bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of site and age on biochemical characteristics of the collagen network of equine articular cartilage
Authors: Brama Pieter A. J. , TeKoppele Johan M. , Bank Ruud A. , van Weeren P. René , Barneveld Albert
Published: January 2024

Objective

To determine variations in biochemical characteristics of equine articular cartilage in relation to age and the degree of predisposition for osteochondral disease at a specific site.

Sample Population

Articular cartilage specimens from 53 horses 4 to 30 years old.

Procedure

Healthy specimens were obtained from 2 locations on the proximal articular surface of the first phalanx that had different disease prevalences (site 1 at the mediodorsal margin and site 2 at the center of the medial cavity). Water, total collagen, and hydroxylysine contents and enzymatic (hydroxylysylpyridinoline [HP]) and nonenzymatic (pentosidine) crosslinking were determined at both sites. Differences between sites were analyzed by ANOVA (factors, site, and age), and age correlation was tested by Pearson’s product-moment correlation analysis. Significance was set at P < 0.01.

Results

Correlation with age was not found for water, collagen, hydroxylysine contents, and enzymatic crosslinking. Nonenzymatic crosslinking was higher in older horses and was linearly related to age (r = 0.94). Water and collagen contents and HP and pentosidine crosslinks were significantly higher at site 1. Hydroxylysine content was significantly lower at site 1.

Conclusions

Except for nonenzymatic glycation, the composition of articular cartilage collagen does not change significantly in adult horses. A significant topographic variation exists in biochemical characteristics of the articular cartilage collagen network in equine metacarpophalangeal joints. These differences may influence local biomechanical properties and, hence, susceptibility to osteochondral disease, as will greater pentosidine crosslinks in older horses that are likely to cause stiffer and more brittle cartilage. (Am J Vet Res 1999;60:341-345)
Effects of extrathoracic airway obstruction on intrathoracic pressure and pulmonary artery pressure in exercising horses
Authors: Hackett Richard P. , Ducharme Norm G. , Ainsworth Dorothy M. , Erickson Bruce K. , Erb Hollis N. , Soderholm Leo V. , Thorson Lisa M.
Published: January 2024

Objective

To determine whether dorsal displacesment of the soft palate (DDSP) results in pulmonary artery hypertension and leads to increases in transmural pulmonary artery pressure (TPAP); to determine whether pulmonary hypertension can be prevented by prior administration of furosemide; and to determine whether tracheostomy reduces pulmonary hypertension.

Animals

7 healthy horses.

Procedure

Horses were subjected to 3 conditions (control conditions, conditions after induction of DDSP, and conditions after tracheostomy). Horses were evaluated during exercise after being given saline (0.9% NaCI) solution or furosemide.

Results

Controlling for drug, horse, and speed of treadmill, DDSP-induced increase in intrathoracic pressure was associated with a significant increase in minimum (36 mm Hg), mean (82 mm Hg), and maximum (141 mm Hg) pulmonary artery pressure, compared with values for control horses (30, 75, and 132 mm Hg, respectively). Increases in pulmonary artery pressure did not induce concomitant increases in TPAP. Tracheostomy led to a significant reduction of minimum (53 mm Hg), and mean (79 mm Hg) TPAP pressure, compared with values for control horses (56 and 83 mm Hg, respectively). When adjusted for horse, speed of treadmill, and type of obstruction, all aspects of the pulmonary artery and TPAP curves were significantly decreased after administration of furosemide, compared with those for horses given saline (0.9% NaCI) solution.

Conclusions

DDSP was associated with increases in pulmonary artery pressure but not with increases in TPAP.

Clinical Relevance

Expiratory obstructions such as DDSP are likely to result in pulmonary hypertension during strenuous exercise, but may not have a role in the pathogenesis of exercise-induced pulmonary hemorrhage. (Am J Vet Res 1999;60:485-494).
Alveolar clearance in horses with chronic obstructive pulmonary disease
Authors: Votion Dominique M. , Vandenput Sandrina N. , Duvivier Dominique H. , Lambert Philippe , van Erck Emmanuelle , Art Tatiana , Lekeux Pierre M.
Published: January 2024

Objective

To assess sensitivity of scintigraphic alveolar clearance rate as an indicator of alveolar epithelium damage in horses.

Animals

5 healthy horses (group A) and 5 with chronic obstructive pulmonary disease (COPD; group B).

Procedure

Horses underwent clearance rate (k [%/min]) determination. Clearance rate of group-B horses was determined after remission of the disease following 2 months at pasture (remission 1), stabling in a controlled environment (remission 2), and during crisis induced by exposure to moldy hay and straw. Methacholine challenge test was performed at each investigation period to determine nonspecific pulmonary airway hyperresponsiveness. Pulmonary function tests (PFT) also were performed, and cell populations in bronchoalveolar lavage (BAL) fluid were determined on another occasion.

Results

Group-B horses had significantly faster mean clearance rate during crisis (k = 4.30 ± 0.95%/min), compared with that for remission 1 (k = 1.98 ± 0.55%/min), which did not differ from the rate in group-A horses (k = 1.95 ± 0.33%/min). Despite lack of clinical signs of COPD during remission when stabled in a controlled environment, an intermediate value was found (k = 3.20 ± 0.72%/min).

Conclusions

This technique allowed grading of lung damage induced by COPD, whereas use of PFT and determination of BAL fluid cell populations failed to differentiate between remission 1 and remission 2.

