bluuebunny/crossref_metadata_2025 huggingface dataset:
Pathologic changes associated with experimental lasalocid and monensin toxicosis in cattle
Authors: Galitzer S. J. , Kruckenberg S. M. , Kidd J. R.
Published: February 2025

The acute toxicity of lasalocid and monensin was studied in 36 Holstein steers. The cattle were given (orally) a single dosage of lasalocid (1, 10, 50, or 100 mg/kg of body weight) or monensin (25 mg/kg of body weight) or rice hulls. Animals were observed once a day until they died or were euthanatized at 32 days after the dose was given. All cattle were necropsied. Heart, kidney, adrenal gland, liver, spleen, pancreas, lungs, brain, sciatic nerve, skeletal muscle, small intestine, large intestine, and rumen tissue sections, stained with hematoxylin and eosin, were studied microscopically. Lasalocid was lethal at dosages of 50 and 100 mg/kg, and monensin was lethal at the dosage given (25 mg/kg). Cattle dying of lasalocid and monensin toxicoses had gross and microscopic lesions consistent with cardiomyopathy. Dilated heart or petechial and ecchymotic hemorrhages were observed with both drugs. Microscopically, multifocal areas of myocyte necrosis were observed. Those cattle that died within 3 days of dosing with either drug had a marked degranulation of pancreatic acinar cells. Changes were not observed in any other tissues.
Response of goats to vaccination with temperature-sensitive mutants of Chlamydia psittaci obtained by nitrosoguanidine mutagenesis
Authors: Rodolakis Annie , Souriau Armel
Published: February 2025

Two temperature-sensitive strains of ovine Chlamydia psittaci, IB and 1H, obtained by mutagenesis were used as live-organism vaccines; 31 goats were given 4 × 106 plaque-forming units (pfu) of strain IB, and 31 were given 5 × 106 pfu of strain 1H 2 months before they were bred. The consequences of the vaccination of the goats were studied during pregnancy by recording complement-fixation antibody titer, chlamydial excretion, and kidding performances and were compared with those of goats inoculated under the same conditions with 100 × smaller dose of virulent caprine abortive strain AC1. The vaccination did not disturb pregnancy, and none of the vaccinated goats excreted chlamydiae. In contrast, 2 of 28 goats inoculated with AC1 aborted and shed chlamydiae.

One year after the goats were vaccinated, they were challenge exposed by intradermal inoculation of 106 pfu of the caprine strain AC1 at 79 to 98 days of pregnancy. Although 13 of the 14 control nonvaccinated goats aborted and excreted chlamydiae, none of the pregnant goats vaccinated with 1H and only 1 of the pregnant goats vaccinated with IB aborted and excreted chlamydiae.
Airborne particle concentration and meteorologic conditions associated with pneumonia incidence in feedlot cattle
Authors: MacVean Duncan W. , Franzen David K. , Keefe Thomas J. , Bennett Bill W.
Published: February 2025

To elucidate the role of air quality on the occurrence of pneumonia in feedlot cattle, the following environmental values were measured at a feedlot: suspended particulates in 5 particle-size fractions, relative humidity, air temperature, and barometric pressure. Pneumonia incidence data were classified by the number of days the cattle had been at the feedlot (days on feed). The concentration of airborne particles, range of temperature, days on feed, and season of the year were associated with incidence of pneumonia in cattle. Pneumonia incidence rates were greatest both within 15 days of arrival at the feedlot and during the fall sampling periods. The incidence of pneumonia in the 16 to 30 days-on-feed group was closely associated with the concentration of particles 2.0 to 3.3 μm in diameter and the range of daily temperature when exposure occurred 15 days before the onset of disease in the fall and 10 days before in the spring.
Genetic studies of neuraxonal dystrophy in the Morgan
Authors: Beech Jill , Haskins Mark
Published: February 2025

A naturally occurring disease condition, neuraxonal dystrophy, was identified in 27 male and 15 female Morgans, many of which were closely related. Five-generation pedigrees were constructed for 33 of these horses and were compared with those for 29 randomly selected age- and sex-matched Morgans. Their mean coefficient of inbreeding was not statistically different (P > 0.1, 1 tailed t test; P < 0.001, median test). Breeding of 2 severely affected and 2 normal stallions to 2 severely affected, 3 mildly affected, and 6 normal mares produced 10 mildly affected, 8 suspect affected, and 6 normal offspring. Breeding 4 normal stallions to 17 normal mares produced 22 normal offspring. Neuraxonal dystrophy seems to have a familial component, although neither a simple dominant not recessive mode of inheritance could be demonstrated. The condition could be inherited in a polygenic mode or as a dominant disorder with variable expression.
Energy metabolism in canine erythrocytes associated with inherited high Na+- and K+-stimulated adenosine triphosphatase activity
Authors: Maede Yoshimitsu , Inaba Mutsumi
Published: February 2025

