bluuebunny/crossref_metadata_2025 huggingface dataset:
Cardiopulmonary effects of halothane anesthesia in cats
Authors: Grandy Jacqueline L. , Hodgson David S. , Dunlop Colin I. , Curtis Charles R. , Heath R. Bruce
Published: February 2025

The cardiopulmonary effects of 2 planes of halothane anesthesia (halothane end-tidal concentrations of 1.78% [light anesthesia] and 2.75% [deep anesthesia]) and 2 ventilatory modes (spontaneous ventilation [sv] or mechanically controlled ventilation [cv]) were studied in 8 cats. Anesthesia was induced and maintained with halothane in O2 only, and each cat was administered each treatment according to a Latin square design. Cardiac output, arterial blood pressure, pulmonary arterial pressure, heart rate, respiratory frequency, and PaO2) PaCO2, and pH were measured during each treatment. Stroke volume, cardiac index, and total peripheral resistance were calculated. A probability value of < 5% was accepted as significant.

In the cats, cardiac output, cardiac index, and stroke volume were reduced by deep anesthesia and cv, although only the reduction attributable to cv was significant. Systemic arterial pressure was significantly reduced by use of deep anesthesia and cv. Respiratory frequency was significantly lower during cv than during sv. Arterial PO2 was significantly decreased at the deeper plane of anesthesia, compared with the lighter plane. At the deeper plane of anesthesia, arterial PCO2 and pulmonary arterial pressure were significantly lower during cv than during sv.

The deeper plane of halothane anesthesia depressed cardiopulmonary function in these cats, resulting in hypotension and considerable hypercapnia. Compared with sv, cv significantly reduced circulatory variables and should be used with care in cats. Arterial blood pressure was judged to be more useful for assessing anesthetic depth than was heart rate or respiratory frequency.
Studies of the immunomodulatory effects of low-level infection with Ostertagia ostertagi in calves
Authors: Wiggin Cynthia J. , Gibbs Harold C.
Published: February 2025

Possible immunomodulation by low-level infection with Ostertagia ostertagi was studied in 4-month-old calves. Six groups of 4 calves each were subjected to the following regimens: group 1—non parasitized controls; group 2—nonparasitized, but challenge exposed at day 64 with Brucella abortus strain 19 vaccine (ba) and at day 78 with iv administration of a soluble third-stage larval (L3) antigen preparation of O ostertagi (oag); group 3—nonparasitized, but challenge exposed at day 78 with 75 × 103 L3 of O ostertagi; group 4—continuously parasitized by weekly dosing with 30 × 103 L3 of O ostertagi; group 5—continuously parasitized by weekly dosing with 30 × 103 L3 of O ostertagi, then challenge exposed on day 64 with ba and on day 78 with iv inoculation of oag; and group 6—continuously parasitized by weekly dosing with 30 × 103 L3 of O ostertagi, then challenge exposed on day 78 with 75 × 103 L3 of O ostertagi.

Over the initial 10 weeks of the study, nonparasitized calves, (groups 1, 2, and 3) had higher body weight, blood lymphocyte (bl) response to phytohemagglutinin (pha), and significantly (P < 0.05) higher feed consumption and lymphocyte numbers, whereas parasitized calves (groups 4, 5, and 6) had higher bl responses to pokeweed mitogen (pwm) and significantly (P < 0.05) higher neutrophil and eosinophil numbers, plasma pepsinogen (pp) values, and bl response to oag.

During the challenge-exposure period (weeks 10 through 13), group-5 calves had significantly (P < 0.05) higher eosinophil numbers and pp values for week 11 (ba challenge exposure) and for week 13 (oag challenge exposure) than did group-2 calves, but differences were not observed in bl responses to pha, pwm, and oag. Oral L3 challenge exposure at week 13 induced significantly (P < 0.05) lower lymphocyte numbers, higher eosinophil numbers (P < 0.05), and higher pp values, but lower bl response to pha, pwm, and oag in group-6, compared with group-3 calves. In continuously parasitized calves, comparison of iv oag challenge exposure with oral L3 challenge exposure indicated that group-6 (L3) calves had significantly lower (P < 0.05) lymphocyte numbers and higher pp values than did group-5 (oag) calves. Results of elisa revealed significantly (P < 0.05) higher antibody titer to oag in parasitized calves, compared with nonparasitized calves.

Abomasal mucosal pathologic changes were most severe in the continuously parasitized calves. Calves of groups 4, 5, and 6 had thicker mucosae (edema), significantly (P < 0.05) higher eosinophil numbers, and higher globule leukocyte and mast cell numbers in the fundic and pyloric regions than did calves of groups 1, 2, and 3.

Calves of groups 4, 5, and 6 also had significantly (P < 0.05) larger abomasal lymph node masses than did nonparasitized calves. In group-1 calves, nodes had the lowest mass. Differences were not observed among groups for lymphocyte responses to proliferative and suppressive assays performed on the abomasal lymph node lymphocytes.
In vitro ultrasonographic appearance of the normal and verminous equine aorta, cranial mesenteric artery, and its branches
Authors: Wallace K. D. , Selcer B. A. , Tyler D. E. , Brown J.
Published: February 2025

Ninety-one equine aortic and cranial mesenteric arterial segments were evaluated ultrasonographically in a water bath. On the basis of pathologic evidence of verminous arteritis, arterial segments were classified into 4 categories, and the ultrasonographic characteristics of each group were evaluated. Normal arteries (class 1) were ultrasonographically characterized by a smooth luminal surface layer and uniform wall thickness and echogenicity. Arteries with only histopathologic evidence of verminous arteritis (class 2) were ultrasonographically characterized by a smooth luminal surface layer, uniform thickness, uniform echogenicity, and the presence of a hyperechoic luminal layer. Arteries with both gross and histopathologic evidence of verminous arteritis (class 3) were characterized ultrasonographically by an irregular luminal surface layer, varying wall thickness, varying wall echogenicity, and the presence of a hyperechoic luminal layer. The ultrasonographic characteristics of arteries with luminal thrombosis (class 4) were an irregular luminal surface, varying wall thickness, and nonuniform echogenicity.
Neochondrogenesis in free intra-articular, periosteal, and perichondrial autografts in horses
Authors: Vachon Anne , McIlwraith C. Wayne , Trotter Gayle W. , Norrdin Robert W. , Powers Barbara E.
Published: February 2025

