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Biomedical subjects

P K Shires

Publications and source records attributed to P K Shires.

16 recordsLinked to original sources
PubMed1996

Biomechanics of the thoracolumbar vertebral column of dogs during lateral bending.

OBJECTIVE: To study biomechanical characteristics of the normal and surgically altered canine thoracolumbar vertebral column to determine the effects of surgery and trauma on lateral stability. ANIMALS: The T13-L1 vertebral motion units of 48 mixed-breed dogs were dissected free of surrounding musculature and prepared for biomechanical testing by cross-pinning the vertebral bodies and mounting in polymethylmethacrylate. PROCEDURE: Normal and surgically altered spinal specimens were subjected to lateral bending. The mean slope of the bending moment versus angular displacement curve and the load to failure were compared between treatment groups and significance was determined by the method of least squares (P < 0.05). Specimens were surgically altered by facetectomy, lateral fenestration, diskectomy, and combinations of these procedures. Each specimen was subjected to lateral bending to failure at a rate of 2.5 cm/min in a swing arm bending jig designed to simulate 4-point bending and subject the specimen to pure bending. RESULTS: Only specimens undergoing diskectomy had a significant decrease in slope and load at failure. Unilateral and bilateral facetectomies and fenestration induced a nonsignificant decrease in stiffness, compared with control specimens. CONCLUSIONS: Fenestrations and facetectomies do not appear to increase the risk of injury to the canine thora-columbar spinal cord during lateral bending. CLINICAL RELEVANCE: Fenestrations and facetectomies, as used in routine laminectomies, may be performed without concern for significant destabilization of the spine in lateral bending; however, it is possible that thoracolumbar spinal fractures involving only the vertebral body may significantly destabilize the spine in all modes of bending.

Animals↗
PubMed1993

Intracapsular repairs for cranial cruciate ligament ruptures.

Two intracapsular techniques and their modifications are described that can be regarded as the most accepted procedures in general use today. The difficulty in rationalizing a choice between intra- and extracapsular techniques is discussed with some principles being suggested to help the surgeon choose a technique.

Animals↗
PubMed1991

Effect of left hepatic vein ligation on hepatic circulation, function, and microanatomy in dogs.

Eighteen healthy dogs were allotted to 3 groups (n = 6 dogs each). All dogs were evaluated at the beginning of the study by complete physical examination; total and differential WBC counts; serum biochemical analysis (alanine transaminase and alkaline phosphatase activities and bilirubin and albumin concentrations); sulfobromophthalein excretion, ammonia tolerance, and glucagon response testing; portal and intraparenchymal pressure determinations; operative mesenteric portography; and histologic assessment of hepatic biopsy specimens. The left hepatic vein was ligated completely in dogs of groups 1 and 2. Group-3 (control) dogs had a ligature placed loosely around the left hepatic vein. Dogs of groups 1 and 3 were reevaluated 24 hours after surgery by use of the aforementioned hematologic and biochemical tests. Group-1 dogs were reevaluated by use of portal and intraparenchymal pressure determinations, jejunal vein portography, and complete necropsy at 48 hours after surgery. At 4 weeks after surgery, dogs of groups 2 and 3 were reevaluated by use of all aforementioned tests. Results indicated transient hepatic congestion, which resolved by the fourth postoperative week. Longstanding effect on hepatic structure, circulation, or function was not found. We concluded that left hepatic vein ligation in clinically normal dogs does not cause severe or permanent liver damage.

Alanine Transaminase↗
PubMed1986

Respiratory paralysis secondary to epidural anesthesia in a dog.

Transient respiratory paralysis developed in a 12-year-old spayed female Cocker Spaniel that received an anesthetic epidurally for excisional biopsy of perianal masses. Paralysis developed almost immediately after injection of 2.5 ml of 2% lidocaine (1 ml/4.9 kg), and was managed by mechanical ventilation and appropriate fluid therapy IV until spontaneous respiration returned. The respiratory paralysis was attributed to the excessive cranial extent of the anesthetic block.

Anesthesia, Epidural↗
PubMed1986

Diskospondylitis in a kennel of dogs: clinicopathologic findings.

Selected aspects pertaining to the cause and pathogenesis of diskospondylitis were investigated in a kennel of 45 Airedale Terriers. Diskospondylitis was detected via spinal radiography in 17 male and 14 female dogs. Bacteria isolated from the coat, vagina, and urine of affected Airedales were not statistically different from those isolated from clinically normal Airedales. Serologic evidence of Brucella canis infection was not detected. There was no difference in response to thyrotropin stimulation tests between affected and clinically normal dogs. Necropsy findings in affected dogs included hypercellular renal glomeruli and pulmonary arterial thrombi.

Animal Husbandry↗
PubMed1985

Carpal hyperextension in two-month-old pups.

Abnormal carpal configuration was observed in a litter of ten 2-month-old pups raised in a research colony. Five of the pups were exercised daily, and carpal configuration returned to normal within 7 to 10 days. The other 5 pups remained confined, and their carpal configuration returned to normal after 6 weeks. It was concluded that poor muscle tone was responsible for the carpal hyperextension.

Age Factors↗
PubMed1984

Ventral approach for stabilization of atlantoaxial subluxation secondary to odontoid fracture in a foal.