Energy metabolism in canine erythrocytes associated with inherited high Na+- and K+ -stimulated adenosine triphosphatase [(Na,K)-ATPase] activity (HK cells) was compared with that in normal canine erythrocytes (LK cells). Activities of some of the glycolytic enzymes in the HK cells were significantly higher than those in LK cells. The concentrations of adenosine triphosphate (atp) and glycolytic intermediates in HK cells were almost equal to those in LK cells. Glucose utilization and lactate production by HK cells in vitro and incorporation of [32P]orthophosphate or [14C]glucose into 2,3-diphospho-glycerate in HK cells were higher than in LK cells. Radioactivity of [32P]atp in HK cells was lower than in LK cells, but increased to approximately that of LK cells when (Na,K)-ATPase of HK cells was completely blocked by ouabain. When HK cells and LK cells were incubated in the absence of glucose, the concentration of atp in HK cells was decreased more than that of LK cells. Although ouabain reduced the rate of decrease in atp in HK cells, the decrease in atp in HK cells was still 2-fold that in LK cells. The half-life of HK cells was about one-half that of LK cells. The results indicated that glycolysis is greater in HK cells than in LK cells, and that the increased glycolysis in HK cells was stimulated by an increased rate of atp breakdown for active cation transport by the (Na,K)-ATPase and by increased degradation of atp for some other pathway, eg, glutathione synthesis. Thus, the increased demand for atp in HK cells might result in shortening the lifespan of HK erythrocytes.
Plasma lactate measurements in healthy Beagle dogs
Authors: Evans G. O.
Published: February 2025

Plasma lactate concentrations were determined in venous blood samples collected from 60 healthy Beagles aged 5 to 9 months. The range of values (0.42 to 3.58 mmol/L) obtained with an enzymatic method in the present study was similar to values reported in smaller studies with the colorimetric procedures.
Clinical effects of low dietary phosphorus concentrations in feed given to lactating dairy cows
Authors: Call J. W. , Butcher J. E. , Shupe J. L. , Lamb R. C. , Boman R. L. , Olson A. E.
Published: February 2025

Thirty-four Holstein cows, pregnant with their second calf, were individually fed diets containing 3 concentrations of phosphorus (P): 24 cows for 12 months and 10 cows for 7.5 months of lactation. Cows were randomly allotted to the specific dietary groups 2 months before expected parturition. The 3 dietary concentrations of P were 0.24%, 0.32%, and 0.42% in diet. Cows given 0.24% P in diets produced significantly less milk than did cows in the other groups. Other clinical signs of P deficiency in the cows fed the diet with 0.24% P included loss of body weight, decreased feed consumption, and lower inorganic serum P concentration 2 to 10 weeks after parturition. There were no significant differences in the variables measured between cows given dietary P concentrations of 0.32% and 0.42%. There was no evidence of hemoglobinuria after parturition. Reproductive performance did not differ significantly, although the trend was in favor of the cows fed the diet with 0.24% P.
Escherichia coli-induced lung and liver dysfunction in dogs: Effects of flunixin meglumine treatment
Authors: Hardie Elizabeth M. , Rawlings Clarence A. , Shotts Emmet B. , Waltman Douglas W. , Rakich Pauline M.
Published: February 2025

Twelve dogs were infused with 1010 Escherichia coli/kg of body weight through a portal vein catheter over a 1-hour period; 6 dogs were treated with flunixin meglumine (1 mg/kg) 15 minutes after the infusion had begun. Six dogs (controls) were infused with a comparable volume of sterile saline solution over the same period. Over a 4-hour monitoring period, nontreated septicemic dogs developed systemic hypotension, decreased cardiac output, increased portal pressure, increased serum alanine transaminase values, increased extravascular liver water, increased liver glycogen depletion, and decreased arterial oxygen tension compared with control dogs. Accumulations of polymorphonuclear leukocytes and E coli were found in the livers and lungs of septicemic dogs. Flunixin meglumine treatment prevented systemic hypotension and hypoxemia, reversed the early but not the late stages of portal hypertension, and decreased E coli concentrations in the lungs. Other effects of treatment were not noticed.
Cardiovascular and respiratory measurements in awake and isoflurane-anesthetized horses
Authors: Steffey E. P. , Dunlop C. I. , Farver T. B. , Woliner M. J. , Schultz L. J.
Published: February 2025

Circulatory and respiratory function was monitored in nonmedicated, spontaneously breathing horses (n = 7) immediately before, during, and 1 hour after 85 ± 4.1 (X ± sem) minutes of constant 1.57% isoflurane in O2 anesthesia. Comparison of values during anesthesia with those obtained while horses were awake revealed a significant (P < 0.05) decrease in arterial blood pressure that was related to a slight, but insignificant, decrease in cardiac output and peripheral vascular resistance. Although isoflurane anesthesia and recumbency resulted in a significant (P < 0.05) decrease in stroke volume, cardiac output did not decrease significantly because heart rate tended to increase. Isoflurane and recumbency also significantly (P < 0.05) increased Paco2, peak expiratory gas flow, total expiratory time, and pcv and significantly decreased Pao2, minute expired ventilation, and the ratio of peak inspired to expired gas flow. Differences imposed by isoflurane anesthesia were reversed by 1.5 hour after anesthesia.
Campylobacter jejuni infection in the ferret: An animal model of human campylobacteriosis
Authors: Fox James G. , Ackerman Joel I. , Taylor Nancy , Claps Megan , Murphy James C.
Published: February 2025

Campylobacter infection in weanling ferrets (Mustela putorius furo) was studied as an animal model for enteric campylobacteriosis in persons. The screening of fecal cultures on selective campylobacter media showed that Campylobacter jejunilcoli was not present in the normal enteric flora. Intragastric feeding of a mixture of cat feed and 2.5 × 108 C jejuni isolated from ferrets with naturally occurring proliferative colitis was accomplished. All ferrets (n = 8) became infected on 3 days after they were inoculated, and at 5 to 7 days, they had bile-tinged, liquid feces with excessive mucus and blood. Ferrets gradually recovered from the diarrhea, and feces were normal 10 to 14 days after inoculation was done. Feces contained C jejuni at 14, 23, 28, 39, 46, 60, 91, 101, 109, and 144 days.

