Long-term temporal evaluation of ground reaction forces during development of experimentally induced osteoarthritis in dogs

Force Plate Gait Analysis in Dogs After Femoral Head and Neck Excision

Femoral head and neck excision (FHNE) remains a common orthopedic surgical procedure in many countries. However, data on postoperative outcomes regarding changes in hindlimb function are limited. This study aimed to evaluate hindlimb function after FHNE in dogs of different weights. Twenty-seven dogs that underwent FHNE were block-randomly assigned to two groups based on weight (≤20 kg and >20 kg). Hindlimb function was evaluated using force plate gait analysis to measure peak vertical force (PVF), alongside other orthopedic evaluations and a composite orthopedic assessment score at 1, 2, 3, 4, 5, 6, 9, and 12 months after surgery. Kaplan-Meier survival analysis and the log-rank test were used for statistical comparisons. The findings demonstrated no significant difference in PVF between the operated and non-operated limbs in either weight groups (≤20 kg and >20 kg) at four and three months postoperatively (median functional recovery time) (p = 0.33), nor were there significant differences in lameness scores at trot between weight groups five and three months after FHNE (p = 0.64). These results indicate that FHNE provides satisfactory functional outcomes and can be considered a suitable orthopedic intervention for medium- to large-breed dogs.

Evaluation of forelimb gait variation overground at a walk in sound and lame dogs using a combination of diagnostic techniques

BACKGROUND

Kinetic and kinematic gait analysis is increasingly practised as a part of lameness evaluation in dogs. The aim of this study was to examine the normal short- and long-term variation in forelimb gait in sound control dogs (CD) at a walk using seven selected variables of objective kinetic and kinematic gait analyses. Also, to compare the findings in CD to a group of forelimb lame dogs with elbow osteoarthritis (OAD). An additional aim was to test a kinetic based graphic method for lameness detection; symmetry squares (SS). A prospective longitudinal study was carried out on client owned CD and OAD. Clinical and orthopaedic evaluations were performed to ensure soundness and detect and grade lameness. Seven kinetic and kinematic variables and SS were tested for lameness evaluation. The CD were divided into two subgroups, CD1 and CD2, and examined twice: CD1 with two months interval and CD2 with 3-4 h interval. The OAD group was evaluated once and compared to the CD groups' first examination.

RESULTS

Thirteen CD and 19 OAD were included. For CD1 and CD2, there were no significant differences in any examined variable between examination occasions. Total peak force/impulse symmetry and fore-hind peak force/impulse symmetry differed significantly between OAD and CD. Symmetry squares had a 74% agreement to subjective orthopaedic evaluations.

CONCLUSIONS

In CD, no difference in the examined variables was seen between examination occasions. Four out of seven objective variables differed significantly between CD and OAD. The graphic SS method might have diagnostic potential for lameness detection, making it possible to detect a shift from lame to non-lame limbs. Potentially, this might be especially helpful in bilaterally lame dogs, which often represent a clinical challenge in lameness evaluation.

Vergleichende Langzeitergebnisse zwischen Tibial Plateau Leveling Osteotomy und Modified Maquet Procedure nach Ruptur des vorderen Kreuzbandes beim Hund

Gegenstand und Ziel Ziel dieser Studie ist es, die Modified Maquet Procedure (MMP) mit der Tibial Plateau Leveling Osteotomy (TPLO) anhand von Langzeitkontrollen über ein Jahr (∅ 3,15 Jahre) mittels klinischer Untersuchung, röntgenologischer Beurteilung der Arthroseprogression und Ganganalyse durch Laufbanduntersuchung zu vergleichen. Zusätzliches Ziel ist es, den Einfluss der Erfahrung der Chirurgen bei der TPLO-Technik zu überprüfen.

Material und Methoden Bei dieser klinischen Studie wurden 67 Kniegelenke von 50 Hunden verschiedener Rassen zwischen 20 und 40 Kilogramm Körpergewicht einbezogen, die mittels TPLO beziehungsweise MMP (n = 19) nach Ruptur des vorderen Kreuzbandes operiert wurden. Die TPLO-Gruppe unterteilte sich in eine Gruppe, welche von 2 erfahrenen Chirurgen (TPLO1, n = 25) operiert wurde und eine zweite Gruppe, die von mehreren Chirurgen unterschiedlicher Erfahrung (TPLO2, n = 23) versorgt wurden. Die Hunde wurden nach mindestens über einem Jahr (3,15 ± 1,21 Jahre) postoperativ orthopädisch, röntgenologisch und ganganalytisch uni- und bilateral getrennt untersucht. Zusätzlich wurden die Daten der Ganganalyse mit einer orthopädisch gesunden Kontrollgruppe verglichen.

Ergebnisse Bei der orthopädischen Untersuchung wurden keine signifikanten und klinisch relevanten Unterschiede zwischen den 3 Gruppen festgestellt.

Die Arthroseprogression zeigte in allen 3 OP-Gruppen ähnliche Werte, wobei die der TPLO2-Gruppe durchschnittlich pro Jahr gerechnet signifikant etwas geringer war als die der TPLO1- und der MMP-Gruppe.

Die ganganalytische Untersuchung im Schritt konnte vor allem im Vergleich mit der gesunden Kontrollgruppe signifikante Unterschiede bei bilateralen Rupturen für die Peak Vertical Force und den Vertical Impulse zeigen. Die Standphasendauer wies keine signifikanten Unterschiede auf. Im Trab konnten keine signifikanten Unterschiede zwischen den 3 OP-Gruppen festgestellt werden.

Schlussfolgerung Beide Operationstechniken erzielten in den 3 Gruppen bei den Langzeitkontrollen gute klinische, radiologische und ganganalytische Ergebnisse auch im Vergleich mit einer gesunden Kontrollgruppe.

Klinische Relevanz Die MMP kann als schnell durchführbare Alternative zur etablierten TPLO mit ebenfalls guten Ergebnissen beim Hund angesehen werden. Die Erfahrung des Chirurgen scheint keinen Einfluss auf das Ergebnis zu haben.