Atlantoaxial subluxation secondary to odontoid fracture in a 30-day-old foal was corrected by alignment of the atlantoaxial joint and stabilization with 2 ventrally placed dynamic compression plates. At 90 days after surgery, healing of the fracture, with adequate alignment of the atlantoaxial joint, was confirmed radiographically. The foal was only slightly tetraparetic at that time. At 1 year after surgery, the gait was normal. It was concluded that the technique has advantages over the use of Steinmann's pins or external coaptation for stabilization. The ventral approach allows decompression, anatomic alignment, and immediate stabilization of the subluxation. Potential complications of the ventral approach include laryngeal paralysis.

Animals↗
PubMed1984

The effect of postoperative electromagnetic pulsing on canine posterior spinal fusions.

An experimental canine study was devised to evaluate the efficacy of a noninvasive adjunct to improve the rate and quality of the posterior fusion mass over the standard surgical technique. Ten large adult mongrel dogs underwent a three-level lumbar spinal fusion. Bone excised from the spinous processes was packed in removed facet joints and over the decorticated laminae. To insure rigid internal fixation, custom-made distraction instrumentation was placed bilaterally under the laminae of the vertebrae above and below the three fused vertebrae. Five dogs underwent electromagnetic pulsing, and five dogs acted as controls. Two dogs were sacrificed at 4, 6, 9, 12, and 15 weeks to assess the radiographic and histologic status of the fusion mass. Preoperative and preautopsy hematologic studies as well as gross and histologic autopsy specimens revealed no abnormalities attributable to the electromagnetic pulsing. High-resolution radiography and histologic studies showed earlier incorporation of the graft, improved new bone formation, and better organization of the fusion mass in the 4-, 6-, and 9-week stimulated specimens. However, by 12 and 15 weeks there did not appear to be any histologic or radiographic differences between the stimulated and control dogs. Although electromagnetic pulsing appears to produce an early accelerated osteogenic response, it does not appear to improve the overall results of primary canine spinal fusions.

Animals↗
PubMed1982

Effect of localized trauma and temporary splinting on immature skeletal muscle and mobility of the femorotibial joint in the dog.

The right pelvic limbs of 2 groups of dogs were splinted in extension for 2 weeks. In 1 of these groups, the dogs were anesthetized and the distal portion of the quadriceps femoris muscle was traumatized before splinting. Two groups of control dogs were also used; neither group was splinted, but 1 group was anesthetized, and their muscles were traumatized. The range of motion of the femorotibial joint was measured in all 4 groups before splinting and 3 and 9 weeks after splinting. Types I and II muscle fiber diameters and percentages were also recorded at 3 and 9 weeks in all groups. Flexion of the femorotibial joint was limited after splinting (P less than 0.001), but less so after trauma and splinting than after splinting alone (P less than 0.0001). A reversible type I fiber atrophy occurred in most restricted muscles (P less than 0.001) and early type II fiber atrophy was seen in a few muscles after trauma and splinting (P less than 0.002). Multifocal fiber necrosis was the only irreversible change seen after 3 weeks of splinting with or without concurrent muscle trauma. Relative fiber percentages did not change appreciably during splinting or recovery.

Animals↗
PubMed1980

Type I fiber atrophy in the vastus lateralis muscle in dogs with femoral fractures treated by hyperextension.

A syndrome characterized by limb hyperextension, generalized muscle atrophy, abducted gait, and a limited range of joint motion is reported in five dogs, four of which were immature. Distal femoral fractures, of traumatic origin, were found in all dogs; four dogs were subjected to limb immobilization in extension for three to seven weeks. Lesions in muscle biopsies included fiber size variability, increased prominence of subsarcolemmal nuclei, increased perimysial fibrosis and focal necrosis. Histochemical and morphometric studies demonstrated a significant (p less than 0.05), Type I fiber atrophy in the vastus lateralis muscles in the limbs with femoral fractures treated by hyperextension. The shortest time period between onset of fracture and the presence of type I fiber atrophy was seven weeks.

Animals↗
PubMedDate not supplied

Evaluation of canine lumbosacral stenosis using intravenous contrast-enhanced computed tomography.

The objective of this study was to evaluate intravenous contrast-enhanced computed tomography as a technique for predicting the within-level location(s) of compressive soft tissues in the canine lumbosacral spine. Pre-operative intravenous contrast-enhanced computed tomography of the L5-S3 vertebral levels was performed in 12 consecutive large breed dogs with lumbosacral stenosis. The images were evaluated for enhancement of soft tissues by two radiologists who were unaware of the surgical findings. For each within-level location (dorsal canal, ventral canal, right lateral recess, left lateral recess) enhancement was classified as present, absent or equivocal. The results were compared with the results of surgical exploration and histopathology of excised tissues. The positive predictive values of intravenous contrast-enhanced computed tomography for compressive soft tissues involving the dorsal canal, ventral canal and lateral recesses were 83%, 100%, and 81% respectively. Negative predictive values for compressive soft tissues involving these locations were 29%, 50%, and 40% respectively.

Animals↗
PubMedDate not supplied

Sacral fractures in dogs: a review of 32 cases.

Sacral fractures have not been described well in dogs. The records of 32 dogs diagnosed with sacral fractures were evaluated for neurologic deficits at presentation and discharge. Follow-up was in the form of telephone survey or physical examination at recheck. A score was assigned for each dog at presentation, discharge, and follow-up (0 for normal, 1 for minor deficits, and 2 for major deficits). Fractures located lateral to the sacral foramina were called abaxial, and those medial to the sacral foramina were called axial. Axial fractures had significantly more severe deficits at presentation (p = 0.00017) and discharge (p = 0.03063), but not at follow-up. Neurologic status did not improve significantly during hospitalization in either fracture group, but had improved significantly at follow-up.

Accidents, Traffic↗