In the second experiment, weanling ferrets initially were treated with 10% sodium bicarbonate, and 1 × 1010 C jejuni organisms were administered in the cat feed. Diarrhea with fecal leukocytes and occult blood with occasional mucus appeared in almost all of the 21 ferrets from days 4 through 7. Campylobacter jejuni was isolated from the blood of 11 ferrets between 3 hours to 14 days after they were inoculated. Campylobacter jejuni bactericidal antibodies were present in serum samples at 14 days, with titers of 1:16 to 1:32. Intestinal lesions including cellular infiltration with mononuclear and polymorphonuclear leukocytes were in the lamina propria of the pyloric mucosa and small intestine of infected and control ferrets. The colon of 3 infected ferrets had small focal infiltrates of neutrophils on the lamina propria; one ferret had perivascular cuffing.

Since the inoculations in the ferret leads to disease mimicking that seen in persons and elicits significant circulating antibody titers to the infecting strain of C jejuni, the ferret may prove useful in exploring the feasibility of using vaccines to provide protection against diarrhea caused by pathogenic strains of C jejuni.
Topographie localization of gastric lesions and key role of plasma bicarbonate concentration in dogs with experimentally induced gastric dilatation
Authors: Pfeiffer Carl J. , Keith James C. , April Milton
Published: February 2025

The canine gastric response to acute dilatation, its correlation with selected systemic cardiovascular changes, and preliminary study of its modulation by membrane-stabilizing agents were studied in 21 Beagle dogs. Gastric mucosal damage and adverse cardiovascular sequelae were induced by inflation of an intragastric balloon to 60 mm of Hg in each anesthetized dog for 2.5 hours. At this time, dogs were given 1 of 4 treatments: (1) control; (2) lidocaine HCl, 2.2 mg bolus + 66 μg/min, iv; (3) prednisolone succinate, 6.6 mg, iv; and (4) zinc sulfate, 2.2 mg bolus + 66 μg/min, iv. After treatments were given, there was a 4-hour deflation period. Throughout the 6.5 hours, continuous measurements were made of stroke volume, arterial blood pressure, Pao2, Paco2, and plasma HCO3− concentration.

Gastric lesions, assessed by planimetric analysis of ulcer indices, were limited to the fundus and corpus and were significantly decreased by lidocaine administration. As seen by histopathologic examination, a sharply delineated transverse area bordering the corporeal-antral junction near the lesser curvature demonstrated minimal resistance to ulceration and showed mucus depletion. Plasma HCO3− concentration, base excess, and CO2 values were negatively correlated with development of gastric damage, indicating that plasma HCO3− concentration has a key role in mucosal resistance to ulcerogenesis.
Infestivity of Psoroptes ovis on ivermectin-treated cattle
Authors: Strickland Robert K. , Gerrish Robert R.
Published: February 2025

Psoroptes ovis was not transmitted by natural contact to susceptible cattle which were exposed to infested, ivermectin-treated cattle 6, 12, 14, 16, and 18 days after treatment was given. However, clinical scabies did develop in 2 calves naturally exposed to P ovis-infested, ivermectin-treated calves at 10 days after treatment was given subcutaneously (200 µg/kg).

Psoroptes ovis was transmitted to stanchioned cattle manually exposed to 200 to 300 ml of hair and skin scrapings from infested, ivermectin-treated cattle at 6, 10, 12, 14, and 16 days after treatment was given subcutaneously (200 µg/kg). Scabies did not develop in cattle exposed to skin scrapings obtained from infested, treated cattle at 18 and 20 days after they were treated with ivermectin.

The 14-day isolation of P ovis-infested, ivermectin-treated cattle from susceptible cattle recommended by the US Department of Agriculture, although marginal, is adequate under natural conditions to prevent transmission of scabies from treated to noninfested cattle.
Herd evaluation of Fasciola hepatica infection levels in Louisiana cattle by an enzyme-linked immunosorbent assay
Authors: Welch R. D. , Smith P. H. , Malone J. B. , Holmes R. A. , Geaghan J. P.
Published: February 2025

An enzyme-linked immunosorbent assay (elisa) was evaluated as a method of determining relative immunoconversion rates in calves and how immunoconversion rates and strength of optical density values correlate with prevalence of Fasciola hepatica fecal egg shedding. Ten to 55 calves and cows were examined from each of 10 separate beef cattle herds in central and southern Louisiana. Infection prevalence rates for calves averaged 8% higher when elisa optical density values were used than those when fecal egg count data were used. Of 55 calves in 8 herds that were elisa positive, 39 were shedding F hepatica eggs; of 53 calves that were shedding eggs, 14 were elisa negative. Significant correlation of calf fecal and elisa prevalence was observed for 8 herds by linear regression analysis. A χ2 analysis showed that calf elisa and fecal egg shedding data were not independent. Results indicate that positive elisa reactions for as few as 10 to 15 calves from the fall calf crop of a given herd are sufficiently accurate to be used to assess F hepatica herd infection rates, the likelihood of liver condemnations at feedlot destinations, and variation between individual farms in fascioliasis infection risk. The test was less valuable as a diagnostic test when used in adult animals previously exposed to F hepatica or on an individual animal basis.
Ormetoprim-sulfadimethoxine in cattle: Pharmacokinetics, bioavailability, distribution to the tears, and in vitro activity against Moraxella bovis
Authors: Wilson W. David , George Lisle W. , Baggot J. Desmond , Adamson Peter J. W. , Hietala Sharon K. , Mihalyi Judy E.
Published: February 2025