Periosteal autografts were obtained from the medial aspect of the proximal portion of the tibia, and perichondrial autografts were obtained from the sternum. Using arthroscopic visualization, each autograft was placed as a loose body into 1 tarsocrural joint in 6 young horses (2 to 4 years old). Horses were hand-walked daily, starting the day after surgery, for a total of 6 h/wk for 8 weeks. Eight weeks after autograft implantation, radiographs were taken of each tarsocrural joint and were interpreted with regard to mineralization in the transplanted autografts. Autografts were then surgically removed, and examined macroscopically and microscopically for viability, size, and production of chondroid tissue.

All autografts appeared viable and most had evidence of growth. Longest-by-shortest axis value, cross-sectional area, and perimeter were greater in perichondrial autografts than in their periosteal counterparts in 3 horses, but the difference was not significant. Neochondrogenesis was observed in 5 of 6 periosteal grafts and in 1 of 6 perichondrial grafts. Furthermore, the amount of chondroid tissue produced in periosteal autografts was significantly (P < 0.05) greater than that produced in the 1 perichondrial graft. The chondroid tissue produced by periosteal autografts had morphologic and matrical staining properties similar to those of hyaline cartilage.
Comparison of left ventricular ejection fractions determined in healthy anesthetized dogs by echocardiography and gated equilibrium radionuclide ventriculography
Authors: Sisson D. David , Daniel Greg B. , Twardock A. Robert
Published: February 2025

Left ventricular ejection fractions (lvef) of 8 pentobar-bital-anesthetized dogs were calculated by gated equilibrium radionuclide ventriculography (rvg) and by M-mode and two-dimensional echocardiography (2-de) prior to and during constant iv infusion of isoproterenol. Mean lvef (± sd), determined with rvg by use of an automatic edge detection algorithm (rvg-auto) to define the left ventricular region of interest, increased from a resting value of 53.5% (± 4.9%) to 71.9% (± 6.8%) during isoproterenol infusion. Mean lvef, determined with rvg by use of visual inspection (rvg-manual) to define the left ventricular region of interest increased from a resting value of 51.6% ± 3.8% to 67.0% ± 5.6% during isoproterenol infusion. Using 2-de and the bullet formula to calculate left ventricular volume (lvv = ⅚ × cross-sectional area × length), mean lvef increased from 52.3% (± 3.50) to 74.7% (± 5.0%). Using 2-de area measurements and Teicholz formula, mean lvef increased from 48.9% (± 5.1%) to 69.5% (± 6.0%). Using M-mode echocardiographic left ventricular diameter measurements and Teicholz formula, mean lvef increased from 52.3 (± 9.0%) to 78.3% (± 8.1%). Before and during isoproterenol infusion, the mean lvef values calculated by rvg agreed closely with mean lvef values calculated from M-mode and 2-de. Correlation coefficients determined from linear regression analysis of lvef by echocardiography vs lvef by radionuclide ventriculography ranged from 0.79 to 0.88. Correlation coefficients were higher and sem were lower when lvef was determined by rvg-manual, rather than by rvg- auto methods and when lvef was calculated from 2-de measurements, rather than from M-mode measurements.
Naloxone reversal of oxymorphone effects in dogs
Authors: Copland Virginia S. , Haskins Steve C. , Patz John
Published: February 2025

Oxymorphone was administered iv to dogs 4 times at 20-minute intervals (total dosage, 1 mg/kg of body weight, iv) on 2 separate occasions. Minute ventilation, mixed-expired carbon dioxide concentration, arterial and mixed venous pH and blood gas tensions, arterial, central venous, pulmonary arterial, and pulmonary wedge pressures, and cardiac output were measured. Physiologic dead space, base deficit, oxygen transport, and vascular resistance were calculated before and at 5 minutes after the first dose of oxymorphone (0.4 mg/kg) and at 15 minutes after the first and the 3 subsequent doses of oxymorphone (0.2 mg/kg). During 1 of the 2 experiments in each dog, naloxone was administered 20 minutes after the last dose of oxymorphone; during the alternate experiment, naloxone was not administered. In 5 dogs, naloxone was administered iv in titrated dosages (0.005 mg/kg) at 1-minute intervals until the dogs were able to maintain sternal recumbency, and in the other 5 dogs, naloxone was administered im as a single dose (0.04 mg/kg).

Naloxone (0.01 mg/kg, iv or 0.04 mg/kg, im) transiently reversed most of the effects of oxymorphone. Within 20 to 40 minutes after iv naloxone administration and within 40 to 70 minutes after im naloxone administration, most variables returned to the approximate values measured before naloxone administration. The effects of oxymorphone outlasted the effects of naloxone; cardiovascular and pulmonary depression and sedation recurred in all dogs. Four hours and 20 minutes after the last dose of oxymorphone, alertness, responsiveness, and coordination improved in all dogs after im administration of naloxone. Cardiac arrhythmia, hypertension, or excitement was not observed after naloxone administration.
Cardiovascular effects of vasopressors in halothane-anesthetized dogs before and after hemorrhage
Authors: Curtis Michael B. , Bednarski Richard M. , Majors Lynda
Published: February 2025

Exogenously administered vasopressors (sympathomimetics) were evaluated in halothane-anesthetized dogs to determine the effects of these drugs on cardiovascular function before and after hemorrhage.

