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Abstract

Objective—To determine those bones in the distal aspect of the limbs of Greyhounds with fatigue fractures that have the greatest left-to-right differences in bone-mineral density (BMD).

Sample Population—Limbs obtained from 20 Greyhounds.

Procedure—Dual-energy x-ray absorptiometry (DXA) of the distal aspect of each limb and isolated bones from 10 dogs with a fracture of the central tarsal bone (CTB) of the right pelvic limb was performed. Highresolution scanning was performed on excised bones, and BMD measurements of CTB also were obtained from limbs of dogs without a CTB fracture.

Results—The BMD of the accessory carpal bone and calcaneus was not significantly different from the BMD of those bones in the contralateral limb. Although BMD of the CTB of the entire right pelvic limb and isolated bones from dogs with a CTB fracture was lower, compared with values for the entire left pelvic limb, values for isolated CTB from dogs without a CTB fracture were not significantly different. Metacarpal or metatarsal and thoracic or pelvic limb significantly affected BMD for measurements of the entire limb and isolated bones. Left-to-right differences in BMD were greatest for metacarpal 5.

Conclusions and Clinical Relevance—Asymmetric adaptive remodeling of metacarpal 5 can be detected by DXA. The potentially confounding effects of CTB fracture and unknown racing history made it difficult to interpret BMD changes in the CTB of these specimens. Densitometry could be developed as an in vivo assessment for risk of fractures in racing Greyhounds. (Am J Vet Res 2000;61:1214–1219)

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE

To evaluate the diagnostic capabilities of a novel helical fan beam CT system used for imaging of horses with a range of clinical distal limb problems.

ANIMALS

167 horses.

PROCEDURES

Medical records were reviewed of horses presented for CT of the distal limb at 2 university-based veterinary hospitals. The following data were recorded: age, sex, breed, presenting complaint, sedation used for imaging, scanning time, procedure time, other diagnostic imaging methods performed, imaging diagnosis, clinical diagnosis, and complications during imaging.

RESULTS

Most horses were Thoroughbreds and Quarter Horses. Procedure times ranged from 15 to 40 minutes, with scanning completed in 15 to 45 seconds for each region of interest. The foot or pastern region was commonly scanned (88/167 [53%] horses), with navicular bone disease diagnosed in 42 of 88 (48%) horses. The fetlock region was also commonly scanned (42/167 [40%] horses), with palmar or plantar osteochondral disease diagnosed in 17 of 42 (40%) horses. Horses were compliant during scanning, and no complications with sedation or damage to the scanner occurred. A specific imaging diagnosis for the lameness was achieved more frequently with CT imaging (166/167 [99%]) than with planar digital radiography (26/58 [45%]).

CLINICAL RELEVANCE

The helical fan beam CT system could be used safely to scan sedated standing horses from the carpal or tarsal region distally. Subjectively, the machine was easy to operate, allowing CT to be incorporated into lameness investigations. CT imaging was very likely to result in a clinical diagnosis in horses with distal limb lameness.

Open access
in Journal of the American Veterinary Medical Association

Abstract

OBJECTIVE

To evaluate the diagnostic capabilities of a novel helical fan beam CT system used for imaging of horses with clinical problems of the head and neck.

ANIMALS

120 horses.

PROCEDURES

Medical records were reviewed of horses presented for CT of the head or neck at 2 university hospitals. The following data were recorded: age, sex, breed, presenting complaint, sedation used for imaging, scanning time, procedure time, other diagnostic imaging methods performed, imaging diagnosis, clinical diagnosis, and complications during imaging.

RESULTS

Quarter Horses and Warmbloods were the most common breeds, and the most common complaint was nasal discharge. The head (101/120 [84%] horses) was scanned most frequently, and the most common diagnoses were primary dental disease and a space-occupying lesion of the paranasal sinuses. Nuchal bursitis was the most common imaging diagnosis in the neck region. Procedure time ranged from 20 to 45 minutes with a scanning time of 30 to 40 seconds. No complications with horse sedation occurred, and horses tolerated scanning well. An imaging diagnosis was more frequently achieved with CT (109/120 [91%] horses) than with planar digital radiography (23/61 [38%] horses).

CLINICAL RELEVANCE

The helical fan beam CT system had fast scanning times and could be used safely for routine imaging of the teeth and sinuses in horses. The caudal extent of scanning in the neck region was limited by the shape of the horse’s neck and thorax.

Open access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To compare 2 methods of quantitating chondrocyte viability and to determine chondrocyte response to thermal injury over time.

Sample Population—108 stifle joints from 54 adult rats.

Procedures—Cartilage from the distal aspect of the femur was treated ex vivo with radiofrequency energy at a probe setting that would result in immediate partial-thickness chondrocyte death; untreated sections served as controls. Explants were cultured, and cell viability was compared by use of lactate dehydrogenase (LDH) histochemical staining and calcein AM and ethidium homodimer-1 confocal laser microscopy (CLM) cell viability staining. Terminal deoxynucleotidyl transferase–mediated X-dUTP nick end labeling (TUNEL) was used to detect apoptosis. All labeling studies were performed 0, 1, 3, 7, 14, and 21 days after treatment.