The pharmacokinetics, bioavailability, and distribution to the tears of ormetoprim (omp; 5.5 mg/kg of body weight) and sulfadimethoxine (sdm; 27.5 mg/kg of body weight) were determined following iv or oral administration to 6 Holstein steers. After iv administration, the disposition kinetics of both drugs were best described by a 2-compartment open model. Sulfadimethoxine had a moderately rapid distribution phase, followed by a slower elimination phase, with a mean half-life (t½) of 7.91 hours. The mean volume of distribution of sdm was 185 ml/kg, and the mean body clearance was 0.28 ml/min·kg. The concentration of sdm in tears was lower than the corresponding plasma concentration, and the elimination of sdm from tears (t½ = 3.02 hours) was significantly faster than its elimination from plasma (t½ = 7.91 hours). The disposition of omp administered iv was characterized by a rapid distribution phase, followed by a rapid elimination phase (t½ = 1.37 hours). The high values of the mean volume of distribution (1,450 ml/kg) and mean rate of body clearance (13.71 ml/min·kg) indicated that omp was widely distributed in the body and was rapidly cleared from the body. Ormetoprim concentrations in tears exceeded corresponding plasma concentrations, and the elimination of omp from tears was significantly slower (t½ = 1.91 hours) than from plasma (t½ = 1.37 hours).

After oral administration of an omp-sdm combination in bolus form, the absorption of sdm was slow (absorption t½, = 3.32 hours), but complete. Systemic availability was 56.6% during the first 24 hours and we estimated that the drug would eventually be completely (100%) absorbed. Sulfadimethoxine concentrations in tears were low (< 2.5 µg/ml). Absorption of omp was too poor to determine systemic availability. Peak plasma concentrations of omp exceeded 0.5 µg/ml in only 1 steer and detectable tear concentrations of omp were not achieved in any of the steers evaluated.

The antimicrobial susceptibility of Moraxella bovis was evaluated in vitro. The 13 isolates evaluated were highly susceptible to the omp-sdm combination (minimum inhibitory concentration [mic] ≤ 0.25/4.75 µg/ml]. Susceptibility of M bovis to sdm alone was inconsistent, with an mic range of 1 to 16 µg/ml. All isolates were resistant to omp alone at concentrations of ≤ 2 µg/ml. After iv administration of sdm, tear concentrations of sdm that exceeded the mic of sdm alone for susceptible isolates were maintained for < 2 hours. Based on the data derived from the 2 studies in which sdm or omp alone were administered iv, we estimated that if sdm and omp had been administered simultaneously iv, tear concentrations of the omp-sdm combination that exceeded the mic of all 13 M bovis isolates would have been maintained for 6 hours. Oral administration of the omp-sdm combination did not result in inhibitory concentrations of the drugs in tears.
Determination of thyroxine, triiodothyronine, and Cortisol changes during simultaneous adrenal and thyroid function tests in healthy dogs
Authors: Moriello Karen A. , Halliwell Richard E. W. , Oakes Matt
Published: February 2025

Changes in thyroxine (T4), triiodothyronine (T3), and Cortisol during a combined adrenal (dexamethasone suppression/adrenocorticotrophic hormone response test) and thyroid function tests (thyroid-stimulating hormone [tsh] response test) were determined in 20 healthy hospitalized pet dogs. The effect of dexamethasone on T4 and T3 changes was evaluated during a simultaneous tsh response/dexamethasone suppression adrenocorticotrophic hormone response test. Greater ranges in basal Cortisol concentrations and slower changes after dexamethasone was administered were observed in healthy pet dogs kenneled in a hospital setting than those reported for conditioned laboratory dogs. Pet dogs were observed to demonstrate Cortisol suppression more reliably at 4 hours than at 2 hours after dexamethasone was administered. Dexamethasone had no effect on the response to tsh as assessed by T4 and T3 assays, thus supporting the validity of combining adrenal and thyroid response tests in a 5-hour period.
Swine antibody-dependent cellular cytotoxicity against Pseudorabies virus-infected cells
Authors: El-Awar Faisal Y. , Hahn Edwin C.
Published: February 2025

In pseudorabies virus (prv) infection of pigs, antibody-dependent cellular cytotoxicity (adcc) may be an early defense mechanism. Peripheral blood leukocytes (pbl) and pulmonary macrophages mediate adcc activity. Antibody-dependent cellular cytotoxicity against prv-infected target cells was assessed, and the effect of infection of cells having an adcc-effector function was determined. Although pulmonary lavage cells (plc) had adcc activity, in vitro infection of plc led to prv replication, loss of cell viability, and loss of adcc activity. In contrast, infection of pbl did not lead to replication, decreased cell viability, or reduced adcc activity, compared with those in non-infected controls. Measuring adcc activity in a longitudinal study revealed that pbl from neonates had lower adcc activity than did pbl from pigs > 3.5 months old. Peripheral blood leukocytes and not plc may have a greater role in control of prv dissemination in the pig. The difference in activity between cells from neonates and older pigs might explain, in part, the age dependency in the severity of the disease.
Use of hexadimethrine bromide as a heparin-neutralizing agent in canine plasma
Authors: Green R. A. , LaFollette K. A. , Greig B.
Published: February 2025

Hexadimethrine bromide was evaluated as a heparin-neutralizing agent in a simple modification of the activated partial thromboplastin time test in canine plasma. Addition of various amounts of heparin in vitro to canine plasma indicated that heparin could be neutralized by adding 0.5 μg of hexadimethrine bromide 15 s before CaCl2 was added to the reaction mixture of the activated partial thromboplastin time test.

