bluuebunny/crossref_metadata_2025 huggingface dataset:
Morphologic changes and immunohistochemical detection of viral antigen in ovaries from cattle persistently infected with bovine viral diarrhea virus
Authors: Grooms Daniel L. , Ward Lucy A. , Brock Kenny V.
Published: January 2024

Objective

To identify morphologic differences in ovaries from cows persistently infected with bovine viral diarrhea virus (BVDV) and determine ovarian cell types infected in these cows.

Design

A comparative study of ovaries in cattle persistently infected with BVDV and cattle not persistently infected with BVDV, using morphologic and immunohistochemical analysis.

Animals

6 postpubertal cows persistently infected with BVDV and 6 postpubertal cows not persistently infected with BVDV.

Procedure

Ovaries were compared morphologically by counting the number of normal structures present on 3 histologic sections taken from each ovary. Immunohistochemistry was accomplished, using an indirect, monoclonal antibody-linked, avidin-biotin-peroxidase complex procedure.

Results

Significant (P < 0.01) decrease in the number of tertiary follicles, graafian follicles, atretic follicles, and corpus hemorrhagicum/luteum/albicans was observed in cows persistently infected with BVDV. No difference in numbers of primordial or secondary follicles was observed. Immunostaining of BVDV antigen in luteal cells and macrophage-like cells was evident in ovaries from cows persistently infected with BVDV.

Conclusions

Cows persistently infected with BVDV appear to have significant morphologic changes in their ovaries that suggest reduction in normal ovarian activities. Furthermore, BVDV antigen can be identified in specific ovarian cell types in cattle persistently infected with BVDV.

Clinical Relevance

The changes observed may reduce reproductive performance in cows persistently infected with BVDV, and may be of importance when trying to salvage valuable genetic material from persistently infected cows through embryo transfer. It is yet to be determined whether similar findings are true in cows acutely infected with BVDV. (Am J Vet Res 1996;57:830–833)
Liquid-phase blocking sandwich enzyme-linked immunosorbent assay for detection of antibodies against foot-and-mouth disease virus in water buffalo sera
Authors: Araújo J. P. , Montassier H. J. , Pinto A. A.
Published: January 2024

Objective

To develop and apply the liquid-phase blocking sandwich ELISA (BLOCKING-ELISA) for the quantification of antibodies against foot-and-mouth disease virus (FMDV) strains O1 Campos, A24 Cruzeiro, and C3 Indaial.

Design

Antibody quantification.

Sample Population

158 water buffalo from various premises of São Paulo State-Brazil. The sera were collected either from systemically vaccinated or nonvaccinated animals.

Procedure

The basic reagents of BLOCKING-ELISA (capture and detector antibodies, virus antigens, and conjugate) were prepared and the reaction was optimized and standardized to quantify water buffalo antibodies against FMDV. An alternative procedure based on mathematical interpolation was adopted to estimate more precisely the antibody 50% competition titers in the BLOCKING-ELISA. These titers were compared with the virus-neutralization test (VNT) titers to determine the correlation between these techniques. The percentages of agreement, cutoff points, and reproducibility also were determined.

Results

The antibody titers obtained in the BLOCKING-ELISA had high positive correlation coefficients with VNT, reaching values of 0.90 for O1 Campos and C3 Indaial, and 0.82 for the A24 Cruzeiro (P <0.0005). The cutoff points obtained by use of the copositivity and conegativity curves allowed determination of high levels of agreement between BLOCKING-ELISA and VNT antibody titers against the 3 FMDV strains analyzed.

Conclusions

The results characterized by high correlation coefficients, levels of agreement, and reproducibility indicate that the BLOCKING-ELISA may replace the conventional VNT for detection and quantification of antibodies from water buffalo sera to FMDV. (Am J Vet Res 1996;57:840–843)
Vagal esophagomotor nerve function and esophageal motor performance in dogs with congenital idiopathic megaesophagus
Authors: Holland Christopher T. , Satchell Paul M. , Farrow Brian R. H.
Published: January 2024

Objectives

To examine the integrity of the vagal efferent innervation to the esophagus and to assess esophageal motor performance in dogs with congenital idiopathic megaesophagus.

Design

An acute experimental protocol performed in control dogs and dogs with naturally acquired congenital idiopathic megaesophagus under pentobarbitone anesthesia.

Animals

4 dogs with congenital idiopathic megaesophagus and 16 control dogs.

Procedure

Esophageal motor nerve conduction studies were performed by recording evoked compound motor action potentials from the tunica muscularis of the distal thoracic portion of the esophagus in response to supramaximal stimulation of the cervical portion of the vagus nerve at cranial and caudal sites. Subsequently, esophageal motor performance was measured over a wide range of esophageal muscle lengths by recording intraesophageal pressure responses to supramaximal twitch and tetanic stimulation of the cervical portion of the vagus at varying, stepwise amounts of esophageal distention.

Results

In dogs with congenital idiopathic megaesophagus, no electrophysiologic evidence was found for segmental demyelination or axonal degeneration in cervical vagal motor fibers innervating striated muscle of the thoracic esophagus portion. Nor was spontaneous EMG activity, indicative of esophageal muscle denervation or a primary myopathy, observed. In contrast, esophageal motor performance, which was dependent on esophageal dimensions, was reduced in dogs with congenital idiopathic megaesophagus.