Six dogs were anesthetized with thiamylal sodium (20 mg/kg of body weight) and halothane (1.25 minimal alveolar concentration) in 100% oxygen. After instrumentation, cardiac output, systemic arterial blood pressure (sap), heart rate (hr), left ventricular pressure, pulmonary arterial pressure, and an index of cardiac contractility (dP/dT) were measured. Stroke volume, cardiac index (ci), stroke index (si), rate-pressure product, and systemic vascular resistance (svr) were calculated. Epinephrine (0.1, 0.3. and 0,5 μg/kg/min (low, medium, and high doses respectively]) and dobutamine (1, 5, and 10 μg/kg/min [low, medium, and high doses, respectively]) were infused. Methoxamine was given in a bolus of 0.22 mg/kg, iv. All measurements were taken at 2.5 minutes after infusion, and were repeated after removal of 40% of the estimated blood volume.

Dobutamine administered at the low dose before hemorrhage increased sap and dP/dT. At the high and medium dose, dobutamine significantly increased ci, si dP/dT, and sap, with no significant change in hr or svr. The nedium dose of epinephrine was the most effective dose of epinephrine at increasing key variables (ci, si, dP/dT). The response of ci and si to this dose was not significantly different from the changes seen with high-dose administration of dobutamine. The dP/dT was significantly lower with epinephrine than with dobutamine, and svr and hr were unchanged with epinephrine, except at the low dose, which decreased svr. Methoxamine significantly deceased ci, si and hr, whereas svr and sap were increased significantly.

After hemorrhage, the only variables that had a signficant change in the absolute magnitude of the response, to a drug, relative to the response before hemorrhage, were a significantly reduced ability of dobutamine and nethoxamine to increase sap, and a significantly debased ability of methoxamine to decrease ci.

We concluded that dobutamine and epinephrine provide beneficial short-term support of the cardiovascular system in the halothane-anesthetized dog during acute hypovolemia.
Cardiovascular effects of vasopressors in isoflurane-anesthetized dogs before and after hemorrhage
Authors: Curtis Michael B. , Bednarski Richard M. , Majors Lynda
Published: February 2025

Exogenously administered vasopressors (sympathomimetics) were evaluated in isoflurane-anesthetized dogs to determine the effects of these drugs on cardiovascular function before and after hemorrhage.

Six dogs were anesthetized with thiamylal sodium (20 mg/kg of body weight) and isoflurane (1.25 minimal alveolar concentration) in 100% oxygen. After instrumentation, cardiac output, systemic arterial blood pressure, heart rate (hr), left ventricular pressure, pulmonary arterial pressure, and an index of cardiac contractility (dP/ dT) were measured. Stroke volume, cardiac index (ci), stroke index (si), rate-pressure product, and systemic vascular resistance (svr) were calculated. Epinephrine (0.1, 0.3, and 0.5 μg/kg/min [low, medium, and high doses, respectively]) and dobutamine (1,5, and 10 μg/kg/min [low, medium, and high doses, respectively]) were infused. Methoxamine was given in a bolus of 0.22 mg/kg, iv. All measurements were taken at 2.5 minutes after infusion, and were repeated after removal of 40% of the estimated blood volume.

Before hemorrhage, administration of high doses of dobutamine and medium and high doses of epinephrine were equally effective at increasing ci and si. The dP/dT was increased to the greatest degree by administration of high doses of dobutamine. Administration of the low dose of dobutamine increased dP/dT, whereas administration of the low dose of epinephrine increased ci, hr, and si, and decreased svr. The hr and svr were not increased by administration of any dose of dobutamine or of the medium and high doses of epinephrine. However, methoxamine increased svr and decreased hr. Methoxamine decreased ci, si, and dP/dT, but increased systemic arterial pressure to the same degree as that attributed to administration of high doses of dobutamine and epinephrine.

After hemorrhage, effectiveness of the drugs in eliciting a response was unchanged, except for a decreased ability of dobutamine to increase rate-pressure product. Further, when the results of this study were compared with those of an earlier halothane study, there were no significant differences in the response of a variable to drug infusion on the basis of the anesthetic. The drugs were equally effective with halothane or isoflurane anesthesia. Results indicated that dobutamine and epinephrine are effective short-term treatments for hypovolemia during volume resuscitation, and that they work equally well with halothane or isoflurane anesthesia.
Small-volume resuscitation with hypertonic saline solution in hypovolemic cats
Authors: Muir William W. , Sally Jan
Published: February 2025

We evaluated the hemodynamic effects of iv and intraaortic (aortic root) administration of 7.5% NaCl solution on hemodynamics in anesthetized cats with severe hypovolemia. Hypovolemic shock was induced by exsanguinating cats to a mean arterial blood pressure of 50 mm of Hg, which was maintained for 30 minutes prior to treatment. Shed blood volume was 38.4 ± 2.1 ml/kg of body weight. The cats were treated with a small volume (4 ml/kg) of 0.9% NaCl solution iv, 7.5% NaCl solution iv, or 7.5% NaCl solution administered into the aortic root.