Clinical and Radiographic Evaluation of Short- and Long-Term Outcomes of Different Treatments Adopted for Elbow Medial Compartment Disease in Dogs

Medial compartment disease is a common occurrence in dogs affected by elbow dysplasia. Despite many treatments suggested in the literature, only few studies reported comparative outcomes in the short and long term. The aim of this study is to report and compare short- and long-term clinical and radiographic outcomes of dogs treated for medial compartment disease (MCD) by distal dynamic ulnar ostectomy (DUO), bi-oblique dynamic proximal ulnar osteotomy (BODPUO) and conservative management (CM). From 2016 to 2018, all medium to large dogs, aged between 5 and 12 months, affected by uni/bilateral MCD and treated by DUO, BODPUO or CM, were enrolled in this study and followed up for 24 months. Orthopedic and radiographic examinations were performed at T₀, T₂, T₁₂ and T₂₄ months after treatment. Lameness score, elbow arthralgia, elbow range of motion (ROM), osteoarthritis (OA) score and percentage of ulnar subtrochlear sclerosis (%STS) were evaluated at each time point. According to the treatment performed, dogs were divided into three groups: DUO, BODPUO and CM. Forty-five elbows from twenty-six dogs, treated with DUO (n = 17), BODPUO (n = 17) or CM (n = 11), were prospectively enrolled in the study. The patients enrolled in the CM group were older and showed more severe radiographic signs of OA, compared to those enrolled in the other two groups. Lameness and arthralgia scores (p < 10⁻⁴) were significantly decreased in patients that underwent surgical treatment and increased in patients managed conservatively (lameness p < 10⁻⁴, arthralgia p = 0.3068), at T₁₂ and T₂₄. OA score (p < 0.0040) and ROM (DUO, CM p < 10⁻⁴; BODPUO p = 0.0740) worsened in every study group, but %STS decreased in DUO (p = 0.0108), increased in the CM group (p = 0.0025) and remained unchanged in the BODPUO group (p = 0.2740). This study supports the clinical efficacy of DUO and BODPUO in reducing lameness, arthralgia and progression of %STS. Early diagnosis and surgical attention in patients affected by MCD can improve the short- and long-term outcome and reduce the progression of secondary changes.

Best practices for measuring and reporting ground reaction forces in dogs

Kinetic gait analysis and ground reaction forces (GRFs) have been used in hundreds of scientific manuscripts. Specific methodology, interpretation of results, and translation to clinical veterinary medicine have been inconsistent. This impedes the advance of veterinary medicine and poses a risk to patients. The objective of this report was to address methodological variations and share our consensus on a recommended approach with viable alternatives to data collection methods, analysis, reporting, and interpretation for GRFs in the dog. Investigators with experience performing kinetic gait analysis reviewed the literature and discussed the topics that most influenced GRF data collection, reporting, and interpretation. Methodological variations were reported and a consensus from the group was devised. There are several reasonable alternatives to collect, report, and interpret GRFs in dogs appropriately. Attention to detail is required in several areas to collect and report them. This review and consensus report should assist future investigations and interpretations of studies, optimize comparison between publications, minimize use of animals, and limit the investment in cost and time.

Compensatory Changes in Ground Reaction Forces in Small and Large Breed Dogs with Unilateral Hindlimb Lameness in Comparison to Healthy Dogs

OBJECTIVE

 The aim of this study was to investigate whether small- to medium-sized dogs with a naturally occurring unilateral hindlimb lameness show the same compensatory changes in ground reaction forces as large-breed dogs and how the changes are displayed compared with healthy small- to medium-sized dogs.

STUDY DESIGN

 Small- to medium-sized dogs (n = 15) and large-breed dogs (n = 16) with unilateral rupture of the cranial cruciate ligament were examined. The kinetic parameters peak vertical force and vertical impulse of the two groups were compared with each other and compared with healthy Beagles (n = 15) and with healthy Labrador Retrievers (n = 17), respectively.

RESULTS

 The healthy Beagle group showed a significantly higher weight loading on the forelimbs compared with the healthy Labrador group. The affected groups in comparison with the corresponding healthy groups showed a higher load on the non-affected body half and a significant lower weight bearing on the affected limb. Comparing the two affected groups, no significant difference could be found.

CONCLUSION

 Despite a substantially different initial situation regarding weight distribution of the examined small- to medium-sized dogs and large dogs, a unilateral hindlimb lameness leads to the same compensatory changes (cranial and lateral shift of the body mass centre).

Center of Pressure in the Paws of Clinically Sound Dogs in Comparison with Orthopedically Diseased Dogs

Simple Summary

The analysis of the center of pressure is an important tool that allows conclusions to be drawn about the body balance of a patient. This balance can be altered by orthopedic or neurological diseases. To date, there are few data on the center of pressure in the paws of walking dogs. This study aimed to show the compensatory changes in the center of pressure parameters within the paw during stance-phase in the walking dog, with data being collected non-invasively by walking dogs with osteoarthritis and healthy dogs (control group) over a pressure platform. Differences in the center of pressure parameters were found between the affected and non-affected limbs of the diseased dogs, but also in comparison to the corresponding limbs of sound dogs. It was shown that dogs with osteoarthritis show different compensatory changes in the center of pressure parameters depending on whether a front or a hind limb are affected. This can reflect a compensatory redistribution of the body mass as well as compensatory changes of body balance. Based on these observations, a deeper investigation of the center of pressure within the paws of dogs would be of interest and a diagnostic application could become possible in the future.

Abstract

The center of pressure (COP) is recognized as a valuable tool for the assessment of orthopedic and neurologic disorders in humans. Relatively few studies are available in veterinary medicine, particularly concerning the COP in the individual paw. This study assessed the dynamic paw COP parameters during the stance phase of dogs with cox- or cubarthrosis (20 dogs each), as well as of 20 sound dogs. Data were obtained by walking over a pressure platform and analyzed within the diseased groups in comparison to the control group. Both diseased groups showed significant differences between the affected and non-affected limbs, but also in comparison to the reference limbs of sound animals. For coxathrosis, the primary increase was in the medio-lateral COP displacement and the COP area in both hind limbs. For cubarthrosis, the most prominent changes were an increase in the medio-lateral COP displacement in the ipsilateral hind limb and in the cranio-caudal COP displacement in the lame limb. Additionally, the COP area increased in both hind limbs. This can reflect a compensatory redistribution of the body mass as well as compensatory changes of body balance.

Comparison of the Vertical Force Distribution in the Paws of Dogs with Coxarthrosis and Sound Dogs Walking over a Pressure Plate

Simple Summary

The study of biomechanics for dogs with coxarthrosis is an important tool for diagnosis and treatment evaluation. Seeking a better view of the load distribution during the gait in dogs with coxarthrosis, we used a pressure plate to measure the vertical forces in the paws. The results suggested that walking dogs with coxarthrosis redistributed the load mainly to the caudal quadrants of the paws of the unaffected limbs. The performed methodology is another new possibility for the evaluation and clarification of biomechanical events in the course of coxarthrosis.

