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  • Author or Editor: Yasushi Hara x
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Abstract

OBJECTIVE To assess effects of vertebral distraction-fusion techniques at a treated segment (C5-C6) and an adjacent segment (C4-C5) of canine cervical vertebrae.

SAMPLE Cervical vertebrae harvested from cadavers of 10 skeletally mature Beagles.

PROCEDURES Three models (intact, titanium plate, and polymethylmethacrylate [PM MA]) for stabilization of the caudal region of the cervical vertebrae (C4 through C7) were applied to the C5-C6 vertebral segment sequentially on the same specimens. Biomechanical assessments with flexion-extension, lateral bending, and axial rotational tests were conducted after each procedure. Range of motion (ROM) for a torque load applied with a 6-axis material tester was measured at C4-5 and C5-6 and calculated by use of a 3-D video measurement system.

RESULTS In both the plate and PMMA models, ROM significantly increased at C4-5 and significantly decreased at C5-6, compared with results for the intact model. The ROM at C5-6 was significantly lower for the plate model versus the PMMA model in lateral bending and for the PMMA model versus the plate model in axial rotation. Conversely, ROM at C4-5 was significantly higher in axial rotation for the PMMA model versus the plate model. No significant differences were identified in flexion-extension between the PMMA and plate models at either site.

CONCLUSIONS AND CLINICAL RELEVANCE Results of this study suggested that vertebral distraction and fusion of canine vertebrae can change the mechanical environment at, and may cause disorders in, the adjacent segment. Additionally, findings suggested that effects on the adjacent segment differed on the basis of the fusion method used.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To compare activities of interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, and matrix metalloproteinase (MMP)-3 and contents of sulfated glycosaminoglycan (S-GAG) in joint fluid obtained from dogs with hip dysplasia (HD) and clinically normal dogs, evaluate correlations among these markers in joint fluid obtained from dogs with HD, and evaluate correlations between each marker and clinical and radiographic variables.

Animals—26 dogs with HD (clinical group) and 43 clinically normal Beagles (control group).

Procedure—Joint fluid was aseptically collected from the hip joints of all dogs. For each dog in the clinical group, age, duration of lameness, radiographic osteoarthritis (OA) score, and Norberg angle in each affected joint were recorded. Activities of IL-1β, IL-6, TNF-α, and MMP-3 and S-GAG contents were measured. Values were compared between groups by use of Mann-Whitney U tests, and the Spearman rank correlation test was used to evaluate correlations among markers and between each marker and clinical or radiographic variables.

Results—Values of all markers were significantly higher for the clinical group, compared with values for the control group. There was a moderate positive correlation between lameness duration and IL-6 activity and a strong negative correlation between the Norberg angle and IL-1β activity.

Conclusions and Clinical Relevance—Analysis of our results indicated that there was a significant increase in markers of OA in dogs with HD. Activities of IL-1β and IL-6 in joint fluid of dogs with HD may be influenced by the severity of laxity in the hip joint and lameness duration, respectively. (Am J Vet Res 2005;66:2028–2033)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate the effects of mitotane administration on the function and morphology of pituitary corticotrophs in clinically normal dogs.

Animals—12 clinically normal adult Beagles.

Procedures—Dogs were randomly assigned to the control group or the mitotane treatment group. In mitotane treatment group dogs, mitotane was administered for 1 month. In both groups, ACTH stimulation testing and corticotrophin-releasing hormone (CRH) stimulation testing were performed. Magnetic resonance imaging (MRI) of the pituitary gland and brain was performed in mitotane treatment group dogs before and after administration of mitotane. After CRH stimulation testing and MRI, dogs were euthanatized and the pituitary gland and adrenal glands were excised for gross and histologic examination.

Results—ACTH concentrations in mitotane treatment group dogs were significantly higher than in the control group dogs following CRH stimulation. Magnetic resonance imaging revealed that pituitary glands were significantly larger in treatment group dogs after administration of mitotane, compared with before administration. On gross and histologic examinations, the adrenal cortex was markedly atrophied. Immunohistochemistry revealed hypertrophy of corticotrophs in pituitary glands of mitotane treatment group dogs.

Conclusions and Clinical Relevance—These findings indicate that inhibition of the adrenal cortex by continuous administration of mitotane leads to functional amplification and morphologic enhancement of corticotrophs in clinically normal dogs. In instances of corticotroph adenoma, hypertrophy of individual corticotrophs induced by mitotane may greatly facilitate enlargement of the pituitary gland and increases in ACTH secretion.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine the effects of continuous low-dose infusion of lipopolysaccharide (LPS) on the expression of E-selectin and intercellular adhesion molecule-1 (ICAM-1) mRNA and neutrophil accumulation in the lungs, liver, spleen, small intestine, and pancreas in dogs.

Animals—11 healthy adult Beagles.