Clinical Relevance

Determination of alveolar clearance rate by use of scintigraphy is a sensitive indicator of lung damage. A modified clearance rate was found despite the lack of clinical and functional changes. (Am J Vet Res 1999;60:495-500)
Evaluation of the role of endotoxin and cortisol on modulation of CD18 adhesion receptors in cows with mastitis caused by Escherichia coli
Authors: Roets Eddy , Burvenich Christian , Diez-Fraile Araceli , Noordhuizen-Stassen Elsbeth N.
Published: January 2024

Objective

To determine the effect of mastitis caused by Escherichia coli on expression of CD18 cell surface receptors and to evaluate the involvement and regulation of receptors by lipopolysaccharide (LPS) and cortisol.

Animals

11 clinically normal lactating Holstein-Friesian cows.

Procedure

Binding of CD18 monoclonal antibodies to neutrophils was studied, using flow cytometry, before and after intramammary inoculation of E coli organisms. Effect of LPS and cortisol on expression of adhesion receptors was investigated, using a whole-blood model.

Results

Expression of CD18 adhesion receptors on bovine neutrophils increased 35% by 12 hours after intramammary inoculation of E coli. By 24 hours after inoculation, the number of receptors had returned to control values. High cortisol concentrations (100 nmol/L) were seen 12 to 18 hours after inoculation. Addition of LPS to blood induced a 30% increase in the number of CD18 receptors, and maximal number of receptors was expressed at an LPS concentration of 0.1 ng/ml. A decrease in the number of CD18 receptors was induced by incubation with cortisol or dexamethasone before challenge-exposure with LPS.

Conclusions

An increase in the number of CD18 receptors on neutrophils is mediated by local production of LPS. Subsequent endogenous release of cortisol may prevent additional increases in the number of receptors.

Clinical Relevance

During acute mastitis caused by E coli, there is an increase in the number of CD18 receptors on circulating neutrophils. Cortisol induces a decrease in the number of CD18 receptors, probably modulating the acute inflammatory response in mammary glands of lactating cows. (Am J Vet Res 1999;60:534–540)
Longitudinal study of lymphocyte subsets and major histocompatibility complex-class II expressing cells in mammary glands of sows
Authors: Magnusson Ulf
Published: January 2024

Objective

To determine whether there is variation attributable to reproductive stage in lymphocyte subsets and major histocompatibility complex (MHC) class II expressing cells in mammary glands of sows.

Animals

8 healthy primiparous crossbred sows that had been nursing piglets for 30 to 35 days.

Procedure

Needle biopsy of the mammary gland was performed after parturition, at midlactation, and after weaning. Various lymphocyte subsets and MHC class II expressing cells were detected immunohistochemically, using monoclonal antibodies.

Results

The number of CD8+ cells was significantly lower after parturition than after weaning but not significantly lower than at midlactation. The number of IgA-bearing cells was lower after parturition and after weaning than at midlactation. There were more B cells at midlactation than after weaning. There was no change over time in the number of CD4+ cells or MHC class II expressing cells. Immunohistochemically positive cells were detected only in interalveolar tissue.

Conclusions and Clinical Relevance

Certain lymphocyte subsets in mammary glands of sows are affected by reproductive stage. The data do not support the hypothesis that development of postparturient coliform mastitis may be the result of impaired mammary immune defenses at parturition. (Am J Vet Res 1999;60:546–548)
Distribution and environmental risk factors for paratuberculosis in dairy cattle herds in Michigan
Authors: Johnson-Ifearulundu Yvette , Kaneene John B.
Published: January 2024

Objective

To determine prevalence of paratuberculosis among dairy cattle herds and to identify associated soil-related risk factors.

Sample Population

Serum and soil samples for 121 Michigan dairy herds.

Procedure

Blood samples were collected from cows at each farm and tested for Mycobacterium paratuberculosis, using an antibody ELISA. Soil samples were collected from pastures and exercise lots; pH and available iron content were determined. A questionnaire was administered to collect data regarding farm management practices and productivity.

Results

55% of the herds tested had ≥ 2 M paratuberculosis-positive cattle. Adjusting sample prevalence for distribution of herd size strata yielded a statewide herd prevalence of 54%. Of 3,886 cattle tested, 267 had positive results. Prevalence of test-positive cattle was 6.9%. For every part per million (ppm) increase in soil iron content, there was a 1.4% increase in the risk of a herd being test-positive. An increase in soil pH of 0.1 was associated with a 5% decrease and an increase in soil iron content of 10 ppm was associated with a 4% increase in the number of test-positive cattle. Application of lime to pasture areas was associated with a herd being only 10% as likely to be paratuberculosis positive and with a 72% reduction in number of test-positive cattle.

Conclusions and Clinical Relevance

Prevalence of paratuberculosis-positive dairy herds in Michigan (54%) was greater than expected, but prevalence of paratuberculosis-positive cattle (6.9%) was within anticipated values. These prevalences were associated positively with acidic soil and increased soil iron content. Application of lime to pasture areas was associated with reduced risk of paratuberculosis. (Am J Vet Res 1999;60:589–596)
Health and growth performance of barrows reared in all-in/all-out or continuous flow facilities with or without a chlortetracycline feed additive
Authors: Ice A. D. , Grant A. L. , Clark L. K. , Cline T. R. , Einstein M. E. , Martin T. G. , Diekman M. A.
Published: January 2024

Objective

To compare health and growth peformance in barrows reared in all-in/all-out (AIAO) or continuous flow (CF) management systems.

Animals

400 barrows.