Abstract

In the present study, we used a pressure plate to investigate the ground reaction forces of limbs and the vertical force distribution (VFD) within the paws of dogs with coxarthrosis. We included 23 sound dogs (G_Sou) and 23 dogs with hip osteoarthrosis (G_Cox). The dogs walked over a pressure plate and the peak vertical force (PFz), vertical impulse (IFz) as the percentage of the total force, and time of occurrence of PFz as a percent of the stance phase duration (TPFz%) were evaluated, as well for the entire limb as in the paws (where the paws were divided into four quadrants). The G_Cox presented a lower PFz% in the lame hind limb than in others and transferred the weight to the caudal quadrants of the front limbs. IFz% was lower in the lame limb and was counterbalanced through higher loading of the caudal quadrants in all unaffected limbs. TPFz% was reached later in the lame limb than in the contralateral limb and the G_Sou, specifically in the caudomedial quadrant. In conclusion, we found complex compensatory effects of lameness in the hind limb, and this methodology was useful to define the VFD within the paws of dogs.

Comparison of vertical force redistribution in the pads of dogs with elbow osteoarthritis and healthy dogs

Kinetic analyses are becoming increasingly important for biomechanical research in veterinary medicine and as a diagnostic tool for orthopaedic examinations in dogs. Such analysis enables accurate evaluation of the vertical force distribution (VFD) in canine paw pads. The aim of this study was to assess peak vertical force (PFz) as a percent of total force (%TF), vertical impulse (IFz, %TF) and time of occurrence of PFz (TPFz) as a percent of the stance phase (%SP) in the pads of all four limbs in 23 dogs with osteoarthritis in the elbow joint and 22 healthy dogs. Dogs walked over a pressure plate, and the pads were divided into four quadrants for VFD analysis. For statistical analysis, a general linear model was used to examine the difference in VFD between both groups, between fore- and hindlimbs, between body sides, and between medial/lateral and cranial/caudal quadrants. Lame dogs had lower PFz in the lame forelimb than in other limbs and transferred their weight to the caudal quadrants of the contralateral forelimb and the caudomedial quadrant of both hindlimbs. IFz was also lower in the affected forelimb and was compensated through higher loading of the caudal quadrants of the contralateral forelimb, the caudomedial quadrants of both hindlimbs and the caudolateral quadrant of the contralateral hindlimb. TPFz (%SP) occurred later in both forelimbs of the lame dogs than in those of healthy dogs. The analysis of force distribution over the paw quadrants can be used for further biomechanical studies of dogs with orthopaedic and neurological diseases.

Evaluation of recovery of limb function by use of force plate gait analysis after tibial plateau leveling osteotomy for management of dogs with unilateral cranial cruciate ligament rupture

OBJECTIVE

To evaluate recovery of limb function by use of gait force analysis after tibial plateau leveling osteotomy (TPLO) in dogs with unilateral cranial cruciate ligament (CrCL) rupture.

ANIMALS

19 dogs with unilateral CrCL rupture treated with TPLO.

PROCEDURES

Force plate gait analysis was performed before and 1, 2, 4, and 7 months after TPLO. Ground reaction forces (GRFs; which comprised peak vertical force [PVF], vertical impulse [VI], peak braking force, braking impulse, peak propulsion force [PPF], and propulsion impulse), time to switching from braking to propulsion, and vector magnitude at PVF in the forelimbs and hind limbs were evaluated.

RESULTS

GRFs in the affected hind limb were significantly lower than in the contralateral hind limb before TPLO. These variables, except for PPF, were not significantly different 7 months after TPLO. Time to the switching point in the affected hind limb was significantly less from before to 2 months after TPLO. Vector magnitude at PVF had a similar pattern as PVF and VI during the recovery process. The PVF in the ipsilateral forelimb was significantly higher than in the contralateral forelimb before TPLO.

CONCLUSIONS AND CLINICAL RELEVANCE

A similar pattern was detected between PVF or VI and craniocaudal force during recovery of dogs that underwent TPLO. Rupture of he CrCl resulted in a decrease in GRFs in the affected hind limb as well as in the switching point and PVF of limbs. However, weight distribution for the craniocaudal force was normalized before PVF or VI. Vector magnitude at PVF might be effectively evaluated by combining vertical force and craniocaudal force.

Variability of vertical ground reaction forces collected with one and two force plates in healthy dogs

Objective: To compare peak vertical force (PVF) and vertical impulse (VI) data collected with one and two force plates during the same collection time period in healthy dogs at a trot.

Animals: Seventeen healthy client-owned adult dogs.

Methods: Vertical ground reaction force (GRF) data were collected in a crossover study design, with four sessions on two consecutive days, and then two weeks apart (days 1, 2, 15, and 16) using both one and two force plates collection methods. A repeated measures model analysis of variance (ANOVA) was used to test for differences in force plate PVF, VI, and average time per trial (ATT) between days, weeks, and systems (1 plate versus 2 plates). Coefficients of variation for PVF and VI were also calculated separately by forelimbs and hindlimbs, plates, day, and week.

Results: The time required to obtain a valid trial was significantly longer using a single force plate when compared with two force plates. Comparing GRF data for all dogs, significant differences in PVF data were found between one and two force plates, however, these differences were diminutive in absolute magnitude, and of unknown clinical importance. Examination of the coefficients of variation for PVF and VI during the different collection periods yielded similar results.

Conclusions: Use of two force plates decreased trial repetition and collection time. Vertical GRF data had a similar coefficient of variation with either one or two force plates collection techniques in healthy dogs.

Effects of trial repetition, limb side, intraday and inter-week variation on vertical and craniocaudal ground reaction forces in clinically normal Labrador Retrievers

Objectives: To document the contributions of trial repetition, limb side, and intraday and inter-week measurements on variation in vertical and craniocaudal ground reaction force data.

Methods: Following habituation, force and time data were collected for all four limbs of seven Labrador Retrievers during sets of five valid trot trials. Each set was performed twice daily (morning and afternoon), every seven days for three consecutive weeks. A repeated measures analysis of variance was used to determine the effects of limb, trial, intraday, and inter-week factors on ground reaction force data for the thoracic and pelvic limbs.

Results: Of the four factors evaluated, variation due to trial repetition had the largest magnitude of effect on ground reaction forces. Trial within a set of data had an effect on all craniocaudal, but not vertical, ground reaction force variables studied, for the thoracic limbs. The first of five trials was often different from later trials. Some thoracic limb and pelvic limb variables were different between weeks. A limb side difference was only apparent for pelvic limb vertical ground reaction force data. Only pelvic limb craniocaudal braking variables were different between sets within a day.

