bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of the neodymium:yttrium aluminum garnet laser on postoperative neuroma formation after neurectomy in rats
Authors: Nickels Frank A. , Patterson Jon S. , Arnoczky Steven P.
Published: January 2024

The effect of neodymium:yttrium aluminum garnet (Nd:YAG) laser-performed neurectomy was compared with conventional scalpel-performed neurectomy, using the rat sciatic nerve model. Sixteen male Sprague-Dawley rats underwent unilateral transection of the sciatic nerve by 1 of 3 methods. The sciatic nerve of rats under general anesthesia was transected by use of a steel scalpel blade (group 1, n = 5); a contact Nd:YAG laser at 6 W of power (group 2, n = 6); or an Nd:YAG laser at 12 W of power (group 3, n = 5). Thirty days after surgery, all rats were euthanatized and the nerves were harvested, imbedded in paraffin, fixed, and sectioned for light microscopy. Neurodegenerative changes and perineurial cell proliferation were least severe in the nerves transected by use of a steel scalpel (group 1), and were most severe in nerves transected by use of the laser at 6 W of power (group 2). There was a significant difference in prevalence of perineurial proliferation between the scalpel and laser neurectomy groups (P = 0.029). There was no significant difference in prevalence of neuroma formation or neurodegeneration between the laser and scalpel neurectomy groups, although neuromas were found in 3 rats (2 from group 2 and 1 from group 3). Within the limits of this study, we found that the Nd:YAG laser was less successful than sharp division, using a scalpel, in preventing neuroma formation after nerve transection.
Complete primary sequence of equine cartilage link protein deduced from complementary DNA
Authors: Dudhia Jayesh , Platt David
Published: January 2024

Investigation of the structure of equine articular cartilage link protein (lp) from individuals ranging in age from 1 to 15 years identified 3 distinct isoforms having molecular weights of 46,000, 43,000, and 41,000. The relative amounts of each of the 3 isoforms altered with age. The largest form did not change with age; however, amounts of the Mr 43,000 and 41,000 forms increased with increasing age. The results suggested that an accumulation, in the extracellular matrix of cartilage, of these 2 smaller products may have arisen from proteolytic cleavage. The complete amino acid sequence of the protein core was determined from complementary dna products prepared by polymerase chain reaction amplification of cartilage lp mRNA. The sequence had 96% similarity with human lp and with that of other species for which the primary structure has been determined. This high degree of sequence conservation and the isoform data indicate that extracellular processing of lp occurs by similar mechanisms in various species. At the transcription level, equine chondrocytes were found to express lp as 2 abundant mRNA of 5.0 and 3.0 kb, and a smaller mRNA of 1.5 kb. Processing of the lp mRNA in horses, thus, appears to be similar to that found in other species investigated, and although multiple transcripts are present, the coding region remains unaltered and only 1 protein product is made.
Effect of bethanechol, neostigmine, metoclopramide, and propranolol on myoelectric activity of the ileocecocolic area in cows
Authors: Steiner Adrian , Roussel Allen J. , Martig Johannes
Published: January 2024

The effect of bethanechol, neostigmine, metoclopramide, and propranolol on myoelectric activity of the ileum, cecum, and proximal loop of the ascending colon was determined in 6 healthy Jersey cows implanted with 8 pairs of bipolar electrodes. Assigned at random, each cow received each of 5 treatments in 3-day intervals. The treatments included bethanechol (0.07 mg/kg of body weight, sc), neostigmine (0.02 mg/kg, sc), metoclopramide (0.15 mg/kg, im), dl-propranolol (0.2 mg/kg, im), and 0.9% sodium chloride (NaCl) solution (20 ml, sc). All drugs were administered during early phase I of the migrating myoelectric complex in the ileum. Myoelectric activity was recorded for 4 hours after treatment, and data were analyzed for each hour separately.

Bethanechol and neostigmine significantly (P < 0.05) increased the number of cecocolic spikes per minute per electrode, duration of cecocolic spike activity (%), and number of cecocolic propagated spike sequences per 10 minutes, relative to NaCl, during 1 or more hours of the recording period. The effect of bethanechol was more pronounced on duration of spike activity and number of propagated spike sequences, whereas neostigmine mainly increased the number of (uncoordinated) spikes. Metoclopramide and propranolol had no significant effect on cecocolic myoelectric activity, relative to NaCl.

It was concluded that bethanechol and, less likely, neostigmine at the dosage used in this study may be suitable for medical treatment of cecal dilatation in cattle in which hypomotility of the cecum and proximal loop of the ascending colon has to be reversed. The potential advantage of bethanechol vs neostigmine for medical treatment of cecal dilatation is worth further evaluation.
Ultrasonography as a method to determine tendon cross-sectional area
Authors: Gillis Carol , Sharkey Neil , Stover Susan M. , Pool Roy R. , Meagher Dennis M. , Willits Neil
Published: January 2024

Ultrasonographic cross-sectional area (csa) measurements of equine superficial digital flexor (sdf) tendon were obtained to determine the feasibility of ultrasonography for csa measurement of tendon in vivo and in vitro. Ultrasonographic measurements were compared with a more traditional csa measurement method, ink-blot analysis. In addition, values for ultrasonographic sdf tendon mean echogenicity were obtained in vivo and in vitro. The left forelimb sdf tendons of 23 horses were evaluated ultrasonographically. Cross-sectional images were acquired at 4-cm intervals distal to the base of the accessory carpal bone (dacb) to the level of the proximal sesamoid bones while horses were standing squarely. After euthanasia, the left forelimbs were mounted in a materials testing system (mts) and loaded under tension to standing load. Ultrasonographic images were again acquired at the same locations. The ultrasonographic images were digitized, and values for ultrasonographic csa and mean echogenicity were obtained for each level.