Procedure

Barrows (approx 2 months old) were allotted to 4 replications (100 barrows each); barrows were housed in AIAO or CF rooms (10 pens/room), and 50 pigs/replicate received chlortetracycline (CTC, 110 mg/kg of feed). Barrows from each pen were slaughtered at 3, 4, 5, and 6 months old.

Results

Barrows in the AIAO room had greater total daily gain (TDG) and lean daily gain (LDG) than did barrows in the CF room. Addition of CTC did not improve TDG or LDG in either environment. Barrows in the AIAO room reached body weight of 104.5 kg in 169.7 days, compared with 177.3 days for barrows in the CF room. Feed-to-gain ratio was not affected by management or CTC. Lungs from barrows reared in AIAO facilities had a lower percentage of lesions than did lungs of barrows reared in CF facilities (1.74% vs 9.52%). Addition of CTC did not affect prevalence and extent of lung lesions. Extent of lung lesions was positively correlated with change in serum optical density (OD) to Mycoplasma hyopneumoniae (r = 0.35), but not with change in serum OD to Actinobacillus pleuropneumoniae. Lean growth and serum OD to M hyopneumoniae and A pleuropneumoniae were not correlated.

Conclusions

Health and growth performance were better for barrows in an AIAO facility, compared with a CF facility, but addition of CTC to feed failed to enhance health or performance of barrows in either facility. (Am J Vet Res 1999;60:603–608).
In vitro contractile responses and contracture testing of skeletal muscle from Quarter Horses with exertional rhabdomyolysis
Authors: Lentz Linnea R. , Valberg Stephanie J. , Mickelson James R. , Gallant Esther M.
Published: January 2024

Objective

To determine whether increased sensitivity to pharmacologic agents was a general property of equine exertional myopathies, including polysaccharide storage myopathy (PSSM) in Quarter Horses.

Animals

5 adult Quarter Horses with exertional rhabdomyolysis and abnormal polysaccharide accumulation in skeletal muscle and 4 clinically normal adult Quarter or Quarter-type horses.

Procedures

Twitch time course measurements and contracture responses to various concentrations of caffeine and halothane for small bundles of intact external intercostal muscle fibers were measured in all horses.

Results

Caffeine contracture threshold of muscles from Quarter Horses with PSSM was not different from that of clinically normal horses (5 mM in both groups). Muscles from horses with PSSM and from clinically normal horses did not have contracture in response to up to 2% halothane.

Conclusions and Clinical Relevance

Results were in contrast to the increased sensitivity to caffeine and halothane for muscles from Thoroughbreds with recurrent exertional rhabdomyolysis (RER). Although clinical signs of muscular stiffness after exercise are similar between Quarter Horses with PSSM and Thoroughbreds with RER, these breeds appear to have 2 distinct myopathies with different pathophysiologic bases. Unlike RER in Thoroughbreds, PSSM in Quarter Horses does not appear to be accompanied by a defect in regulation of muscle contraction. (Am J Vet Res 1999;60:684–688)
Effect of intramammary infusion of β-1,3-glucan or interleukin-2 on leukocyte subpopulations in mammary glands of sheep
Authors: Waller K. Persson , Colditz I. G.
Published: January 2024

Objective

To investigate effects of intramammary infusion of β-1,3-glucan or recombinant ovine interleukin-2 (rOvIL-2) on blood and mammary leukocyte subpopulations and their expression of various surface antigens in sheep.

Animals

12 healthy multiparous, nonpregnant, non-lactating fine-wool Merino ewes.

Procedure

β-1,3-Glucan in pyrogen-free saline solution (PFSS; n = 6), rOvIL-2 in PFSS (3), or PFSS (3) was infused on days 0 and 7 in 1 udder half of each ewe. Jugular vein blood and mammary secretion samples were taken before infusion and on days 2, 7, and 21 after infusion. Total and differential leukocyte counts were obtained, and blood and mammary cells were labeled for flow cytometry.

Results

Slight swelling of the mammary glands was observed on day 2 after rOvIL-2 but not after β-1,3-glucan infusion. Both substances induced significant increase in mammary secretion leukocyte numbers, compared with controls. β-1,3-Glucan induced an influx of monocyte/macrophages, whereas neutrophils were the predominating cell population after rOvIL-2 infusion. β-1,3-Glucan induced selection for CD4+, B-cell+, WC1+, and L-selectin+ lymphocytes on day 14 after infusion. By comparison, rOvIL-2 induced selection for B-cell+ and L-selectin+ lymphocytes on days 14 and 21 and depletion of CD8+ and, to some degree, of IL-2R+ lymphocytes. β-1,3-Glucan induced an increase in the proportion of CD14+ leukocytes, indicating selective migration of monocyte/macrophages to the nonlactating udder.

Conclusion

β-1,3-Glucan and rOvIL-2 can modulate nonspecific immunity in the udder of sheep but may exert their effects by differing mechanisms.

Clinical Relevance

Stimulation of the nonspecific defense against udder infections may improve control of mastitis. (Am J Vet Res 1999;60:703–707)
Genomic screening for fucosidosis in English Springer Spaniels
Authors: Skelly Barbara J. , Sargan David R. , Winchester Bryan G. , Smith Mary O. , Herrtage Michael E. , Giger Urs
Published: January 2024

Objective

To develop a robust molecular genetic test for α-l-fucosidosis in English Springer Spaniels and to screen dogs from the United Kingdom and United States for the mutant allele.

Animals

35 English-bred English Springer Spaniels, 60 American-bred English Springer Spaniels, and 1 affected dog and its parents from a family of English Springer Spaniels in Colorado.