Discussion and clinical significance: When controlling for speed, handler, gait, weight and dog breed, variation in ground reaction forces mainly arise from trial repetition and inter-week data collection. When using vertical peak force and impulse to evaluate treatment, trial repetition and inter-week data collection should have minimal effect of the data.

Kinetic gait analysis in English Bulldogs

Background

Canine breed conformation may interfere with locomotion and may predispose to orthopedic disease. Bulldogs have a high incidence of orthopedic diseases such as hip dysplasia. Kinetic gait analysis provides an objective way to assess and analyze locomotion. The aim of this study was to study the vertical forces of English Bulldogs during walk using a pressure sensitive walkway. We hypothesize that Bulldogs affected by orthopedic diseases have decreased weight bearing and asymmetric locomotion in the limbs despite having mild to no sings during clinical examination. Thirty English Bulldogs were tested. Peak vertical force, vertical impulse, rate of loading, stance phase duration, symmetry index, goniometry and incidence of orthopedic diseases were recorded.

Results

Although none of the dogs showed signs of pain or discomfort upon manipulation of the hip joints, all dogs had radiographic evidences of hip dysplasia and lack of significant peak vertical force, vertical impulse and stance time differences. The dogs had a mean hind limb symmetry index of 19.8 ± 19.5% and rates of loading ranged from 1.0 to 3.1.

Conclusions

Despite the lack of evident decrease in weight bearing, subclinical lameness can be inferred. The examined dogs had a mean hind limb symmetry index of 19.8 ± 19.5%. Symmetry indices reported in dogs free from orthopedic diseases range from 0.3 to 9.6%. Given non-lame dogs are expected to have a symmetry index close to 0%, data from this study suggests that Bulldogs have gait dysfunctions, which translates into hind limb asymmetries and rate of loading was consistent with severe hip dysplasia despite no visible signs of gait dysfunction. Future studies comparing lame and non-lame Bulldogs are warranted.

Influence of trial repetition on lameness during force platform gait analysis in a heterogeneous population of clinically lame dogs each trotting at its preferred velocity

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.

Current and Future Issues in the Development of Spinal Agents for the Management of Pain

Targeting analgesic drugs for spinal delivery reflects the fact that while the conscious experience of pain is mediated supraspinally, input initiated by high intensity stimuli, tissue injury and/or nerve injury is encoded at the level of the spinal dorsal horn and this output informs the brain as to the peripheral environment. This encoding process is subject to strong upregulation resulting in hyperesthetic states and downregulation reducing the ongoing processing of nociceptive stimuli reversing the hyperesthesia and pain processing. The present review addresses the biology of spinal nociceptive processing as relevant to the effects of intrathecally-delivered drugs in altering pain processing following acute stimulation, tissue inflammation/injury and nerve injury. The review covers i) the major classes of spinal agents currently employed as intrathecal analgesics (opioid agonists, alpha 2 agonists; sodium channel blockers; calcium channel blockers; NMDA blockers; GABA A/B agonists; COX inhibitors; ii) ongoing developments in the pharmacology of spinal therapeutics focusing on less studied agents/targets (cholinesterase inhibition; Adenosine agonists; iii) novel intrathecal targeting methodologies including gene-based approaches (viral vectors, plasmids, interfering RNAs); antisense, and toxins (botulinum toxins; resniferatoxin, substance P Saporin); and iv) issues relevant to intrathecal drug delivery (neuraxial drug distribution), infusate delivery profile, drug dosing, formulation and principals involved in the preclinical evaluation of intrathecal drug safety.

Effect of intraarticular inoculation of mesenchymal stem cells in dogs with hip osteoarthritis by means of objective force platform gait analysis: concordance with numeric subjective scoring scales

Background

Subjective pain assessment scales have been widely used for assessing lameness in response to pain, but the accuracy of these scales has been questioned. To assess scale accuracy, 10 lame, presa Canario dogs with osteoarthritis (OA) associated with bilateral hip dysplasia were first treated with mesenchymal stem cells. Then, potential lameness improvement was analyzed using two pain scales (Bioarth and visual analog scale). These data were compared with similar data collected using a force platform with the same animals during a period of 6 months after treatment.

Results

The F test for intraclass correlation showed that concordance in pain/lameness scores between the 2 measuring methodologies was not significant (P value ≥ 0.9213; 95 % confidence interval, –0.56, 0.11). Although subjective pain assessment showed improvement after 6 months, force platform data demonstrated those same animals had returned to the initial lameness state.

Conclusion

Use of pain assessment scales to measure lameness associated with OA did not have great accuracy and concordance when compared with quantitative force platform gait analysis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12917-016-0852-z) contains supplementary material, which is available to authorized users.

Influence of leash side and handlers on pressure mat analysis of gait characteristics in small-breed dogs

OBJECTIVE

To characterize the gait of small-breed dogs walked on a pressure walkway by handlers moving at a metronome-set tempo and to determine the influence of handler and leash side on gait characteristics.

DESIGN

Prospective study.

ANIMALS

5 healthy adult small-breed dogs weighing < 11.4 kg (25 lb).

PROCEDURES

Dogs were walked by each of 5 handlers moving at a metronome-set tempo (100 beats/min). Velocity, cadence, stance time, number of activated sensors, total pressure index (TPI), left or right hind reach, and symmetry indices were obtained with the leash on the left and right sides of each dog for each handler.

RESULTS

Coefficients of variation for TPI and stance time approximated 30%, whereas coefficients of variation for symmetry indices remained < 20%. Changing handlers and leash side did not influence hind limb variables. Changing handlers influenced the TPI of the forelimbs, inducing changes of up to 8%. Leash side accounted for 12% and 14% of the variation in symmetry indices of TPI and number of sensors activated between forelimbs, respectively (mean alterations for recorded variables, 9%).

CONCLUSIONS AND CLINICAL RELEVANCE

Symmetry indices appeared to vary less than variables obtained for individual dog limbs, and it may therefore be advantageous to determine those indices during large trials. Handlers or leash side may be changed in studies focusing on dogs' hind limbs without affecting results. Use of symmetry indices is recommended in forelimb studies requiring multiple handlers. Pressure walkway analyses of the forelimbs should include equal distribution of left- and right-sided leash-led trials, given that small-breed dogs tended to shift weight toward the forelimb opposite the leash.