Procedure—Dogs received a continuous infusion of a low dose (10 µg/kg/h, IV) of LPS ( Escherichia coli055:B5) or saline (0.9% NaCl) solution (20 mL/kg/h, IV) for 8 hours. Activity levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) and the number of WBCs in circulation were examined before and 1, 2, 4, and 8 hours after the onset of LPS infusion. Expression of E-selectin and ICAM-1 mRNA and the number of neutrophils in each tissue were examined.

Results—After the onset of LPS infusion, serum TNF-α and IL-1β activities transiently increased. Thereafter, IL-6 activity increased, and high IL-6 activity was maintained throughout the experiment. In dogs in the LPS group, expression of E-selectin mRNA increased only in the lungs, and expression of ICAM-1 mRNA increased in the lungs and liver; the number of neutrophils in the tissue increased in the lungs and liver.

Conclusions and Clinical Relevance—Results suggested that expression of E-selectin and ICAM-1 mRNA increased during sepsis, particularly in the lungs and liver, and that this increase was associated with neutrophil accumulation. Hence, inhibiting the activation of endothelial cells in the lung and liver may decrease organ damage caused by accumulated neutrophils and help regulate multiple-organ dysfunction. (Am J Vet Res 2005;66:1259–1266)

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE

To investigate the effects of intervertebral distraction screw (IDS) fixation of the lumbosacral joint (LSJ) on the intervertebral foraminal area (IFA) and intervertebral stabilization of the LSJ and adjacent lumbar segments in dogs.

ANIMALS

7 healthy Beagles.

PROCEDURES

Dorsal laminectomy was performed at the LSJ in each dog to expose the intervertebral disk. The IDS was then inserted into the L7-S1 disk. Computed tomography was performed before and after laminectomy and after IDS insertion (intact, laminectomy, and IDS conditions, respectively) to measure the intervertebral range of motion (ROM) and intervertebral distance (ID) at L7-S1, L6-7, and L5-6 with the LSJ in a flexed and extended position. The intervertebral foramina stenosis rate was calculated from the intervertebral foramina area in entrance, middle, and exit zones. Results were compared among conditions.

RESULTS

The ROM at L7-S1 after IDS insertion was lower than that observed before and after laminectomy; no other differences were identified among conditions. With the LSJ in the flexed position, the ID at L7-S1 was larger after IDS insertion than before and after laminectomy; no other differences in ID were identified. In all evaluated zones, the stenosis rate was lower after IDS insertion than before and after laminectomy. No differences in ROM, ID, and stenosis rate were identified among conditions at L6-7 or L5-6.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that IDS fixation of the LSJ restricted lumbosacral ROM and prevented decreases in lumbosacral ID and IFA in healthy dogs. There were no changes at L6-7 and L5-6.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate effects of long-term administration of carprofen on healing of a tibial osteotomy in dogs.

Animals—12 healthy female Beagles.

Procedures—A mid-diaphyseal transverse osteotomy (stabilized with an intramedullary pin) of the right tibia was performed in each dog. The carprofen group (n = 6 dogs) received carprofen (2.2 mg/kg, PO, q 12 h) for 120 days; the control group (6) received no treatment. Bone healing and change in callus area were assessed radiographically over time. Dogs were euthanized 120 days after surgery, and tibiae were evaluated biomechanically and histologically.

Results—The osteotomy line was not evident in the control group on radiographs obtained 120 days after surgery. In contrast, the osteotomy line was still evident in the carprofen group. Callus area was significantly less in the carprofen group, compared with the area in the control group, at 20, 30, and 60 days after surgery. At 120 days after surgery, stiffness, elastic modulus, and flexural rigidity in the carprofen group were significantly lower than corresponding values in the control group. Furthermore, histologic evaluation revealed that the cartilage area within the callus in the carprofen group was significantly greater than that in the control group.

Conclusions and Clinical Relevance—Long-term administration of carprofen appeared to inhibit bone healing in dogs that underwent tibial osteotomy. We recommend caution for carprofen administration when treating fractures that have delays in healing associated with a reduction in osteogenesis as well as fractures associated with diseases that predispose animals to delays of osseous repair.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine the effects of intestinal ischemia and reperfusion on the expression of tumor necrosis factor (TNF)-α and interleukin (IL)-6 mRNAs in the jejunum, liver, and lungs of dogs.

Animals—8 healthy adult Beagles.

Procedures—In each dog, the cranial mesenteric artery was occluded for 0 (control group; n = 4) or 60 (I-R group; 4) minutes, followed by reperfusion for 480 minutes; serum TNF-α and IL-6 activities and expression levels of TNF-α and IL-6 mRNAs in jejunal, hepatic, and lung tissues were measured before and at the end of the ischemic period and at intervals during reperfusion. For each variable, values were compared between the control and I-R groups at each time point.