Procedure

Polymerase chain reaction analysis was used to amplify the mutated region in the gene encoding α-l-fucosidase. High guanine-cytosine (GC) content of the region required use of an amplification buffer with high pH. Mutant and normal alleles were separated by polyacrylamide gel electrophoresis. Molecular genetic test results were compared with enzyme data.

Results

A 262-bp PCR product was amplified from normal dogs and compared with a 248-bp product from affected dogs. Carriers had 1 copy of each allele, distinguishable by the 14-bp size difference. Two carriers among the English-bred dogs were identified by use of enzyme and genomic DNA analyses. The molecular defect in dogs from Colorado was proven to be the same as that in British and Australian dogs. None of the other 60 American-bred dogs carried the mutant allele.

Conclusions and Clinical Relevance

A PCR method that can be used to identify dogs affected with or carriers of the autosomal recessive disease fucosidosis was established. Amplification was achieved within a GC-rich region, using a method that may be useful in overcoming amplification problems in GC-rich areas within other genes. Using this test, fucosidosis can be controlled and ultimately eradicated from the English Springer Spaniel population. (Am J Vet Res 1999;60:726-729)
Pulmonary distribution of aerosolized technetium Tc 99m pentetate after administration of a single dose of aerosolized albuterol sulfate in horses with recurrent airway obstruction
Authors: Rush Bonnie R. , Hoskinson James J. , Davis Elizabeth G. , Matson Charles J. , Hakala Joyce E.
Published: January 2024

Objective

To determine whether pulmonary distribution of aerosolized technetium Tc 99m pentetate is improved after inhalation of a single dose of albuterol sulfate in horses susceptible to recurrent airway obstruction (heaves).

Animals

6 horses with heaves and 4 horses with normal respiratory tract function.

Procedure

Images were obtained during ventilation of horses at baseline (maximal change in pleural pressure during tidal breathing [ΔPplmax] > 15 cm H2O) and after aerosolized albuterol sulfate (360 µg) administration, with a 24-hour washout period between experiments. The ΔPplmax was determined prior to the baseline scan, prior to albuterol sulfate administration, and 5 minutes after albuterol sulfate administration. Images were assessed by visual inspection (semiquantitative scoring system) and histogram analysis.

Results

Images obtained from horses with heaves had nonuniform pulmonary distribution of radionuclide characterized by poor penetration in peripheral lung fields and excess deposition in large airways. Histogram analysis of images of the caudal portions of the lungs revealed nonuniform radionuclide deposition in horses with heaves and uniform radionuclide deposition in control horses.

Conclusion

Administration of a single dose of aerosolized albuterol sulfate improved pulmonary distribution of aerosolized radiolabeled pentetate suspension in horses with heaves but did not alter pulmonary distribution in clinically normal horses.

Clinical Relevance

Precedent bronchodilator administration may improve pulmonary distribution of aerosolized, surface-active anti-inflammatory preparations. (Am J Vet Res 1999;60:764–769)
Safety and efficacy of vaccination of pregnant gilts against porcine reproductive and respiratory syndrome
Authors: Mengeling William L. , Lager Kelly M. , Vorwald Ann C.
Published: January 2024

Objective

To determine the safety and efficacy of vaccination of pregnant gilts with an attenuated strain of porcine reproductive and respiratory syndrome virus (PRRSV).

Animals

16 pregnant gilts.

Procedure

Pregnant gilts free of antibodies for PRRSV were assigned (4 gilts/group) to the following groups: group I, untreated controls; group II, vaccinated on day 60 of gestation; group III, vaccinated on day 60 of gestation and exposed to virulent PRRSV on day 90 of gestation; and group IV, exposed to virulent PRRSV on day 90 of gestation. Safety and efficacy of vaccination was evaluated by group comparisons of prenatal and postnatal survival of fetuses and pigs, respectively, and by the condition and rate of weight gain of liveborn pigs.

Results

Collective (prenatal and postnatal) death losses up to day 15 after farrowing (conclusion of study) were similar for groups I (7/47, 14.9%) and II (7/44, 16.9%) but were greater for group III (18/49, 36.7%) and were greater still for group IV (23/37, 62.2%). Mean body weight 15 days after farrowing was greatest for pigs in litters of group I (4.46 kg) and progressively less for the other groups (3.87, 3.76, and 2.18 kg for groups II, III, and IV, respectively).

Conclusions

Using these conditions, vaccination of gilts during midgestation appeared to be safe. However, it provided only partial protection against subsequent exposure to virulent virus.

Clinical Relevance

Attenuated-PRRSV vaccines may have to be administered to naive gilts > 30 days before conception to provide maximum protection throughout gestation. (Am J Vet Res 1999;60: 796–801)
Upregulation of thyroid hormone receptor β1 and β2 messenger RNA in the myocardium of dogs with dilated cardiomyopathy or chronic valvular disease
Authors: Shahrara Shiva , Tidholm Anna , Drvota Viktor , Häggstöm Jens , Sylvén Christer
Published: January 2024

Objective

To investigate whether expression of thyroid hormone receptor (TR) messenger RNA (mRNA) is changed in the myocardium of dogs with heart failure.

Animals

21 dogs.

Procedure

Concentrations of TR α2, β1 and β2 mRNA in the myocardium were determined for clinically normal dogs (n = 7) and dogs with heart failure caused by dilated cardiomyopathy (DCM; 7) or chronic valvular disease (CVD; 7). Concentrations were quantified by use of reverse transcription-polymerase chain reaction and ELISA.