Immediately after mechanical testing, a 1-cm-thick transverse section of sdf tendon at 12 cm dacb was removed. Three ink blots were prepared from each end of the removed tendon section and digitized. The 6 csa values were averaged to generate a value for morphologic csa for each sdf tendon at 12 cm dacb.

Standing ultrasonographic tendon csa at 12 cm dacb was consistently smallest (mean ± sd csa = 86 ± 11 mm2), followed by mts ultrasonographic csa (mean, 95 ± 12 mm2), ink-blot morphologic csa being largest (mean, 99 ± 15 mm2). Comparison of standing and mts ultrasonographic csa values at 12 cm dacb revealed a strong positive linear correlation between methods (R2 = 0.74, P = 0.001). Comparison of ink-blot csa at 12 cm dacb with standing and mts ultrasonographic csa revealed strong positive linear correlations (R2 = 0.64, P = 0.001 and R2 = 0.72, P = 0.001, respectively).

For ultrasonographic mean echogenicity, standing values insignificantly exceeded mts values at each level. The authors conclude that ultrasonography is a useful technique for the noninvasive assessment of sdf tendon csa that can be applied in vivo and in vitro.
Intracranial pressure and cerebral perfusion pressure in clinically normal equine neonates
Authors: Kortz Gregg D. , Madigan John E. , Goetzman Boyd W. , Durando Mary
Published: January 2024

Intracranial pressure (icp) and cerebral perfusion pressure (cpp) were determined in 8 clinically normal neonatal foals. After the foals oriented themselves and nursed the mares, they were sedated as necessary, and local anesthesia was provided for making the skin incisions. Using a technique similar to that used in human beings, an indwelling subdural catheter was placed to measure icp. Carotid artery catheterization was used to measure arterial blood pressure. Cerebral perfusion pressure was calculated as the difference between mean arterial blood pressure and icp.

Intracranial pressure and cpp readings were taken twice during each 24-hour period, starting at 6 hours of age and continuing through 72 hours of age. Mean (± sd) icp were 5.83 ± 1.82, 8.81 ± 2.06, and 9.55 ± 1.55 mm of Hg (range, 2 to 15 mm of Hg), and mean cpp were 80.19 ± 10.34, 75.30 ± 10.86, and 76.80 ± 12.59 mm of Hg (range, 50 to 109 mm of Hg) for each of the first three 24-hour periods after birth, respectively. All 8 foals had physical and neurologic examinations, csf analysis, and computerized axial tomography evaluations. The foals manifested normal behavior during the interval of measurements, and adverse effects of the procedure were not detected during the monitoring period. Establishment of normal values for icp and cpp are important to clinicians who have the opportunity to apply this technique for monitoring and evaluating neonatal foals with signs of cns dysfunction.
Thyroid, renal, and splanchnic circulation in horses at rest and during short-term exercise
Authors: Manohar Murli , Goetz Thomas E. , Saupe Beth , Hutchens Elizabeth , Coney Elizabeth
Published: January 2024

Using radionuclide-labeled 15-μm-diameter microspheres injected into the left ventricle, we examined blood flow to the thyroid gland, adrenal glands, kidneys, and various gastrointestinal tract tissues in 9 healthy horses while they were standing quietly (rest) and during exercise at 2 work intensities (8 and 13 m/s). Hemodynamic measurements were made during steady-state conditions, as judged by the stability of heart rate as well as aortic, pulmonary, and right atrial pressures. The similarity of blood flow values for the left and the right kidneys during each of the 3 conditions indicated adequate mixing of microspheres with blood. In standing horses, of all tissues examined, the thyroid gland had the highest blood flow (1,655.2 ± 338.5 ml/min/100 g)—being about threefold that in the kidneys. Adrenal blood flow, by contrast, was only 25% of that in the kidneys (589.5 ± 50.4 ml/min/100 g). Among the gastrointestinal tract tissues, glandular stomach and pancreas had the highest blood flows (214.3 ± 21.6 and 197.6 ± 23.4 ml/min/100 g, respectively). Small intestinal perfusion was not different from that in the ventral colon and cecum, but their values exceeded those for the dorsal and small colons. Exercise at 8 and 13 m/s caused significant increase in adrenal blood flow as vascular resistance decreased significantly. In the kidneys, blood flow was only insignificantly affected during exercise at 8 m/s, but at 13 m/s there was a profound reduction in renal blood flow as intense renal vasoconstriction occurred. Vasoconstriction also caused thyroid and pancreatic blood flow to decrease significantly at both levels of exertion. Significant vasoconstriction occurring in all gastrointestional tract tissues at 8 and 13 m/s caused blood flow to be diverted away from these vascular beds. Thus, our data indicated that renal, adrenal, and splanchnic organ/tissue blood flow responses of strenuously exercising horses closely resemble those described for exercising ponies.
Effects of tumor necrosis factor blockade on interleukin 6, lactate, thromboxane, and prostacyclin responses in Miniature Horses given endotoxin
Authors: Cargile Jana L. , MacKay Robert J. , Dankert John R. , Skelley Leslie
Published: January 2024