In 8 dogs given (subcutaneous injection) 500 USP units of sodium heparin/kg, marked individual variations in clotting time prolongations were observed over the 12-hour period of study. The hexadimethrine bromide modification effectively neutralized the heparin-related clotting time prolongations to values that were not significantly different from base-line (preheparin) activated partial thromboplastin time values. The modification seems to be useful in confirming the presence of heparin and in monitoring heparin therapy in dogs.
Ultrastructural and microprobe analysis of simian lung mite pigments
Authors: Kim James C. S. , Cole Richard
Published: February 2025

Using light microscopy, polarizable amorphorous bodies with tinctorial characteristics of lipochromes and flocculent pigmental materials were found within the alveolar macrophages and peribronchiolar region of the lungs in a pig-tailed macaque (Macaca nemistrina) infected with simian lung mite (Pneumonyssus simicola). Examination of these pigmental bodies, using a high-voltage (1.2 meV) electron microscope and an energy-dispersive X-ray analysis system, indicated that the pigmental bodies contained a high concentration of silica. One female adult P simicola also was examined, and its digestive tract had visible, polarizable pigment and a high concentration of silica. Thus, lesions associated with lung mite infection in Old World monkeys may be superimposed by this silicotic condition, which may be associated with their arid, dusty, environment. Therefore, until the link between lung mite infection and silicosis is clarified, experimental inhalation toxicologic findings in mite-infected Old World monkeys should be interpreted cautiously.
In vitro characterization of porcine juvenile articular cartilage
Authors: Lamar C. H. , Eller L. L. , Turek J. J.
Published: February 2025

Dispersed cell cultures were established from the articular cartilage of the proximal portion of the humerus of young pigs. Articular and epiphyseal portions of the cartilage were separated, minced, and enzymatically dispersed, using bacterial collagenase. Morphologically, 2 cell types were observed, using phase-contrast microscopy. Smaller polygonal cells (32.5 ± 3.5 μm diameter) containing cytoplasmic granules were found in both areas of the cartilage. In cultures from the articular region, cells grew as monolayer cultures and initially did not demonstrate contact inhibition. In cultures from the epiphyseal region, cells grew in a multilayered manner in a colonial arrangement with cells being released from the center of the colony into the culture medium. Small granular particles (0.03 to 0.08 μm diameter) were secreted by cells in both culture systems. Particle secretion was greater in epiphyseal cultures than in articular cultures with the rate decreasing as confluency was approached. These particles stained positively for lipid and alkaline phosphatase. Acridine orange was also incorporated into the granules. The 2nd cell type, a stellate-shaped cell (60 ± 7.6 μm diameter), was found mainly surrounding the outside of colonial areas in epiphyseal cultures. These cells did not secrete small granular particles and stained positive for factor VIII.

Evaluation of cultures by scanning and transmission electron microscopy further supported the presence of 2 cell types. With scanning electron microscopy, the smaller polygonal cell was characterized by varying sizes of blebs (0.03 to 0.1 μm diameter) associated with the cell membrane and small cytoplasmic processes projecting from the cell's surface. Stellate-shaped cells presented a smooth-appearing cell surface. Using transmission electron microscopy, smaller cells were shown to contain a nonmembrane-bound, finely granular-to-amorphous cytoplasmic material reacting positively for proteoglycans. Blebs seen with a scanning electron microscope contained small vesicles (0.07 to 0.2 μm diameter). Ultrastructural evaluation of vesicles isolated from the culture medium by ultracentrifugation revealed particles morphologically similar to matrix vesicles.
Importance of the medullary macrophage in the replication of lymphoid leukosis virus in the bursa of Fabricius of chickens
Authors: Gilka F. , Spencer J. L.
Published: February 2025

Electron microscopy and immunocytochemistry were used to study the development of lymphoid leukosis virus infection in the bursa of Fabricius of experimentally infected chicken embryos and chickens. In embryos infected at 7 days of incubation and killed 10 days later, virus particles and group-specific viral antigen were confined mainly to the connective tissue of the lamina propria of the bursal mucosal folds; a few developing follicles had discrete virions and group-specific antigen between cells. In chickens infected at 1 day of age, infection (as determined by use of electron microscopy and immunocytochemistry) was maximal in 1- to 4-month-old birds, and the greatest concentration of virus and group-specific viral antigen was in the medulla of the follicles. Although lymphoid leukosis virus was released from lymphocytes, epithelial cells, and macrophages, virus replication in the medullary macrophages was more active than that in the other cells. Normal medullary macrophages had cell membrane vesicles (50 to 80 nm in diameter) that covered part or all of the cell membrane surface. In infected chickens, virus particles frequently developed within these vesicles. Comparable vesicles were not found on cortical macrophages. Results of the present study indicated that the medullary macrophage was the principal host cell for replication of lymphoid leukosis virus in the bursa of Fabricius of the chicken.
Histopathologic changes in bovine fetuses after repeated reintroduction of a spirochete-like agent into pregnant heifers: Association with epizootic bovine abortion
Authors: Osebold John W. , Osburn Bennie I. , Spezialetti Rosanne , Bushnell Robert B. , Stott Jeffrey L.
Published: February 2025