Conclusions

In dogs with congenital idiopathic megaesophagus, the vagal efferent innervation to the esophagus is likely to be normal, a primary esophageal myopathy is unlikely to be present, and the observed reduction in esophageal motor performance may arise as a secondary consequence of altered esophageal biomechanical properties rather than from a primary neuromuscular abnormality. (Am J Vet Res 1996;57:906–913)
Comparison of the degree of abdominal adhesion formation associated with chromic catgut and polypropylene suture materials
Authors: Rochat Mark C. , Lin Jauhorng , Pope Eric R. , Carson William L. , Wagner-Mann Colette C. , Pace Lanny W.
Published: January 2024

Objective

To evaluate the histologic pattern and biomechanical properties of adhesions caused by chromic catgut and polypropylene sutures, using an enteropexy model.

Design

Enteropexies were created in dogs, using chromic catgut and polypropylene suture. The adhesions associated with the enteropexies were examined histologically and mechanically.

Animals

6 mixed-breed dogs weighing 16 to 20 kg.

Procedure

72 enteropexies were created between the jejunum and abdominal wall. 36 sites were sutured with chromic catgut, and 36 were sutured with polypropylene. 3 dogs were euthanatized after 1 week. The remaining dogs were euthanatized after 1 month. Samples of the enteropexy sites were obtained for histologic examination. The remaining sites were mechanically distracted until failure of the enteropexy site or adjacent tissue occurred.

Results

Histologic examination of the enteropexy sites did not reveal substantial differences in the degree of inflammation between the 2 suture types at 1 week or 1 month. The degree of inflammation decreased and the maturity of fibrous tissue formed at the enteropexy sites increased for all specimens over time. No statistically significant difference in breaking strength was observed between suture types at 1 week or 1 month.

Conclusion

In dogs, the formation and strength of intentionally created abdominal adhesions are not increased by use of chromic catgut.

Clinical Relevance

Selection of chromic catgut suture for use in surgical procedures where adhesions are desired is unwarranted. (Am J Vet Res 1996;57:943–947)
Oral bioavailability and in vitro stability of pivampicillin, bacampicillin, talampicillin, and ampicillin in horses
Authors: Ensink J. M. , Vulto A. G. , van Miert A. S. J. P. A. M. , Tukker J. J. , Uiterwijk Winkel M. B. , Fluitman M. A. H. M.
Published: January 2024

Objectives

To determine the oral bioavailabilities of 3 ampicillin esters (pivampicillin, bacampicillin, and talampicillin) and ampicillin sodium, and to determine in vitro stability of the ampicillin esters in ileal contents (pH 8.3 to 8.5).

Design

A crossover design to administer the 4 drugs orally, and ampicillin IV, to all horses in the study.

Animals

4 healthy adult horses.

Procedure

The drugs were administered intragastrically to the horses at a dosage equimolar to 15 mg of ampicillin/kg of body weight. Also, ampicillin sodium was administered IV at the same dosage. Blood samples were taken up to 12 hours after drug administration, and ampicillin concentrations in plasma were determined. For the in vitro study, the ampicillin esters were incubated at 37 C in ileal contents obtained from ponies with cecal fistulas. After incubation, the remaining intact ester and the formed ampicillin were measured.

Results

Absolute oral bioavailability was 31, 39, 23, and 2% for pivampicillin, bacampicillin, talampicillin, and ampicillin sodium, respectively. In the in vitro study, 90% decomposition of the ester took place in 30, 60, and 5 minutes, for pivampicillin, bacampicillin, and talampicillin, respectively.

Conclusions

Pivampicillin and bacampicillin are promising candidates for oral antibiotic treatment of horses. The rapid decomposition of ampicillin esters is caused by chemical hydrolysis at the high pH of equine ileal contents. (Am J Vet Res 1996;57:1021–1024)
Effect of 5-hydroxytryptamine type-2 receptor blockade on pulmonary function in calves with experimentally induced Pasteurella haemolytica pneumonia
Authors: Hare Jonathan E. , Tesarowski David B. , Dawe Gail E. , Vlaminck Kathleen , Shewen Patricia E. , Viel Laurent
Published: January 2024

Objective

To evaluate a 5-hydroxytryptamine type-2 receptor antagonist, metrenperone (MET), in alleviating respiratory distress associated with experimentally induced Pasteurella haemolytica pneumonia in feedlot calves.

Design

Double-blind controlled clinical trial.

Animals

30 healthy 6- to 8-month-old Hereford-type calves (250 to 450 kg).

Procedure

Initial measurements were made of rectal temperature (RT), arterial blood gas (ABG) tensions, and pulmonary mechanics. Calves were then infected with P haemolytica in logarithmic phase of growth by intratracheal inoculation. 18 hours later, determination of RT and ABG tensions, and pulmonary function testing were repeated and calves were selected for inclusion in the study on the basis of having 2 of the following: respiratory rate > 50 breaths/mm, RT > 40 C, or Pao2 > 20 mm of Hg below the baseline value. MET (0.1 mg/kg of body weight, IM) or an equivalent vehicle dose was then administered. RT, ABG, and pulmonary mechanics measurements were repeated at 0.5, 1, 2, 3, 4, 6, 12, and 24 hours after treatment. Calves were then euthanatized, and gross necropsy scoring and histologic examination were performed on the lungs.

Results

Infection with P haemolytica caused significant increases in RT and respiratory rate, and reduction in Pao2, Paco2, and tidal volume 18 hours after inoculation. MET-treated calves had significantly reduced rectal temperature between 1 and 12 hours, compared with vehicle-treated calves. In addition, MET-treated calves had reduced respiratory rate with concomitantly increased tidal volume between 0.5 and 2 hours after treatment, compared with vehicle-treated calves. Necropsy revealed acute lobar bronchopneumonia in all 30 calves, but there was no difference in necropsy score between treatment groups.