Intermittent applied mechanical loading induces subchondral bone thickening that may be intensified locally by contiguous articular cartilage lesions

OBJECTIVES

Changes in subchondral bone (SCB) and cross-talk with articular cartilage (AC) have been linked to osteoarthritis (OA). Using micro-computed tomography (micro-CT) this study: (1) examines changes in SCB architecture in a non-invasive loading mouse model in which focal AC lesions are induced selectively in the lateral femur, and (2) determines any modifications in the contralateral knee, linked to changes in gait, which might complicate use of this limb as an internal control.

METHODS

Right knee joints of CBA mice were loaded: once with 2 weeks of habitual use (n = 7), for 2 weeks (n = 8) or for 5 weeks (n = 5). Both left (contralateral) and right (loaded) knees were micro-CT scanned and the SCB and trabecular bone analysed. Gait analysis was also performed.

RESULTS

These analyses showed a significant increase in SCB thickness in the lateral compartments in joints loaded for 5 weeks, which was most marked in the lateral femur; the contralateral non-loaded knee also showed transient SCB thickening (loaded once and repetitively). Epiphyseal trabecular bone BV/TV and trabecular thickness were also increased in the lateral compartments after 5 weeks of loading, and in all joint compartments in the contralateral knee. Gait analysis showed that applied loading only affected gait in the contralateral himd-limb in all groups of mice from the second week after the first loading episode.

CONCLUSIONS

These data indicate a spatial link between SCB thickening and AC lesions following mechanical trauma, and the clear limitations associated with the use of contralateral joints as controls in such OA models, and perhaps in OA diagnosis.

A validated approach for collecting fine-wire electromyographic recordings in four canine shoulder muscles during highly dynamic tasks

This study investigated the feasibility of obtaining ultrasound-guided intramuscular fine-wire electromyographic (fEMG) recordings from four canine shoulder muscles during highly dynamic activities. Four cadaveric canines were utilised to confirm the appropriate anatomical landmarks and the use of real time ultrasound guidance for electrode placement for four shoulder muscles: Biceps Brachii (BB), Supraspinatus (SP), Infraspinatus (IF), and Triceps Brachii – Long Head (TBLH). Electromyographic activity of the left BB, S P, IF, and TBLH was then recorded in two research dogs while walking and trotting to refine the data collection procedures. Finally, the full experimental protocol was piloted with two client-owned, specially-trained agility dogs, confirming the feasibility of collecting fEMG recordings while performing dynamic, highly-specific agility-related tasks and verifying our EMG amplitude normalisation protocol to enable comparisons across muscles and performance tasks. We present specific guidelines regarding the placement of fEMG electrodes and data collection/normalisation procedures to enable investigations of muscle activation during dynamic activities.

Use of an inverse dynamics method to compare the three-dimensional motion of the pelvic limb among clinically normal dogs and dogs with cranial cruciate ligament-deficient stifle joints following tibial plateau leveling osteotomy or lateral fabellar-tibial suture stabilization

OBJECTIVE

To compare the 3-D motion of the pelvic limb among clinically normal dogs and dogs with cranial cruciate ligament (CCL)-deficient stifle joints following tibial plateau leveling osteotomy (TPLO) or lateral fabellar-tibial suture (LFS) stabilization by use of an inverse dynamics method.

ANIMALS

6 clinically normal dogs and 19 dogs with CCL-deficient stifle joints that had undergone TPLO (n = 13) or LFS (6) stabilization at a mean of 4 and 8 years, respectively, prior to evaluation.

PROCEDURES

For all dogs, an inverse dynamics method was used to describe the motion of the pelvic limbs in the sagittal, frontal, and transverse planes. Motion and energy patterns for the hip, stifle, and tibiotarsal (hock) joints in all 3 planes were compared among the 3 groups.

RESULTS

Compared with corresponding variables for clinically normal dogs, the hip joint was more extended at the beginning of the stance phase in the sagittal plane for dogs that had a TPLO performed and the maximum power across the stifle joint in the frontal plane was greater for dogs that had an LFS procedure performed. Otherwise, variables in all planes were similar among the 3 groups.

CONCLUSIONS AND CLINICAL RELEVANCE

Gait characteristics of the pelvic limb did not differ between dogs that underwent TPLO and dogs that underwent an LFS procedure for CCL repair and were similar to those of clinically normal dogs. Both TPLO and LFS successfully provided long-term stabilization of CCL-deficient stifle joints of dogs with minimal alterations in gait.

Short- and long-term outcomes after arthroscopic treatment of young large breed dogs with medial compartment disease of the elbow

OBJECTIVES

To report short- and long-term outcomes after arthroscopic treatment in young large breed dogs affected by medial coronoid process disease (MCPD) and identify variables affecting outcome.

STUDY DESIGN

Prospective observational case series.

ANIMALS

Large breed dogs <3 years old (n = 15; 23 elbows).

METHODS

MCPD was confirmed by radiography, computed tomography, and arthroscopy. Dogs were treated by arthroscopy. Variables recorded at time of treatment included radioulnar incongruity (RUI) and degree of cartilage erosion. Variables recorded before, 6 weeks, and ≥23 months after surgery included radiographic score for osteoarthritis, trochlear notch sclerosis, muscle circumference, range of motion (ROM), and the load distribution of vertical ground reaction forces between thoracic and pelvic limbs.

RESULTS

A greater load distribution to the pelvic limbs was identified preoperatively in dogs with RUI than in dogs with congruent elbows. Load distribution was not significantly improved at 6 weeks compared with preoperatively. Muscle circumference and vertical impulse distributions were improved at long-term evaluation despite an increased osteoarthritis score. This improvement was more obvious in dogs with RUI or a high degree of cartilage erosion at initial presentation.

CONCLUSION

Some evidence of improvement in long-term function was found in dogs with MCPD after arthroscopic treatment. RUI and cartilage erosion at the time of diagnosis were associated with more lameness preoperatively but did not affect the final gait assessment or osteoarthritis score in this small cohort.

Pain assessment in animal models of osteoarthritis

Assessment of pain in animal models of osteoarthritis is integral to interpretation of a model's utility in representing the clinical condition, and enabling accurate translational medicine. Here we describe behavioral pain assessments available for small and large experimental osteoarthritic pain animal models.

Intra-articular anaesthesia mitigates established pain in experimental osteoarthritis: a preliminary study of gait impulse redistribution as a biomarker of analgesia pharmacodynamics

OBJECTIVE

Develop a sensitive, functional biomarker of persistent joint pain in a large animal model of experimental osteoarthritis. Evaluate Impulse Ratio as a measure of weight distribution among supporting limbs throughout the early natural history of osteoarthritis and with local anaesthesia and analgesia.