Results

The ratio of expression of TR α2, β1, and β2 mRNA was typically 100:10:1. Differences in concentration of TR α2 mRNA among the 3 groups of dogs were not detected, but concentrations of TR β1 and β2 mRNA were greater in diseased myocardium. Thyroid hormone receptor β1 mRNA was upregulated approximately threefold, and TR β2 mRNA was upregulated approximately eightfold in myocardium of dogs with DCM and CVD, compared with clinically normal dogs. There was no difference in TR β1 and β2 mRNA upregulation between dogs with DCM and CVD.

Conclusions and Clinical Relevance

Altered regulation of transcription of the TR β gene may be one facet of the myocardial phenotype in heart failure. Because this phenotypic response did not differ on the basis of cause (DCM vs CVD), it appears to be a secondary effect of heart failure and the alteration in metabolism of thyroid hormone. Treatment of dogs with heart failure with thyroid hormone or thyroid hormone analogues may improve cardiac performance. (Am J Vet Res 1999;60:848–852)
Use of a urea breath test to evaluate short-term treatments for cats naturally infected with Helicobacter heilmannii
Authors: Neiger Reto , Seiler Gabriela , Schmassmann Adrian
Published: January 2024

Objective

To evaluate efficacy of 3 short-term treatments in cats naturally infected with Helicobacter heilmannii.

Animals

29 cats infected with H heilmannii that had positive results for a urea breath test, rapid urease test, and Helicobacter species-specific polymerase chain reaction test.

Procedures

Cats anesthetized for routine surgical procedures were randomly allocated to 4 groups: group 1, control cats; group 2, cats treated with azithromycin, tinidazole, ranitidine, and bismuth once daily for 4 days; group 3, cats treated with clarithromycin, metronidazole, ranitidine, and bismuth twice daily for 4 days; and group 4, cats treated with clarithromycin, metronidazole, ranitidine, and bismuth twice daily for 7 days. Efficacy was determined on the basis of results of a urea breath test performed 10 and 42 days after end of treatment.

Results

Ten days after treatment, 0 of 4, 4 of 6, 11 of 11, and 8 of 8 cats in groups 1 to 4, respectively, had a negative result for a urea breath test. Forty-two days after treatment, 0 of 4, 3 of 6, 7 of 11, and 4 of 8 cats in groups 1 to 4, respectively, still had a negative result.

Conclusions and Clinical Relevance

Treatments used in this study regularly suppressed breath 13CO2 production. However, although 23 of 25 (92%) cats had negative results for a urea breath test 10 days after treatment, only 14 of 25 (56%) cats still had negative results 42 days after treatment. It is difficult to achieve a definitive long-term cure in cats naturally infected with H heilmannii. (Am J Vet Res 1999;60:880–883)
Adrenergic, cholinergic, and nonadrenergic-noncholinergic intrinsic innervation of the jejunum in horses
Authors: Malone Erin D. , Kannan Mathur S. , Brown David R. , Turner Tracy A. , Trent Ava M.
Published: January 2024

Objective

To determine the major neurotransmitters that regulate contractile activity in the jejunum of horses.

Sample Population

Jejunal specimens from 65 horses without gastrointestinal tract lesions.

Procedure

Jejunal smooth muscle strips, oriented in the plane of the circular or longitudinal muscular layer, were suspended isometrically in muscle baths. Neurotransmitter release was induced by electrical field stimulation (EFS) delivered at 30 and 70 V intensities and at various frequencies on muscle strips maintained at low or high muscle tone. To detect residual nonadrenergic-noncholinergic neurotransmission, the response of muscle to EFS in the presence of adrenergic and cholinergic blockade was compared with the response in the presence of tetrodotoxin.

Results

Atropine (ATR) decreased the contractile response of muscle strips to EFS under most conditions. However, ATR increased the contractile response of high-tone circular muscle. Adrenergic blockade generally increased the muscle responses to 30 V EFS and in high-tone longitudinal muscle but decreased contractile responses in high-tone circular muscle. Tetrodotoxin significantly altered the responses to EFS, compared with adrenergic and cholinergic receptor blockade.

Conclusions

Acetylcholine and norepinephrine appear to be important neurotransmitters regulating smooth muscle contractility in the equine jejunum. They induce contraction and relaxation, respectively, in most muscle preparations, although they may cause opposite effects under certain conditions. In addition, nonadrenergic-noncholinergic excitatory and inhibitory influences were detected.

Clinical Relevance

Acetylcholine or norepinephrine release within the myenteric plexus of horses may alter gastrointestinal motility. (Am J Vet Res 1999;60:898–904)
Circadian changes in blood ionized calcium, sodium, potassium, and chloride concentrations and pH in cattle
Authors: Bajcsy Csaba Á. , Reiczigel Jenő , Szenci Ottó
Published: January 2024

Objective

To explore diurnal variation in blood ionized calcium, sodium, potassium, and chloride concentrations and pH in pregnant dairy cows.

Animals

14 dairy cows in their third or later pregnancy approximately 6 weeks before expected parturition.

Procedure

Throughout a 24-hour period, blood samples were taken at 2-hour intervals and analyzed for ionized calcium (iCa2+), potassium (K+), sodium (Na+), and chloride (Cl−) concentrations and pH. Paired t-tests were used to compare initial and final values. Circadian changes were tested by use of repeated-measures ANOVA. Additionally, a nonparametric analysis was performed for each animal to determine minimal and maximal values for the variables.

Results

Significant differences were not detected between initial and final values of any variable. Repeated-measures ANOVA indicated significant diurnal fluctuations in all variables. With the exception of Cl− concentration, nonparametric analysis of individual values also revealed significant changes over time.