The iv administration of 0.9% NaCl solution did not improve hemodynamics. The iv administration of 7.5% NaCl solution induced rapid restoration of arterial blood pressure, aortic blood flow, and cardiac contractility. Total peripheral vascular resistance decreased. The administration of 7.5% NaCl solution into the aortic root induced a further deterioration in hemodynamics resulting in death in 3 cats and a marked improvement in hemodynamics similar to that observed after iv administration of 7.5% NaCl solution in 2 cats. The duration of the beneficial hemodynamic effects after iv or intra-aortic administration of 7.5% NaCl solution did not exceed 60 minutes. Results of these studies suggested that either the iv or intra-aortic administration of 7.5% NaCl solution in cats can induce beneficial hemodynamic effects that may be of value in the field resuscitation of hypovolemic patients.
Clinical reference values for serum protein electrophoresis for the llama (Lama glama)
Authors: Mulrooney Donna M. , Johnson Mardine R. , Smith Bradford B. , Zimmerman Gary L.
Published: February 2025

Serum protein electrophoresis was performed on 71 clinically healthy juvenile and adult llamas (6 juvenile males, 7 juvenile females, 25 adult males, 13 adult females, and 20 pregnant females) to determine normal serum protein concentrations. Values were reported for each of the 5 groups because the groups were not homogeneous in all 8 peaks. Although the values reported here may serve as reference values for adults, they represent only a guideline for the juveniles because of the limited number of animals in each of these groups.
Whole blood platelet aggregation in dogs with liver disease
Authors: Willis Saundra E. , Jackson Marion L. , Meric Susan M. , Rousseaux Colin G.
Published: February 2025

Whole blood platelet aggregation was determined in response to collagen, arachidonic acid, and adenosine diphosphate in 20 dogs with liver disease and in 20 control dogs. Platelet aggregation in response to collagen and arachidonic acid was reduced in dogs with liver disease, compared with control dogs (P < 0.05), whereas there was no significant difference in platelet response to adenosine diphosphate between the 2 groups of dogs. Adenosine diphosphate was found not to be a reliable aggregation agent for determination of whole blood platelet aggregation in dogs. Dogs whose platelets did not aggregate in response to collagen and/or arachidonic acid manifested bleeding tendencies that could be attributed to platelet dysfunction.
Twenty-four hour urinary protein loss in healthy cats and the urinary protein-creatinine ratio as an estimate
Authors: Monroe William E. , Davenport Deborah J. , Saunders Geoffrey K.
Published: February 2025

Urinary protein loss was determined in 12 healthy cats. Voided urine was collected and protein quantitated by the Coomassie blue method. Mean protein loss for all cats was 12.65 mg/kg/24 h (5.45 sd). Protein loss for male cats (n = 6) was 16.62 mg/kg/24 h (3.3 sd), which was significantly different (P < 0.01) from 8.69 mg/kg/24 h (4.09 sd) for females (n = 6). A single urine protein-creatinine ratio correlated well with the total urinary protein loss in mg/kg/24 h. The correlation coefficient for the protein- creatinine ratio in voided urine (upcv) vs 24-hour urinary protein (up-24) loss was 0.968, and that for the protein- creatinine ratio in urine obtained by cystocentesis (UPCC) vs up-24 was 0.945. The regression equations were upcv = 0.02145 + 0.02338 × up-24 (mg/kg), and UPCC = 0.02667 + 0.02133 × up-24 (mg/kg). Using the mean value plus 3 sd of urinary protein loss from the healthy cats in this study, a healthy cat would be expected to have a urinary protein loss of < 29 mg/kg/24 h. A protein- creatinine ratio from a single urine sample provides an accurate estimate of urinary protein loss in healthy cats.
Evaluation of antithrombin-III activity as a coindicator of disseminated intravascular coagulation in cats with induced feline infectious peritonitis virus infection
Authors: Boudreaux M. K. , Weiss R. C. , Cox N. , Spano J. S.
Published: February 2025

Six adult specific-pathogen-free cats were inoculated intraperitoneally with a cell culture-adapted strain of feline infectious peritonitis virus. Plasma samples were evaluated for antithrombin-III (at-III) activities at postinoculation days (pid) 0, 4, and 11 and at termination on pid 16 (1 cat) or 21 (5 cats). Other hemostatic values evaluated were activated partial thromboplastin times, pro-thrombin times, thrombin times, fibrinogen, platelet counts, and fibrin/fibrinogen degradation products.

Antithrombin-III activity remained within normal or above normal range (89 to 246%) in all cats, with the exception of one cat on pid 4 (at-III, 70%). Mean baseline at-III activity for 6 cats at pid 0 was 123%. Mean at-III activity on pid 4, 11, and 16 or 21 was 98, 162, and 130%, respectively. On pid 4 and 16 or 21, results of coagulation screening tests indicated that all cats had disseminated intravascular coagulation. Histologically, cats also had severe fibrinonecrotizing thrombovasculitis.
Immunohistologic study of pulmonary and lymphatic tissues from gnotobiotic pigs inoculated with ara-T-resistant strain of pseudorabies virus
Authors: Narita Minoru , Imada Tadao , Haritani Makoto , Kawamura Hitoshi
Published: February 2025

Ara-T-resistant strain of pseudorabies virus (prv) was inoculated intranasally into six 2-week -old gnotobiotic pigs. Five inoculated pigs were sneezing and coughing. In pigs 1 to 4 killed on postinoculation days (pid) 3, 5, 7, and 9, respectively, prv antigen was detected in respiratory epithelial cells, and pigs had severe pneumonitis. In pigs 5 and 6 killed on pid 11 and 13, respectively,prv antigen was localized in macrophages in alveoli and necrotizing nodules. Immunoglobulin-containing cells (IgG, IgM and IgA) were detected first in pneumonic lesions in pig 4 killed on pid 9. Detection of immunoglobulin-containing cells was coincident with pulmonary inflammation and regeneration of pneumonic lesions. The number of IgG containing cells was greater than that of IgM- and IgA containing cells. Corresponding to transient viral multiplication, IgG-, IgM-, and IgA-containing cells were demonstrated first inlymphatic tissues in pig 1 killed on pid and their number was 5 to 10 times more than those in control pigs 7 and 8. Seemingly, prv replication in lymphatic tissues stimulated the proliferative response specific immunoglobulin-producing cells, and the appearance of immunoglobulin-containing cells in the lungs was associated with clearance of prv and regeneration of pneumonic lesions.
A new bacteriophage of Corynebacterium glutamicum isolated from swine waste
Authors: Bourque Denis , Bisaillon Jean-Guy , Ackermann Hans-W. , Berthiaume Laurent , Alain Robert , Beaudet Réjean
Published: February 2025