Conclusions and Clinical Relevance

MET may have an antipyretic effect on calves with pneumonia caused by P haemolytica. Its influence on pulmonary mechanics was minimal however, and it did not induce lung lesions in the short term. (Am J Vet Res 1996;57:1034–1039)
Pharmacokinetics of atenolol in clinically normal cats
Authors: Quiñones M. , Dyer D. C. , Ware W. A. , Mehvar R.
Published: January 2024

Objectives

To determine the pharmacokinetics of atenolol (AT) after IV and oral administrations in cats, to assess duration of β-blocking effect, and to determine whether AT can be effectively used once per day.

Animals

9 clinically normal cats.

Procedure

Single doses of 1 (IV) or 3 (oral) mg of AT/kg of body weight were administered to each cat on different occasions, and serial blood samples were collected. Plasma concentrations of AT were subsequently determined, using high-performance liquid chromatography. The plasma concentration data were analyzed, using noncompartmental analysis. An isoproterenol challenge test was used to determine the β-blocking effect of AT on heart rate after 3 consecutive days of oral treatment (3 mg/kg, once a day).

Results

After IV administration, mean ± SD apparent volume of distribution at steady state and systemic clearance values were 1,088 ± 148 ml/kg and 259 ± 72 ml/ h/kg, respectively. Bioavailability was 90 ± 9% after oral administration. The half-life values were 3.44 ± 0.5 and 3.66 ± 0.39 hours after IV and oral administrations, respectively. Compared with baseline values prior to AT administration, heart rates at 6 and 12 hours after administration of AT were significantly reduced.

Conclusions

AT has high oral bioavailability in cats, resulting in small interindividual variability in its kinetics in this species. The drug has β-blocking effect in cats, as indicated by the attenuated heart rate response to isoproterenol; this effect persists for at least 12 hours in clinically normal cats. (Am J Vet Res 1996;57:1050–1053)
Effect of high-molecular weight dextran macromolecules on low-flow ischemia and reperfusion of the large colon in horses
Authors: Moore Rustin M. , Bertone Alicia L. , Muir William W.
Published: January 2024

Objective

To evaluate the effect of high-molecular weight (MW) dextran macromolecules on low-flow ischemia and reperfusion of the large colon in horses.

Design

Horses subjected to low-flow ischemia and reperfusion of the large colon were treated with either 0.9 NaCI (group 1, n = 6) or high-MW dextran (group 2, n = 6) solutions.

Animals

12 adult horses.

Procedure

Horses were subjected to 3 hours' low-flow ischemia followed by 3 hours' reperfusion. A dose of either 0.9% NaCI or a 6% solution of high-MW (250,000) dextran (10 ml/kg of body weight) was administered IV, 30 minutes prior to reperfusion. Hemodynamic variables were recorded at 30-minute intervals. Systemic arterial and colonic venous blood were collected for determination of PCV, plasma total protein, and whole blood lactate concentrations, and for blood gas and oximetry analyses. Histologic examination of large-colon biopsy specimens was performed.

Results

Mean arterial pressure was greater in group-2 horses, compared with group-1 horses, from 3 to 3.25 hours, but there were no significant differences between groups for any of the other hemodynamic variables. Compared with baseline values, colonic blood flow was significantly lower from 0.5 to 3 hours and was significantly greater from 3.25 to 6 hours. Arterial and colonic venous PCV were significantly lower than baseline values from 3 to 3.25 hours, and at 3 hours, respectively, in group-2 horses. These values were significantly lower in group-2 horses, from 3 to 6 and 3 to 5 hours, respectively. There was significant mucosal necrosis, hemorrhage, edema, and neutrophil infiltration in horses of both groups; however, there were no significant differences between the 2 groups.

Conclusions

High-MW dextran did not protect the colonic mucosa from low-flow ischemia and reperfusion; there were no deleterious effects on colonic mucosa or on systemic hemodynamic or metabolic variables.

Clinical Relevance

Reperfusion with high-MW dextran solution probably would not protect the large colon from ischemia-reperfusion injury associated with large-colon volvulus. (Am J Vet Res 1996;57:1067–1073)
Involvement of nitric oxide in inhibitory neuromuscular transmission in equine jejunum
Authors: Rakestraw Peter C. , Snyder Jack R. , Woliner Michael J. , Sanders Kenton M. , Shuttleworth William R.
Published: January 2024

Objectives

To evaluate the role of nitric oxide (NO), vasoactive intestinal peptide (VIP), and a transmitter acting through an apamin-sensitive mechanism in mediating inhibitory transmission in the equine jejunal circular muscle, and to determine the distribution of VIP-and NO-producing nerve fibers in the myenteric plexus and circular muscle.

Procedure

Circular muscle strips were suspended in tissue baths containing an oxygenated modified Krebs solution and attached to isometric force transducers. Responses to electrical field stimulation (EFS), tetrodotoxin, the NO antagonists l-N-nitro-arginine-methyl-ester (L-NAME) and N-nitro-l-arginine, apamin, VIP, authentic NO, and the NO donar sodium nitroprusside were tested. Immunostaining for VIP-like and NADPH diaphorase histochemical staining were performed on paraformaldehyde-fixed tissue.