A monoclonal antibody (mab) against equine tumor necrosis factor-α (Eq tnf) was used to investigate the role of tnf in cytokine, eicosanoid, and metabolic responses of Miniature Horses given endotoxin. Plasma concentrations of interleukin 6 (il-6), lactate, thromboxane A2 metabolite, and prostacyclin metabolite (6-keto-pgf1α) were measured in 10 Miniature Horses given 0.25 µg of lipopolysaccharide (lps; Escherichia coli O55:B5)/kg of body weight. Five horses were given Eq tnf mab and 5 were given isotype-matched mab as control. All horses were given 1.86 mg of antibody/kg by iv infusion, 5 minutes before lps was given iv. Blood samples were taken 20 minutes before and at multiple intervals for 24 hours after lps was given. Interleukin 6 bioactivity in plasma was measured, using il-6-dependent cell line (B9). Eicosanoid activities were assessed by enzyme immunoassay, and plasma lactate concentration was determined enzymatically. Data were analyzed by anova and Tuke's honest significant difference test for significant (P < 0.05) effect of treatment. Horses given Eq tn mab had significantly (P < 0.050) lower peak mean ± sem il-6 (59 ± 29 U/ml), lactate (16 ± 2.00 mg/dl), and 6-keto-pgf1α (254 ± 79 pg/ml) values then did horses given control mab (880 ± 375 U/ml for il-6; 26 ± 0.04 mg/dl for lactate; and 985 ± 290 pg/ml for 6-keto-pgf1α). There was no effect of anti-tnf treatment on lps-induced thromboxane A2 metabolite production. Tumor necrosis factor mediated il-6, lactate, and prostacyclin responses, without affecting thromboxane production in horses given lps.
Pathologic effects in brain after intracranial pressure monitoring in clinically normal dogs, using a fiberoptic monitoring system
Authors: Bagley Rodney S. , Keegan Robert D. , Greene Stephen A. , Harrington Michael L. , Moore Michael P.
Published: January 2024

During 2 separate studies, intracranial pressure (icp) was measured in 13 healthy dogs (group A, n = 7; group B, n = 6), using a fiberoptic monitoring system implanted surgically in the right superficial cerebral cortex. Average icp was measured for 15 minutes after a 15-minute post-implantation period of equilibration. Intracranial pressure was measured in group-A dogs at 2.0 and 1.3% end-tidal isoflurane concentrations. Mean ± 1 sd icp in group-A dogs at 2.0 and 1.3% end-tidal isoflurane concentrations was 11 ± 2 and 11 ± 3 mm of Hg, respectively. Dogs of group A were euthanatized immediately after measurements were obtained. Mean icp ± 1 sd in group-B dogs was 11 ± 3 mm of Hg. After monitoring, but prior to euthanasia, group-B dogs underwent callosotomy, and were maintained for 30 days after surgery. The brain was removed from all dogs, formalin fixed, and examined grossly and microscopically for lesions associated with fiberoptic cable implantation. Variable degrees of hemorrhage and mechanical brain damage were seen focally around the catheter site in all brains from group-A dogs, especially when the cable entered through a sulcus. In 1 dog, local vacuolation was seen in the brain immediately adjacent to the tract associated with implantation of the fiberoptic catheter. In all other dogs, the additional cortex was histologically normal. Histologic lesions associated with cable implantation were not observed in group-B dogs.
Pharmacokinetics of bacampicillin in equids
Authors: Sarasola Patxi , McKellar Quintin A.
Published: January 2024

Bacampicillin hydrochloride is an ester prodrug that is hydrolyzed to ampicillin after its absorption from the gastrointestinal tract. It was administered intragastrically at a dose rate of 13.5 mg/kg of body weight to ponies and horses, and was highly bioavailable (F = 41.0%), compared with other penicillins in adult horses. The high peak ampicillin plasma concentration of 6,1 ± 0,5 µg/ml achieved and persistence of the antibiotic at concentration of 0.3 ± 0.1 µg/ml 6 hours after its intragastric administration, suggest that bacampicillin hydrochloride may reach suitable bactericidal concentrations for treatment of infections caused by susceptible microorganisms.

In a separate experiment, dichlorvos, an organo-phosphate compound that inhibits some of the esterase activity in plasma, was administered orally to the same animals at a dose rate of 40 mg/kg, followed by intragastric administration of bacampicillin hydrochloride at a dose of 13.5 mg/kg. Plasma pseudocholines-terase and erythrocyte acetylcholinesterase activities were reduced to < 5% of reference (predichlorvos) values after dichlorvos administration. However, rate of hydrolysis of bacampicillin into ampicillin was not affected. Consequently, the disposition and fate of bacampicillin when administered intragastrically 1 day after dichlorvos administration were similar to the values obtained after administration of bacampicillin alone.

Intragastric coadministration of probenecid at a dose rate of 75 mg/kg and bacampicillin at 13.5 mg/ kg limited absorption of the antibiotic from the gastrointestinal tract. This suggests existence of a common transport mechanism for bacampicillin and probenecid in the gastrointestinal wall, and precludes use of this combination for treatment. The bioavailable fraction of ampicillin after combination treatment indicated prolonged residence time in the plasma, presumably as a consequence of reduced renal tubular secretion.
Kinematic differences between the distal portions of the forelimbs and hind limbs of horses at the trot
Authors: Back Willem , Schamhardt Henk C. , Hartman Wrister , Barneveld Albert
Published: January 2024

In literature, it has been hypothesized that the concussion at impact in the equine forelimb is larger than that in the hind limb, and therefore, eventually more clinical lameness may develop in the distal portion of the forelimbs. As the functional anatomy of the distal forelimb and hind limb segments is similar, a study was undertaken to compare the kinematics of hoof and fetlock in the forelimbs and hind limbs. For this purpose, the trot of 24 clinically normal (sound) horses on a treadmill (4 m/s) was recorded, using modern gait analysis equipment.