Results—In the treated tissues, a greater percentage of viable cells were found with CLM, compared with LDH staining. This result contrasted that of control tissues in which LDH staining indicated a greater percentage of live cells than CLM. The greatest number of TUNEL-positive chondrocytes was present at day 3, declining at later time intervals.

Conclusions and Clinical Relevance—CLM and LDH histochemistry techniques yield different absolute numbers of live and dead cells, resulting in differing percentages of live or dead cells with each technique. These differences may be related to the enzymes responsible for activation in each technique and the susceptibility of these enzymes to thermal injury. Results of TUNEL indicate that apoptosis contributes to chondrocyte death after thermal injury, with a peak signal identified 3 days after insult.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine the effects of 2 doses of recombinant human bone morphogenetic protein-2 in an absorbable collagen sponge (rhBMP-2/ACS) on bone healing in dogs.

Animals—27 adult dogs.

Procedures—Dogs underwent a mid-diaphyseal (1-mm) tibial osteotomy (stabilized with external skeletal fixation) and received an ACS containing 0.28 mg (0.2 mg/mL) or 0.56 mg (0.4 mg/mL) of rhBMP-2 or no treatment (control dogs). All dogs were examined daily; bone healing was assessed via radiography and subjective lameness evaluation every 2 weeks. After euthanasia at 8 weeks, tibiae were evaluated biomechanically and histologically.

Results—Control dogs required antimicrobial treatment for pin-site–related complications more frequently than did rhBMP-2/ACS–treated dogs. At 4 and 6 weeks, weight bearing was greater in dogs treated with rhBMP-2/ACS (0.2 mg/mL) than in control dogs, albeit not significantly. Compared with control treatment, both doses of rhBMP-2/ACS accelerated osteotomy healing at 4, 6, and 8 weeks, and the 0.2 mg/mL dose enhanced healing at 2 weeks; healing at 6 weeks was greater for the lower-dose treatment than for the higher-dose treatment. Histologically, healing at 8 weeks was significantly improved for both rhBMP-2/ACS treatments, compared with control treatment. Among groups, biomechanical variables did not differ, although less osteotomy-site failures occurred in rhBMP-2/ACS–treated groups.

Conclusions and Clinical Relevance—In dogs that underwent tibial osteotomy, rhBMP-2/ACS (0.2 mg/mL) appeared to accelerate bone healing and reduce lameness (compared with control treatment) and apparently augmented bone healing more than rhBMP-2/ACS (0.4 mg/mL). Compared with control dogs, rhBMP-2/ACS–treated dogs required antimicrobial treatments less frequently.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To compare expression of tartrate-resistant acid phosphatase (TRAP) and cathepsin K and histologic changes in canine cranial cruciate ligaments (CCLs) and human anterior cruciate ligaments (ACLs).

Study Population—Sections of cruciate ligaments from 15 dogs with ruptured CCLs, 8 aged dogs with intact CCLs, 14 human beings with ruptured ACLs, and 11 aged human beings with intact ACLs.

Procedure—The CCLs and ACLs were evaluated histologically, and cells containing TRAP and cathepsin K were identified histochemically and immunohistochemically, respectively.

Results—The proportion of ruptured CCLs that contained TRAP+ cells was significantly higher than the proportion of intact ACLs that did but similar to proportions of intact CCLs and ruptured ACLs that did. The proportion of ruptured CCLs that contained cathepsin K+ cells was significantly increased, compared with all other groups. Numbers of TRAP+ and cathepsin K+ cells were significantly increased in ruptured CCLs, compared with intact ACLs. The presence of TRAP+ cells was correlated with inflammatory changes, which were most prominent in ruptured CCLs.

Conclusion and Clinical Relevance—Results suggest that synovial macrophage-like cells that produce TRAP are an important feature of the inflammation associated with CCL rupture in dogs. Identification of TRAP and cathepsin K in intact CCLs and ACLs from aged dogs suggests that these enzymes have a functional role in cruciate ligament remodeling and repair. We hypothesize that recruitment and activation of TRAP+ macrophage-like cells into the stifle joint synovium and CCL epiligament are critical features of the inflammatory arthritis that promotes progressive degradation and eventual rupture of the CCL in dogs. (Am J Vet Res 2005;66:2073–2080)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine fibroblast viability, assess development of apoptosis, and evaluate tissue hypoxia via histochemical, in-situ hybridization, or immunohistochemical staining in ruptured and intact cranial cruciate ligaments (CCLs) of dogs.

Animals—32 dogs with ruptured CCLs, and 8 aged and 19 young dogs with intact CCLs.

Procedure—Markers of cell viability (lactate dehydrogenase [LDH]), apoptosis (terminal deoxynucleatidyl transferase-mediated deoxyuridine triphosphate-nick end labeling [TUNEL] method), and hypoxia (hypoxiainducible factor-1α [HIF-1α] monoclonal antibody) were applied to CCL specimens; positive cells were assessed objectively (LDH) and subjectively (TUNEL and HIF-1α) in the main axial tissue component (core) and synovial intima and subintima (epiligamentous tissue).

