bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of phagocytosis and chemiluminescence by blood and mammary gland neutrophils from multiparous and nulliparous cows
Authors: Dulin Anne M. , Paape Max J. , Nickerson Stephen C.
Published: February 2025

Neutrophils were isolated from the blood and mammaiy gland of 3 multiparous lactating cows and 3 nulliparous heifers. Neutrophil function was evaluated by phagocytosis and luminol-dependent chemiluminescence. Peroxidase activity was detected by use of transmission electron microscopy. Compared with that for blood neutrophils, percentage of phagocytosis was 9.6% lower for neutrophils isolated from the mammary gland of lactating cows, but this difference was not observed between neutrophils isolated from the mammary gland and from the blood of heifers. Similarly, after subtraction of chemiluminescence values in the absence of zymosan, phagocytosing neutrophils from the mammary gland of lactating cows had lower chemiluminescence than did those from the blood of such cows. For heifers, however, chemiluminescent activity by phagocytosing neutrophils obtained from the mammary gland was similar to that of blood neutrophils. Chemiluminescent activity of resting neutrophils from the mammary gland of lactating cows pretreated with cytochalasin B was not inhibited, compared with that of nontreated resting neutrophils (controls). This was attributed to xanthine oxidase activity. Transmission electron microscopy of mammary gland neutrophils from lactating cows revealed peroxidase-positive material associated with milk-fat globule membranes and with phagosomes containing zymosan. Results indicated that ingestion of fat and casein by neutrophils isolated from milk caused a decrease in phagocytic and chemiluminescent activity. Also, luminol-dependent chemiluminescence was not a reliable measure of milk neutrophil function, because of interference by xanthine oxidase.
Effect of transport on feeder calves
Authors: Cole N. A. , Camp T. H. , Rowe L. D. , Stevens D. G. , Hutcheson D. P.
Published: February 2025

One hundred fifty feeder steers (mean body weight, 195 kg) were assigned to 1 of 3 transport groups and were deprived of feed and water (fasted) for 24 hours. Additionally, calves were transported on a commercial livestock trailer for 0 (control—fasted only), 12 (short haul), or 24 (long haul) hours. Blood samples were obtained from the jugular vein before calves were loaded on the transport vehicle and immediately after calves of the long-haul group returned to the research feedlot. Complete blood counts were performed and 32 mineral, enzyme, and biochemical constituents were measured. Calf morbidity, mortality, and average daily weight gain were evaluated during the next 56 days. Duration of transport did not affect average daily gain; however, calves of the short-haul group had significantly (P < 0.05) higher morbidity and mortality than did those of the control and long-haul groups. In all groups, results of differential leukocyte counts were indicative of stress response. Significant (P < 0.05) linear contrasts were observed between duration of transport and erythrocyte, leukocyte, segmented neutrophil, lymphocyte, and eosinophil counts and results of serum enzyme (alanine transaminase, hydroxybutyrate dehydrogenase, total lactate dehydrogenase [ld], and ld-1, ld-3, and ld-4 isoenzymes), iron, urea nitrogen, β-globulin, glucose, and urea nitrogen-to-creatinine ratio determinations. Significant (P < 0.05) quadratic contrasts were observed between duration of transport and serum unsaturated iron binding capacity, total iron binding capacity, and ld-5 percentage. Calf source had a significant (P < 0.05) effect on almost all variables tested. Results indicated that transport is a stressful event to feeder calves; however, other factors, possibly related to the timing of stress events or adaptation to several different stressors during a short period, may have a greater effect on feeder calves' subsequent health.
Yohimbine increases plasma insulin concentrations and reverses xylazine-induced hypoinsulinemia in dogs
Authors: Hsu Walter H.
Published: February 2025

Xylazine (1.1 mg/kg of body weight, iv), an α2-adrenoreceptor agonist, suppressed the increase in plasma insulin concentration induced by glucose (0.6 g/kg, iv) in dogs. Yohimbine (0.11 mg/kg, iv), an α2-adrenoreceptor antagonist, given 5 minutes after xylazine, reversed effects of xylazine, whereas yohimbine alone increased plasma insulin and decreased plasma glucose concentrations. Seemingly, α2-adrenoreceptors exert a negative control of insulin release.
Maternal and fetal toxicity of poison hemlock (Conium maculatum) in sheep
Authors: Panter K. E. , Bunch T. D. , Keeler R. F.
Published: February 2025

Poison hemlock (Conium maculatum) was toxic to pregnant ewes and their fetuses when fed during gestation days 30 through 60. Maternal effects included trembling, muscular weakness in the neck initially, then progressing to the limbs, ataxia, frequent urination and defecation, and death. Convulsive seizures were not observed. Fetotoxic effects included excessive flexure of the carpal joints with lateral deviation in the front limbs and kinked tails. At term, 7 of 11 lambs had varying degrees of the limb abnormalities, but all lambs appeared clinically normal at 8 weeks after parturition.
Borreliosis in equids in northeastern United States
Authors: Magnarelli Louis A. , Anderson John F. , Shaw Eric , Post John E. , Palka Frank C.
Published: February 2025

During 1982 and 1985, blood samples from 705 equids were examined for antibodies to Borrelia burgdorferi. By indirect immunofluorescence staining, IgM and total immunoglobulin (IgM and IgG) antibodies were detected in 37 (5.3%) and 90 (12.8%) serum specimens, respectively. The geometric mean titer for IgM antibody (140.4) was highest during July, whereas total immunoglobulin ranged from 94.1 in October to 338 in May. Eighty-six equids with total immunoglobulin to B burgdorferi lived in areas of Connecticut where the primary tick vector, Ixodes dammini, was present. Of the 86 equids, 9 from Lyme, Connecticut and Westchester County, New York had antibodies to B burgdorferi and developed limb or joint disorders that resulted in single or recurrent episodes of lameness.
Serum proteins of neonatal pigs orally inoculated with Isospora suis oocysts
Authors: Jarvinen Julie Ann C. , Zimmerman Gary L. , Schons Debra J. , Guenther Christine
Published: February 2025