Results

Subpopulations of myenteric neurons and nerve fibers in the circular muscle were positive for NADPH diaphorase and VIP-like staining. EFS caused a frequency-dependent inhibition of contractile activity. Tetrodotoxin prevented the EFS-induced inhibition of contractions. L-NAME (200 μM) and apamin 0.3 μM) significantly (P < 0.01) reduced EFS-stimulated inhibition of contractile activity at most frequencies tested. The effects of L-NAME and apamin were additive. In their combined presence, EFS induced excitation instead of inhibition (196.7% increase at 5 Hz, n = 28, P < 0.01). Inhibition of contractile activity by EFS was mimicked by sodium nitroprusside. Authentic NO (3-6 μM) abolished contractile activity. VIP induced a dose-dependent inhibition of contractile activity (89.1 ± 6.3% reduction at approximately 0.3 μM, n = 16). Antagonism of NO synthesis did not alter the response to VIP.

Conclusion

NO, VIP, and a substance acting through an apamin-sensitive mechanism appear to comediate inhibitory transmission in the equine jejunal circular muscle.

Clinical Relevance

These findings may suggest new therapeutic targets for motility disorders, such as agents that inhibit the synthesis or actions of NO. (Am J Vet Res 1996;57:1206-1213)
Biomechanics of the thoracolumbar vertebral column of dogs during lateral bending
Authors: Schulz K. S. , Waldron D. R. , Grant J. W. , Shell L. , Smith G. , Shires P. K.
Published: January 2024

Objective

To study biomechanical characteristics of the normal and surgically altered canine thoracolumbar vertebral column to determine the effects of surgery and trauma on lateral stability.

Animals

The T13-L1 vertebral motion units of 48 mixed-breed dogs were dissected free of surrounding musculature and prepared for biomechanical testing by cross-pinning the vertebral bodies and mounting in polymethylmethacrylate.

Procedure

Normal and surgically altered spinal specimens were subjected to lateral bending. The mean slope of the bending moment versus angular displacement curve and the load to failure were compared between treatment groups and significance was determined by the method of least squares (P < 0.05). Specimens were surgically altered by facetectomy, lateral fenestration, diskectomy, and combinations of these procedures. Each specimen was subjected to lateral bending to failure at a rate of 2.5 cm/min in a swing arm bending jig designed to simulate 4-point bending and subject the specimen to pure bending.

Results

Only specimens undergoing diskectomy had a significant decrease in slope and load at failure. Unilateral and bilateral facetectomies and fenestration induced a nonsignificant decrease in stiffness, compared with control specimens.

Conclusions

Fenestrations and facetectomies do not appear to increase the risk of injury to the canine thoracolumbar spinal cord during lateral bending.

Clinical Relevance

Fenestrations and facetectomies, as used in routine laminectomies, may be performed without concern for significant destabilization of the spine in lateral bending; however, it is possible that thoracolumbar spinal fractures involving only the vertebral body may significantly destabilize the spine in all modes of bending. (Am J Vet Res 1996;57:1228-1232)
Neuromuscular effects of toxins isolated from Southern Prickly Ash (Zanthoxylum clava-herculis) bark
Authors: Bowen J. M. , Cole R. J. , Bedell D. , Schabdach D.
Published: January 2024

Objective

To define the nature and mechanisms of neuromuscular effects of toxic principles in bark of Southern Prickly Ash tree (Zanthoxylum clava-herculis) that might contribute to its clinical toxicity in cattle.

Animals

31 rats, 1 dog, and 4 rabbits.

Procedures

Extracts were prepared from bark samples, using 2 extraction methods. Contractile responses, resting potentials, miniature end-plate potentials (MEPP), and end-plate potentials of rat phrenic nerve-hemidiaphragm preparations were recorded. Blood pressure and contractile responses of the cranial tibial muscle to nerve stimulation were recorded in an anesthetized dog. Topical anesthetic activity in rabbits was determined by evaluation of the corneal reflex.

Results

One extract usually stimulated muscle contractile response, whereas the other inhibited this response when evoked by nerve stimulation, but not when evoked by direct muscle stimulation. Inhibitory extract (Xl) had a hypotensive effect, but lacked topical anesthetic activity and effect on resting potentials. This extract also reduced amplitude of MEPP and end-plate potentials, but did not affect their time course or the frequency of MEPP. Stimulatory extract was not active in presence of neuromuscular blocking agent tubocurarine.

Conclusion

Active principles in Southern Prickly Ash extracts appear to exert their action on neuromuscular transmission probably through blockade of postjunctional, end-plate receptors (Xl) or enhanced release of neurotransmitter (stimulatory extract).

Clinical Relevance

Signs of clinical toxicity in cattle were best correlated with effects of Xl, which can be antagonized by Ca2+ and neostigmine. (Am J Vet Res 1996;57:1239-1244)
Effect of antibodies to staphylococcal α and β toxins and Staphylococcus aureus on the cytotoxicity for and adherence of the organism to bovine mammary epithelial cells
Authors: Cifrian Eduardo , Guidry Albert J. , O'Brien Celia N. , Marquardt Warren W.
Published: January 2024

Objective

To determine the effect of antibodies to staphylococcal α and β toxins and Staphyloco ccus aureus on the toxicity for and adherence of S aureus to bovine mammary epithelial cells.

Sample Population

Cultured bovine mammary epithelial cells and Staphylococcus aureus obtained from a cow with mastitis.

Procedure

Cultured bovine epithelial cells were incubated with antisera to α and β toxins of S aureus and culture supernatant; cell damage and S aureus adherence to cells were measured.