It appeared that vertical hoof velocity at impact and the resulting vertical hoof acceleration were higher in the forelimb than in the hind limb. In contrast, horizontal hoof velocity at impact and the resulting horizontal acceleration were higher in the hind limb. Just after impact, the fetlock was more rapidly extended in the forelimb than the hind limb. The peak maximal and minimal accelerations of that joint also were significantly (P < 0.05) higher in the forelimb than in the hind limb.

Results of this study indicate that, at the beginning of the stance phase, the distal portion of the forelimb is subjected to more kinematic stress than the distal portion of the hind limb. The higher angular velocity of the fetlock can be interpreted as more rapid loading of this joint, whereas the higher peak accelerations represent the higher oscillatory changes in fetlock movement. It is known from literature that repetitive impulsive joint loading and rapid oscillations in joint movement, even within physiologic limits, contribute to development of osteoarthrosis. Therefore, the differences between distal forelimb and hind limb kinematics found in this study may be related to the generally known higher incidence of chronic lameness in the forelimbs.
Thoracic lymphatic cannulation for the study of pulmonary immune responses in lung lymph of calves
Authors: Gershwin Laurel J. , Gunther Robert A. , Smith Steven G. , Boyle Gabrielle A. , Friebertshauser Kathleen E.
Published: January 2024

Objective

To develop a system for analysis of immune response variables in the lymph draining the lung and to establish baseline data for clinically normal calves.

Design

Surgery was performed on 6 calves to insert a cannula into the efferent lymphatic duct of the caudal mediastinal lymph node to create a long-term thoracic lymph fistula draining to the exterior. Lymph was collected daily, and on the fifth postoperative day, calves were exposed to an aerosol of cell culture medium (mock infection). For the next 10 days, lymph was collected for analysis and, on the tenth day, necropsy was performed.

Animals

Six 6- to 8-week-old Holstein bull calves.

Procedures

Daily lymph samples were evaluated for: flow rate; total and differential cell counts; and IgG, IgM, IgA, IgE, and protein concentrations. On days −4, −1, 1, 4, 7, and 10, cells were stained and quantitated by fluorescence-activated cell sorter analysis for T, B, CD4+, and CD8+ cells. Blood lymphocytes were evaluated on days -1 and 10 for comparison.

Results

Flow was established for up to 25 days, with a mean rate between 11 and 22 ml/h. Protein concentrations in lymph and plasma did not indicate a protein drain. Although mean lymphocyte counts reflected a slight gradual decrease in lymph lymphocytes, this effect was not apparent in every calf, nor was the effect seen in blood lymphocytes. There were no significant changes in IgG, IgM, IgA, or IgE concentration, with the exception of IgA concentration in 1 calf that developed an abscess at the cannulation site. The T-cell subset absolute numbers of CD4+ and CD8+ cells decreased slightly over time, but the CD4+-to-CD8+ cell ratio remained almost constant at near 2.

Conclusions

Creation of a thoracic lymphatic fistula appears to be a useful technique for studying effects of lung infection on immunologic variables, with potential application to bacterial and viral respiratory tract diseases.

Clinical Relevance

Thoracic lymphatic cannulation can be used in studies to determine pathogenic mechanisms in respiratory tract disease and to develop more effective vaccines against respiratory tract pathogens.
Absorption of diazepam after its rectal administration in dogs
Authors: Papich Mark G. , Alcorn Jane
Published: January 2024

A cross-over study was performed in 6 healthy mixed-breed dogs and 4 healthy Beagles. Diazepam was administered per rectum to Beagles (0.5 mg/kg of body weight) and mixed-breed dogs (2 mg/kg), and iv (0.5 mg/kg) to both groups of dogs. Each dog received the drug by both routes, with a 1-week washout period between dosages. After diazepam administration, blood samples were collected to measure plasma concentration of diazepam and its active metabolites, desmethyldiazepam and oxazepam, by use of reverse-phase high-performance liquid chromatography (hplc). Systemic availability was assessed by comparing the area under the curve for diazepam metabolites for each route of administration. Mean (± sd) diazepam concentrations in plasma after rectal administration were low in comparison with those obtained after iv administration, with systemic availability of only 7.4 (± 5.9) and 2.7 (± 3.2)% for the high and low dose, respectively. However, diazepam was converted to its metabolites within minutes after administration. Accounting for the total concentration of benzodiazepines (diazepam plus desmethyldiazepam and oxazepam) in plasma, systemic availability was 79.9 (± 20.7) and 66.0 (± 23.8)% for the high and low dosage, respectively. After iv administration, diazepam concentration decreased, with a half-life of only 14 to 16 minutes, but desmethyldiazepam and oxazepam concentrations decreased more slowly, with a half-life of 2.2 to 2.8 hours and 3.5 to 5.1 hours, respectively.

Each of the metabolites is reported to have anticonvulsant activity. After rectal administration of the high dose, mean total benzodiazepine concentration was above 1.0 μg/ml within 10 minutes and was maintained above this concentration for at least 6 hours. We conclude that diazepam is absorbed after rectal administration in dogs, and that the pharmacologic effects are probably caused by the active metabolites, not the parent drug. Samples also were analyzed by use of a nonspecific commercial benzodiazepine fluorescence polarization immunoassay (fpia). Correlation between the fpia and hplc assay was strongest for diazepam (R2 = 0.84), weak for desmethyldiazepam (R2 = 0.09), and nonexistent for oxazepam. We conclude from a comparison of assays that hplc is preferred over the fpia method for measuring benzodiazepines in dogs.
Evidence for endothelium-derived relaxing factor/nitric oxide in equine digital arteries
Authors: Cogswell Andria M. , Johnson Philip J. , Adams H. Richard
Published: January 2024

Objective

To test the hypothesis that endothelium-derived nitric oxide modulates vasomotor reactivity in equine digital arteries.