Serum proteins were evaluated by agarose electrophoresis at periodic intervals between postinoculation days (pid) 2 and 35 in 4 litters of pigs inoculated orally at 36 to 38 hours of age with 70,000 sporulated Isospora suis oocysts and in 4 litters of age-matched noninoculated control pigs. In inoculated pigs, clinical disease characterized by vomiting and diarrhea began at pid 3 to 4 and was resolved by pid 11. Isospora suis oocysts were detected in feces of inoculated pigs from pid 5 to 25, with peak numbers present on pid 5 to 6. Of 43 pigs inoculated with I suis oocysts, 4 (9.3%) died of coccidiosis, and samples were not obtained for serum protein evaluation. Of 39 noninoculated control pigs, all remained clinically normal, and I suis oocysts were not detected in their feces.

Serum protein fraction values in inoculated and control groups compared at each sample collection time did not differ significantly, except at pid 15, when β-globulin values were lower in inoculated pigs (P = 0.02). At pid 35, total serum proteins, albumin, and α1-, β-, and γ-globulin values of inoculated pigs were lower than those of controls, but there were too few pigs examined for definitive statistical analysis. Differences in trends over time were observed between inoculated and control groups for several serum protein fractions. In inoculated pigs, total proteins (P < 0.1) and β-globulins (P < 0.01) decreased with time, whereas those of control pigs increased. Similar differences in trends were noticed for albumin and α1-globulins, but these were not significant. For individual inoculated pigs, there was a significant positive relationship between the number of I suis oocysts per gram of feces and γ-globulin values (P < 0.001), as well as a negative relationship between oocyst numbers and α1-globulin values (P < 0.01). Age-related changes in serum protein values also were confirmed.
Effect of butorphanol, pentazocine, meperidine, or metoclopramide on intestinal motility in female ponies
Authors: Sojka Janice E. , Adams Stephen B. , Lamar Carlton H. , Eller Lisa L.
Published: February 2025

Effect of butorphanol, pentazocine, meperidine, and metoclopramide on jejunal and pelvic flexure myoelectric and mechanical activity in 4 female ponies was investigated. The agent to be tested or saline solution was administered iv at the start of a 6-hour recording trial. In the jejunum, duration between activity fronts of regular spiking activity, defined as the length of the migrating myoelectric complex (mmc), was measured. The average duration of the mmc during control trials was 150 ± 46 minutes. The average duration of the mmc after meperidine, butorphanol, pentazocine, and metoclopramide administration was 295 ±70 minutes, 260 ± 60 minutes, 275 ± 60 minutes, and 163 ± 64 minutes, respectively. Meperidine, butorphanol, or pentazocine significantly increased the mmc duration (P < 0.05), and did not significantly alter the pelvic flexure activity. Seemingly, meperidine, butorphanol, and pentazocine inhibited cyclic myoelectric activity in the jejunum. Metoclopramide had no effect on jejunal or pelvic flexure motility.
Pharmacokinetics of gentamicin in cats given Escherichia coli endotoxin
Authors: Jernigan Antoinette D. , Hatch Roger C. , Wilson Robert C. , Brown John , Tuler Sheila M.
Published: February 2025

Nineteen cats were given 3 mg of gentamicin sulfate/kg of body weight by rapid iv, sc, or im injection for base-line values. Serum concentration of gentamicin vs time data were analyzed using a noncompartmental model based on statistical moment theory. One week later, each cat was given 0.5 μg of Escherichia coli endotoxin/kg, iv. After cats had an increase in rectal temperature of at least 1 C, 3 mg of gentamicin/kg was administered by the same route used the previous week.

Serum concentration of gentamicin vs time data were analyzed, and pharmacokinetic values were compared with base-line values. For iv studies, the half-life (t1/2) of gentamicin and the mean residence time were significantly different (P < 0.05) compared with base line, whereas the total body clearance and apparent volume of distribution at steady state were not. The harmonic mean ± pseudo sd for the t1/2 of gentamicin after iv administration was 76.8 ± 12.6 minutes for base line and was 65.2 ± 12.2 minutes in the same cats given endotoxin. The t1/2 of gentamicin after sc administration was 74.6 ± 6.2 minutes for base line and was 65.2 ± 13.6 minutes in the same cats given endotoxin. After im administration, the t1/2 of gentamicin was 60.3 ± 10 minutes for base line and was 59.7 ± 13.6 minutes in the same cats given endotoxin.

After iv administration of gentamicin, the arithmetic mean ± sd for the mean residence time was 102.4 ± 16.1 minutes for base line vs 79.2 ± 18.4 minutes in the same cats given endotoxin. The volume of distribution at steady state was 0.20 ± 0.03 L/kg for base line and was 0.19 ± 0.02 L/kg in the same cats given endotoxin. Total body clearance was 2 ± 0.2 ml/min/kg for base line and 2.6 ± 0.7 ml/min/kg in the same cats given endotoxin. A recommended dosage of 3 mg of gentamicin/kg administered every 8 hours iv, im, or sc was calculated on the basis of pharmacokinetic values.
Plasma and synovial fluid concentrations of gentamicin in horses after intra-articular administration of buffered and unbuffered gentamicin
Authors: Lloyd K. C. Kent , Stover Susan M. , Pascoe John R. , Baggot J. Desmond , Kurpershoek Cornelis , Hietala Sharon
Published: February 2025

The concentration of gentamicin in plasma and synovial fluid of normal adult horses was measured periodically for 24 hours after iv (2.2 mg/kg of body weight), intra-articular (ia; 150 mg), and simultaneous iv and ia administrations. Gentamicin also was buffered with sodium bicarbonate (3 mEq) and then was administered ia and simultaneously iv and ia. Synovial fluid specimens were obtained via an indwelling catheter placed into the antebrachiocarpal joint.