A bacteriophage for Corynebacterium glutamicum strain LP-6 was isolated from swine waste. It belongs to the Siphoviridae family or Bradley morphologic group B, has a narrow host range, and is sensitive to chloroform and resistant to carbon tetrachloride. The phage is unstable (96% inactivation) in swine waste stored for 4 months at 22 C. The dna has a molecular weight of approximately 20 Md, cohesive ends, and numerous restriction endonuclease sites. The phage differs from other known C glutamicum phages.
Transformation of Actinobacillus Pleuropneumoniae and analysis of R factors by electroporation
Authors: Lalonde Guy , Miller Jeff F. , Tompkins Lucy S. , O'Hanley Peter
Published: February 2025

An efficient method for dna transfer is essential for the genetic manipulation of any organism. Such a capacity will be required for the genetic analysis of Actinobacillus pleuropneumoniae as a swine pathogen, as well as for its manipulation for vaccination purposes. For this reason, the use of electroporation as a means of plasmid dna introduction into this species was examined. The multiply: antibiotic-resistant strain 80-8141 of Actinobacillus pleuropneumoniae harbors 3 plasmids: pYGlO, pYG15, and pYG12 of 5.0, 2.7, and 2.5 kb, respectively. Electroporation of A pleuropneumoniae strain 4074 with a plasmid extract of strain 80-8141 showed that pYGlO encodes chloramphenicol resistance and that pYG12 encodes ampicillin resistance. Electrical pulse conditions for efficient electroporation of strain 4074 were examined by use of pYGlO dna isolated from a 4074 transformant. Efficiency, expressed as transformants per microgram of plasmid dna, increased directly with pulse amplitude. However, high efficiencies were only observed in a narrow window of pulse duration (T = 12 to 22 ms at 6.25 kV/cm). Longer pulse durations resulted in cell death. Electroporation efficiencies increased with cell density. Yield of transformants increased directly with dna concentration. Results indicate that electroporation can be used to efficiently transform A pleuropneumoniae and that pYGlO and pYG12 are suitable plasmid vectors for use in the genetic manipulation of this organism.

Actinobacillus (Haemophilus) pleuropneumoniae is a prominent cause of respiratory infections in swine.1 Clinical isolates of A pleuropneumoniae have been reported to be resistant to tetracycline, triple sulfonamides, ampicillin, and streptomycin.2,3 There has been particular concern over the increasing incidence of resistance to chloramphenicol, which may be related to the extensive use of this antibiotic for treatment of swine pleuropneumonia. In 1980, 95% of the strains of A pleuropneumoniae isolated from the St-Hyacinthe region of Quebec, Canada, were found to be sensitive to chloramphenicol; whereas in 1982, only 57% of surveyed strains were still sensitive to this antibiotic.4

Resistance to ampicillin, streptomycin, and sulfadiazine in A pleuropneumoniae strains has been shown to be plasmid-mediated.5 6 The purpose of the study reported here was to use electroporation to analyze plasmids carried by a multiply antibiotic-resistant clinical isolate of A pleuropneumoniae. Electroporation involves the use of brief high-voltage electrical discharges to induce reversible permeability in both prokaryotic and eukaryotic membranes.7-9 Using a 5.0-kb A pleuropneumoniae plasmid encoding resistance to chloramphenicol, we have optimized electroporation as a means to transform this species. Conditions permitting an efficiency of over 10® transformants (Tfs)/μg of plasmid dna are described.
Experimental rotavirus infection in three-week-old pigs
Authors: Shaw Daniel P. , Morehouse Lawrence G. , Solorzano Robert F.
Published: February 2025

Thirteen 3-week-old pigs that had been allowed to nurse for the first 16 to 18 hours after birth were orally inoculated with 1 × 106.5 tcid50 of porcine rotavirus. All developed diarrhea, anorexia, and vomiting by postinoculation (PI) hour 30. These signs had abated by Pl day 6. Villus blunting in the small intestine was most severe in the jejunum and ileum of pigs euthanatized between pi days 3 and 5. Villi had returned to nearly normal length by PI day 6, although fused villi were seen in a few locations in the distal portion of the jejunum and in the ileum. Virus was detected in the feces of inoculated pigs by isolation in cell cultures and by electron microscopy during the 7-day course of the experiment. There was 1 extraintestinal virus isolation from the lung of 1 pig at PI day 2. Infection and disease developed in the presence of serum-neutralizing antibody obtained by nursing seropositive sows. There was no significant change in neutralizing antibody titers in the 3-week-old pigs over the course of the experiment. In this experimental work, a model to study rotavirus infection in 3-week-old pigs has been developed.
Lectin binding to small intestinal goblet cells of newborn, suckling, and weaned pigs
Authors: Jaeger L. A. , Lamar C. H. , Turek J. J.
Published: February 2025

Lectin binding of small intestinal goblet cells was examined in newborn, suckling, and weaned pigs. Sections of duodenum, proximal portion of the jejunum, distal portion of the jejunum, and ileum were embedded in a hydrophilic acrylic resin and treated with each of the following lectins: Canavalia ensiformis, Ricinus communis I, Glycine max, Ulex europaeus I, and Triticum vulgaris. Percentages of goblet cells binding each lectin were calculated within intestinal regions. Differences in lectin- binding affinity were detected among pigs of various ages and among various intestinal regions within pig age groups.
Effect of vaccination with a pentavalent leptospiral vaccine containing Leptospira interrogans serovar hardjo type hardjo-bovis on type hardjo-bovis infection of cattle
Authors: Bolin Carole A. , Zuerner Richard L. , Trueba Gabriel
Published: February 2025

