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Abstract

Objective—To compare microcrack density and length in the proximal and distal metaphyses of the humerus and radius in dogs.

Sample Population—Left humerus and radius from each of 10 dogs of medium to large size.

Procedure—Metaphyseal specimens were bulk stained in 1% basic fuchsin in graded alcohols and embedded in methylmethacrylate. For quantification of fatigue-induced microscopic damage, transverse sections were prepared from proximal and distal metaphyseal regions, and length and density of microcracks were determined, using light microscopy.

Results—Bone region, age, and body weight were not significantly associated with microcrack density or length.

Conclusions and Clinical Relevance—The hypothesis that fatigue-induced injury (increased microcrack density and length) caused by cyclic loading associated with daily activity is greater in bone regions prone to development of osteosarcoma was not supported by data from this study. (Am J Vet Res 2000;61:6–8)

Full access
in American Journal of Veterinary Research

Abstract

Objective

To determine cross-sectional geometry and bone mineral density of the Greyhound radius and correlate these values with torsional failure load and torsional stiffness in an ex vivo model.

Design

3 regions, proximal, middle, and distal portions of the diaphysis, were studied. 5 levels of cross section were evaluated geometrically within each region.

Specimens

10 paired radiuses from skeletally mature Greyhounds.

Procedure

Cortical area and area moment of inertia were measured from plain radiographic views and from digitized computed tomographic images. Bone mineral density was measured, using dual-energy x-ray absorptiometry. Torsional stiffness and torsional failure load were then determined mechanically.

Results

Minimum area moment of inertia and area moment of inertia estimated from plain radiographic views were significantly different in different regions of interest (P < 0.05). Significant bivariate correlations (P < 0.05) between torsional mechanical parameters and bone properties of the radius were identified for the distal portion of the diaphysis in particular. When independent variables for the distal portion were analyzed, estimate of area moment of inertia was entered into the model for torsional failure load as a predictor and minimum area moment of inertia was entered into the model for torsional stiffness as a predictor. Bone mineral density of the distal portion of the diaphysis was not a significant predictor.

Conclusion

If accurate noninvasive predictors of bone failure load can be identified, further study of fracture risk should be possible. (Am J Vet Res 1996;57:1094–1097)

Free access
in American Journal of Veterinary Research
in Journal of the American Veterinary Medical Association

Abstract

Objective—To quantify geometric, inertial, and histomorphometric properties at the mid-diaphyseal level of left and right metacarpal bones (MCB) of racing Greyhounds.

Sample Population—MCB from 7 racing Greyhounds euthanatized for reasons unrelated to MCB abnormalities.

Procedures—Mid-diaphyseal transverse sections of left and right MCB were stained with H&E or microradiographed. Images of stained sections were digitized, and cross-sectional area, cortical area, and maximum and minimum area moments of inertia of each bone were determined. Histomorphometric data (osteonal density, osteonal birefringence, and endosteal new lamellar bone thickness) were collected in 4 quadrants (dorsal, palmar, lateral, medial). Values were compared between limbs and among bones and quadrants.

Results—Cross-sectional area, cortical area, and maximum and minimum moments of inertia of left MCB-IV and -V were significantly greater, compared with contralateral bones. Overall osteonal densities in the dorsal quadrants of left MCB were greater, compared with lateral and medial quadrants. Also, percentage of birefringent osteons was significantly greater in the dorsal quadrant of left MCB-III, -IV, and -V, compared with the palmar quadrant. Thickness of new endosteal lamellar bone was not significantly influenced by limb, bone, or quadrant.

Conclusions and Clinical Relevance—Increased cortical thickness and geometric properties of left MCB-IV and -V of Greyhounds, together with altered turnover and orientation of osteons in the dorsal quadrants of left MCB, are site-specific adaptive responses associated with asymmetric cyclic loading as a result of racing on circular tracks. Site-specific adaptive remodeling may be important in the etiopathogenesis of fatigue fractures in racing Greyhounds. (Am J Vet Res 2001;62:787–793)

Full access
in American Journal of Veterinary Research

Abstract

Dog owners are increasingly interested in using commercially available testing panels to learn about the genetics of their pets, both to identify breed ancestry and to screen for specific genetic diseases. Helping owners interpret and understand results from genetic screening panels is becoming an important issue facing veterinarians. The objective of this review article is to introduce basic concepts behind genetic studies and current genetic screening tests while highlighting their value in veterinary medicine. The potential uses and limitations of commercially available genetic testing panels as screening tests are discussed, including appropriate cautions regarding the interpretation of results. Future directions, particularly with regard to the study of common complex genetic diseases, are also described.

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate efficacy and adverse effects of leflunomide for the treatment of naturally occurring immune-mediated polyarthritis (IMPA) in dogs.

Design—Retrospective case series.

Animals—14 dogs with cytologically confirmed IMPA.

Procedures—Medical records were used to identify dogs with a diagnosis of IMPA that were treated with leflunomide. Signalment, radiographic findings, laboratory data, dosage of leflunomide, treatment duration, treatment response, and occurrence of adverse effects were determined from medical records.

Results—Mean ± SD initial dosage of leflunomide was 3.0 ± 0.5 mg/kg (1.4 ± 0.2 mg/lb) PO once daily. Treatment duration for the initial starting dosage ranged from 1 to 6 weeks. Of the 14 dogs treated with leflunomide, 8 had complete resolution of clinical signs of IMPA initially, 5 had partial response to treatment, and 1 had minimal response to treatment. Adverse effects from treatment with leflunomide were not observed during the treatment period.