The peak mean plasma gentamicin concentration (8.30 μg/ml) after iv administration was significantly (P < 0.05) greater than that (0.69 μg/ml) after ia administration of gentamicin and that (0.55 μg/ml) after administration of gentamicin buffered with sodium bicarbonate. Gentamicin concentration greater than a therapeutic concentration was not attained in the plasma after ia administration of buffered or unbuffered gentamicin.

The peak mean synovial fluid concentration (1,828 μg/ml) after ia administration of unbuffered gentamicin was significantly (P < 0.05) greater than that (2.53 μg/ml) after iv administration and significantly (P < 0.05) less than that (5,720 μg/ml) after simultaneous iv and ia administration. The peak mean synovial fluid concentration after ia administration of buffered gentamicin, with and without simultaneous iv administration (2,128 and 2,680 μg/ml, respectively), was not significantly different than that after ia treatment with unbuffered gentamicin. Mean synovial fluid concentration did not differ significantly between groups after ia administration of gentamicin in any combination at postinjection hours 8, 12, and 24, but remained significantly (P < 0.05) greater than that at the same times after iv administration.

The mean apparent half-life of gentamicin in the synovial fluid after ia administration (259 minutes) was 2.8 times longer than that in the plasma after iv administration (92 minutes). The mean volume of distribution of gentamicin after iv administration was 297 ml/kg. The mean clearance of gentamicin from the plasma after iv administration was 2.18 ml/min/kg; the mean clearance from the synovial fluid (not normalized for body weight) after ia administration was 1.22 ml/min. Further, the mean synovial fluid concentration of gentamicin remained well above the minimal inhibitory concentration of gentamicin for many common equine bacterial pathogens for 24 hours after ia administration of gentamicin in any combination.
Comparison of an enzyme-linked immunosorbent assay and a complement-fixation test for the detection of IgG to bovine herpesvirus type 4 (bovine cytomegalovirus)
Authors: Guo W. Z. , Shen D. T. , Evermann J. F. , Gorham J. R.
Published: February 2025

An indirect elisa for the detection of bovine immunoglobulin to bovine herpesvirus type 4 (bhv-4) was developed. Three methods of antigen preparation were compared. They included (1) bhv-4-infected Madin Darby bovine kidney (mdbk) cells treated with glycine and then frozen and thawed, (2) bhv-4-infected mdbk cells treated with glycine and then sonicated, and (3) bhv-4-infected mdbk cells treated with a detergent. The antigen preparation that gave the highest reactivity was the first method. We obtained serum samples from 178 cattle in the field and assayed the serum by elisa and the complement-fixation (cf) test. Eighty-six percent (153) of the serum samples were positive by elisa, and 70% (124) were positive by the cf test. The elisa had a higher degree of sensitivity than did the cf test. Also, the elisa was specific, and the prevalence of bhv-4 infection was more common in beef and dairy herds than previously recognized.
Effects of infection with parainfluenza-3 virus and infectious bovine rhinotracheitis virus on neutrophil functions in calves
Authors: Briggs R. E. , Kehrli M. , Frank G. H.
Published: February 2025

Calves were challenge exposed in separate experiments with parainfluenza-3 (pi-3) virus or infectious bovine rhinotracheitis (ibr) virus. Blood neutrophils were assayed for functional activity every other day for at least 3 weeks by random migration, Staphylococcus aureus ingestion, antibody-dependent cell-mediated cytotoxicity, cytochrome-c reduction, iodination, and native chemiluminescence.

Exposure to pi-3 virus resulted in a brief febrile response and no other clinical signs. Alterations in total or differential wbc counts were not detected. Chemiluminescence and iodination activities were reduced from activities before exposure.

Exposure to ibr virus resulted in mild clinical signs and a febrile response of several days' duration. Total wbc and mononuclear cell counts were reduced. Random migration was reduced, whereas S aureus ingestion was enhanced.

We concluded that infection of calves with ibr virus and pi-3 virus might directly or indirectly result in alterations of neutrophil function. The functional alterations apparently are different for each virus. These virus-induced alterations in neutrophil function might predispose calves to secondary bacterial pneumonia.
Histologic lesions in broiler chicks given cyclopiazonic acid orally
Authors: Cullen J. M. , Wilson M. , Hagler W. M. , Ort J. F. , Cole R. J.
Published: February 2025

Cyclopiazonic acid dissolved in corn oil was administered by gavage to broiler chicks (n = 80) daily, from the day of hatching for 23 days. Chicks were assigned to 3 groups (1, 2, or 4 mg of cyclopiazonic acid/kg of body weight); a control group was given corn oil. Each group was composed of 10 male and 10 female chicks. Surviving chicks were euthanatized and necropsied on day 24. Histologic examination revealed that the most common lesions consisted of necrosis and hemorrhage or hyperplasia of the mucosa of the proventriculus and hepatocellular vacuolation. Skeletal muscle degeneration, characterized by myofiber swelling or fragmentation accompanied by an infiltrate of macrophages and heterophils, was detected in the group given 4 mg/kg. This degeneration was associated with an increase of plasma creatine kinase activity. Focal hepatocellular and splenic necrosis also developed in the groups given 4 mg/kg.
Prevalence of ocular microorganisms in hospitalized and stabled horses
Authors: Moore Cecil P. , Heller Nancy , Majors Lynda J. , Whitley R. David , Burgess Elizabeth C. , Weber JoAnne
Published: February 2025