Design

Digital arteries were isolated from adult horses, and their vasodilator properties were examined in an in vitro controlled environment.

Animals

Five adult horses (1 gelding, 4 mares) without evidence of hoof or vascular disease were studied.

Procedure

Arterial rings with or without endothelium were exposed to endothelium-dependent vasodilator drugs in the presence or absence of a pharmacologic inhibitor of the enzyme nitric oxide synthase.

Results

Vasodilator effects of 3 endothelium-dependent vasorelaxant agents were significantly greater in endothelium-intact vessels than in endothelium-denuded vessels. Moreover, a nitric oxide synthase inhibitor reduced vasodilator responses to endothelium-dependent vasodilators in endothelium-intact arteries, but had no discernable effects in endothelium-denuded arteries.

Conclusions

These findings indicate the presence of endothelium-derived relaxing factor/nitric oxide in blood vessels of horses, and identify vascular endothelium as an endogenous modulator of vasomotor tone in the digital arteries of this species.
Epidemiological characteristics of bovine clinical mastitis caused by Staphylococcus aureus and Escherichia coli studied by DNA fingerprinting
Authors: Lam T. J. G. M. , Lipman L. J. A. , Schukken Y. H. , Gaastra W. , Brand A.
Published: January 2024

Objective

To study the epidemiology of clinical mastitis caused by Escherichia coli and Staphylococcus aureus by differentiating isolates with DNA fingerprinting techniques, using polymerase chain reaction.

Design

Milk samples were collected from cases of clinical mastitis in dairy cows. Escherichia coli and S aureus isolates from these cases were compared within and between cows and herds.

Sample Population

Seven dairy herds with an average bulk milk somatic cell count < 150,000/ml, and incidence of cows with clinical mastitis of > 25%/y.

Procedure

Chromosomal DNA was isolated from E coli and S aureus strains isolated from cases of clinical mastitis, and amplified by polymerase chain reaction, using enterobacterial repetitive intergenic consensus primers for E coli and a random amplified polymorphic DNA primer for S aureus. Escherichia coli and S aureus strains were identified and differentiated, using their DNA polymorphism pattern.

Results

Multiple E coli genotypes were found in each of the herds. Persistent infections with E coli were sporadic. Only a limited number of different S aureus genotypes was found in each of the herds studied. Recurrent cases of S aureus mastitis were found in 25% of quarters with clinical S aureus mastitis. Comparing S aureus isolates from different herds indicated that 1 S aureus genotype was most prevalent.

Conclusions

Because different quarters were infected with different genotypes, it was concluded that E coli is an environmental pathogen, and does not generally spread from quarter to quarter. The hypothesis that S aureus mastitis is a contagious disease, spreading from infected to uninfected quarters, could not be rejected. (Am J Vet Res 1996;57:39-42)
Transmission of two pseudorabies virus strains that differ in virulence and virus excretion in groups of vaccinated pigs
Authors: Bouma A. , De Jong M. C. M. , Kimman T. G.
Published: January 2024

Objective

To determine whether 2 Pseudorabies virus (PRV) strains that differ in virulence differ in transmission among vaccine strain 783-inoculated pigs.

Design

Three experiments were conducted, each with 2 groups of 10 pigs inoculated with the glycoprotein E-negative vaccine 783. In the first 2 experiments, half of one group was inoculated with the mildly virulent strain Sterksel, and half of the other group was inoculated with the virulent strain NIA-3. The remaining pigs were contact-exposed to the inoculated pigs. In the third experiment, 2 pigs in each group were inoculated with strain NIA-3, and the other 8 pigs in each group were contact-exposed to these 2 pigs.

Animals

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

Procedure

Estimation of the transmission of virus in each group was based on a stochastic model, in which the observable variable was the number of contact infections. The sole parameter of the model was the reproduction ratio θ. A glycoprotein E ELISA was used to determine whether infection occurred. Virus excretion in the oropharyngeal fluid was determined by plaque assay to measure infectivity.

Results

Vaccinated pigs had a significant difference in virus excretion between the mildly virulent and virulent strains. Sterksel strain-inoculated pigs shed significantly more virus than did NIA-3 strain-inoculated pigs. Despite this difference in virus excretion, the 2 strains did not differ in transmission.

Conclusions

Both PRV strains would be eliminated from a population of vaccine strain 783-inoculated pigs. (Am J Vet Res 1996;57:43-47)
Distribution and appearance of elastic fibers in the dermis of clinically normal dogs and dogs with solar dermatitis and other dermatoses
Authors: Frank Linda A. , Calderwood-Mays Maron B. , Kunkle Gail A.
Published: January 2024

Objective

To determine the distribution and amount of elastic fibers in the dermis of clinically normal dogs and dogs with dermatoses, particularly solar dermatitis.

Design

Skin specimens from 7 anatomic sites were obtained from 19 clinically normal dogs after euthanasia to evaluate the normal distribution o elastic fibers. Biopsy specimens also were obtained from 34 dogs with dermatoses, including 16 with solar dermatitis. Tissue sections were stained with H&E, Verhoeff-van Gieson, and periodic acid-Schiff.

Animals

19 clinically normal dogs and 34 dogs with dermatoses.