Conclusions and Clinical Relevance

The magnitude of daily fluctuations does not make it necessary to standardize time of sample collection for routine diagnostic examination of blood iCa2+, Na+, K+, and Cl− concentrations and pH. However, it may be important to standardize time of sample collection in comparative studies in which more discrete differences may be identified. (Am J Vet Res 1999;60:945-948)
Gastric hemorrhage in dogs given high doses of methylprednisolone sodium succinate
Authors: Rohrer Cécile R. , Hill Richard C. , Fischer Andrea , Fox Leslie E. , Schaer Michael , Ginn Pamela E. , Casanova Jackie M. , Burrows Colin F.
Published: January 2024

Objective

To determine whether healthy dogs given high doses of methylprednisolone sodium succinate (MPSS) develop gastrointestinal tract ulcers and hemorrhage.

Animals

19 healthy male hound-type dogs.

Procedure

Dogs were assigned randomly to intravenously receive high doses of MPSS (30 mg/kg of body weight, initially, then 15 mg/kg 2 and 6 hours later, and, subsequently, every 6 hours for a total of 48 hours; n = 10) or an equal volume of saline (0.9% NaCl) solution (9). Gastroduodenoscopy was performed before and after treatment. Endoscopic evidence of gross hemorrhage in the cardia, fundus, antrum, and duodenum of each dog was graded from none (0) to severe (3), and a total stomach score was calculated as the sum of the regional gastric scores. Number of ulcers were recorded. The pH of gastric fluid and evidence of occult gastric and fecal blood were measured. Food retention was recorded.

Results

Gastric hemorrhage was evident in all dogs after MPSS administration and was severe in 9 of 10 dogs but not visible in any dog after saline treatment. Occult gastric blood was detected more commonly (9/10 vs 2/9), median gastric acidity was greater (pH 1 vs pH 3), and food was retained more commonly (7/10 vs 1/9) in the stomach of MPSS-treated dogs.

Conclusions and Clinical Relevance

High doses of MPSS cause gastric hemorrhage in dogs. All dogs treated with high doses of MPSS should be treated with mucosal protectants or antacids to prevent gastric hemorrhage. (Am J Vet Res 1999;60:977–981)
Abnormal regulation of muscle contraction in horses with recurrent exertional rhabdomyolysis
Authors: Lentz Linnea R. , Valberg Stephanie J. , Balog Edward M. , Mickelson James R. , Gallant Esther M.
Published: January 2024

Objective

To determine whether abnormal regulation of muscle contraction similar to that associated with malignant hyperthemia (MH) was evident in intact external intercostal muscle cells from Thoroughbreds with recurrent exertional rhabdomyolysis (RER).

Animals

5 adult Thoroughbred horses with RER and 7 clinically normal adult Thoroughbred or mixed-breed horses.

Procedures

Twitch time course variables and contracture responses to various concentrations of potassium, caffeine, and halothane were measured in small bundles of intact external intercostal muscle cells from clinically normal horses and horses with RER.

Results

Threshold for significant contracture induced by potassium depolarization was lower for RER-affected muscles, compared with normal muscles, although the relationship between potassium concentration and membrane potential were not different. Thresholds for contracture induced by caffeine and halothane were also lower for RER-affected muscles, compared with normal muscles. Lower thresholds for caffeine- and halothane-induced contractures, as well as depolarization-elicited contractures, in RER-affected muscles suggest a defect in myoplasmic calcium regulation.

Conclusions and Clinical Relevance

Regulation of muscle contraction is abnormal in Thoroughbreds with RER. The specific defect may be attributable to abnormal intracellular calcium regulation. Knowledge of the specific defect involved in RER may lead to improved prevention and treatment of RER-affected horses. (Am J Vet Res 1999;60:992-999)
Evaluation of genetic, common-litter, and within-litter effects on preweaning mortality in a birth cohort of puppies
Authors: van der Beek Sijne , Nielen Angelique L. J. , Schukken Ynte H. , Brascamp E. W.
Published: January 2024

Objective

To determine relative impact of genetic, common-litter, and within-litter factors on puppy mortality.

Animals

2,622 Boxer puppies of 413 litters born during a 14-month period.

Procedure

For each puppy, pedigree was determined, and litter in which it was born was registered. Overall mortality and mortality per specific cause of death were analyzed by use of a model that included an additive genetic effect, common-litter effect, within-litter effect, and regression of mortality on inbreeding coefficient. Relative importance of the effects was determined from estimates of the variance in mortality explained by each factor.

Results

22% of the puppies died before reaching 7 weeks old. Stillbirth was the most frequent cause of death, followed by infection. Most observed differences were attributable to within-litter factors, which explained 67% of the variance in death attributable to infection and ≤ 96% of the variance in death attributable to asphyxia. Common-litter factors were more important than additive genetic factors. Variance attributed to common-litter factors ranged from 2% for cheiloschisis, palatoschisis, or cheilopalatoschisis to 30% for death attributable to infection, and variance attributed to additive genetic factors ranged from 0% for asphyxia to 14% for euthanatized because of white color. Inbreeding coefficient had a significant effect on death attributable to infection, which increased 0.26% for each percentage increase of inbreeding.