Results

Antisera to α, β, and α + β toxins inhibited cytotoxicity of S aureus culture supernatant. Antiserum to α + β toxin was the most effective inhibitor of cytotoxicity and antiserum to β toxin was the least effective. All 3 antisera decreased the percentage of S aureus adhered to the mammary epithelial cell monolayers and numbers of organisms per cluster of adhered bacteria. In this study, antisera to α and α + β toxins decreased the number of S aureus clusters per dish, but antiserum to β toxin had no significant effect. Antiserum to α + β toxin decreased the percentage of epithelial cells with adhered S aureus, but neither antiserum to α nor β toxin had significant effect. Antiserum to S aureus decreased the percentage of S aureus adhered, number of clusters per dish, number of organisms per cluster, and percentage of epithelial cells with S aureus adhered.

Conclusions

Antibodies to staphylococcal α and β toxins inhibit adherence to and cytotoxicity of S aureus for bovine mammary epithelial cells, and antibodies to S aureus inhibit adherence of S aureus to bovine mammary epithelial cells. (Am J Vet Res 1996;57:1308-1311)
Pulmonary vascular pressures of strenuously exercising Thoroughbreds after administration of phenylbutazone
Authors: Manohar Murli , Goetz Thomas E. , Griffin Richard , Sullivan Eileen
Published: January 2024

Objective

To determine the effects of phenylbutazone administration on heart rate and right atrial and pulmonary vascular pressures in Thoroughbreds during rest and during exercise performed at maximal heart rate.

Animals

7 healthy, exercise-conditioned Thoroughbreds.

Procedure

Horses were studied on 3 occasions: without medication (control), after IV administration of phen-ylbutazone (4.4 mg/kg of body weight) at 12-hour intervals for 2 days and a final dose given 1 hour before exercise, and after IV administration of phenylbutazone for 2 days in the same manner, but with the final dose given 24 hours before exercise. Horses were studied at rest and during exercise performed at maximal heart rate on a treadmill. Right atrial and pulmonary vascular pressures were measured with catheter-tip manometers referenced at the point of the shoulder.

Results

We did not detect significant differences in heart rate or right atrial and pulmonary vascular pressures among values recorded when horses were not given medication and values recorded when phenylbutazone was administered by either regimen. Exercise-induced pulmonary hemorrhage occurred in 6 of the 7 horses re-gardless of whether phenylbutazone was administered or the dosage regimen used.

Conclusions

In these Thoroughbreds, phenylbutazone treatment did not modify heart rate or right atrial and pulmonary vascular pressures at rest or during exercise capable of eliciting exercise-induced pulmonary hemorrhage. Thus, because phenylbutazone is a potent inhibitor of cyclooxygenase, prostaglandins probably do not play a role in mediating exercise-induced pulmonary hypertension in horses.

Clinical Relevance

Phenylbutazone administration did not modify the pulmonary capillary hypertension in the strenuously exercising Thoroughbreds, and therefore, is unlikely to alter the prevalence or severity of exercise-induced pulmonary hemorrhage in Thoroughbred race-horses. (Am J Vet Res 1996;57:1354-1358)
Effects of ozone and airway inflammation on glutathione status and iron homeostasis in the lungs of horses
Authors: Mills P. C. , Roberts C. A. , Smith N. C.
Published: January 2024

Objective

To investigate the effects of ozone and airway inflammation on indices of oxidant injury in horses.

Animals

5 clinically normal horses and 25 horses referred for poor performance

Procedure

Blood, tracheal wash, and bronchoalveolar lavage fluid samples were collected before and after ozone exposure (n = 5) or from clinical cases (n = 25), and were analyzed for reduced glutathione (GSH), glutathione disulfide (GSSG), and free and total iron (Fe) values. A scor ing system (0 to 5) was used to assess airway inflammation on the basis of clinical signs and cytologic analysis of the tracheal wash and bronchoalveolar lavage fluid samples.

Results

Ozone induced significant (P < 0.05) increases in GSH (195.4 ± 68.5 μM, GSSG (19.4 ± 6.4 μM). and free (25.5 ± 16.1 μM) and total (93.1 ± 13.4 μM) Fe values in the pulmonary epithelial lining fluid, compared with preozone samples (49.2 ± 18.6, 2.4 ± 1.2, 0.0, and 33.1 ± 5.9 μM, respectively). The presence of airway inflammation (19/25) was associated with high GSSG and free and total Fe, but not GSH, values in epithelial lining fluid, compared with values for clinically normal horses (6/25). There were no differences in the systemic values of GSH, GSSG, and free and total Fe between any of the groups. A strong correlation (r = 0.84; P < 0.001) existed between inflammation score and the glutathione redox ratio (GSSG/IGSH + GSSG]) in the 25 horses admitted for clinical examination

Conclusions

Oxidant injury in the lung will induce changes in the glutathione status and Fe homeostasis that could affect pathogenesis of the disease.

Clinical Relevance

Measurement of indices of oxidant injury may be useful in the diagnosis of airway inflammation and the response to inhaled oxidants. (Am J Vet Res 1996;57:1359-1363)
Postimplantation increase in plasma fibrinogen concentration with increase in relaxin concentration in pregnant dogs
Authors: Concannon Patrick W. , Gimpel Terry , Newton Lucy , Castracane V. Daniel
Published: January 2024

Objective

To determine time courses of pregnancy-related changes in plasma fibrinogen, serum relaxin, and serum C-reactive protein-like immunoreactivity (CRP-LI) concentrations in pregnant and nonpregnant dogs.

Animals

16 pregnant and 13 nonpregnant Beagles, 6 pregnant Beagles, and 3 pregnant and 3 nonpregnant dogs of other breeds.

Procedure

Fs'brinogen was measured by nephelometric centrifugal analysis of light scatter in plasma samples of all dogs, and CRP-LI was measured by fluorescence immunoassay in selected sera from 10 pregnant and 10 nonpregnant dogs. Relaxin was measured in selected sera from 7 pregnant and 7 nonpregnant dogs.