DESIGN

The distribution of weight bearing in the trot of 11 skeletally-mature dogs was analyzed before and after unilateral surgical intervention (cranial cruciate transection or distal femoral focal impact). The short-term effects of two analgesic treatments (intra-articular lidocaine and intra-dermal meloxicam) were then evaluated as an index of pain relief based on the redistribution of weight-bearing impulse between normal and injured limbs.

RESULTS

Impulse Ratio was able to resolve weight redistribution between limbs in both long-term (weekly for over 400 days) and short-term (15 min intervals) joint evaluations. Joint pain relief from lidocaine administration could be reliably tracked over its brief acting time course. Meloxicam administration resulted in ambiguous results, where average weight bearing in the injured limb did not increase, but the variability of limb use changed transiently and reversibly.

CONCLUSION

Joint function and the role of persistent joint pain in the development of osteoarthritis can be investigated effectively and efficiently in a large animal model through the use of Impulse Ratio. Impulse Ratio can be a functionally relevant and sensitive biomarker of locomotion-related joint pain.

Compensatory load redistribution in walking and trotting dogs with hind limb lameness

This study evaluated adaptations in vertical force and temporal gait parameters to hind limb lameness in walking and trotting dogs. Eight clinically normal adult Beagles were allowed to ambulate on an instrumented treadmill at their preferred speed while the ground reaction forces were recorded for all limbs before and after a moderate, reversible, hind limb lameness was induced. At both gaits, vertical force was decreased in the ipsilateral and increased in the contralateral hind limb. While peak force increased in the ipsilateral forelimb, no changes were observed for mean force and impulse when the dogs walked or trotted. In the contralateral forelimb, the peak force was unchanged, but the mean force significantly increased during walking and trotting; vertical impulse increased only during walking. Relative stance duration increased in the ipsilateral hind limb when the dogs trotted. In the contralateral fore and hind limbs, relative stance duration increased during walking and trotting, but decreased in the ipsilateral forelimb during walking. Analysis of load redistribution and temporal gait changes during hind limb lameness showed that compensatory mechanisms were similar regardless of gait. The centre of mass consistently shifted to the contralateral body side and cranio-caudally to the side opposite the affected limb. These biomechanical changes indicate substantial short- and long-term effects of hind limb lameness on the musculoskeletal system.

Evaluation of construct and criterion validity for the 'Liverpool Osteoarthritis in Dogs' (LOAD) clinical metrology instrument and comparison to two other instruments

Objective

To test the ‘Liverpool Osteoarthritis in Dogs’ (LOAD) questionnaire for construct and criterion validity, and to similarly test the Helsinki Chronic Pain Index (HCPI) and the Canine Brief Pain Inventory (CBPI).

Design

Prospective Study.

Animals

222 dogs with osteoarthritis.

Procedure

Osteoarthritis was diagnosed in a cohort of dogs on the basis of clinical history and orthopedic examination. Force-platform analysis was performed and a “symmetry index” for peak vertical force (PVF) was calculated. Owners completed LOAD, CBPI and HCPI instruments. As a test of construct validity, inter-instrument correlations were calculated. As a test of criterion validity, the correlations between instrument scores and PVF symmetry scores were calculated. Additionally, internal consistency of all instruments was calculated and compared to those previously reported. Factor analysis is reported for the first time for LOAD, and is compared to that previously reported for CBPI and HCPI.

Results

Significant moderate correlations were found between all instruments, implying construct validity for all instruments. Significant weak correlations were found between LOAD scores and PVF symmetry index, and between CBPI scores and PVF symmetry index.

Conclusion and Clinical Relevance

LOAD is an owner-completed clinical metrology instrument that can be recommended for the measurement of canine osteoarthritis. It is convenient to use, validated and, as demonstrated here for the first time, has a correlation with force-platform data.

Clinical validity of outcome pain measures in naturally occurring canine osteoarthritis

Background

The conceptual validity of kinetic gait analysis and disability outcome assessment methods has guided their use in the assessment of pain caused by osteoarthritis (OA). No consensus on the best clinical methods for pain evaluation in canine OA exists, particularly, when evaluating treatments where a smaller treatment effect is anticipated than with pharmacological pain killers. This study thus aimed at determining the technical validity of some clinical endpoints on OA pain in dogs using the green-lipped mussel (GLM)-enriched diet.

Twenty-three adult dogs with clinical OA completed the prospective controlled study. All the dogs were fed a balanced diet over a 30-day control period followed by a GLM-enriched diet over a 60-day period. The kinetic gait analysis parameter (PVF_BW, peak vertical force adjusted for body weight change), electrodermal activity (EDA), and a standardized multifactorial pain questionnaire (MFQ) were performed on day (D) 0 (inclusion), D30 (start) and D90 (end). The owners completed a client-specific outcome measures (CSOM) instrument twice a week. Motor activity (MA) was continuously recorded in seven dogs using telemetered accelerometric counts. We hypothesized that these methods would produce convergent results related to diet changes. A Type I error of 0.05 was adjusted to correct for the multiplicity of the primary clinical endpoints.

Results

Neither the EDA nor the MFQ were found reliable or could be validated. Changes in the PVF_BW (P_adj = 0.0004), the CSOM (P_adj = 0.006) and the MA intensity (P_adj = 0.02) from D0 to D90 suggested an effect of diet(s). Only the PVF_BW clearly increased after the GLM-diet (P_adj = 0.003). The CSOM exhibited a negative relationship with the PVF_BW (P = 0.02) and MA duration (P = 0.02).

Conclusions

The PVF_BW exhibited the best technical validity for the characterization of the beneficial effect of a GLM-enriched diet. The CSOM and MA appeared less responsive following a GLM-diet, but these measures appeared complementary to gait analysis. Apparently, the CSOM provides the capacity to rely on pain OA assessment influenced by both lameness quantification (PVF_BW) and physical functioning (MA).

An un-commissioned randomized, placebo-controlled double-blind study to test the effect of deep sea fish oil as a pain reliever for dogs suffering from canine OA

BACKGROUND

An un-commissioned randomized, double-blinded, placebo controlled clinical study was planned using a deep sea fish oil product for pets. Seventy-seven client-owned dogs with osteoarthritis were randomly assigned to supplement the food with either the fish oil product or corn (=placebo) oil. Our main outcome variables were force platform variables peak vertical force (PVF) and impulse, the validated Helsinki Chronic Pain Index (HCPI) and the use of rescue NSAIDs. Secondary outcome variables were a locomotion visual analog scale (VAS), a Quality of life VAS, a comparative questionnaire, a veterinary assessment, owners' final assessment of outcome and guessing the product given.