Microorganisms from normal eyes of hospitalized and stabled horses were identified, and the frequency of isolation was compared between the 2 groups. Using standard techniques, swab specimens from both eyes of 22 hospitalized horses and both eyes of 18 stabled horses were cultured for aerobic bacteria and fungi. Ninety-six aerobic bacteria and 57 fungi were isolated. The predominant bacterial isolates were gram-positive organisms, most of which belonged to the genera Corynebacterium, Bacillus, Staphylococcus, and Streptomyces. Gram-negative organisms comprised less than one-fourth of the bacterial isolates, with the genera Neisseria, Moraxella, and Acinetobacter being the most commonly isolated. Environmental fungi Cladosporium and Alternaria accounted for half of all fungal isolates. In only 5 horses were fungi isolated without accompanying isolation of bacteria. The frequency of isolation of fungi was higher (P < 0.01) in stabled horses. For bacteria, the frequency of isolation was higher (P < 0.08) in male horses. Results of susceptibility testing were recorded as the percentage of all isolates susceptible to a given antimicrobic drug. Bacterial isolates were highly susceptible (≥ 90%) to neomycin, polymixin B, gentamicin, and chloramphenicol. Overall, filamentous fungi had highest susceptibility to natamycin (97%). Miconazole was highly efficacious (100% susceptibility) against Fusarium and Aspergillus.
Renal microcirculatory and correlated histologic changes associated with dirofilariasis in dogs
Authors: Ludders J. W. , Grauer G. F. , Dubielzig R. R. , Ribble G. A. , Wilson J. W.
Published: February 2025

Nine 7-month-old Beagle dogs were inoculated with 200 third-stage larvae of Dirofilaria immitis. The development of cardiac disease secondary to heartworm infection was confirmed by thoracic radiography, echocardiography, and angiography with blood pressure measurements. The only indication of renal disease was mild-to-moderate proteinuria. The dogs were euthanatized approximately 18 months after inoculation. The mean microfilarial count in blood at the time of euthanasia was 88,700/ml, with a mean of 89 adult heartworms in the vena cavae, heart, and pulmonary arteries. The kidneys were perfused for microangiographic and correlative histologic examination of the intrarenal microvasculature and associated renal morphologic features.

Angiograms of whole kidneys from 6 dogs revealed attenuation or truncation of the major renal vessels. Microangiograms of all kidney slices revealed attenuation in the microangiographic appearance of the glomerular capillaries. Histologic examination of all kidney slices revealed mild-to-intense, diffuse, chronic interstitial nephritis and generalized membranoproliferative glomerulonephritis. Microfilariae were observed within the glomerular capillaries and the medullary vessels. The microangiographic changes correlated with and were explained in part by the histologic changes in the renal parenchyma.
In vitro depression of bovine lymphocyte function by treatment of cultured bovine lymphocytes with physiologic concentrations of hydrocortisone
Authors: Ojo-Amaize Emmanuel A. , Guidry Albert J. , Paape Max , Mayer Harald K.
Published: February 2025

The effect of hydrocortisone (hydrocortisone sodium succinate) on bovine lymphocyte blastogenesis in response to Staphylococcus aureus antigens and phytohemagglutinin was measured in vitro. Lymphocytes isolated from the blood of cows were treated for 6 to 8 days with physiologic hydrocortisone concentrations known to be inducible by environmental stress (10 ng/ml), acute clinical mastitis (25 ng/ml), or adrenocorticotropin treatment (45 ng/ml). All 3 concentrations of hydrocortisone caused a depression (P < 0.01) in lymphocyte blastogenesis in response to phytohemagglutinin and S aureus antigen extract. Hydrocortisone concentrations as low as 10 pg/ml caused a depression in the lymphocyte blastogenic response to phytohemagglutinin. Marked variation existed among cows in the normal response of their nontreated lymphocytes and in the degree of depression of lymphocyte function after the in vitro treatment with hydrocortisone.

Macrophage depletion experiments showed that the suppressive effect of hydrocortisone was not mediated by induction of suppressor macrophages. The data suggest that T-cell function was impaired directly by hydrocortisone treatment.
Effect of levamisole on immune function and reproductive performance in first-litter gilts
Authors: Purswell B. J. , Dawe D. L. , Brown John , Williams D. J.
Published: February 2025

First-litter commercial cross-bred gilts were treated with levamisole (1.5, 2.5, or 3.5 mg/kg of body weight) weekly during the last 4 weeks of gestation, because similar treatment of dairy heifers had improved postpartum maternal health and neonatal survival. In the gilts, differences in reproductive performance were not found on the basis of pig survival at birth, pig survival at weaning, birth weight, or weaning weight. Also, differences between treated and control gilts were not found in response of circulating lymphocytes to mitogen stimulation (phytohemagglutinin A, concanavalin A, and pokeweed mitogen). In all gilts, the lymphocyte response to mitogen stimulation was decreased during the first week after farrowing.
Aerosolized Micropolyspora faeni antigen as a cause of pulmonary dysfunction in ponies with recurrent airway obstruction (heaves)
Authors: Derksen F. J. , Robinson N. E. , Scott J. S. , Stick J. A.
Published: February 2025

Ponies with recurrent airway obstruction (principal ponies) and their controls were given aerosolized Micropolyspora faeni antigen via endotracheal tube during a period when the principal ponies were in disease remission. In both groups of ponies, we performed bronchoalveolar lavage (bal) and measured pulmonary function at base line, and 5 hours after aerosol administration of 30 ml of 0.9% NaCl solution or 30 ml of 1% w/v particulate M faeni antigen in 0.9% NaCl solution. In both groups of ponies, aerosolized M faeni antigen increased wbc count, neutrophil numbers, and albumin concentration in bal fluid, but macrophage numbers decreased. In the principal ponies, bal mast cell numbers were decreased 5 hours after administration of M faeni antigen. The M faeni antigen had no effect on the mechanical properties of the lungs or on gas exchange in the control ponies, but did increase respiratory frequency minute ventilation and pulmonary resistance, and decreased arterial oxygen tension in the principal ponies.