Results

During pregnancy, fibrinogen concentration increased between days 21 and 30 after the luteinizing hormone surge, and was > 280 mg/dl between days 29 and 50 in 84 of 86 samples, with peak values 539 ± 29 mg/dl higher (P < 0.01) than those in nonpregnant dogs (188 ± 8 mg/dl), higher values from days 21 to 50 (P < 0.01) than those in nonpregnant dogs, and values similar to those in nonpregnant dogs after day 50. Relaxin concentration was increased from days 26 to 30 and 0 to 4 days after fibrinogen concentration increased in pregnant dogs, and was not detectable in nonpregnant dogs. The CRP-LI concentration was higher in pregnant dogs at days 26 to 50, but values were inconsistent within and among dogs, and near the limit of sensitivity of the assay.

Conclusions

Concentration of the acute-phase reactant protein fibrinogen increases after day 20 following implantation in dogs, at or just before the pregnancy-specific increase in relaxin concentation from days 26 to 30, and persists until day 50.

Clinical Relevance

Fibrinogen assay may be useful for pregnancy diagnosis in dogs. (Am J Vet Res 1996;57:1382–1385)
In vitro determination of equine third metacarpal bone unloading, using a full limb cast and a walking cast
Authors: Brommer Harold , Back Wim , Schamhardt Henk C. , Rijkenhuizen Astrid B. M. , Barneveld Ab
Published: January 2024

Objective

To improve fracture treatment, in vitro experiments were performed to study the influence of a full limb cast and a walking cast on the loading regimen of bones in the distal portion of the equine forelimb.

Animals

6 forelimbs of 6 Shetland ponies.

Procedure

Loading of the third metacarpal bone was considered a representative measure for distal limb loading. Electrical resistance rosette strain gauges were attached to the dorsal, palmar, medial, and lateral surfaces of the midshaft of this bone in 6 forelimbs of 6 Shetland ponies. The limbs were tested in a pneumatic loading device to a maximal load of 1,500 N.

Results

Both casts decreased the amount of compressive forces acting on the metacarpal bone. Application of a full limb cast resulted in a variable and eccentric decrease, remaining strains ranging from 84 to 7% of the baseline value. A walking cast was superior in that it gave a centric and more uniform reduction of compressive loading to <11 % of the baseline value. Moreover, a walking cast neutralized the bending and torsion components of the loading.

Conclusion

This study confirmed the clinical experience that a walking cast creates more reliable and favorable conditions for healing of fractures than does a full limb cast. (Am J Vet Res 1996;57:1386-1389)
Resting energy expenditure in dogs with nonhematopoietic malignancies before and after excision of tumors
Authors: Ogilvie Gregory K. , Walters Lisa M. , Salman M. D. , Fettman Martin J.
Published: January 2024

Objective

To determine whether apparently resting dogs with nonhematopoietic malignancies have increased resting energy expenditure (REE), compared with clinically normal dogs.

Animals

46 client-owned dogs with nonhematopoietic malignancies and 30 client-owned dogs that were clinically normal.

Procedure

Apparently resting, client-owned dogs with nonhematopoietic malignancies before (n = 46) and 4 to 6 weeks after (n = 30) surgical removal of tumors were compared with apparently resting, clinically normal, client-owned dogs (n = 30). An open flow indirect calorimetry system was used to determine the following: rate of oxygen consumption (ml/min/kg of body weight); rate of carbon dioxide production (mls/min/kg), REE (kcal/kg/d), and respiratory quotient. Because of the wide range of body weight, REE and oxygen consumption were also expressed per kg of body weight0.75.

Results

Surgical removal of the tumor did not significantly alter any of the variables measured when all dogs with tumors were assessed as a single group, or when the dogs were divided on the basis of having the following types of tumors: carcinomas and sarcomas, osteosarcomas, and mammary adenocarcinomas. None of the data obtained prior to surgical treatment from any of the dogs grouped by tumor type were significantly different from clinically normal dogs.

Conclusions

REE (54.4 ± 16 kcal/kg/d or 125 ± 19 kcal/kg0.75/d) and, presumably, caloric requirements of dogs with nonhematopoietic malignancies are not significantly different from those obtained from clinically normal dogs (53.9 ± 16 kcal/kg/d or 116 ± 32 kcal/kg0.75/d). Furthermore, these variables do not change significantly when the tumor is excised and the dog is reassessed after 4 to 6 weeks.

Clinical Relevance

Knowledge that REE in dogs with solid tumors is not significantly different from REE of clinically normal dogs may be of value when planning nutritional treatment for dogs with nonhematopoietic malignancies. (Am J Vet Res 1996;57:1463-1467)
Lack of serum antibodies against glycoprotein E in pseudorabies virus-immune pigs infected with wild-type virus
Authors: Jacobs Liesbeth , Kimman Tjeerd G. , Bianchi Andre
Published: January 2024

Objective

To examine whether pigs with solid immunity against pseudorabies virus (PRV) could harbor latent infection with wild-type PRV without developing antibodies against glycoprotein E (gE), which is used as a marker protein to differentiate pigs that have been vaccinated from pigs infected with wild-type PRV.

Animals

Specific-pathogen-free pigs that were seronegative for antibodies to PRV.

Procedure

Oropharyngeal swab specimens were collected, and virus content was measured. Serum samples were obtained 1 week before and 2 and 4 weeks after challenge exposure. Four weeks after challenge exposure, pigs were slaughtered; various tissues were collected for virus isolation, and DNA was analyzed by polymerase chain reaction.