Conclusions and Clinical Relevance

Additive genetic factors have less impact on preweaning mortality than common-litter factors, which in turn have less impact than within-litter factors. Mortality attributable to infection increases significantly with increases in inbreeding. (Am J Vet Res 1999;60:1106-1110)
Effect of surgical technique and use of a rigid centralizing device on stem positioning and geometric reconstruction in the sagittal plane during total hip replacement in canine cadavers
Authors: Schulz Kurt S. , Stover Susan M. , Kass Philip H. , Vasseur Philip B. , Koehler Carl
Published: January 2024

Objective

To determine the effect of surgical technique and use of a rigid centralizing device on stem positioning and geometric reconstruction in the sagittal plane during total hip replacement in dogs.

Sample Population

Bilateral femurs from 8 adult mixed-breed canine cadavers.

Procedure

Femurs were prepared for femoral stem implantation, using 4 variations in technique. Proximal femoral reconstruction and femoral stem positioning were evaluated on radiographs.

Results

Implants evaluated in this study accurately reconstructed displacement of the femoral head of the intact canine femur in the sagittal plane. Centralization of the distal aspect of the stem was optimized by use of an undersized femoral stem. Ostectomy at the level of the lesser trochanter resulted in the smallest diaphysis-to-implant angle. Anteversion and retroversion of implants significantly decreased the distance between the distal tip of the implant and the adjacent cortex, compared with normoversion. The centralizing device significantly increased the minimum distance between the distal tip of the implant and adjacent cortex but did not improve the odds of actually centralizing the tip of the implant.

Conclusions and Clinical Relevance

Malpositioning of implants in the sagittal plane may be minimized through ostectomy at the lesser trochanter and use of an undersized implant positioned in normoversion. Use of a polymethylmethacrylate centralizing device will help eliminate contact between the implant tip and adjacent cortex. Implantation of an undersized femoral component, avoidance of substantial anteversion or retroversion, and use of a rigid centralizing device are recommended when using the prosthesis described-for total hip replacement of dogs. (Am J Vet Res 1999;60:1126–1135)
Determination of solid- and liquid-phase gastric emptying half times in cats by use of nuclear scintigraphy
Authors: Costello Margaret , Papasouliotis Kostas , Barr Frances J. , Gruffydd-Jones Timothy J. , Caney Sarah M. A.
Published: January 2024

Objective

To use nuclear scintigraphy to establish a range of gastric emptying half times (t1/2) following a liquid or solid meal in nonsedated cats.

Animals

12 clinically normal 3-year-old domestic shorthair cats.

Procedure

A test meal of 75 g of scrambled eggs labeled with technetium Tc 99m tin colloid was fed to 10 of the cats, and solid-phase gastric emptying t1/2 were determined by use of nuclear scintigraphy. In a separate experiment, 8 of these cats plus an additional 2 cats were fed 18 ml (n = 5) or 36 ml (n = 5) of a nutrient liquid meal labeled with technetium Tc 99m pentetate. Liquid-phase gastric emptying t1/2 then were determined by use of scintigraphy.

Results

Solid-phase gastric emptying t1/2 were between 210 and 769 minutes (median, 330 minutes). Median liquid-phase gastric emptying t1/2 after ingestion of 18 or 36 ml of the test meal were 67 minutes (range, 60 to 96 minutes) and 117 minutes (range, 101 to 170 minutes), respectively. The median t1/2 determined for cats receiving 18 ml of the radiolabeled liquid was significantly less than that determined for cats receiving 36 ml of the test meal.

Conclusions and Clinical Relevance

The protocol was tolerated by nonsedated cats. Solid-phase gastric emptying t1/2 were prolonged, compared with liquid-phase t1/2, and a major factor governing the emptying rate of liquids was the volume consumed. Nuclear scintigraphy may prove useful in assessing gastric motility disorders in cats. (Am J Vet Res 1999;60:1222–1226)
Primary nucleotide structure of predominant and alternate splice forms of equine insulin-like growth factor I and their gene expression patterns in tissues
Authors: Nixon Alan J. , Brower-Toland Brent D. , Sandell Linda J.
Published: January 2024

Objective

To isolate, clone, and determine primary nucleotide sequence of equine insulin-like growth factor I (IGF-I) and to examine IGF-I gene expression in tissues and cartilage from horses.

Animals

Horses of various ages.

Methods

Total RNA was isolated from tissues and purified. Complementary DNA (cDNA) was derived by reverse transcription and polymerase chain reaction (PCR) amplification and subcloned to plasmid vectors for sequencing and comparison with other species. Total RNA from various tissues was probed with radiolabeled cDNA or complimentary RNA constructs by use of northern blotting, tube hybridization, or PCR procedures to determine IGF-I expression patterns.

Results

Nucleotide sequence of equine IGF-I was 90% homologous to that of cows, 88% homologous to that of humans and sheep, and 77% homologous to that of rats. Amino acid sequence was identical to that of humans, cows, dogs, and pigs. A larger PCR product (IGF-IB) was consistent with alternate splicing with retention of IGF-I exon 4 sequence, similar to rats and mice. Northern blot analysis revealed multiple IGF-I transcripts; predominant sizes were 1.6 and 4.5 kb. The IGF-I message was commonly detected in liver, kidney, and cartilage from young foals and was diminished in cartilage from a 12-month-old horse.

