. , Samuelson Don A. , Gelatt Kirk N.
Published: February 2025

In uveoscleral outflow, aqueous humor leaves the anterior chamber and passes caudally through the trabecular meshwork and the sclerociliary cleft to enter the supraciliary and suprachoroidal spaces. The fluid is then absorbed by choroidal and scleral circulations.

Using 3H-labeled dextran, uveoscleral outflow was quantitated in normotensive and glaucomatous Beagles under general anesthesia. The intrascleral plexus was isolated and 3H-labeled dextran was injected into the anterior chamber. Intrascleral plexus contents were sampled every 5 minutes over a 30- to 60-minute period. The eyes were enucleated, sectioned, and prepared for scintillation counting.

Uveoscleral outflow accounted for 15% and 3% of the total aqueous humor outflow in the normotensive dogs and in the advanced glaucomatous dogs, respectively. In the advanced glaucomatous Beagle, conventional and uveoscleral outflow pathways were reduced and contributed to the etiopathogenesis of glaucoma.
Morphologic studies of uveoscleral outflow in normotensive and glaucomatous Beagles with fluorescein-labeled dextran
Authors: Barrie Kathleen P. , Gum Glenwood G. , Samuelson Don A. , Gelatt Kirk N.
Published: February 2025

Aqueous humor leaves the anterior chamber through 2 pathways: the trabecular meshwork of the iridocorneal angle and the unconventional uveoscleral route. In the latter route, aqueous humor leaves the anterior chamber, passes caudally through the trabecular meshwork and sclerociliary cleft to enter the supraciliary and suprachoroidal spaces. The fluid is absorbed by the choroidal and scleral circulation.

Fluorescein-labeled dextran was slowly infused into the posterior chamber of healthy and glaucomatous Beagles for 30 minutes. The eyes were fixed in a mixture of 70% alcohol and formalin, placed in epoxy resin for histologic evaluation, and examined by fluorescent microscopy. Fluorescence was detected in the healthy dogs throughout the uveoscleral pathway. In the glaucomatous dogs, the uveoscleral outflow was decreased or completely absent.
Mastitis associated with ovine progressive pneumonia virus infection in sheep
Authors: Cutlip Randall C. , Lehmkuhl Howard D. , Brogden Kim A. , Bolin Steven R.
Published: February 2025

Eighteen ewes were experimentally infected with ovine progressive pneumonia virus and their mammary glands were examined for lesions and virus at 2.5 to 10 years postinoculation. Lesions were seen in 14 of 18 sheep; virus was isolated from 4 of 8 sheep. Lesion consisted of an interstitial accumulation of lymphocytes with periductal lymphoid nodules, and epithelial vacuolation and necrosis at the site of the lymphoid nodules.
Experimental infection of calves with Leptospira interrogans serovar hardjo: Conjunctival versus intravenous route of exposure
Authors: Thiermann Alex B. , Handsaker Annette L.
Published: February 2025

Eight-month-old calves, housed under maximum isolation, were exposed to pathogenic Leptospira interrogans serovar hardjo by the conjunctival route or iv. One calf served as an unexposed control.

Infection was monitored serologically (microscopic agglutination test and enzyme-linked immunosorbent assay; elisa) and by leptospiral culture isolation from periodic urine samples and from the kidneys, epididymides, and aqueous humor collected at slaughter.

Microscopic agglutination test titers of ≥ 1:40 were detected among all iv exposed calves at postinoculation day (pid) 7 and among conjunctival exposed calves at pid 14. By elisa, all iv exposed calves were positive by pid 3, whereas conjunctival exposed calves were positive at pid 14. The elisa was more sensitive for the detection of antibodies against leptospires in cattle.

Leptospires were isolated from the urine of 4 calves and from the kidney of 3 calves exposed by the conjunctival route, but not from iv exposed calves.

The results indicated that the conjunctival route of exposure was a more natural and successful route for experimental infection of cattle with serovar hardjo.
Pharmacokinetics and bioavailability of cefazolin in horses
Authors: Sams R. A. , Ruoff W. W.
Published: February 2025

The pharmacokinetics and bioavailability of cefazolin given (iv, im) to horses at the dosage of 11 mg/kg were investigated. The disposition of cefazolin given by iv route was characterized by a rapid disposition phase with a half-life of 5 to 10 minutes and a subsequent slower elimination phase with a half-life of 35 to 46 minutes. The total plasma clearance of cefazolin averaged 5.51 ml/min/kg and was due mainly to renal clearance (5.39 ml/min/kg) of unchanged drug. The volume of distribution at steady-state averaged 188 ml/kg. Plasma protein binding of cefazolin at a concentration of 10 μ/ml averaged 8.1 ± 1.9%.