Effectiveness of 2 pentavalent leptospiral vaccines containing Leptospira interrogans serovar hardjo was evaluated for protection of steers from infection with serovar hardjo type hardjo-bovis. The hardjo component of 1 vaccine was prepared from serovar hardjo type hardjoprajitno. The hardjo component of the other vaccine was prepared from serovar hardjo type hardjo-bovis. Two steers were vaccinated once and 4 steers were vaccinated twice with the pentavalent vaccine containing type hardjoprajitno. Four steers were vaccinated once and 4 steers were vaccinated twice with the pentavalent vaccine containing type hardjo-bovis. Four steers were maintained as nonvaccinated controls. Steers given vaccine containing type hardjo-bovis developed higher mean serum microscopic agglutination titers against serovar hardjo than steers given vaccine containing hardjoprajitno. Six months after the first vaccination, all steers were challenge-exposed on 3 occasions by conjunctival instillation of 107 serovar hardjo type hardjo-bovis organisms, and on 1 occasion by conjunctival instillation of urine from a steer shedding hardjo-bovis. All control and all vaccinated steers became infected and shed serovar hardjo type hardjo-bovis in the urine. Lesions were detected in kidneys of 3 of 4 nonvaccinated control steers, 5 of 6 steers given hardjoprajitno vaccine, and 6 of 8 steers given hardjo-bovis vaccine. Leptospires were detected in kidneys of 4 of 4 control steers and 13 of 14 vaccinated steers.
Comparison of the effect of polysulfated glycosaminoglycan, corticosteroids, and sodium hyaluronate in the potentiation of a subinfective dose of Staphylococcus aureus in the midcarpal joint of horses
Authors: Gustafson Scott B. , McIlwraith C. Wayne , Jones Robert L.
Published: February 2025

Four groups of 8 horses each had 1 midcarpal joint injected with 33 colony-forming units (cfu) of viable Staphylococcus aureus plus: 1 ml of saline solution (group 1, control), 250 mg of polysulfated glycosaminoglycan (psgag, group 2), 100 mg of methylprednisolone acetate (group 3), or 20 mg of sodium hyaulronate (group 4). Horses were euthanatized, and samples were obtained on the basis of clinical signs of septic arthritis that were nonresponsive to phenylbutazone administration. One group-1 horse, all 8 group-2 horses, 3 group-3 horses, and 4 group-4 horses were culture-positive for S aureus and had clinical signs, results of synovial fluid analysis, and histopathologic findings that were consistent with sepsis. The addition of 250 mg of psgag increased the development of sepsis significantly (P = 0.001), compared with results in control horses. Differences in the development of sepsis between horses injected with methylprednisolone acetate or sodium hyaluronate and control horses were not significant.
Further investigations into the potentiation of infection by intra-articular injection of polysulfated glycosaminoglycan and the effect of filtration and intra-articular injection of amikacin
Authors: Gustafson Scott B. , McIlwraith C. Wayne , Jones Robert L. , Dixon-White Heidi E.
Published: February 2025

Polysulfated glycosaminoglycan (psgag) recently have been reported to potentiate the infectivity of Staphylococcus aureus in horses with experimentally induced septic arthritis. Four groups of 8 horses each had 1 midcarpal joint injected with approximately 33 viable colony-forming units (cfu) of S aureus plus either 1 ml of saline solution (group 1), 250 mg of psgag (group 2), 250 mg of psgag passed through a 0.6-μm filter (group 3), or 250 mg of psgag plus 125 mg of amikacin (group 4). Horses that developed clinical signs consistent with sepsis were euthanatized, and samples were collected at necropsy. Horses that survived had samples obtained by use of arthroscopy at days 13 and 14 after injection. Staphylococcus aureus was isolated from 1 group-1 horse, 8 group-2 horses, and 7 of 7 group-3 horses that met protocol, but was not isolated from any group-4 horses. All 16 aforementioned horses had clinical signs, results of synovial fluid analysis, and gross pathologic and synovial membrane histopathologic findings that were consistent with septic arthritis. Polysulfated glycosaminoglycan (250 mg) increased the infectivity of 33 cfu of S aureus (P = 0.001); filtering the psgag had no effect. Intra-articular injection of 125 mg of amikacin immediately after inoculating the joint with 33 cfu of S aureus significantly (P = 0.001) decreased potentiation of infection by the psgag.
Reference ranges for hematologic and serum biochemical values in llamas (Lama glama)
Authors: Fowler Murray E. , Zinkl Joseph G.
Published: February 2025

Hematologic and serum biochemical values were determined in 174 llamas of all age groups and both sexes from ranches in California and Nevada.

Compared with hematologic values for horses and cattle, llama erythrocytes were more numerous (10.1 to 17.3 × 106/μl), but the pcv was lower (25 to 45%) because the smaller elliptical cells pack tighter. The mean corpuscular volume was half that of horses and cattle (22 to 29.5 fl). The mean corpuscular hemoglobin concentration was higher (38.9 to 46.2 g/dl), and the mean corpuscular hemoglobin slightly lower (9.6 to 12.6 pg). Most serum biochemical values were similar to those of cattle and horses, with the exception of triiodothyronine (48 to 468 ng/dl) and thyroxin (9.8 to 30 μg/dl), which are up to 10 times higher than values for other domestic species.
Detection of Brucella abortus in mammalian tissue, using biotinylated, whole genomic DNA as a molecular probe
Authors: Hopper B. Russell , Sanborn Mark R. , Bantle John A.
Published: February 2025