RESULTS

When comparing the two test groups at the end of the trial (16 weeks) there was no significant difference in any of the main outcome variables but owners of dogs that had taken fish oil were significantly happier with the treatment at the end visit and did significantly better at guessing what group their dogs had been in, compared to the placebo group. When comparing variables within the fish oil group as change from baseline to trial end, there were significant positive changes in PVF, HCPI, NSAID use, Quality of life VAS, as well as in all three scores in the comparative questionnaire (locomotion, every-day situations, and skin & coat). There were similar positive trends in force platform impulse and in the veterinary assessment variables, although they did not reach significance. Within the placebo group there were significant positive changes only in the HCPI and a significant deterioration according to veterinary assessment.

CONCLUSIONS

When compared to placebo, there was not a major statistically significant benefit in using deep sea fish oil as a pain reliever in our study population of dogs suffering from osteoarthritis. However, the fish oil treated patients improved significantly in many of the variables, when comparing baseline values to the study-end values within the group, indicating a true but small relief in symptoms. Deep sea fish oil supplementation could be considered a part of the multimodal pain relieving approach currently recommended for dogs suffering from OA, especially for individuals that do not tolerate anti-inflammatory drugs.

Complete ACL/MCL deficiency induces variable degrees of instability in sheep with specific kinematic abnormalities correlating with degrees of early osteoarthritis

People are not equally disabled by combined anterior cruciate ligament (ACL)/medial collateral ligament (MCL) injuries, nor do they all develop osteoarthritis (OA). Although biological/biomechanical causes are not clear, some association presumably exists between joint instability and OA development. We hypothesized that degree of OA development following standardized complete ACL/MCL injuries will vary directly with the degree of biomechanical abnormality between individuals. Three groups of sheep were used to test the hypothesis: 17 normal, 9 ACL/MCL transected, and 7 sham animals. Normal joints were assessed morphologically while sham and experimental animals had gait assessment pre- and at 4 and 20 weeks post-surgery, with cartilage and bone changes being mapped and graded at sacrifice at 20 weeks. Sham joints were morphologically normal and had only one minor kinematic change at 20 weeks. Although variable, ACL/MCL deficient animals showed significant kinematic abnormalities in 4/6 degrees of freedom (DOFs), as well as cartilage/bone damage by 20 weeks (p < 0.05). Linear regression analysis revealed that changes in medial-lateral (ML) translation were related to the current level of joint degradation as represented by total gross OA score (p = 0.0044, R(2)  = 0.71) in the ACL/MCL transected group. Even identical ACL/MCL injuries result in inter-animal variations in instability and OA, however significant kinematic abnormalities in ML translation do relate to early OA in sheep.

Accuracy of pressure plate kinetic asymmetry indices and their correlation with visual gait assessment scores in lame and nonlame dogs

OBJECTIVE

To determine the accuracy of pressure plate kinetic asymmetry indices (ASIs) for diagnosis of unilateral hind limb lameness in dogs and their correlation with visual gait assessment (VGA) scores.

ANIMALS

9 healthy dogs and 16 dogs with previously diagnosed unilateral rupture of the cranial cruciate ligament and concurrent unilateral hind limb lameness.

PROCEDURES

Dogs were walked over a pressure plate to determine paw contact area (PCA), peak vertical pressure (PVP), peak vertical force (PVF), and vertical impulse (VI) of both hind limbs. An ASI was calculated for each gait variable. Simultaneously, gait was assessed visually and scored by use of a numeric rating scale (0 to 10). The ASI of each variable was tested for its usefulness in discrimination between lame and nonlame dogs and for correlation with VGA scores.

RESULTS

Sensitivity and specificity of ASIs to discriminate between lame and nonlame dogs were excellent for PVF, VI, and PCA; these values were substantially lower for ASI of PVP. Cutoff values to discriminate between lame and nonlame dogs were determined by use of ASIs for PVF, VI, and PCA; however, this could not be done for ASI of PVP. Correlations between ASIs of PVF, VI, and PCA and VGA scores were higher than correlation between the ASIs of PVP and VGA scores.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that ASIs of PVF and VI determined via analysis of pressure plate measurements were reliable indicators of clinical lameness in dogs, but the ASI of PVP was not. The ASI of PCA is an interesting new variable for assessment of limb loading symmetry.

Reliability and validity of a visual analogue scale used by owners to measure chronic pain attributable to osteoarthritis in their dogs

OBJECTIVE

To assess validity and reliability for a visual analogue scale (VAS) used by owners to measure chronic pain in their osteoarthritic dogs.

SAMPLE

68, 61, and 34 owners who completed a questionnaire.

PROCEDURES

Owners answered questionnaires at 5 time points. Criterion validity of the VAS was evaluated for all dogs in the intended-to-treat population by correlating scores for the VAS with scores for the validated Helsinki Chronic Pain Index (HCPI) and a relative quality-of-life scale. Intraclass correlation was used to assess repeatability of the pain VAS at 2 baseline evaluations. To determine sensitivity to change and face validity of the VAS, 2 blinded, randomized control groups (17 dogs receiving carprofen and 17 receiving a placebo) were analyzed over time.

RESULTS

Significant correlations existed between the VAS score and the quality-of-life scale and HCPI scores. Intraclass coefficient (r = 0.72; 95% confidence interval, 0.57 to 0.82) for the VAS indicated good repeatability. In the carprofen and placebo groups, there was poor correlation between the 2 pain evaluation methods (VAS and HCPI items) at the baseline evaluation, but the correlation improved in the carprofen group over time. No correlation was detected for the placebo group over time.

CONCLUSIONS AND CLINICAL RELEVANCE

Although valid and reliable, the pain VAS was a poor tool for untrained owners because of poor face validity (ie, owners could not recognize their dogs' behavior as signs of pain). Only after owners had seen pain diminish and then return (after starting and discontinuing NSAID use) did the VAS have face validity.

Inverse dynamics analysis of the pelvic limbs in Labrador Retrievers with and without cranial cruciate ligament disease

OBJECTIVES

To quantify net joint moments, joint powers, and joint reaction forces (JRF) across the hock, stifle, and hip joints in Labrador Retrievers with and without cranial cruciate ligament (CCL) disease. To investigate differences in joint mechanics between normal, CCL deficient, and contralateral pelvic limbs.

STUDY DESIGN

Cross-sectional clinical study.