A spirochete-like organism was found in the plasma of bovine fetuses affected with epizootic bovine abortion (eba). The spirochete-like organism was frequently found in abattoir-collected fetuses as an inapparent infection, and eba was found in cattle on foothill rangeland where the vector tick Ornithodorus coriaceus could repeatedly reintroduce the infectious agent into pregnant cattle (superinfection). Epizootic bovine abortion resembled a naturally acquired superinfection in circumstances where the agent was frequently present in the environment under conditions favoring transmission. Therefore, to determine whether fetal lesions could be experimentally induced in utero, spirochete-like organisms collected from clinically normal fetuses at an abattoir were inoculated iv and subcutaneously into 2 pregnant heifers 5 times over a 4-month period to mimic repeated tick transmission in the field. Macroscopic and microscopic examinations of tissues from 2 cesarean-collected fetuses and from 3 calves born at term with the naturally acquired spirochete infection indicated that the calves had evidence of an infection that caused morphologic changes compatible with immunologic stimulation and mild reticuloendothelial hyperplasia. Compared with findings in the calves, lesions in the superinfected fetuses were more severe, and the lesion distribution in various organs was more extensive. The spirochete-like organism appeared to be a mild pathogen because of its persistence in the host. Clinical disease from the infection may only develop with repeated superinfections. Therefore, a relationship between this microorganism and eba is probable.
Assessment of antibody response of swine infected with Mycoplasma hyopneumoniae by immunoblotting
Authors: Young Theresa F. , Ross Richard F.
Published: February 2025

An immunoblot procedure was used to evaluate porcine antibody response to inoculation with Mycoplasma hyopneumoniae. Mycoplasmas solubilized with sodium dodecyl sulfate were used as antigens. Antibodies to 5 antigens, estimated to be of molecular weight (mol wt) 110,000, 64,000, 50,000, 41,000, and 36,000, were detected in sera collected during the course of induced mycoplasmal pneumonia. Mycoplasma hyopneumoniae antigens, mol wt 110,000, 50,000, 41,000, and 36,000, cross-reacted with M flocculare when antigen prepared from M flocculare or hyperimmune serum against it were used in the immunoblot procedure. The 36,000-dalton (D) antigen reacted with M hyopneumoniae and M hyorhinis convalescent sera. The 64,000-D M hyopneumoniae antigen was the only antigen that did not cross-react with M flocculare or M hyorhinis. Exposure of immunoblot strips with antigens to trypsin before reacting them with the convalescent sera abolished binding ability of the 110,000-D and 36,000-D antigens, but had no effect on binding by 64,000-D, 50,000-D, or 41,000-D antigens. None of the 5 antigens bound to 11 lectins.
Clinical observations in Collies given ivermectin orally
Authors: Paul A. J. , Tranquilli W. J. , Seward R. L. , Todd K. S. , DiPietro J. A.
Published: February 2025

An oral liquid form of ivermectin was administered to 14 purebred Collies (12 rough coated, 2 smooth coated). All Collies were given ivermectin at dosages of 100 and then 200 μg/kg of body weight. Three of the dogs developed mild clinical signs of toxicosis (salivation, vomiting, confusion, ataxia, and tremors) with the 100 μg/kg dosage. After the 200 μg/kg dosage, 7 dogs (including 1 smooth-coated Collie) developed severe toxicosis (seizurelike activity, recumbency, nonresponsiveness, and coma). Because dogs that developed severe toxicosis were not retreated, only the 7 remaining dogs were given ivermectin at 600 μg/kg. Severe toxic signs were not observed in the dogs given the 600 μg/kg dosage, and only 1 of these 7 dogs developed severe toxicosis when given ivermectin at 2,500 μg/kg. Dogs that developed severe toxicosis were given supportive care while in the comatose state. All dogs recovered completely. The results indicated that Collies (including the smooth-coated Collies) have a wide range of sensitivity to ivermectin-induced toxicosis.
Experimental infection of lactating bovine mammary glands with Streptococcus uberis in quarters colonized by Corynebacterium bovis
Authors: Doane R. M. , Oliver S. P. , Walker R. D. , Shull E. P.
Published: February 2025

Twenty-seven quarters of 18 lactating dairy cows were inoculated intramammarily with 3.6 − 104 colony-forming units (cfu) of a strain of Streptococcus uberis isolated from a cow with clinical mastitis. Before quarters were inoculated, 22 were considered as naturally colonized with Corynebacterium bovis, and 5 were considered bacteriologically negative. Streptococcus uberis was isolated from all quarters within 2 days after inoculation, and all quarters developed clinical mastitis by 3 days after inoculation. Mastitis was acute, and most cows had increased rectal temperatures. The number of somatic cells increased significantly (P < 0.05), and milk production decreased significantly. In many cows, rectal temperatures remained increased, and Str uberis was isolated from infected glands after intramammary and systemic antimicrobial treatments were given.

A decreased number (110 cfu) of the same strain of Str uberis caused equally severe mastitis in 3 quarters colonized with C bovis and in 1 bacteriologically negative quarter in 2 cows. Streptococcus uberis was isolated from all inoculated quarters, and all quarters developed clinical mastitis by 2 days after inoculation.

Two quarters colonized with C bovis and 2 bacteriologically negative quarters were inoculated once with 25 cfu and once with 240 cfu of a different strain of Str uberis (ATCC 27958). Streptococcus uberis was never isolated from inoculated quarters, and changes in milk yield or number of somatic cells were not observed.
Second-generation pseudorabies virus vaccine with deletions in thymidine kinase and glycoprotein genes
Authors: Kit Saul , Sheppard Michael , Ichimura Hiroshi , Kit Malon
Published: February 2025

A modified-live Pseudorabies virus (prv) vaccine, designated prv(dlg92/dltk), with deletions in the thymidine kinase (tk) and glycoprotein-gIII (g92) genes, was derived from the prv (Bucharest [BUK]-dl3) vaccine strain. The vaccine virus also contained a deletion in glycoprotein gI. Despite 3 deletions, prv(dlg92/dltk) replicated to high titers in cell culture from 30 C to 39.1 C. Enzyme assays and autoradiography revealed that prv(dlg92/dltk) did not induce a functional tk activity in infected tk−RAB(BU) cells (rabbit skin).