Changes in pulmonary function were apparent only in the principal ponies, which suggests that neutrophils, per se, do not cause pulmonary dysfunction and that M faeni may be one of the etiologic agents involved in chronic obstructive pulmonary disease.
Anemia of inflammation in dogs infected with Ehrlichia platys
Authors: Baker Dale C. , Gaunt Stephen D. , Babin Shirley S.
Published: February 2025

Ten adult male dogs were inoculated with Ehrlichia platys, and blood samples were collected throughout the infection to evaluate the hematologic changes with respect to serum biochemical analytes. All dogs developed a mild, normocytic, normochromic anemia by postinoculation day 7, with significantly (P < 0.05) decreased serum iron concentration and total iron-binding capacity. Stainable bone marrow iron appeared normal or increased throughout the infection. By postinoculation day 31, the pcv was not significantly different from the pretreatment value. All dogs became hypergammaglobulinemic, leukopenic, hypoalbuminemic, and hypocalcemic during the infection. These findings were compatible with the syndrome of anemia of inflammation.
Association of bovine respiratory syncytial virus with atypical interstitial pneumonia in feedlot cattle
Authors: Collins James K. , Jensen Rue , Smith George H. , Flack D. E. , Kerschen Robert , Bennett Bill W. , Jones Robert L. , Alexander A. F.
Published: February 2025

Thirty-three cattle with fatal respiratory tract disease were examined for gross and histologic lesions and for the presence of viral and bacterial agents in the lungs. Fifteen cattle had lesions characteristic of atypical interstitial pneumonia (aip), and 18 had other respiratoiy tract diseases, including infectious bovine rhinotracheitis, shipping fever pneumonia, bronchopneumonia, pulmonary abscess, and edema of the trachea. Gross necropsy findings in the cattle with aip were uncollapsed and emphysematous lungs; histopathologic findings included interstitial edema, thickening of alveolar walls, hyaline membrane formation, and hyperplasia of type-II pneumonocytes. The infective agents found in the lungs of the 33 cattle included bovine respiratory syncytial virus, bovine herpesvirus type 1, Pasteurella sp, mycoplasmas, and Corynebacterium pyogenes. Bovine respiratory syncytial virus was detected by use of immunofluorescence and immunoperoxidase on lung tissue sections; bovine herpesvirus type 1 was detected by these techniques and by isolation of the virus. Bovine respiratoiy syncytial virus was significantly (P = 0.01) associated with lesions of aip (11 of 15), compared with those of other respiratory tract diseases (5 of 18).
Neuromuscular and cardiovascular effects of atracurium administered to healthy horses anesthetized with halothane
Authors: Hildebrand S. V. , Arpin D.
Published: February 2025

Neuromuscular and cardiovascular effects of atracurium, a nondepolarizing neuromuscular blocking agent, were evaluated in 10 halothane-anesthetized adult horses. Hind limb digital extensor tension (hoof twitch) was measured with a strain gauge to quantitate the muscle relaxant effects of atracurium. Response of facial muscles was compared with hoof twitch. Five injections of atracurium were given. Initial mean (± sem) dosage of 0.07 ± 0.01 mg of atracurium/kg of body weight caused 98.6 ± 0.8% reduction of the preinjection hoof twitch. Subsequent dosages of 0.04 ± 0.003 mg/kg induced a degree of relaxation similar to that induced by the initial dose. Duration of paralysis from maximal effect to 10% recovery of twitch was 12.2 ± 1.5 minutes for the first injection. This was significantly (P < 0.05) different from subsequent paralysis periods, which lasted approximately 7 minutes. The 10% to 75% recovery time after all injections was similar—approximately 16 minutes. The facial muscles were less affected objectively by atracurium than was the hind limb. Atracurium did not cause cardiovascular changes.

When the hoof twitch had recovered to 95% of its tension before atracurium administration, 0.5 mg of edrophonium/kg, was given to antagonize neuromuscular blockade. Within 5 minutes of edrophonium administration, twitch tension exceeded that measured before atracurium administrations. Within 2 minutes of edrophonium administration, blood pressure began to increase and continued to increase approximately 10 mm of Hg above the value measured before edrophonium administration. Heart rate was not affected by edrophonium. Other muscarinic side effects of edrophonium were not observed.

Of the 10 horses, 9 had good, unremarkable recovery to standing position. One horse had a violent recovery period.
Enumeration of T and B lymphocytes in bovine leukemia virus-infected cattle, using monoclonal antibodies
Authors: Williams Diana L. , Amborski Grace F. , Davis William C.
Published: February 2025

Monoclonal antibodies and microfluorimetry were used to determine the absolute number of B and T lymphocytes in the blood of bovine leukemia virus (blv)-infected cows. The blood lymphocyte populations from blv-infected cows were significantly higher than those from blv-negative cows. The increase in the lymphocyte population in 3 blv-infected nonlymphocytotic cows was attributed to a significant increase in the number of T lymphocytes; in 3 blv-infected persistently lymphocytotic cows, the increase was attributed to a significant increase in the number of B and T lymphocytes. One persistently lymphocytotic cow had a high lymphocyte count, and lymphocytes from this cow contained cells that appeared to stain with markers specific for bovine B and T lymphocytes. We concluded that infection of cattle with the B-cell lymphotropic retrovirus, blv, not only affected B cells, but also T cells.
Age-related variations in serum concentrations of the third component of complement in swine
Authors: Tyler Jeff W. , Cullor James S. , Osburn Bennie I. , Parker Kent
Published: February 2025