Conclusions and Clinical Relevance—Oral administration of leflunomide was a safe and effective alternative to oral administration of corticosteroids for treatment of IMPA in dogs. On the basis of findings in this study, a starting dosage for leflunomide of 3 to 4 mg/kg (1.4 to 1.8 mg/lb) PO once daily for at least 6 weeks before making dose adjustments is recommended. Dose adjustments should be based on cytologic evaluation of synovial fluid and clinical signs of IMPA. Hematologic variables, serum biochemical analysis results, and clinical signs of IMPA should be monitored for evidence of adverse effects to treatment with leflunomide.

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine the effect of weight reduction on clinical signs of lameness among overweight dogs with clinical and radiographic signs of hip osteoarthritis

Design—Nonblinded prospective clinical trial.

Animals—9 client-owned dogs with radiographic signs of hip osteoarthritis that weighed 11 to 12% greater than their ideal body weight and were examined because of hind limb lameness.

Procedure—Dogs were weighed, and baseline body condition, hind limb lameness, and hip function scores were assigned. Severity of lameness was scored using a numerical rating scale and a visual analogue scale. Dogs were fed a restricted-calorie diet, with amount of diet fed calculated to provide 60% of the calories needed to maintain the dogs' current weights. Evaluations were repeated midway through and at the end of the weight-loss period.

Results—Dogs lost between 11 and 18% of initial body weight. Body weight, body condition score, and severity of hind limb lameness were all significantly decreased at the end of the weight-loss period.

Conclusions and Clinical Relevance—Results suggest that in overweight dogs with hind limb lameness secondary to hip osteoarthritis, weight reduction alone may result in a substantial improvement in clinical lameness. (J Am Vet Med Assoc 2000;216:1089–1091)

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine prevalence of bacterial contamination of surgical suction tips.

Sample Population—Surgical tips used during 44 surgical procedures performed on 42 dogs and 2 cats.

Procedure—Surgical procedures were classified into 1 of 3 categories according to degree of bacterial contamination of the surgical site (clean, clean-contaminated, contaminated). Two sets of suction apparatuses were used for test and control suction tips. Test tips were used normally to suction blood and fluid, whereas control tips were placed on the surgical drapes but not in the surgical wound. Suction tips were collected aseptically and placed into thioglycolate broth tubes for qualitative aerobic and anaerobic bacterial culture at the end of each procedure.

Results—Test and control suction tips were contaminated with bacteria during 30 of 44 (68%) procedures. Staphylococcus spp were the predominant bacteria in tips used during clean and clean-contaminated surgeries. When surgery was performed on clean-contaminated or contaminated wounds, prevalence of isolation of other bacteria such as Pseudomonas spp, Streptococcus spp, and Escherichia coli from both test and control suction tips was higher than for clean wounds. Mean time of procedures during which both test and control suction tips became contaminated was not significantly different from time of procedures during which neither tip became contaminated.

Conclusion and Clinical Relevance—Surgical suction tips often become contaminated during standard veterinary surgical procedures. The risk of wound infection after surgery may be influenced by bacterial contamination of surgical suction tips. (Am J Vet Res 2000;61:779–783)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate whether body size and anatomic site influence the quantity of bone microdamage in dogs without osteosarcoma (OS).

Sample Population—Pairs of radii were collected from 10 small dogs (< 15 kg) and 10 large dogs (> 25 kg).

Procedure—Specimens were stained in basic fuchsin for bone microdamage. Transverse sections were cut from each proximal and distal radial metaphysis at 15 and 85% of bone length. The following variables were determined for each region: mean microcrack length (CrLe, µm), microcrack density (CrDn, microcracks/mm2), microcrack surface density (CrSDn, µm/mm2), and estimated activation frequency (Acf, microcracks/mm2/y).

Results—Metaphyseal region did not significantly influence CrDn, CrLe, and CrSDn. The CrDn and CrSDn were influenced by body size, with microdamage being increased in large dogs, compared with small dogs. However, mean CrLe was not significantly influenced by body size. Acf significantly decreased with age and was significantly decreased in large dogs and in the distal radial metaphysis, compared with small dogs and the proximal radial metaphysis, respectively.

Conclusion and Clinical Relevance—Our data did not reveal an increase in microdamage or remodeling at the OS predilection site (ie, the distal metaphysis of the radius), suggesting that induction of microdamage and an associated increase in bone remodeling are unlikely to be an important risk factor for induction of OS. (Am J Vet Res 2002;63:896–899)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine localization of tartrate-resistant acid phosphatase (TRAP) and cathepsin K in ruptured and healthy cranial cruciate ligaments (CCL) in dogs.

Animals—30 dogs with ruptured CCL, 8 aged dogs without ruptured CCL, and 9 young dogs without ruptured CCL.

Procedure—The CCL was examined histologically and cells containing TRAP and cathepsin K were identified histochemically and immunohistochemically, respectively.

Results—Cathepsin K and TRAP were detected within the same cells, principally within the epiligamentous region and to a lesser extent in the core region of ruptured CCL. Numbers of cells containing TRAP and cathepsin K were significantly greater in ruptured CCL, compared with CCL from young or aged dogs, and numbers of such cells were greater in CCL from aged dogs, compared with those of young dogs. In aged dogs, small numbers of cells containing TRAP and cathepsin K were seen in intact CCL associated with ligament fascicles in which there was chondroid transformation of ligament fibroblasts and disruption of the extracellular matrix.

Conclusion and Clinical Relevance—Ruptured CCL contain greater numbers of cells with the proteinases TRAP and cathepsin K than CCL from healthy, young, or aged dogs. Results suggest that cell-signaling pathways that regulate expression of these proteinases may form part of the mechanism that leads to upregulation of collagenolytic ligament remodeling and progressive structural failure of the CCL over time. (Am J Vet Res 2002;63:1279–1284).

Full access
in American Journal of Veterinary Research