A method has been developed for the detection of Brucella abortus in complex tissue homogenates. The technique uses tissue homogenization in the presence of sucrose and Triton X-100 and subsequent filtration through a 5-μm pore size filter to remove mammalian nuclei and cellular debris. The dna from the bacteria is then extracted, dot blotted onto nitrocellulose, and hybridized with a biotinylated probe of B abortus strain 19 dna. In the present study, BALB/C mice were inoculated intraperitoneally with either 109 or 1011 B abortus strain 2308S organisms. After 6 days, the mice were euthanatized by cervical dislocation and the livers were removed, weighed, and the appearance of each was noted. The tissues were homogenized, and a viable cell count was performed to determine the number of bacteria in each organ. The dna was extracted, blotted onto nitrocellulose, and hybridized with the Brucella probe. The biotin label was detected by use of a commercially available streptavidin/alkaline phosphatase system. In control experiments, the technique detected 105 organisms in a mixture of bacteria and 1 g of rat liver. The technique also detected 107 B abortus organisms/g of tissue from experimentally inoculated mice. The probe was specific for Brucella and had no affinity for contaminating bovine or bacterial dna.
Microvascular circulation of the ascending colon in horses
Authors: Snyder Jack R. , Tyler Walter S. , Pascoe John R. , Olander Harvey J. , Bleifer Dana R. , Hinds Dave M. , Neves John W.
Published: February 2025

Microvascular circulation of the ascending colon in healthy horses was studied using microangiography, light microscopy, and scanning electron microscopy. The pelvic flexure with 30 cm of ventral and dorsal colon attached was removed from 14 adult horses immediately after horses were euthanatized. The lumen was flushed with warm water, and this section of the ascending colon was placed in a 37-C bath of isotonic NaCl. In sections from 8 horses, colic vessels were perfused with a radio-opaque medium for microangiography. After angiographic evaluation, tissue sections were prepared for light microscopic observation, using standard histologic methods. In sections from 6 horses, injection replicas were made by perfusing the vessels with 2 types of plastics. The results of microangiography, light microscopy, and scanning electron microscopy of vascular replicas were correlated, providing a comprehensive documentation of the microvasculature of the ascending colon at the pelvic flexure.

Arteries branched from mesenteric colic vessels approximately every 2 cm toward the colonic tissue. Immediately after branching, arterial vessels formed an anastomotic plexus, the colonic rete. However, each branch from the colic vessel eventually continued into the colonic tissue. A second set of vessels originated from the colonic rete and supplied the mesenteric lymph nodes. Arterial vessels penetrated the tunica muscularis into the submucosa 3 to 4 cm toward the antimesenteric border forming a submucosal vascular network. From the submucosal arterioles, branching took place at right angles to supply the mucosal capillaries. Capillaries surrounded the colonic glands and anastomosed at the luminal surface, forming a superficial luminal honeycomb-appearing vascular plexus. Venules, sparsely distributed, drained the superficial plexus. Arterial venous anastomoses were not observed within the mucosa.
Distribution of cholinergic and adrenergic nerve fibers in the lacrimal glands of dogs
Authors: Powell Cynthia C. , Martin Charles L.
Published: February 2025

The distribution of postganglionic autonomic nerve fibers in the lacrimal gland and gland of the third eyelid of dogs was studied by use of histochemical techniques. Adrenergic nerve distribution was identified by use of the sucrose-potassium phosphate-glyoxylic acid technique. A loose network of adrenergic nerves was found throughout the interstitium around acini and blood vessels and in vessel walls. Acetylcholinesterase staining was used to identify cholinergic nerve fibers. A cholinergic distribution pattern around acini and blood vessels similar to the adrenergic pattern was found, although the cholinergic innervation appeared more dense than the adrenergic. In the gland of the third eyelid, mucus-secreting lobules and lipid-secreting lobules appeared to be equally innervated by parasympathetic fibers. These lobules could not be differentiated when the sucrose-potassium phosphate-glyoxylic acid technique was used. The techniques used in this study could not demonstrate whether direct contact was made by either cholinergic or adrenergic nerve fibers with secretory or myoepithelial cells. The presence of both nerve fiber types around acini suggests an interrelationship between the sympathetic and parasympathetic nervous system in lacrimal gland secretion in dogs.
Postnatal development of the photoreceptor inner segment of the retina in dogs
Authors: Miller William W. , Albert R. A. , Boosinger Timothy R. , Holloway Clarke L. , Simpson Steven T. , Tojvio-Kinnucan M. A.
Published: February 2025

In dogs, the retina develops during the postnatal period in a manner similar to that in other animals born with closed eyelids. Photoreceptor inner segments are initially observed as a cytoplasmic bulge protruding sclerad through the external limiting membrane. Outer segment formation begins when a centriole within the inner segment attaches to the distal inner segment cell membrane. A few round mitochondria are observed within the early inner segments. As maturation proceeds, the number of mitochondria within the inner segments increases and the mitochondria elongate, orienting parallel to the long axis of the inner segment.
Induction of Escherichia coli mastitis in cows fed selenium-deficient or selenium-supplemented diets
Authors: Erskine R. J. , Eberhart R. J. , Grasso P. J. , Scholz R. W.
Published: February 2025

Ten Holstein heifers were fed a selenium-deficient (SeD) diet (0.04 mg of Se/kg on a total ration dry-matter basis) 3 months before calving and throughout their first lactation. A selenium-supplemented (SeS) diet (2 mg of Se/head/d) was fed to a group of 10 heifers. In about the 14th week of lactation, the cows were challenge-exposed to Escherichia coli by administering 15 to 40 colony-forming units (cfu) into 1 mammary gland. Selenium concentration (μg/ml) in blood around the time of challenge exposure was 0.033 ± 0.002 (mean ± sem) in SeD and 0.132 ± 0.006 in SeS cows. Infections were established in all challenge-exposed quarters. The frequency of quarter atrophy and agalactia, and reduction in whole-udder milk yield in the first 4 days after challenge exposure, were greater (P < 0.05) in the SeD cows.