Results

Of the intranasally inoculated pigs, only 1 pig shed virus (for 1 day) but none developed antibodies directed against gE. Of the inoculated IM pigs, 3 pigs shed virus (for several days) and 5 developed antibodies directed against gE. One pig did not shed virus and did not develop detectable gE antibodies. However, variable amounts of wild-type virus DNA were detected in various tissues.

Conclusions

Immunized pigs can be infected with wild-type PRV without being detected by the gE-specific ELISA, which is routinely used to discriminate between infected and vaccinated pigs. The implication for eradication programs is that these pigs might be a source of new outbreaks. (Am J Vet Res 1996;57:1525–1528)
Pharmacokinetics, effects on renal function, and potentiation of atracurium-induced neuromuscular blockade after administration of a high dose of gentamicin in isoflurane-anesthetized dogs
Authors: Martinez Elizabeth A. , Mealey Katrina L. , Wooldridge Anne A. , Mercer Dana E. , Cooper Jonathan , Slater Margaret R. , Hartsfield Sandee M.
Published: January 2024

Objective

To determine pharmacokinetics, renal effects, and effect on atracurium-induced neuromuscular blockade of a high dose of gentamicin in isoflurane-anesthetized dogs.

Animals

6 healthy, adult, mixed-breed dogs, anesthetized twice and receiving gentamicin (6 mg/kg of body weight, IV) or saline solution.

Procedure

Blood samples were collected before and at intervals after gentamicin administration. Pharmacokinetic values were evaluated by use of multivariant stepwise linear regression analysis. Gentamicin-induced renal changes were assessed by comparing pretreatment and 12- to 24-hour posttreatment values for serum urea nitrogen, serum creatinine, urine creatinine-to-γ-glutamyltransferase ratio, and urinalysis. Neuromuscular blockade, maintained by atracurium infusion, was assessed, using the train-of-four response. At stable 50% depression of first twitch (T1) gentamicin or saline solution was given. Before and at posttreatment intervals for 60 minutes, T1% and fourth twitch-to-T1 ratio were recorded. The infusion was discontinued and 50 to 75% T1 recovery time was recorded. At 75% T1, edrophonium (0.5 mg/kg) was administered IV.

Results

Mean values for volume of distribution and clearance were 0.263 L/kg and 2.0 ml/min/kg, respectively. Mean maximal serum concentration of gentamicin was 46.4 μg/ml. Pre and posttreatment values for serum urea nitrogen, serum creatinine, urine creatinine-to-γ-glutamyltransferase ratio, and other urine analytes were not significantly different. Mean (± SD) values for T1% and fourth twitch-to-T1 ratio decreased significantly after gentamicin (depression was maximal at 5 minutes). Recovery time (50 to 75% T1) was not different between groups. Edrophonium restored twitch to baseline.

Conclusions

Mean values for apparent volume of distribution and total body clearance of gentamicin were similar to values in unanesthetized dogs. Mean maximal serum concentration of gentamicin was greater than that in unanesthetized dogs. Renal function was unaffected. Gentamicin potentiated atracurium-induced neuromuscular blockade, but did not affect recovery time. (Am J Vet Res 1996;57:1623–1626)
Comparative pharmacokinetics of phenylbutazone and its metabolite oxyphenbutazone in clinically normal horses and donkeys
Authors: Mealey Katrina L. , Matthews Nora S. , Peck Kenneth E. , Ray Allen C. , Taylor T. S.
Published: January 2024

Objective

To compare plasma disposition of phenylbutazone and its metabolite oxyphenbutazone after IV administration of phenylbutazone in horses and donkeys.

Animals

4 clinically normal horses and 6 clinically normal donkeys.

Procedure

Blood samples were collected from each animal at time 0 (before) and 5, 10, 20, 30, 45, 60, 90, 120, 180, 240, 300, 360, and 480 minutes after IV administration of a bolus dose of phenylbutazone. Serum was analyzed in triplicate by use of high-performance liquid chromatography for determination of phenylbutazone and oxyphenbutazone concentrations. The serum concentration-time curve for each horse and donkey was analyzed separately to estimate model-independent pharmacokinetic variables.

Results

Significant differences were found in several pharmacokinetic variables of phenylbutazone and oxyphenbutazone in horses, compared with donkeys. Mean total body clearance of phenylbutazone in horses was fivefold less than that in donkeys (29.3 and 170.3 ml/kg/h, respectively). Mean values for area under the curve and mean residence time in horses (118.3 µg/h/ml and 3.6 hours, respectively) were significantly greater than values in donkeys (28.3 µg/h/ml and 1.7 hours, respectively). Mean values for apparent volume of distribution at steady state were not significantly different between horses and donkeys. For oxyphenbutazone, mean time to peak concentration in donkeys was significantly less than that in horses (1.6 and 6.4 hours, respectively).

Conclusion

Phenylbutazone clearance in donkeys was higher than that in horses, and appearance of the metabolite oxyphenbutazone in serum was more rapid in donkeys than in horses, indicating that hepatic metabolism of phenylbutazone is more rapid in donkeys than in horses.

Clinical Relevance

Because serum concentration of phenylbutazone after single IV bolus administration (4.4 mg/kg of body weight) decreases more rapidly in donkeys, compared with horses, phenylbutazone may require more frequent administration in donkeys to achieve therapeutic efficacy. (Am J Vet Res 1997;58:53–55)
Endotoxemia associated with experimentally induced multiple portosystemic shunts in dogs
Authors: Howe Lisa M. , Boothe Dawn M. , Boothe Harry W.
Published: January 2024

Objective

To document presence of endotoxin in portal and systemic blood in a model of canine multiple portosystemic shunts (PSS), and compare values in clinically normal dogs, before and after vena caval banding.