Procedure

Numbers of elastic fibers were graded subjectively. Comparisons between clinically normal dogs and dogs with dermatoses were made.

Results

Normal elastic fibers were present in low numbers in the dermis of adult dogs, regardless of anatomic site or presence or severity of dermatitis. Condensed elastotic material was visualized in only 2 dogs with solar dermatitis. In both dogs, the elastotic material was Verhoeff-van Gieson and periodic acid-Schiff stain positive but was not visible with H&E stain. The most frequent histopathologic finding in the dermis of dogs with solar dermatitis was superficial dermal fibrosis.

Conclusions

The dermis of clinically normal dogs does not contain abundant elastic fibers. Alterations of elastic fibers in dogs with solar dermatitis are rare. Superficial dermal fibrosis may be a better indicator of solar damage.
Analgesic, hemodynamic, and respiratory effects of caudal epidurally administered xylazine hydrochloride solution in mares
Authors: Skarda Roman T. , Muir William W.
Published: January 2024

Objective

To examine effects of 0.25 mg of xylazine/kg of body weight diluted to a total volume of 6 ml/450 kg with sterile 0.9% NaCl, administered into the epidural space of the sacrococcygeal joint on perineal analgesia, sedation, ataxia, and respiratory and cardiovascular function in standing mares:

Design

Randomized, blinded study, using xylazine (treatment) and 0.9% NaCl (controls). At least 2 weeks elapsed between the treatments.

Animals

Eight healthy mares.

Procedure

Blood samples were drawn. Systemic hemodynamics were determined, including cardiac output and pulmonary arterial, systemic arterial, and right atrial pressures. Two-way ANOVA with repeated measures was used to detect significant (P < 0.05) differences between mean scores of analgesia, sedation, ataxia, and cardiorespiratory variables before and during a 3-hour testing period. Analgesia was determined by lack of sensory perception to electrical stimulation at the perineal dermatome and no response to needle prick stimulation extending from coccyx to S3 dermatomes. Sedation was determined by head ptosis.

Results

Epidurally administered xylazine induced variable bilateral caudal analgesia extending from coccyx to S3, with minimal sedation, ataxia, and cardiovascular and respiratory depression in standing mares. Analgesia was attained at 15 ± 6 minutes and lasted for 165 to over 180 minutes. Heart and respiratory rates, systolic, diastolic, and mean arterial blood pressure, PCV, hemoglobin concentration, arterial oxygen content, and oxygen transport were decreased after xylazine, but not 0.9% NaCl, treatment. Cardiac output, stroke volume, mean right atrial pressure, mean pulmonary artery pressure, systemic vascular resistance, pulmonary vascular resistance, arterial and mixed venous pH and gas tensions (Po2 and Pco2), oxygen consumption, blood temperature, and rectal temperature did not change significantly (P < 0.05) after epidural administration of xylazine or 0.9% NaCl.

Conclusions

Caudal epidurally administered xylazine (0.25 mg/kg in 6 ml of 0.9% NaCl) can be given safely to induce prolonged (> 2 hours) caudal analgesia with minimal sedation, ataxia, and circulatory and respiratory disturbances in conscious, standing mares.
Effects of inhalation anesthetic agents on response of horses to three hours of hypoxemia
Authors: Whitehair Karen J. , Steffey Eugene P. , Woliner Michael J. , Willits Neil H.
Published: January 2024

Objective

To study the effects of inhalation anesthetic agents on the response of horses to 3 hours of hypoxemia.

Design

Controlled crossover study.

Animals

Five healthy adult horses.

Procedure

Horses were anesthetized twice: once with halothane, and once with isoflurane in O2. Anesthetized horses were positioned in left lateral recumbency. Constant conditions for the study began at 2 hours of anesthesia. A constant agent dose of 1.2 minimum alveolar concentration, PaO2 of 50 ± 5 mm of Hg, and PaCO2 of 45 ± 5 mm of Hg were maintained for 3 hours. Circulatory measurements were made at 0.5, 1, 2, and 3 hours of hypoxemia (anesthesia hours 2.5, 3, 4, and 5). Blood was collected from horses for biochemical analyses before anesthesia, within a few minutes after standing, and at 1, 2, 4, and 7 days after anesthesia.

Results

Cardiac index was greater (P = 0.018) during isoflurane than halothane anesthesia. Cardiac index remained constant during the 3 hours of hypoxemia during halothane anesthesia, whereas it decreased from the baseline during isoflurane anesthesia. Marginally nonsignificant P values for an agent difference were detected for arterial O2 content (P = 0.051), and oxygen delivery (P = 0.057). Serum activities of aspartate transaminase (P = 0.050) and sorbitol dehydrogenase (P = 0.017) were higher in halothane-anesthetized horses than in isoflurane-anesthetized horses. Circulatory function was better in hypoxemic horses anesthetized with isoflurane than with halothane. Isoflurane resulted in less muscular injury in hypoxemia horses than did halothane anesthesia. Halothane anesthesia and hypoxemia were associated with hepatic insult.

Conclusion

Isoflurane is better than halothane for hypoxemic horses.(Am J Vet Res 1996;57:351-360)
Effects of vitamin E on mammary and blood leukocyte function, with emphasis on Chemotaxis, in periparturient dairy cows
Authors: Politis I. , Hidiroglou N. , White J. H. , Gilmore J. A. , Williams S. N. , Scherf H. , Frigg M.
Published: January 2024

Objective

To determine the effect of vitamin E supplementation on the immune system of dairy cows.

Design

The following immune parameters were followed: production of chemotactic factors and superoxide by mammary macrophages and chemotactic responsiveness of blood neutrophils.