Rabbit skin cells were infected with prv(dlg92/dltk), with vaccine strains derived from BUK or Bartha K strains of prv or with the virulent Illinois (ILL), Indiana-Funkhauser (IND-F), and Aujeszky (Auj) strains of prv and were labeled with [3H]mannose from 4 or 5 to 24 hours after infection to investigate whether these viruses induced the synthesis of glycoprotein gIII. Nonionic detergent extracts were prepared and immunoprecipitated with antisera from pigs vaccinated with tk−-prv(BUK-dl3) or tk+-Bartha K, pigs vaccinated with tk+-prv(BUK) strains and then challenge exposed to tk+-prv(IND-F), naturally infected domestic or feral pigs, and pigs vaccinated with tk−-prv(dlg92/dltk). Mouse monoclonal antibodies against prv glycoproteins gIII, gp50, and gII were also studied. After immunoprecipitation, labeled prv-specific proteins were analyzed by sodium dodecylsulfate-polyacrylamide gel electrophoresis and autoradiography. The prv glyco-protein-gII complex, but not glycoprotein gIII, was synthesized in prv(dlg92/dltk)-infected cells. Glycoprotein gII and gIII were made in cells infected with prv vaccine strains BUK, Bartha K, and BUK-dl3 and with virulent prv strains ILL, IND-F, and Auj. Cells infected with prv(dlg92/dltk) and with prv strains ILL, IND-F, Auj, Bartha K, BUK, and BUK-dl3, excreted into the cell culture medium a highly sulfated glycoprotein gX of about 90 kilodaltons. Antibodies to glycoprotein gIII were not detected in the sera of pigs inoculated with prv(dlg92/dltk), but were found in all other swine sera.
Effect of prostaglandin E1 on the periosteal regional acceleratory phenomenon in fractured ribs: Histomorphometric study in Beagles
Authors: Shih Mei-Shu , Norrdin Robert W.
Published: February 2025

Transverse fractures were made surgically in the midshaft of the left 9th and 10th ribs in adult Beagles. A buffer vehicle (n = 4) or 0.2 mg of prostaglandin (pg) e1/day (n = 6) was injected into the fracture sites twice a day for 10 days, and dogs were euthanatized on day 30. Double-pulsed fluorescent labels were given with each of 2 fluorochrome markers—calcein before surgical treatment and Oxytetracycline HCl before euthanasia. Histomorphometric analysis was carried out on specimens collected in adjacent regions of the healing defects.

The surface extent and width of the osteoid on fractured (P < 0.01, P < 0.05, respectively) and nonfractured (P < 0.05) sites in the treated group were greater than those in the nontreated group. The net loss of mineralizing surfaces was noticed on both ribs of both groups. Of 11 samples on the fractured side in the treated group, 4 contained periosteal new bone proliferation. There was increased osteoid formation and decreased mineralizing surfaces in the pge1-treated group. Seemingly, administration of pge1 induced bone matrix formation on periosteal envelope adjacent to a fracture site and its contralateral matching site.
Logarithmic normal distribution of incubation times for canine diseases (Sartwell's model)
Authors: Glickman Lawrence T. , Lee Lisa A. , Cohen Noah D.
Published: February 2025

The distribution of incubation periods for most infectious diseases follows a logarithmic normal distribution (Sartwell's model). The same is true for human neoplastic diseases of known cause and for genetic diseases, when the age at onset of the disease was used as a surrogate measure of the incubation period. In this study, a similar distribution was observed when Sartwell's model was applied to canine diseases of known genetic cause, but not to diseases of an environmental cause. The model was also applied to canine diseases of suspected multifactorial causes for the purpose of distinguishing between the relative importance of genetic and environmental factors that act before or after birth. Limitations of this method were discussed.
C-reactive protein in dogs
Authors: Caspi D. , Snel F. W. J. J. , Batt R. M. , Bennett D. , Rutteman G. R. , Hartman E. G. , Baltz Marilyn L. , Gruys E. , Pepys M. B.
Published: February 2025

Serum concentrations of C-reactive protein (crp) in dogs with various diseases or undergoing various procedures were measured by specific immunoassay. In 20 healthy dogs from various sources, values were all < 5 mg/L, but in 22 healthy dogs from a single source, values ranged from < 5 mg/L in 14 dogs and from 8 to 67 mg/L in 8 dogs. Increased concentrations of serum crp were attained 24 hours after injection of casein (n = 9; median 188 mg/L), ovariohysterectomy (n = 11; median, 144 mg/ L), or elective, nonacute orthopedic surgery (n = 10; median, 83 mg/L). After inoculation of Leptospira interrogans serovar canicola (n = 5), the behavior of serum crp as an acute-phase reactant provided a sensitive and precise objective reflection of in vivo response. The crp concentration in random single-serum samples from 73 dogs with other inflammatory and noninflammatory disorders ranged from normal (< 5 mg/L) to 246 mg/L and generally correlated with the extent and activity of disease.
Time-related responses of spontaneously breathing, laterally recumbent horses to prolonged anesthesia with halothane
Authors: Steffey E. P. , Kelly A. B. , Woliner M. J.
Published: February 2025