Animals

6 control dogs and 10 dogs with dimethylnitrosamine-induced multiple PSS that were subjected to vena caval banding.

Procedure

Dimethylnitrosamine was administered orally (2 mg/kg of body weight, twice weekly) to the 10 dogs in the diseased group until multiple PSS developed. Surgery was then performed on all 16 dogs (both groups), and shunts were confirmed in the diseased dogs. Blood was collected from the portal vein, hepatic vein, and caudal vena cava for baseline endotoxin determination and aerobic and anaerobic blood culturing. Baseline pressure measurements were taken from the portal venous catheter; then vena caval banding was performed. Blood for endotoxin determinations was taken from all vessels 20, 40, 60, 120, 240, and 360 minutes after banding; portal pressure measurements were taken at the same time as sample acquisition. Blood for culturing was taken from the portal and hepatic venous catheters at 120, 240, and 360 minutes after banding.

Results

Dogs in the diseased group had significantly greater overall presence of endotoxin in the portal vein (P ≤ 0.0002), hepatic vein (P ≤ 0.0001), and caudal vena cava (P ≤ 0.0004) than did control dogs. With respect to time, endotoxin presence was greater in the diseased group before banding (P ≤ 0.0002), and at 20 (P ≤ 0.0008), 40 (P ≤ 0.002), 60 (P ≤ 0.006), and 120 (P ≤ 0.01) minutes after banding.

Conclusions

Endotoxemia is more frequently present in catheterized dogs with dimethylnitrosamine-induced hepatic disease and multiple PSS, compared with clinically normal dogs. Additionally, portal pressure changes induced by vena caval banding did not affect endotoxemia.

Clinical Relevance

Endotoxemia may exist in dogs with hepatic disease and multiple PSS, and should be kept in mind when formulating treatment (particularly antimicrobial selection) for dogs with suspected endotoxemia. (Am J Vet Res 1997;58:83–88)
Actions of xylazine in young swine
Authors: de Segura I. A. Gómez , Tendillo F. J. , Mascías A. , Santos M. , Castillo-Olivares J. L. , Steffey E. P.
Published: January 2024

Objective

To determine sedative, analgesic, and basic cardiovascular effects of xylazine administered to pigs.

Animals

6 two-month-old Landrace x Large White pigs.

Procedure

Xylazine was administered IV at increasing dosages (1, 2, 4, 8, and 16 mg/kg of body weight) to otherwise unmedicated, conscious pigs, and the aforementioned effects were determined before xylazine administration and 2, 5, 10, and 15 minutes later. Then a higher xylazine dosage was given after the 15-minute measurements were taken.

Results

None of the xylazine dosages induced sufficient analgesia to prevent painful response to tail clamping; considerable excitation with vocalization and without appreciable sedative effect was observed at all dosages. At lower dosages, cardiovascular effects were characterized by bradycardia and biphasic blood pressure response; initial hypertension was followed by hypotension. At higher dosages, severe hypotension with moderate bradycardia was followed by marked bradycardia and return to normal baseline values or slight increase in blood pressure.

Conclusion

Xylazine did not induce adequate sedative or analgesic effects in pigs at any dosage tested; however, cardiovascular effects were considerable. These effects of xylazine differ from those observed in other domestic species. (Am J Vet Res 1997;58:99–102)
Effect of H1-antihistamines on histamine release from dispersed canine cutaneous mast cells
Authors: García Gloria , DeMora Fernando , Ferrer Lluís , Puigdemont Anna
Published: January 2024

Objective

Because of the implication of histamine in canine atopic dermatitis, H1-antihistamines may provide a valid alternative to glucocorticoid therapy. In vitro study of these drugs prior to clinical testing can allow the most promising compounds to be selected for trials and render trials with drugs of doubtful efficacy unnecessary.

Sample Population

Isolated canine cutaneous mast cells.

Procedure

Cells were preincubated with antihistamines at increasing concentrations and incubated with concanavalin A (1,000 µg/ml), calcium ionophore A23187 (1 µM), and substance P (100 µM). Compound 48/80 was not used because it proved to be cytotoxic.

Results

Generally, significant prodegranulating effect was not observed for most of the studied agents. Only terfenadine increased spontaneous histamine release at concentrations > 30 µM. Cetirizine did not block histamine release at any of the studied concentrations. Ketotifen had a low inhibitory effect only at the highest concentration (100 µM) after concanavalin A- (23.6 ± 2.8%) and calcium ionophore A23187- (29.8 ± 3.0%) induced release. Terfenadine caused a concentration-dependent inhibitory effect after ionophore A23187- (48.1 ± 2.2%) and concanavalin A- (28.9 ± 2.3%) activation, but was inactive against substance P-induced release. In contrast, loratadine had potent dose-dependent inhibition of concanavalin A- and ionophore A23187-induced histamine release, with maximal effect of 85.6 ± 3.1 % and 62.6 ± 4.7%, respectively, at 100 µM concentration. After substance P activation, histamine release was only slightly inhibited by loratadine (14.8 ± 1.1%).

Conclusions

This study documents the behavior of isolated canine cutaneous mast cells in the presence of nonimmunologic stimulation. Using this in vitro method, we were able to determine that loratadine is the only antihistamine that has potent inhibition of histamine release from dog cutaneous mast cells without a substantial prodegranulating effect. Loratadine is, therefore, a good candidate for clinical testing. (Am J Vet Res 1997;58:293–297)