Single radial immunodiffusion was used to determine the concentration of the third component of complement (C3) in serum from swine in the following age groups; 36 to 60 hours (neonates), 6 to 7 weeks (weanlings), 4 to 5 months (adolescents), and > 1 year (adults). Mean serum C3 concentrations, expressed as the percentage of pooled reference sera from 15 adult swine for the 4 groups were 23, 123, 119, and 98%. With the exception of mean values for weanlings and adolescents, all comparisons of group means were significantly different. Regression models were developed to estimate serum C3 concentration in neonates as a function of litter size, birth weight, and total serum IgG concentration. Increases in birth weight and litter size were accompanied by increased serum C3 concentration, possibly reflecting ontogenic variation of the complement system at the end of gestation. Passive transfer of colostral immunoglobulins, as measured by total serum IgG concentration, was inversely related to serum C3 concentration in neonatal swine, suggesting that colostral absorption of C3 has minimal impact on complement activity in neonatal swine.
An immunoperoxidase method of detecting respiratory syncytial virus antigens in paraffin sections of pneumonic bovine lung
Authors: Bryson David G. , Cush P. F. , McNulty M. S. , Platten M. , Allan G. M.
Published: February 2025

Using an avidin-biotin-peroxidase complex immunoperoxidase staining method, respiratory syncytial virus (rsv) antigen was demonstrated in glutaraldehyde-fixed, paraffin-processed lung sections from calves with induced rsv pneumonia. The virus also was detected in formalin-fixed, paraffin-processed lung sections from calves with naturally occurring rsv pneumonia.

Specific immunoperoxidase staining was detected within the cytoplasm of epithelial cells and syncytia in small bronchi, bronchioli, and alveoli. Staining also was detected within exudates in airway lumina and in mononuclear and multinucleate cells within alveolar lumina. Optimal intensity of staining was achieved by proteolytic enzyme treatment of lung sections, using 0.1% pronase and overnight incubation in diluted primary antiserum. The distribution of antigen had a close correlation with presence of lesions. Antigen-staining patterns were similar in lung tissue from calves with naturally occurring and induced rsv disease.
Postweaning diarrhea in swine: Effects of oxytetracycline on enterotoxigenic Escherichia coli infection
Authors: Sarmiento Juan I. , Moon Harley W.
Published: February 2025

Investigators have found that oxytetracycline decreases the adhesion of K88+ Escherichia coli to intestinal epithelial cells in vitro. This occurs with oxytetracycline-sensitive E coli at drug concentrations less than those required to prevent growth and with E coli that are resistant to the drug. We conducted experiments to determine whether oxytetracycline alters the disease caused by an oxytetracycline-resistant K88+ enterotoxigenic strain of E coli. Oxytetracycline-treated pigs (inoculated with K88+ E coli) did not differ from nontreated pigs in the incidence or severity of diarrhea, nor in the shedding of K88+ E coli. However, during recovery, weight gain by treated pigs was slower than that of nontreated pigs. The control pigs were not inoculated with E coli, and they remained clinically normal. Oxytetracycline-treated controls gained weight faster than nontreated controls. Some controls were genetically resistant to K88+ E coli, others were susceptible. The K88-resistant oxytetracycline-treated controls gained weight faster than the K88-susceptible oxytetracycline-treated and nontreated controls.
Pathogenesis of experimentally induced feline immunodeficiency virus infection in cats
Authors: Yamamoto Janet K. , Sparger Elizabeth , Ho Esther W. , Andersen Philip R. , O'Connor Thomas P. , Mandell Carol P. , Lowenstine Linda , Munn Robert , Pedersen Niels C.
Published: February 2025

Feline immunodeficiency virus (fiv; formerly, feline T-lymphotropic lentivirus) is a typical lentivirus resembling human and simian immunodeficiency viruses in morphologic features, protein structure, and reverse transcriptase enzyme. It is antigenically dissimilar, however. The virus is tropic for primary and permanent feline T-lymphoblastoid cells and Crandell feline kidney cells. The virus did not grow in other permanent feline non-lymphoblastoid cells that were tested, or in lymphoid and non-lymphoid cells from man, dogs, mice, and sheep.

During short-term inoculation studies in cats, the feline immunodeficiency-like syndrome found in nature was not experimentally induced, but a distinct primary phase of infection was observed. Fever and neutropenia were observed 4 to 5 weeks after inoculation; fever lasted several days, and neutropenia persisted from 1 to 9 weeks. Generalized lymphadenopathy that persisted for 2 to 9 months appeared at the same time.

Antibodies to fiv appeared 2 weeks after inoculation and then plateaued. Virus was reisolated from the blood of all infected cats within 4 to 5 weeks after inoculation and persisted indefinitely in the face of humoral antibody response. Virus was recovered from blood, plasma, csf and saliva, but not from colostrum or milk.

Contact transmission was achieved slowly in one colony of naturally infected cats, but not between experimentally infected and susceptible specific-pathogen-free cats kept together for periods as long as 4 to 14 months. The infection was transmitted readily, however, by parenteral inoculation with blood, plasma, or infective cell culture fluids. In utero and lactogenic transmission were not observed in kittens born to naturally or experimentally infected queens.