Conclusions

Nucleotide sequences of equine pre-propeptides were different from those of other species, but the sequence coding the mature IGF-I peptide was more closely homologous. The larger IGF-IB form differed substantially in the carboxy-terminal. The biological action of the cleaved terminal was speculated to be autocrine feedback. Expression of IGF-I was apparent in many tissues, including cartilage, and was greater in immature horses. (Am J Vet Res 1999;60:1234–1241)
Cardiorespiratory and metabolic effects of xylazine, detomidine, and a combination of xylazine and acepromazine administered after exercise in horses
Authors: Hubbell John A. E. , Hinchcliff Kenneth W. , Schmall L. Michael , Muir William W. , Robertson James T. , Sams Richard A.
Published: January 2024

Objective

To determine sedative, cardiorespiratory and metabolic effects of xylazine hydrochloride, detomidine hydrochloride, and a combination of xylazine and acepromazine administered IV at twice the standard doses in Thoroughbred horses recuperating from a brief period of maximal exercise.

Animals

6 adult Thoroughbreds,

Procedure

Horses were preconditioned by exercising them on a treadmill to establish a uniform level of fitness. Each horse ran 4 simulated races, with a minimum of 14 days between races. Simulated races were run at a treadmill speed that caused horses to exercise at 120% of their maximal oxygen consumption. Horses ran until they were fatigued or for a maximum of 2 minutes. One minute after the end of exercise, horses were treated IV with xylazine (2.2 mg/kg of body weight), detomidine (0.04 mg/kg), a combination of xylazine (2.2 mg/kg) and acepromazine (0.04 mg/kg), or saline (0.9% NaCl) solution. Treatments were randomized so that each horse received each treatment once, in random order. Cardiopulmonary indices were measured, and samples of arterial and venous blood were collected immediately before and at specific times for 90 minutes after the end of each race.

Results

All sedatives produced effective sedation. The cardiopulmonary depression that was induced was qualitatively similar to that induced by administration of these sedatives to resting horses and was not severe. Sedative administration after exercise prolonged the exercise-induced increase in body temperature.

Conclusions and Clinical Relevance

Administration of xylazine, detomidine, or a combination of xylazine-acepromazine at twice the standard doses produced safe and effective sedation in horses that had just undergone a brief, intense bout of exercise. (Am J Vet Res 1999;60:1271–1279)
Evaluation of structural and functional alterations of circulating neutrophils in calves with experimentally induced pneumonic pasteurellosis
Authors: McClenahan David J. , Fagliari Jose J. , Evanson Oral A. , Weiss Douglas J.
Published: January 2024

Objectives

To determine the structural and functional alterations in circulating neutrophils that may lead to sequestration in lung microvasculature and endothelial injury in calves with experimentally induced pneumonic pasteurellosis.

Animals

10 healthy, 2- to 4-week-old male Holstein calves.

Procedures

Holstein calves were anesthetized and inoculated intrabronchially with Dulbecco phosphate buffered saline (0.9% NaCl) solution (DPBSS; 5 control calves) or 1 × 109 Pasteurella haemolytica organisms (5 infected calves). Blood samples were collected before and 1, 2, 4, and 6 hours after inoculation. Total and differential WBC count, dilute whole blood leukocyte deformability, neutrophil size distribution, and neutrophil surface CD11b expression were measured in blood samples.

Results

A progressive decrease in leukocyte deformability and increase in neutrophil size was detected 1, 2, 4, and 6 hours after inoculation of P haemolytica. Neutrophil surface CD11b expression was greater than baseline values at 6 hours after inoculation of P haemolytica. Two populations of neutrophils with an increase in size were detected in P haemolytica-infected calves. Both subpopulations had increased CD11b expression, compared with neutrophils that were typical in size.

Conclusions and Clinical Relevance

Neutrophils circulate in an activated and nondeformable state in calves with experimentally induced pneumonic pasteurellosis. A decrease in neutrophil deformability and neutrophil aggregation may contribute to neutrophil trapping in the lung microvasculature during pneumonic pasteurellosis in calves. (Am J Vet Res 1999;60:1307–1311)
Pulmonary vascular pressures of strenuously exercising Thoroughbreds during intravenous infusion of nitroglycerin
Authors: Manohar Murli , Goetz Thomas E.
Published: January 2024

Objective

To determine whether intravenous infusion of nitroglycerin would modify pulmonary arterial, capillary, or venous hypertension in strenuously exercising Thoroughbreds.

Animals

5 healthy Thoroughbred horses.

Procedure

Right atrial, right ventricular, and pulmonary vascular pressures were measured. Each horse was used in a control treatment (not medicated) and a nitroglycerin infusion (20 μg/kg of body weight/min) at rest and during exercise on a treadmill. Sequence of treatments was randomized for each horse, and treatments were separated by a 7-day interval. Galloping at 14.2 m/s on a 5% uphill grade elicited maximal heart rate (mean ± SEM, 212 ± 2 beats/min) and could not be sustained for > 90 seconds. Nitroglycerin dosage was selected, because maximal pulmonary and systemic hemodynamic effects of IV nitroglycerin were elicited at 5 μg/kg/min and increasing the dosage to 20 μg/kg/min did not cause adverse effects.

Results

In the control treatment, exercise performed at maximal heart rate resulted in a significant increase in right atrial as well as pulmonary arterial, capillary, and wedge pressures. Nitroglycerin infusion in standing horses significantly decreased right atrial and pulmonary vascular pressures, whereas heart rate increased. Exercise in nitroglycerin-infused horses also resulted in a significant increase in right atrial as well as pulmonary arterial, capillary, and wedge pressures, and these values were not significantly different from data for the control treatment. All horses experienced exercise-induced pulmonary hemorrhage for both treatments.

Conclusions and Clinical Relevance

IV administration of nitroglycerin does not modify exercise-induced pulmonary hypertension and is unlikely to affect the incidence or severity of exercise-induced pulmonary hemorrhage in Thoroughbreds. (Am J Vet Res 1999;60: 1436–1440)