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Abstract

Objective

To characterize normal locomotion of dogs, using nonlinear dynamic stability measurements to analyze two-dimensional kinematic data.

Animals

5 healthy, orthopedically sound Greyhounds.

Procedure

Data were studied by sequentially constructing phase plane portraits from the angular velocity and displacement data; creating first-return (Poincare) maps from periodically sampled data; and evaluating the dynamic stability of the gait, using Floquet multipliers calculated from the assembled data. Retroreflective markers were placed on the left craniodorsal aspect of the iliac spine, greater trochanter, lateral epicondyle of the femur, lateral malleolus, and fifth metatarsophalangeal joint. Each dog was repeatedly led at a trot along a 10-m runway. Data were collected, using a video-based, two-dimensional motion measurement and analysis system. Dogs were considered a nonlinear system and were represented by the joint angular displacements and velocities. Phase plane portraits and first-return maps were constructed to analyze the smoothed data. The Floquet theory was then used to investigate the local stability of critical points of the discrete map.

Results

The femorotibial joint had the highest angular velocity, ranging from −2.5 to 4.9 radians/s. Tarsal joint velocity ranged from −2.7 to 3.2 radians/s, and the coxofemoral angle had the lowest range of −2.2 to 2.2 radians/s. The points on the first-return maps converged to the 45° diagonal line and were clustered together. The largest Floquet multiplier averaged 0.452, which characterized the stability of this population and will be used to draw a comparison between this and future work.

Conclusions

Nonlinear dynamics can be effectively used to analyze two-dimensional kinematic data from animal models to quantify the dynamic stability of animal locomotion through precise mathematical measurements. The method is general and can be applied to normal or abnormal gaits.

Clinical Relevance

Point mapping and quantitative measurement of joint movement have several advantages associated with the application to animal and human locomotion. The clinician can visually distinguish the normal gait pattern from abnormal patterns to assist in the diagnosis of musculoskeletal abnormalities (diseases). (Am J Vet Res 1996;57:1529–1535)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To evaluate the ability of hyaluronic acid (HA), with and without transforming growth factor β (TGF-β), to stabilize the catabolic processes associated with atrophy of articular cartilage.

Animals

20 adult, skeletally normal, hound-type dogs.

Procedure

Dogs (20 to 30 kg) were randomly assigned to 1 of 5 groups. One group served as untreated controls. Bivalve casts were placed on the left hind limbs of the remaining 16 dogs to limit weightbearing and motion of the limb for 92 days. One group served as the cast control. Beginning on day 56, 3 groups received aseptic intra-articular injections in the left stifles of either 5 mg of HA or 5 mg of HA containing either 20 or 50 μg of TGF-β. Intra-articular injections were repeated at 4-day intervals until the end of the study. On day 92, stifles were harvested at necropsy. Medial femoral condyles were histologically processed, and the articular cartilage was stained for the presence of proteoglycans, stromelysin, tumor necrosis factor (TNF) α, and TNF receptors (p55 and p75).

Results

Decreased metachromasia was evident in the cartilage matrix of all cast groups, with the smallest decrease in the HA-treated group. Stromelysin was immunolocalized in articular cartilage of the cast (left) limbs of cast control and both HA/TGF-β-treated groups. TNF-α was localized in articular cartilage of all cast (left) and right limbs, except those of the HA-treated group. Receptors for TNF were observed in both limbs of untreated control and cast control groups and cast limbs of HA/TGF-β-treated groups. The receptors were not localized in the right limbs of the HA with or without TGF-β-treated groups. TGF-β did not decrease stromelysin or TNF-α or receptors at the doses used.

Conclusions

HA may mediate a chondrostabilizing influence on articular cartilage by down-regulating TNF-α. Importantly, HA appeared to exert its inhibitory influence on TNF-α, as well as stromelysin and TNF receptors, on a systemic basis.

Clinical Relevance

Results provide insight into the mode of action of HA as a therapeutic agent for arthritis and its stabilizing influence on cartilage metabolism. (Am J Vet Res 1996;57:1488-1496)

Free access
in American Journal of Veterinary Research

Summary

Force platform analysis of gait provides ground reaction force information that can be used to study limbs with normal or abnormal function. When combined, the interrelated variables of ground reaction forces give a more thorough description of gait than when used individually.

To describe the pattern of ground reaction forces in clinically normal, conditioned, mesomorphic dogs, we studied the data from platform gait analyses of 43 dogs. Mediolateral (Fx), craniocaudal (Fy), and vertical (Fz) forces were measured and recorded. Torque (Tz) around the vertical axis also was calculated.