Given by the im route, cefazolin was rapidly absorbed; the extent of bioavailability was 78.4 ± 18.8%, and the terminal half-life ranged from 49 to 99 minutes. Thus, cefazolin was extensively absorbed, but was eliminated more slowly than after iv administration.
Dental fluorosis in bovine temporary teeth
Authors: Suttie J. W. , Clay A. B. , Shearer T. R.
Published: February 2025

Deciduous incisors from calves born to dams fed an average of 40 mg of fluoride/kg of forage ration (40 ppm) were compared with incisors from calves born to dams fed a normal dairy ration. Skeletal fluoride concentration in the calves born to fluoride-fed dams was increased 5 to 8 fold, but enamel mottling and hypoplasia, typical of permanent bovine incisor dental fluorosis were not seen by gross, histologic, or radiologic examination. Decreases in the amount of enamel on the tooth or hardness of the enamel were not observed. These data do not support recent reports of widespread dental fluorosis of deciduous bovine teeth as a clinical sign of fluoride toxicity.
Cryopreservation of Babesia bigemina for in vitro cultivation
Authors: Vega C. A. , Buening G. M. , Rodriguez S. D. , Carson C. A. , McLaughlin K.
Published: February 2025

Babesia bigemina-infected rbc and merozoites were cryopreserved and used to initiate in vitro cultures in normal bovine rbc; the cryoprotectant was a final 10% polyvinylpyrrolidone in Vega y Martinez solution. A cooling rate of 20 C/min until −80C and then rapid transfer to liquid N2 storage was satisfactory. Samples for culture initiation were rapidly thawed at 37 C, washed in Vega y Martinez solution and resuspended in complete culture media containing 10% normal bovine rbc. The optimum culture conditions to reestablish cultures were a 24-well plate (16 mm id), 5 mm in depth, and an atmosphere of 2% to 5% O2, 5% CO2, and 93% to 90% N2.
Susceptibility of equine bacterial isolates to antimicrobial agents
Authors: Adamson Peter J. W. , Wilson W. David , Hirsh Dwight C. , Baggot J. Desmond , Martin Lori D.
Published: February 2025

In vitro antimicrobic susceptibility patterns of commonly isolated aerobic gram-positive and gram-negative bacterial pathogens of equine origin were determined, using the agar-plate dilution method. All organisms were recent clinical isolates and included Corynebacterium (Rhodococcus) equi, Corynebacterium pseudotuberculosis, (coagulase positive) Staphylococcus sp, Streptococcus equi, Streptococcus zooepidemicus, Actinobacillus sp, Enterobacter cloacae, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Salmonella. In vitro susceptibility levels were outlined for 14 antimicrobics as follows: amikacin ≤ 4.0 μg/ml, ampicillin ≤ 1.0 μg/ml, amoxicillin ≤ 1.0 μg/ml, cefadroxil ≤ 8.0 μg/ml, chloramphenicol ≤ 8.0 μg/ml, erythromycin ≤ 1.0 μg/ml, gentamicin ≤ 2.0 μg/ml, kanamycin ≤ 4.0 μg/ml, penicillin ≤ 1.0 μg/ml, tetracycline ≤ 1.0 μg/ml, sulfadimethoxine ≤ 10.0 μg/ml, ormetoprim/sulfadimethoxine ≤ 0.5/9.5 μg/ml, sulfadiazine ≤ 10.0 μg/ml, and trimethoprim/sulfadiazine ≤ 0.5/9.5 μg/ml.
Prevalence of trichinosis in southern Louisiana swine
Authors: Hugh-Jones M. E. , Stewart T. B. , Raby C. , Morrison J. E. , Isenstein R. S. , Klei T. R.
Published: February 2025

After an outbreak of human trichinosis in Louisiana involving 45 cases and 1 death in 1979 and 1980, a survey of pigs killed in 21 selected small slaughterhouses in southwestern Louisiana was conducted from November 1980 to September 1981. The sera from 1,225 pigs were examined for trichinella antibodies using an enzyme-linked immunosorbent assay (elisa); 1,223 diaphragms were subjected to peptic digestion and examined for the presence of Trichinella spiralis larvae. One diaphragm (0.08%) was found to contain T spiralis (26 larvae/g of muscle) and 4 of the slaughterhouse sera were positive (0.33% seroprevalence). Pigs in 52 herds throughout the state were also tested for elisa antibodies. The elisa-positive pigs were not found among the 267 pigs tested from the 52 herds.
Pharmacokinetics of prednisolone sodium succinate and its metabolites in normovolemic and hypovolemic dogs
Authors: Hankes G. H. , Lazenby L. R. , Ravis W. R. , Belmonte A. A.
Published: February 2025