Animals

16 healthy Holstein dairy cows.

Procedure

Dairy cows were assigned to 1 of 2 experimental groups: control (no vitamin E supplementation) and vitamin E supplemented. Supplementation of vitamin E started 4 weeks before and continued up to 8 weeks after parturition, and included oral supplementation of vitamin E at the rate of 3,000 IU/cow/d. In addition, the same group of cows received 1 injection of vitamin E (5,000 IU) 1 week prior to the expected date of parturition. Blood samples were collected weekly throughout the experimental period.

Results

Vitamin E supplementation enhanced by 30 to 83% (P < 0.05) chemotactic responsiveness of blood neutrophils beginning 2 weeks before to 4 weeks after parturition, compared with controls. There were no differences in production of superoxide or chemotactic factors by mammary macrophages between control and vitamin E-supplemented cows.

Conclusions

Vitamin E supplementation prevents the periparturient inhibition of neutrophil Chemotaxis. It is unlikely that vitamin E affects directly the function of mammary macrophages. (Am J Vet Res 1996;57:468–471)
Disposition and excretion of 6-methoxy-2-naphthylacetic acid, the active metabolite of nabumetone in horses
Authors: Soma L. R. , Uboh C. E. , Rudy J. A. , Smith M. S.
Published: January 2024

Objective

To examine, in horses, the disposition and excretion of the active metabolite 6-methoxy-2-naphthylacetic acid (6MNA) of the nonsteroidal anti-inflammatory prodrug nabumetone.

Design

Pharmacokinetic analysis of 6MNA after oral administration of nabumetone and IV administration of 6MNA.

Procedure

Using a crossover design, 5 horses were orally administered 3.7 mg of nabumetone/kg of body weight. After a 3-week washout period, 4 horses were administered 2.5 mg of 6MNA/kg, IV.

Results

Absorption of nabumetone from the gastrointestinal tract and its metabolism to 6MNA had a median appearance half-life of 0.88 hour. The elimination half-life was 11 hours. Area under the plasma concentration time curve for 6MNA after oral administration of nabumetone was 120.6 mg/h/L. A dose of 2.5 mg/kg of 6MNA administered IV resulted in plasma concentration nearly equivalent to that induced by the orally administered dose. Disposition of 6MNA was modeled as a one-compartment, first-order elimination. The area under the plasma concentration time curve for IV administration of 6MNA was 117.0 mg/h/L, and the specific volume of distribution was 0.247 L/kg. The distribution half-life and the elimination half-life were 0.56 and 7.90 hours, respectively. Percentage of total dose recovered in urine for the 36-hour collection period after the oral and IV administrations was 7.4 and 5.3%, respectively.

Conclusions

Metabolism of nabumetone to 6MNA, as reported in other species, also occurs in horses. There were a number of additional metabolites of nabumetone in urine that could not be fully identified and characterized. (Am J Vet Res 1996;57:517–521)
Inhibition of the protease activity in tracheobronchial aspirates of horses with chronic obstructive pulmonary disease
Authors: Koivunen Anna-Liisa , Maisi Päivi , Fang Weihuan , Sandholm Markus
Published: January 2024

Objectives

To clarify the role of proteolytic enzymes in the pathogenesis of chronic obstructive pulmonary disease (COPD) in horses, and to investigate new possibilities for treatment of this disease by interfering in the proteolytic process.

Design

Effect of antiproteolytic activity of selected protease inhibitors on tracheal aspirates was studied in vitro, and the inhibition profiles were compared with those of purified proteases.

Sample Population

Respiratory tract secretions with antiproteolytic activity from 9 horses with COPD.

Procedure

Caseinolytic agar-diffusion assay.

Results

The protease-inhibition profile of tracheal aspirates differed from horse to horse. The profiles did not resemble that of any of the pure proteases. Acetylcysteine, pentamidine, and diminazene were most effective in inhibiting proteolytic activity in tracheal aspirates in vitro.

Conclusions

A mixed type of proteolytic activity is present in the respiratory tract secretions of horses with COPD.

Clinical Relevance

Acetylcysteine, pentamidine, and diminazene seem to have potential to be used in vivo to protect the lungs of horses with COPD from proteolytic damage. (Am J Vet Res 1996; 57:603–607)
Comparison of hematologic reference intervals between culture system and type of hybrid striped bass
Authors: Hrubec Terry C. , Smith Stephen A. , Robertson John L. , Feldman Bernard , Veit Hugo P. , Libey George , Tinker Mary Kay
Published: January 2024

Objective

To determine and compare hematologic reference intervals for hybrid striped bass from different culture systems and for 2 types of hybrid.

Design

Observational comparison study.

Animals

Clinically normal sunshine bass (reciprocal hybrid striped bass, female Morone chrysops × male M saxatilis) raised in high-density recirculating systems, sunshine bass raised in tanks with biofilters, and palmetto bass (original hybrid striped bass, female M saxatilis × male M chrysops) raised in tanks with biofilters.

Procedure

Hematologic reference intervals were determined for fish from the different production systems, following the National Committee for Clinical Laboratory Standards guidelines. Reference intervals from the 3 groups were compared.

Results

Reference intervals were significantly different between sunshine bass in the 2 culture systems and between sunshine and palmetto bass. Many of the differences were slight, but notable differences were observed. Sunshine bass in recirculating systems had higher total leukocyte, lymphocyte, neutrophil, and monocyte counts than did either hybrid in tanks. Palmetto bass had a greater number of neutrophils than monocytes, whereas sunshine bass had more monocytes than neutrophils. Additionally, palmetto bass had a lower PCV and hemoglobin value than did either group of sunshine bass.