Results—Viable fibroblasts were seen in all intact and ruptured CCLs. More nonviable cells were found in the core regions of ruptured CCLs and intact CCLs of young dogs than in the epiligamentous regions. Number of nonviable cells in the core region of ruptured CCLs was greater than that in intact CCLs of young and aged dogs, whereas the number in the epiligamentous region was similar in all specimens. The TUNEL and HIF-1αstaining was only found in the epiligamentous region of ruptured CCLs.

Conclusions and Clinical Relevance—Ruptured CCLs contained a high number of nonviable cells but not a great number of apoptotic cells. Repair processes in the epiligamentous region of the CCL include a metabolic response to hypoxia, suggesting that necrosis of ligament fibroblasts and transformation of surviving cells to a spheroid phenotype may be a response to hypoxia cause by microinjury or inadequate blood flow. (Am J Vet Res 2003;64:1010–1016)

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE To assess the effects of sedation on results of acoustoelastography of the superficial digital flexor tendons (SDFTs) in clinically normal horses.

ANIMALS 27 clinically normal horses.

PROCEDURES For each horse, the pathology index (PI) for the SDFT of each thoracic limb was determined by use of acoustoelastography at 4 locations (5, 10, 15, and 20 cm distal to the accessory carpal bone). Horses were evaluated before and after they were sedated with a combination of detomidine hydrochloride (0.01 mg/kg, IV) and butorphanol tartrate (0.01 mg/kg, IV). A repeated-measures ANOVA was used for statistical analysis.

RESULTS Overall, the PI was lower after sedation than before sedation. In addition, the PI was lower at more distal locations than at more proximal locations. There was not a significant effect of limb (left or right). Differences among individual horses accounted for the largest variance effect.

CONCLUSIONS AND CLINICAL RELEVANCE Sedation with detomidine and butorphanol facilitated acoustoelastography; however, it decreased the SDFT PI in clinically normal horses and should be used consistently in prospective studies. Variance associated with each individual horse in the sample population had the greatest effect on the PI.

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE To determine variance effects influencing ground reaction forces (GRFs) in a heterogeneous population of lame dogs during trotting.

ANIMALS 30 client-owned dogs with thoracic limb lameness and 31 dogs with pelvic limb lameness.

PROCEDURES GRFs, velocity, height at the dorsal aspect of the scapulae (ie, withers), and shoulder height were obtained. Each dog was trotted across a force platform at its preferred velocity. Variance effects for 12 velocity and associated relative velocity (V*) ranges were examined.

RESULTS Individual dog, velocity, V*, and limb significantly influenced GRFs. Withers height V* ranges were associated with small variance in GRFs, but all absolute and V* ranges were associated with significant effects for all 4 limbs and both types of lameness. Significant changes in lame limb GRFs and velocity in ipsilateral trials in dogs with thoracic limb and pelvic limb lameness were evident with trial repetition. Withers height V* range of 0.55 to 0.93 captured a large proportion of trials (> 90%) in dogs with thoracic limb or pelvic limb lameness, with limited effects on peak vertical force and vertical impulse.

CONCLUSIONS AND CLINICAL RELEVANCE Trial repetition caused alterations to GRFs and subject velocity that may have confounded assessment of lameness, which supported the concept that a priori selection of a velocity or V* range for force platform gait analysis should use a range that captures valid trials efficiently while minimizing GRF variance. These ranges typically would span the preferred velocity of subject dogs, such as withers height V* of 0.55 to 0.93.

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE To develop contact time (ConT) and withers height-normalized relative ConT (ConT*) for force platform gait analysis of dogs.

ANIMALS 29 healthy client-owned dogs.

PROCEDURES Height at the most dorsal aspect of the shoulders (withers) was measured with a framing square. Dogs were trotted across a force platform at their preferred velocity with controlled acceleration (± 0.5 m/s2). Ranges of ConT and ConT* centered on the population mean ConT were created. Variance effects on ground reaction forces (GRFs) for 4 thoracic limb and 4 pelvic limb ConT and associated ConT* ranges were examined. Efficiency of trial capture and effects of velocity ranges on GRF variance were determined.

RESULTS Individual dogs had the greatest effect on GRF variance for thoracic and pelvic limbs. Narrow ConT and ConT* ranges had few significant effects on GRFs but were inefficient at capturing trials. The ConT ranges of 0.22 to 0.29 seconds and 0.19 to 0.25 seconds for thoracic and pelvic limbs, respectively, provided the most efficient rates of trial capture with the fewest significant effects on GRFs. Compared with ConT and ConT* ranges, relative velocity ranges had higher efficiency and smaller GRF variance effects.

CONCLUSIONS AND CLINICAL RELEVANCE Dogs of various morphologies have differing limb velocities. Use of ConT as a surrogate for limb velocity may improve GRF data quality. We identified ConT and ConT* ranges associated with low GRF variance. However, relative velocity ranges captured data more efficiently. Efficient capture of data may help avoid worsening of lameness during gait analysis of dogs.

Full access
in American Journal of Veterinary Research