Tritium-labeled prednisolone sodium succinate was administered iv to 4 healthy, awake, nonsplenectomized dogs. The concentration of prednisolone and its metabolites in the plasma were measured for 10 hours. Forty-one percent of the blood volume of these dogs was removed, and plasma prednisolone was measured again. The data before and after hemorrhage were fitted to a 2-compartment open model. From plasma profiles, a rapid distributional phase, followed by a slower phase, was observed in control and shock groups. Volume of the central compartment of prednisolone before and after hemorrhage was 165 ml/kg of body weight and 110 ml/kg, respectively; and the difference was significant (P < 0.05). The rate of total body clearance of prednisolone before and after hemorrhage was 3.96 ml/min/kg and 2.53 ml/min/kg, respectively the difference was significant. The mean plasma half-lives for prednisolone sodium succinate and its metabolites, before and after hemorrhage, were 166 and 197 minutes, respectively; the difference was not significant. The mean half-life data indicated that prednisolone sodium succinate may be repeated in a patient 2.5 to 3 hours after onset of treatment if signs of hypovolemic shock reappear.
Single-injection method for evaluation of renal function with 14C-inulin and 3H-tetraethylammonium bromide in dogs and cats
Authors: Fettman Martin J. , Allen Timothy A. , Wilke W. Lee , Radin M. Judith , Eubank Mary C.
Published: February 2025

A double-isotope single-injection method without urine collection for the estimation of glomerular filtration rate (gfr) and effective renal plasma flow (erpf) in dogs and cats was evaluated. The gfr was determined, using 14C-inulin and erpf was determined, using [3H]tetraethylammonium bromide. Using a modified single exponential, 1-compartment mathematical model, the renal clearance of these solutes was estimated with a plasma radioactivity disappearance curve constructed from samples collected over a 150-minute time period. In 25 dogs, gfr, erpf, and filtration fraction were 3.55 ± 0.14 ml/kg/min, 10.51 ± 0.72 ml/kg/min, and 0.34 ± 0.02, respectively. In 25 cats, gfr, erpf, and filtration fraction were 3.24 ± 0.14 ml/kg/min, 8.14 ± 0.53 ml/kg/min, and 0.39 ± 0.02, respectively. This time-efficient and reliable method, using β-emitting isotopes, yielded renal functional values well within the normal ranges reported by a variety of other isotopic and nonisotopic procedures. The advantages of the present procedure over previous double-isotope single-injection methods include the use of less costly, lower energy-using, and less penetrating β emittors, as well as a shortened blood sampling schedule.
Serum concentrations of thyroxine, 3,5,3′-triiodothyronine, thyrotropin, and prolactin in dogs before and after thyrotropin-releasing hormone administration
Authors: Kaufman J. , Olson P. N. , Reimers T. J. , Allen T. A. , Soderberg S. F. , Nett T. M. , Wheeler S. L. , Wingfield W. E.
Published: February 2025

Serum concentrations of thyrotropin (tsh), prolactin, thyroxine, and 3,5,3′-triiodothyronine in 15 euthyroid dogs and 5 thyroidectomized and propylthiouracil-treated dogs after thyrotropin-releasing hormone (trh) administration were measured. Although thyroidectomized and propylthiouracil-treated dogs had higher (P < 0.01) base-line concentrations of tsh in serum than did euthyroid dogs, concentrations of tsh after trh administration varied at 7.5, 15, and 30 minutes with 14 of 45 samples obtained from healthy dogs having lower tsh concentrations than before trh challenge. Similarly, concentrations of 3,5,3′-triiodothyronine in the serum of euthyroid dogs 4 hours after trh administration were similar (P > 0.05) to concentrations before trh challenge. Although the mean concentration of thyroxine in serum was elevated (P < 0.05) 4 hours after administration of trh to euthyroid animals, as compared with base-line levels, the individual response was variable with concentrations not changing or decreasing in 4 dogs. Therefore, the trh challenge test as performed in the current investigation was of limited value in evaluating canine pituitary gland function. Although mean concentrations of tsh in serum were higher (P < 0.05) in euthyroid dogs after trh administration, the response was too variable among individual animals for accurate evaluation of pituitary gland function. Concentrations of prolactin in the sera of dogs after trh administration, confirmed previous reports that exogenously administered trh results in prolactin release from the canine pituitary and indicated that the trh used was biologically potent.