Conclusions

Separate reference intervals should be developed for hybrid striped bass in different culture systems and for different types of hybrids.

Clinical Relevance

Determining reference intervals for hybrid striped bass provides a tool to assess the health status of these fish. (Am J Vet Res 1996; 57:618–623)
Blood biochemical reference intervals for sunshine bass (Morone chrysops × Morone saxatilis) in three culture systems
Authors: Hrubec Terry C. , Smith Stephen A. , Robertson John L. , Feldman Bernard , Veit Hugo P. , Libey George , Tinker Mary Kay
Published: January 2024

Objective

To determine and compare biochemical reference intervals for sunshine bass (hybrid striped bass) from 3 culture systems.

Design

Observational comparison study.

Animals

Clinically normal sunshine bass (reciprocal hybrid striped bass, female Morone chrysops × male M saxatilis) raised in high-density recirculating systems (80 g/L), low-density tanks (5 g/L) with biofilters, and cages (70 g/L) in a fresh water pond.

Procedure

Biochemical reference intervals were determined for fish from the different production systems following the National Committee for Clinical Laboratory Standards guidelines. Reference intervals from the 3 groups were compared.

Results

Reference intervals were significantly different between sunshine bass in the various culture systems. Though most of the differences in reference intervals were minor, fish in the high-density recirculating system had higher concentrations of total protein, albumin, globulin, creatinine, and phosphorus, and lower chloride values. There were no significant differences in glucose concentrations among the 3 groups of fish, and no differences in cortisol concentrations between fish in tanks and cages.

Conclusions

Separate reference intervals should be developed for hybrid striped bass in different culture systems.

Clinical Relevance

Determining biochemical reference intervals for hybrid striped bass provides a tool to assess the health status of these fish. (Am J Vet Res 1996; 57:624–627)
Pharmacokinetic model for cefazolin distribution during total hip arthroplasty in dogs
Authors: Marcellin-Little Denis J. , Papich Mark G. , Richardson Daniel C. , DeYoung David J.
Published: January 2024

Objectives

To compare cefazolin pharmacokinetics in serum and concentrations in tissues during total hip arthroplasty in dogs with and without hip dysplasia, and to calculate the optimal dosage of cefazolin for prophylactic use during total hip arthroplasty.

Animals

10 dogs with hip dysplasia and 3 clinically normal dogs.

Procedure

Blood samples and tissue specimens from the coxofemoral joint capsule, acetabulum, and femur were obtained during unilateral total hip arthroplasty. Cefazolin concentrations in serum and tissue specimen supernatant were determined, using high-performance liquid chromatography, for use in pharmacokinetic analysis. Mathematical simulation of serum cefazolin concentrations was used to to predict the optimal dose.

Results

Mean pharmacokinetic constants (SEM) were 0.146 (0.013) mm-1 for α, 4.74 min for t1/2α,, 0.015 (0.004) min-1 for ß, and 46.83 min for t1/2ß. Significant difference was not detected for cefazolin distribution and elimination between dogs with and without hip dysplasia. Additionally, significant difference was not observed in pharmacokinetic parameters describing distribution and elimination between the first and second doses of cefazolin. The predicted optimal dosage regimen was 8 mg/ kg of body weight, IV, every hour or 22 mg/kg, IV, every 2 hours.

Clinical Relevance

For prophylactic IV treatment during total hip arthroplasty, use of cefazolin at a dosage of 8 mg/kg every hour or 22 mg/kg every 2 hours should maintain serum cefazolin concentrations at least 10× the minimum inhibitory concentration for 3 to 4 hours. (Am J Vet Res 1996; 57:720–723)
Hemodynamic effects of medetomidine-midazolam-butorphanol and medetomidine-midazolam-buprenorphine combinations and reversibility by atipamezole in dogs
Authors: Pypendop Bruno , Serteyn Didier , Verstegen John
Published: January 2024

Objective

To characterize the hemodynamic effects of medetomidine (1 mg/m2 of body surface area; dosage, 39 to 46 μg/kg of body weight, IM) and midazolam (1 mg/kg of body weight, IV) combined with butorphanol (0.1 mg/ kg, IV), buprenorphine (10 μg/kg, IV), or saline solution. Reversibility of these effects by atipamezole (2.5 mg/m2; dosage, 97.5 to 115 μg/kg, IM) was evaluated.

Design

2 treated groups and 1 control group, without repetition.

Animals

15 clinically normal dogs (3 groups of 5).

Procedure

Medetomidine was administered at time 0; midazolam and butorphanol, buprenorphine, or saline solution at time 20; and atipamezole at time 60. Heart rate, systemic and pulmonary arterial pressures, central venous pressure, body temperature, cardiac output, and arterial and mixed venous blood gas tensions and pH were measured. Cardiac index, stroke index, systemic and pulmonary vascular resistances, and left and right stroke work indexes were calculated.

Results

Body temperature, heart rate, cardiac index, and stroke index were significantly decreased below baseline values in some groups. Central venous pressure, pulmonary capillary wedge pressure, and systemic vascular resistance were significantly increased above baseline in all groups. Arterial and venous Po2 and pH decreased in all groups and Pco2 increased, but these changes were more pronounced when buprenorphine was administered. Arterial pressure decreased after atipamezole administration.

Conclusions

The combinations seemed to result in cardiorespiratory depressant effects of similar importance and most of these effects, which are related to medetomidine, were reversed by atipamezole. (Am J Vet Res 1996; 57:724–730)