Lymphadenopathy observed during the initial stage of fiv infection was ascribed to lymphoid hyperplasia and follicular dysplasia. A myeloproliferative disorder was observed in 1 cat with experimentally induced infection.
Antigenic relationship between Mycobacterium paratuberculosis and Mycobacterium avium
Authors: Camphausen Raymond T. , Jones Robert L. , Brennan Patrick J.
Published: February 2025

Four prototype strains of Mycobacterium paratuberculosis contained the type-specific glycopeptidolipid antigen of serovar 8 of the M avium complex. This glycolipid was distinguished by a 4,6-(1′-carboxyethylidene)-3-O-methyl-β-d-glucopyranosyl terminal unit. Of 59 low-passage, field isolates of M paratuberculosis, 2 contained this antigen, and these 2 isolates were indistinguishable from M avium serovar 8. However, most M paratuberculosis isolates had no characteristic surface glycopeptidolipid. Seemingly, M paratuberculosis, long regarded as a single species and the causative agent of bovine paratuberculosis, is not a homogeneous taxon. Most isolates obtained from infected ruminants may be antigenically defective, variants of M avium and, thereby, more successful pathogens.
Studies on the ability of a 98-kilodalton pseudorabies virus diagnostic antigen to detect latent infections induced by low-dose exposure to the virus
Authors: Mc Ginley M. J. , Platt K. B.
Published: February 2025

The effect of low-dose challenge of immunity with pseudorabies virus (prv) on subunit-vaccinated pigs was studied in 2 experiments. In the first experiment, we studied the effect of challenge dose on the antibody response to an early excreted 98-kilodalton prv-glycoprotein that was used as a diagnostic antigen in the elisa. In the second experiment, we studied the effect of low doses of virus on the establishment of latent infections in subunit-vaccinated pigs.

The relationship of virus exposure dose and vaccine dose to the response of pigs to diagnostic antigen was studied in 18 pigs. Two groups of 3 pigs were vaccinated with a total of 200 μg of a lectin-derived prv subunit vaccine over a 5-week period. Two groups of 3 pigs were similarly vaccinated with a total of 100 μg. Two groups of 3 pigs served as nonvaccinated controls. One group of pigs from each of the preceding categories was intranasally exposed to 106.0 and 102.7 plaque-forming units (pfu) of virus. Antibody to diagnostic antigen was detected by the elisa and radioimmunoprecipitation 3 to 7 days earlier in pigs exposed to 106.0 pfu, demonstrating that the size of the virus challenge dose affects the antibody response to diagnostic antigen.

The establishment of latent infections by low prv doses and the ability to detect these infections was studied in 10 subunit-vaccinated pigs. Each pig was intranasally exposed to 102.3 pfu of virus (day 0). The serum virus-neutralizing antibody titer of these pigs increased to their highest level 14 to 21 days after exposure and then steadily decreased through day 113, indicating absence of viral recrudescence. All pigs were treated with dexamethasone for 4 consecutive days, beginning on day 113. Latent infections were identified in 8 of 10 pigs on the basis of recovery of virus and/or 2 log2 or greater increases in serum virus-neutralizing titer. Antibody to diagnostic antigen was initially detected in the 8 latently infected pigs on day 14 or 21 and continued to be detected through days 21, 46, 53, 110, and 113 in 1, 2, 1, 1, and 3 pigs, respectively. The antibody titer to diagnostic antigen increased in 6 of the 8 latently infected piers after dexamethasone treatment. However, antibody to diagnostic antigen was not detected by elisa in the remaining 2 latently infected pigs, despite increases in serum virus-neutralizing titers in both pigs and the recovery of reactivated virus from one pig. The failure to consistently detect antibody to diagnostic antigen in latently infected pigs suggests that diagnostic tests using nonvaccine diagnostic antigen may be suitable only for detecting infections in vaccinated herds, but not in individual pigs.
Prevalence and characterization of Staphylococcus aureus in young goats
Authors: de Centorbi O. N. P. , de Cuadrado A. M. A. , de Carrizo S. C. C. , de Milán M. C. C. , Giménez D. F. , Bergdoll M. S.
Published: February 2025

Thirty-six Staphylococcus aureus isolates recovered from 35 of 204 young goats at slaughter were characterized. All isolates were susceptible to cephalothin, clindamycin, chloramphenicol, gentamicin, kanamycin, and amikacin. All but 2 were susceptible to erythromycin and tetracycline, and 19 and 20 were susceptible to penicillin and ampicillin, respectively. Thirteen isolates were classified as biotype A, 9 isolates were classified as biotype B, 8 isolates were classified as biotype C, and 6 isolates were classified as intermediate between B and C or were not biotypable. Six biotype A isolates were enterotoxigenic; 4 produced enterotoxin B, 1 produced enterotoxin C, and 1 produced enterotoxin D. Two biotype B strains produced enterotoxin B, and all 8 biotype C isolates produced enterotoxin C and the toxic shock syndrome toxin-1.
Electromyographic evaluation of conduction time and velocity of the recurrent laryngeal nerves of clinically normal dogs
Authors: Steiss Janet E. , Marshall Arvle E.
Published: February 2025

In 25 adult dogs of various breeds, recurrent laryngeal nerve fibers were electrically stimulated at 2 points along their extralaryngeal course. Evoked compound muscle action potentials were recorded in the ipsilateral intrinsic laryngeal muscles, using a percutaneous needle electrode. Latencies, amplitudes, and durations were measured. Latencies were correlated with neck length (r = 0.88 on left and 0.82 on right). Five of the dogs were euthanatized, and the nerve length between the 2 stimulating needle electrodes was measured; calculated conduction velocities (mean ± sd) were 55 ± 6 m/s (left) and 57 ± 6 m/s (right). In 38 additional canine cadavers, the lengths of the exposed left and right recurrent laryngeal nerves were correlated with neck length (r = 0.44 on left and 0.56 on right). A linear regression model is proposed for predicting normal latencies, despite variations in neck length among different breeds of dogs.
Sensitivity and specificity of latex agglutination tests used to identify Streptococcus agalactiae and Staphylococcus aureus isolated from bulk tank milk
Authors: Hogan Joseph S. , Smith K. Larry , Todhunter Deborah A. , Schoenberger Pam S.
Published: February 2025