Log10 peak bacterial concentrations in milk were higher (P < 0.05) in SeD (7.63 ± 0.34 cfu/ml) than in SeS cows (5.57 ± 0.66 cfu/ml). Mean log bacterial concentration was significantly higher (P < 0.05) from 12 to 20 hours after challenge exposure in SeD than in SeS cows. Duration of infection was significantly greater (P < 0.05) in SeD (162.0 ± 12.0) than in SeS cows (114.4 ± 18.0 hours).

Milk somatic cell counts increased significantly more slowly (P < 0.05) in SeD than in SeS cows from 8 to 16 hours after challenge exposure. Ratios of milk somatic cells to bacteria in milk were significantly lower (P < 0.05) in SeD than in SeS cows at 12 and 16 hours after challenge exposure.
Effects of colostral antibody on susceptibility of calves to Cryptosporidium parvurn infection
Authors: Harp James A. , Woodmansee Douglas B. , Moon Harley W.
Published: February 2025

Effects of colostral antibody on susceptibility of calves to Cryptosporidium parvum infection were examined. Six calves were fed pooled colostrum that contained C parvum antibody, 6 times daily (at 4-hour intervals) for 7 days and then milk replacer for 7 days. Colostrum was obtained from healthy cows or cows inoculated parenterally with C parvum oocysts before parturition. Antibody content was determined in serum and colostrum whey, using an elisa for anticryptosporidia immunoglobulin. Six calves were fed colostrum from healthy cows 1 time, and then milk replacer 6 times daily for 14 days. On day 1, all calves were challenge exposed with C parvum, po, and were monitored daily for diarrhea and oocyst shedding. Bovine colostrum containing specific antibody to C parvum, at elisa titers up to 10,240, was not effective in protecting calves against challenge exposure to C parvum.
Tracheal mucus transport rate in healthy horses
Authors: Sweeney Corinne Raphel
Published: February 2025

Tracheal mucus transport rates were measured over a 10-minute period in 20 healthy horses twice in 24 hours. The mean rate was 1.93 ± 0.55 cm/min on day 1 and 1.99 ± 0.49 cm/min 24 hours later. The mean difference between day 1 and day 2 (0.06 ± 0.42 cm/min) was not significant (P = 0.55). The range on day 1 was 1.12 to 2.9 cm/min and 1.11 to 2.89 cm/min on day 2.
Mathematic model for the population biology of rabies in raccoons in the mid-Atlantic states
Authors: Coyne Michael J. , Smith Gary , McAllister Fiona E.
Published: February 2025

A series of coupled differential equations was used to model the temporal dynamics of rabies in raccoons in the mid-Atlantic region of the United States. The model takes explicit account of the development of natural immunity to rabies and was used to evaluate culling and vaccination elimination strategies. For habitats typical of the mid-Atlantic states, and given the assumptions of the model, it was estimated that elimination of rabies in raccoons by culling may involve the annual removal of over 32% of the raccoon population or the yearly vaccination of up to 99% of the susceptible fraction. Assuming a constant marginal cost for both culling and vaccination, the model suggests that, whatever the actual cost of each method, the cheapest strategy will always involve either culling or vaccination alone. A combined strategy of culling and vaccination will be cheaper than culling alone only when the per capita cost of vaccination is around one-fifth or less the per capita cost of culling.
Serum uric acid concentrations in horses heterozygous for combined immunodeficiency
Authors: Kettler Michelle K. , Weil Michael R. , Perryman Lance E.
Published: February 2025

Serum uric acid concentrations were determined in horses known to be carriers of combined immunodeficiency gene(s) and in presumed noncarrier horses. Uric acid concentrations were significantly higher (P < 0.005) in carrier horses than in presumed noncarrier horses. However, there was some overlap in serum uric acid concentrations between carrier and presumed noncarrier horses.
Protection of mice against Brucella abortus infection by inoculation with monoclonal antibodies recognizing Brucella O-antigen
Authors: Phillips Marshall , Deyoe Billy L. , Canning Peter C.
Published: February 2025

Monoclonal antibodies recognizing the O-polysaccharide portion of Brucella abortus strain 2308 provided BALB/c mice with passive protection against challenge exposure with the homologous strain. Numbers of colony-forming organisms in the spleen were reduced by IgM and IgG monoclonal antibodies. Active immunization of mice, using B abortus 2308S lipopolysaccharide, resulted in production of IgM antibody at 14 days. Clearance of organisms in the actively immunized mice after challenge exposure at 14 days was nearly identical to that in passively immunized mice. Mice either passively or actively immunized were effectively protected from 0 to 28 days. Bacterial colonization of the spleen was observed to increase in both groups of mice at 56 days and indicated that humoral responses were effective in eliminating the organism in the early stages of infection, but other immune mechanisms were necessary for protection of mice in the later stage of infection with virulent strains of B abortus.
Immunoperoxidase evaluation of pneumonic lesions induced by Pasteurella multocida in calves
Authors: Haritani M. , Narita M. , Murata H. , Hashimoto K. , Takizawa T.
Published: February 2025

To evaluate the relationship between pneumonic lesions and distribution of bacteria, lungs from calves inoculated with Pasteurella multocida were examined histologically by use of immunoperoxidase technique. Pneumonic lesions fundamentally consisted of bronchopneumonia with fibrinopurulent pleuritis. The lesions were confirmed to be associated with inoculated P multocida, using the immunoperoxidase technique. The P multocida antigen was detected not only in the bacterial clusters in the lesions, but also in the cytoplasm of infiltrating neutrophils and macrophages. Further, immunoelectron microscopy indicated that the inoculated bacteria generally were phagocytosed and digested by neutrophils.