Mean stance times for forelimbs and hind limbs were 0.278 and 0.261 second, respectively. Among dogs, ground reaction forces were normalized and expressed as percentage of body weight (%bw). The vertical (Fz) peak, average force during stance phase, and force vs time impulses were 106.68, 60.82, and 17.2 %bw in forelimbs, and were 65.11, 35.3, and 9.33 %bw in hind limbs. The forelimb braking/ propulsive (Fy) peaks were −16.74 and +6.73 %bw. In hind limbs, these peaks were −3.76 and +7.69 %bw. The usual mediolateral force (Fx) pattern found in forelimbs was laterally directed, with average peak magnitude of 6.69 %bw, whereas the hind limb patterns were variable.

Free access
in American Journal of Veterinary Research

SUMMARY

The pattern of vertical ground reaction force redistribution among limbs during episodes of acute synovitis of the stifle in 12 mixed-breed dogs was investigated as an adjunct to a blinded nonsteroidal anti-inflammatory drug efficacy study. Without regard to drug efficacy groupings, the redistribution of vertical forces before and during the acute synovitis episode was evaluated by analysis of gait, using a force platform.

Acute synovitis was induced by intrasynovial injection of sodium urate crystals. Simultaneously, each dog was given 1 of 4 treatment regimens, including iv injection of sterile saline solution (as a negative control), phenylbutazone (as a positive control), or 1 of 2 proprietary nonsteroidal anti-inflammatory drugs. Postinjection analyses took place at 2, 4, 8, 12, 24, and 36 hours. The peak vertical force redistribution in the 3 untreated limbs of the dogs was described.

The greatest redistribution was observed 4 hours after substance injection when the synovitis was clinically at maximum. Thereafter, there was steady improvement and the dogs had a clinically normal gait 24 hours after substance injection. During synovitis, peak vertical force increased in the contralateral hind limb. During the more severe synovitis episodes, force was decreased in both forelimbs. There was good correlation between severity of lameness and peak vertical force response in the contralateral hind limb. Results of the study indicate that the untreated limbs of the same animal should not be used as a control during acute lameness studies.

Free access
in American Journal of Veterinary Research

Abstract

Objective

To ascertain the effects of locally injected immunostimulant and tripeptide-copper complex (TCC) on improving healing of pad wounds.

Design

Wounds in pads of large dogs were injected with either medication or physiologic saline solution (controls). Healing was evaluated.

Animals

12 mature English Pointers.

Procedure

Full-thickness 6 × 8-mm wounds in metatarsal and third and fourth digital pads were injected with immunostimulant or TCC at 0, 3, and 6 days after wounding. Wounds on control dogs were injected with physiologic saline solution. Using planimetric measurements at 0, 3, 6, 14, and 21 days, rates of healing were evaluated. Biopsy of the digital pad wounds at 3, 6, and 14 days was used to evaluate collagen content by hydroxyproline analysis. Biopsy specimens were also evaluated for type-I and type-III collagen, using Sirius red differential staining.

Results

Effect on healing rate and hydroxyproline content was best during the first week for immunostimulant. Immunostimulant- and TCC-injected wounds had more type-I collagen than did controls at 6 days; TCC-injected wounds had the most type-I collagen. At 14 days, the amount of type-I collagen in TCC-injected wounds was significantly greater than that in other wounds.

Conclusions

Tested medications had positive effects on healing of pad wounds.

Clinical Relevance

Intralesional injection of medications helps ensure their presence for enhancement of wound healing. The benefit could be lost with topical use in a bandage if the bandage is lost or becomes wet.(Am J Vet Res 1996;57:394-399)

Free access
in American Journal of Veterinary Research

Abstract

Objective—To study the musculoskeletal development of Great Dane puppies fed various dietary concentrations of calcium (Ca) and phosphorus (P) in fixed ratio by use of dual energy x-ray absorptiometry (DEXA), determination of serum insulin-like growth factor I and parathyroid hormone concentrations, radiography, and blood chemistry analysis results.

Animals—32 purebred Great Dane puppies from 4 litters.

Procedure—At weaning, puppies were assigned randomly to 1 of 3 diets. Blood was collected for biochemical analyses and hormone assays, and radiography and DEXA were performed through 18 months of age. Changes in body weight, bone mineral content, fat tissue weight, lean mass, result of serum biochemical analyses, hormonal concentrations, and radius lengths were analyzed through 18 months of age.

Results—Bone mineral content of puppies correlated positively with Ca and P content of the diets fed. Significant differences between groups in bone mineral content, lean mass, and body fat were apparent early. The disparity among groups increased until 6 months of age and then declined until body composition was no longer different at 12 months of age. Accretion rates for skeletal mineral content, fat, and lean tissue differed from each other and by diet group.

Conclusions and Clinical Relevance—Ca and P concentrations in the diet of young Great Dane puppies are rapidly reflected in the bone mineral content of the puppies until 5 to 6 months of age, after which hormonal regulation adjusts absorption and excretion of these minerals. Appropriate Ca and P concentrations in diets are important in young puppies < 6 months of age. (Am J Vet Res 2002;63:1036–1047)

Full access
in American Journal of Veterinary Research