Cardiovascular and respiratory functions were serially evaluated in ten healthy, fasting, spontaneously breathing, laterally recumbent adult horses during five hours of constant 1.06% alveolar halothane (equivalent to 1.2 times the minimum alveolar concentration for horses). Mean carotid arterial pressure was about 25% higher after one hour of constant-dose halothane than after 30 minutes of constant-dose (P < 0.05), and remained increased throughout the study. Mean carotid arterial pressure peaked after 90 minutes, and was about 30% higher than at 30 minutes. Total peripheral vascular resistance initially increased (20% at one hour), then gradually returned to the 0.5-hour value over the next four hours. Cardiac output progressively increased with time (P < 0.05; 20% by two hours; nearly 40% by five hours) because of an increase in stroke volume. An increase (P < 0.05) in mixed venous PO2 accompanied the increase in cardiac output. Heart rate did not change significantly (P > 0.05). Some measures of ventilation changed significantly with time (P < 0.05). After four and five hours of constant alveolar halothane, the Paco2, inspired gas flow, and ratio of inspired vs expired gas flow were significantly higher than the 0.5-hour values. Inspiratory time significantly decreased, beginning at three hours. All horses recovered from anesthesia and recumbency without complications.
Mixed venous oxygen tension as an estimate of cardiac output in anesthetized horses
Authors: Wetmore L. A. , Derksen F. J. , Blaze C. A. , Eyster G. E.
Published: February 2025

The relationship between mixed venous O2 tension and cardiac output was studied in six anesthetized horses breathing 100% O2. Cardiac output, O2 consumption, mean arterial pressure, heart rate, and arterial and venous blood gases were measured after administration of xylazine or dobutamine to horses in lateral, sternal, and dorsal recumbencies. After approximately 3 hours, Escherichia coli endotoxin was administered while horses were in dorsal recumbency, and all measurements were repeated. Relationships between cardiac index (ci) and Pvo2, heart rate, mean arterial pressure, jugular Pvo2, and Pvo2 of blood from a superficial limb vein were evaluated by linear regression analysis. Mean arterial pressure was significantly (P < 0.05) correlated with ci in horses in all positions and after endotoxin administration. However, data points were poorly grouped. Heart rate and ci were significantly correlated in horses in all positions, but not after endotoxin administration. Correlations between jugular Pvo2 and Pvo2 of blood from a superficial limb vein were not significant in horses in sternal recumbency, and Pvo2 of blood from a superficial limb vein was not significantly correlated with ci in horses in lateral recumbency. There was a significant and tight correlation between Pvo2 and ci in horses in all positions and after endotoxin administration.
Dental dolorimetry for the evaluation of an analgesic agent in the horse
Authors: Brunson D. B. , Collier M. A. , Scott E. A. , Majors L. J.
Published: February 2025

A monopolar electrode was implanted surgically in the canine tooth dentine layer to evaluate pain threshold responses of horses. A constant-current stimulator was used to deliver a known electrical current to the tooth pulp nerve. A single stimulus of 2-ms duration, repeated at ≥ 20-s intervals, was used to elicit a head lift response. The lowest current level that produced 3 positive head lift responses was recorded as the pain threshold of the horse.

The testing technique, dental dolorimetry, was easily performed. Tooth pulp pain thresholds (tppt) were established on 8 nonmedicated adult male horses. Electrodes were nonreactive and remained functional for up to 98 days. Base-line tppt values were consistent with repeated measurements on the same day and measurements on subsequent test days. The quantity of electrical current necessary to elicit the tppt was increased after administration of xylazine HCl as a test analgesic.
Evaluation of an antigenic fraction of Taenia hydatigena metacestode cyst fluid for immunodiagnosis of bovine cysticercosis
Authors: Kamanga-Sollo Ernest I. P. , Rhoads Marcia L. , Murrell K. Darwin
Published: February 2025

An antigenic fraction (ThFAS) isolated from Taenia hydatigena metacestode cyst fluid was used in an elisa to detect antibodies to T saginata in experimentally and naturally infected cattle. In 10 calves given 1,000 to 100,000 T saginata eggs (20% to 60% viability), IgG and IgM antibodies were detected in all the calves by post-inoculation week 3. Immunoglobulin G antibody values remained increased until calves were slaughtered at post-inoculation weeks 13 to 26. Six naturally infected calves (determined by postmortem examination) were considered positive, using the elisa. Shared antigens were demonstrated between ThFAS and T saginata and T crassiceps; there were no shared antigens between ThFAS and Haemonchus contortus or Fasciola hepatica. Specific lectin binding to ThFAS indicated the presence of glycoconjugates. Immunoblot analysis indicated that a low molecular weight polypeptide (10,000 Mr) bears the immunodiagnostic antigen.
Immunoperoxidase evaluation of pneumonic lesions induced by Pasteurella haemolytica in calves
Authors: Haritani M. , Nakazawa M. , Oohashi S. , Yamada Y. , Haziroglu R. , Narita M.
Published: February 2025

Calves inoculated with Pasteurella haemolytica serovar 1 developed lesions of coagulation necrosis in the lungs that were sharply demarcated by leukocytes. The P haemolytica antigen was detected in the area of coagulation necrosis in histologic sections, using an immunoperoxidase technique. In the central area of the necrotic tissue, the bacterial antigen was diffusely presented in the necrotic alveolar wall, fibrin, serous exudate, and degenerated leukocyte. The bacterial antigen also was found in some groups of degenerating leukocytes around the necrotic tissue. The bacterial colonies among these leukocytes had strong specific reactions against P haemolytica. The bacterial antigen was observed in the cytoplasm of macrophages in alveoli around the necrotic lesion. These findings confirmed that coagulation necrosis is an important lesion in calves with pneumonia caused by P haemolytica.