Results—Compared with the control group, serum IL-6 activity increased significantly after 180 minutes of reperfusion in the I-R group; also, jejunal TNF-α mRNA expression increased significantly after 60 (peak) and 180 minutes of reperfusion. In the I-R group, expressions of IL-6 mRNA in the liver and TNF-α and IL-6 mRNAs in the lungs increased significantly at 480 minutes of reperfusion, compared with the control group. Serum TNF-α activity, expression of IL-6 mRNA in the jejunum, and expression of TNF-α mRNA in the liver in the control and I-R groups did not differ.

Conclusions and Clinical Relevance—Results indicated that the liver, lungs, and jejunum contributed to the production of TNF-α and IL-6 after intestinal ischemia and reperfusion in dogs, suggesting that intestinal ischemia and reperfusion induce a systemic proinflammatory cytokine response in dogs.

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE To retrospectively evaluate the epidemiological and morphological features and outcome of surgical treatment of incomplete ossification of the dorsal neural arch of the atlas (IODA) in dogs with atlantoaxial instability (AAI).

ANIMALS 106 AAI-affected dogs that underwent ventral fixation of the atlantoaxial joint.

PROCEDURES Medical records and CT images for each dog were reviewed. Dogs were allocated to 1 of 2 groups on the basis of the presence or absence of IODA or of dens abnormalities (DAs) in CT images.

RESULTS Of the 106 dogs with AAI, 75 had and 31 did not have IODA; 70 had and 36 did not have DAs. Incomplete ossification was present in the cranialmost, central, or caudalmost portion of the dorsal neural arch of the atlas in 59, 39, and 28 dogs, respectively; 2 or 3 portions were affected in 29 and 11 dogs, respectively. The mean CT value (in Hounsfield units) for the midline of the dorsal neural arch of the atlas in dogs with IODA was significantly lower than that for the same site in the dogs without IODA. The mean age at surgery for dogs with central IODA was significantly higher than that of the non-IODA group. The severity of spinal cord injury before or after atlantoaxial ventral fixation did not differ between the IODA and non-IODA groups.

CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that concomitant DAs or IODA is common in dogs with AAI. In dogs with incomplete ossification in the central part of the dorsal neural arch of the atlas, surgical treatment of AAI generally occurs at a middle to advanced age.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine whether continuous infusion of a low dose of lipopolysaccharide (LPS) to induce a condition mimicking septic shock in dogs would affect systemic and hepatosplanchnic circulation and oxygenation.

Animals—12 healthy adult Beagles.

Procedure—Dogs received a low dose of LPS (Escherichia coli O55:B5) by continuous IV infusion at a rate of 1 µg/kg/h for 8 hours. Systemic hemodynamics; systemic oxygenation; blood flow in the cranial mesenteric artery, common hepatic artery, and portal vein; intestinal and hepatic tissue blood flow; mesenteric oxygenation; and intramucosal PCO2 were examined before and at selected time points after onset of the LPS infusion.

Results—After onset of the LPS infusion, cardiac index increased and mean arterial pressure (MAP) and systemic vascular resistance decreased, which is characteristic of the hyperdynamic state in septic patients. Hepatosplanchnic blood flow increased during the hyperdynamic state. Intestinal PCO2 was increased even when blood flows increased. During the latter half of the experimental period, MAP was maintained but hepatosplanchnic blood flows decreased and intestinal PCO2 increased further.

Conclusions and Clinical Relevance—Analysis of the results suggested that hepatosplanchnic blood flow enters the hyperdynamic state during the early stages of sepsis and that intestinal tissue oxygenation is threatened even when hepatosplanchnic blood flow is increased or maintained. Hence, improvement of hepatosplanchnic circulation and intestinal tissue oxygenation is important in dogs with clinical evidence of a septic condition. (Am J Vet Res 2004;65:1347–1354)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine whether small intestinal ischemia and reperfusion affects intestinal intramucosal pH (pHi), arterial and portal venous blood gas values, and intestinal blood flow (IBF) and to investigate relationships between regional intestinal tissue oxygenation and systemic variables in dogs.

Animals—15 healthy adult Beagles.

Procedure—Occlusion of superior mesenteric artery (SMA) for 0, 30, or 60 minutes, followed by reperfusion for 180 minutes, was performed; IBF, pHi, arterial and portal venous blood gas values, arterial pressure, and heart rate were measured at various time points; and intestinal mucosal injury was histologically graded.

Results—Occlusion of the SMA induced significant decreases in pHi and IBF. After the release of the occlusion, IBF returned rapidly to baseline values, but improvement in pHi was slow. Arterial and portal venous blood gas analyses were less sensitive than tonometric measurements of pHi, and there was no correlation between results of blood gas analyses and tonometric measurements. Histologic score for intestinal mucosal injury increased significantly, depending on duration of ischemia, and there was a correlation between tonometric results and the histologic score.

Conclusion and Clinical Relevance—Results suggest that it is difficult to accurately evaluate local oxygenation disorders by monitoring at the systemic level, whereas clinically pHi is the only reliable indicator of inadequate regional intestinal tissue oxygenation in dogs. (Am J Vet Res 2002;63:804–810)

Full access
in American Journal of Veterinary Research