Comparisons were made among rapid latex agglutination tests and conventional biochemical tests used to identify Streptococcus agalactiae and Staphylococcus aureus. Ninety-eight streptococci and 149 staphylococci isolated from bulk tank milk were tested. Sensitivity and specificity for the latex agglutination test used for identification of Str agalactiae were 97.6 and 98.2%, respectively. Sensitivity and specificity for the latex agglutination test used for identification of S aureus were 90.2 and 67.5%, respectively. Of 25 staphylococci considered false-positive by the latex agglutination test, 14 (56%) were considered tube coagulase-positive. Fifteen staphylococci considered false-positive by latex agglutination test had biotypes representative of S hyicus or S xylosus.
Efficacy of ivermectin in paste and injectable formulations against microfilariae of Onchocerca cervicalis and resolution of associated dermatitis in horses
Authors: French Dennis D. , Klei T. M. , Foil Carol S. , Miller R. I. , Foil L. D. , Chapman M. R. , McClure J. J.
Published: February 2025

The efficacy of a single dose of ivermectin (0.2 mg/kg), in injectable or paste formulations, against microfilariae of Onchocerca cervicalis and associated skin lesions was evaluated in 20 naturally infected horses during midsummer months in Louisiana. All horses had clinical signs of dermatitis of the ventral midline and/or limbs, shoulders, thorax, and withers. Efficacy was monitored at 21, 42, and 63 days after treatment. Procedures done at these intervals included microfilarial counts of 6-mm skin biopsy specimens of affected ventral midline, grading of gross lesions, and photography and histologic assessment of ventral midline biopsy specimens. Microfilarial numbers were reduced to 0 by 21 days after treatment in all but one horse. Active lesions improved or were resolved completely by 63 days after treatment. Total inflammation, as judged by histologic methods, was reduced in all horses by 63 days after treatment, but there was a residual population of inflammatory cells in all horses. Adverse reactions after treatment were not observed in any of the horses.
Glycoprotein-specific immune responses in cats after exposure to feline herpesvirus-1
Authors: Burgener David C. , Maes Roger K.
Published: February 2025

To obtain synchronous infection, 10 cats were inoculated with feline herpesvirus-1 (fhv-1) on the oral, nasal, and conjunctival mucosa. Swab specimens of the nasal, conjunctival, and pharyngeal mucosa were obtained for virus isolation from each cat before inoculation and at 3-day intervals thereafter until postinoculation day 21. Recovery of virus and evidence of clinical signs were used to document fhv-1 infection.

Serum was obtained from blood samples collected sequentially from each cat between day 0 and postinoculation day 90. Virus-neutralizing antibody titer was determined in all serum specimens. Immunoprecipitation with [35S]methionine- and [14C]glucosamine-labeled viral antigens, followed by sodium dodecyl sulfate-polyacryl amide gel electrophoresis, was performed on each specimen. Three precipitation bands with approximate molecular weights of 105,000, 68,000, and 60,000 were separated from [14C]glucosamine- and [35S]methionine labeled immunoprecipitates.

The concurrent detection of virus-neutralizing antibody and glycoprotein-specific immunoprecipitins implied that in cats, the fhv-1 glycoproteins were important in the induction of virus-neutralizing antibodies to fhv-1.
Production and partial characterization of monoclonal antibodies to Pasteurella haemolytica A1 capsular polysaccharide and lipopolysaccharide
Authors: Penaredondo Maria V. , Maheswaran Samuel K. , Whiteley Laurence O. , Ames Trevor R. , Leininger Joel R.
Published: February 2025

Hybridoma-derived monoclonal antibodies (mab) against the cell surface antigens of Pasteurella haemolytica serotype 1 were obtained by the fusion of murine myeloma cells (P3 × 63 − Ag 8.653) with splenocytes of BALB/c mice immunized with crude logarithmic growth-phase culture supernatant. Initial screening was performed, using an elisa, with the same bacterial growth culture supernatant as coating antigens. Further selection was done, using a panel of purified antigens—either capsular polysaccharide or lipopolysaccharide—as the coating antigen in an elisa, and then performing a leukotoxin-neutralization assay. Two mab, designated IIB-6 and H-2, reacted specifically with the capsular polysaccharide and the other 3, designated IVG-3, IH-3, and IIC-2, reacted with the lipopolysaccharide. One mab, designated IH-6, did not react with leukotoxin, capsular polysaccharide, or lipopolysaccharide. The mab to the capsular polysaccharide (IIB-6 and H-2) were characterized further; both antibodies belonged to the IgM class and were agglutinating. In addition, they promoted neutrophil-mediated opsonophagocytosis and complement-mediated immune bacteriolysis of P haemolytica serotype 1. Results from 3 studies indicated that the mab IIB-6 and H-2 were specific only to the capsular polysaccharide of serotype 1 of P haemolytica. The mab to the lipopolysaccharide (IVG-3, IH-3, and IIC-2) were of the IgG1, IgG3, and IgM classes, respectively and were not characterized further.

The availability of a mab identifying a serotype-specific, surface-exposed determinant on the capsule of P haemolytica serotype 1 should facilitate and expand studies concerning the role of the capsular material and lipopolysaccharide in the pathogenicity of P haemolytica infection in cattle.