ANIMALS

Clinically normal (n=14) and CCL-deficient (n=9) Labrador Retrievers.

METHODS

Each limb was analyzed separately and classified as normal, CCL-deficient or sound contralateral limb. Kinematic, ground reaction force (GRF), and morphometric data were combined in an inverse dynamic approach to compute hock, stifle and hip net moments, powers and JRF, while trotting.

RESULTS

Vertical and braking GRF and JRF were significantly decreased in CCL-deficient limbs. In affected limbs, extensor moments at the hock and hip, flexor moment at the stifle and power in all 3 joints were less than normal. Kinetics also identified a greater joint moment and power of the contralateral limbs compared with normal, particularly of the stifle extensor muscles group.

CONCLUSION

Lameness resulting from CCL disease affected predominantly reaction forces during the braking phase and the extension during push-off. A greater contribution of the contralateral limbs to propel the dog forward was identified.

CLINICAL RELEVANCE

Reductions in joint motion, loads, and muscle contraction were interpreted as modifications adopted to reduce or avoid painful mobilization of the injured stifle joint. The increased joint moment and power of the contralateral compensating side may correlate with the lameness observed, but also with the predisposition of contralateral limbs to CCL deficiency in dogs.

Degeneration, inflammation, regeneration, and pain/disability in dogs following destabilization or articular cartilage grooving of the stifle joint

OBJECTIVE

The most used model for joint instability is the canine anterior cruciate ligament transection (ACLT)-model. The ACLT-model can be extended with a medial meniscectomy (MX) (i.e., ACLT-MX-model) to avoid unintentional, and with that variable, meniscal damage. The present study compares the ACLT-MX-model with the more recently introduced Groove-model on longitudinal measurements of osteophyte formation and gait as a surrogate marker of pain and disability, in addition to structural endpoint parameters.

METHODS

Degenerative joint damage was induced Labrador dogs according to the ACLT-MX-model (n=7) or Groove-model (n=7). Every 4 weeks radiographs were taken to analyze osteophyte formation. Every 2 weeks gait was recorded using force-plate analysis. Joints were analyzed for features of degeneration 12 weeks after surgery.

RESULTS

Both models showed similar osteophyte formation and gait changes for both experimental and contra-lateral control joints, although more pronounced for the ACLT-MX-model. This was supported by the structural endpoint measurements. Cartilage integrity, chondrocyte activity and synovial inflammation revealed similar characteristics of degenerative joint disease in both groups, again more pronounced in the ACLT-MX-model.

CONCLUSIONS

The ACLT-MX-model demonstrates characteristics of joint degeneration that are related to moderate to severe osteoarthritis with clear synovial inflammatory activity. The Groove-model is a less painful and a significantly milder model of joint degeneration. The latter model might be more suitable to study subtle changes as a result of intervention than the more robust ACLT-MX-model.

Relationship between objective and subjective assessment of limb function in normal dogs with an experimentally induced lameness

OBJECTIVE

To evaluate the relationship between previously used subjective and objective measures of limb function in normal dogs that had an induced lameness.

STUDY DESIGN

Prospective, blinded, and induced animal model trial.

ANIMALS

Normal, adult, and mixed-breed dogs (n=24) weighing 25-35 kg.

METHODS

Force platform gait analysis was collected in all dogs before and after induction of lameness. All gait trials were videotaped; 60 video trials were evaluated by 3 surgeons with practice limited to small animal orthopedics and 3 first year veterinary students in an effort to establish the relationship between subjective and objective measures of lameness. Evaluators were unaware of the force platform data.

RESULTS

Concordance coefficients were low for all observers and were similar between students and surgeons. These values were further decreased when normal and non-weight bearing trials were removed. Agreement with the force platform data was low even when observers only had to be within +/-10% of the ground reaction forces. When repeat trials were evaluated surgeons had a much higher repeatability compared with students.

CONCLUSIONS

Subjective evaluation of the lameness in this study varied greatly between observers and agreed poorly with objective measures of limb function.

CLINICAL RELEVANCE

Subjective evaluation of gait should be interpreted cautiously as an outcome measure whether performed from a single or from multiple observers.

Pain mechanisms and their implication for the management of pain in farm and companion animals

Over the last two decades there has been a dramatic increase in the literature relating to the mechanisms and management of pain in domestic animals. Understanding the mechanisms of pain is crucial for its effective management. This review highlights the current understanding of the neurophysiology of nociception and the plastic changes involved in chronic pain states. Additionally, we describe a range of novel molecules and pathways that offer opportunities for the development of mechanism-based analgesic therapies. Pain management in animals is limited by pain assessment which remains highly subjective, with clinicians relying on indirect measures of pain, using rating scales and (less frequently) quantifiable physiological and behavioural parameters. The need for a systematic approach which would assess different pain components is well justified. Species-specific issues on pain assessment and management in mammalian companion and farm animals are addressed in the later part of this review.

Kinematic Study of Back Movement in Clinically Sound Malinois Dogs with Consideration of the Effect of Radiographic Changes in the Lumbosacral Junction

OBJECTIVE

To determine thoracolumbar spinal movement in dogs and the influence of subclinical radiographic changes involving the lumbosacral junction.

STUDY DESIGN

Experimental study.

ANIMALS

Clinically sound Malinois dogs (n=22).

METHODS

Kinematic analysis of markers on the spinal processes of C7, T6, T13, L3, L7, and S3 was performed while dogs were walking on a treadmill. Range of motion (ROM) in the transverse and vertical direction and the time of occurrence (TOO) of the maximal marker position were calculated. ROM and TOO of angulations formed by the corresponding markers were calculated. Initial kinematic analysis was performed without knowledge of the radiographic changes, and then data were reanalyzed to determine whether vertebral changes influenced back motion. Based on the results of radiographic analysis of the lumbosacral junction, dogs were divided into 3 groups: 1=no radiographic changes; 2=shortened L7 vertebra; and 3=transitional vertebrae, spondylosis, subluxations, and spondylarthrosis of the lumbosacral junction. ROM and TOO were compared using ANOVA for repeated measures and a Bonferroni's post hoc test; P<.05 was considered significant.

RESULTS

The highest transverse ROM was achieved by markers T6, T13, and L3, and in the vertical direction by S3; however, there were no significant differences in ROM in horizontal angulations. In the sagittal plane, T13-L3-L7 had a lower angulation than L3-L7-S3. In Group 3, transverse ROM for C7 was significantly higher than in Group 1; the horizontal angular maximum of T13-L3-L7 occurred significantly earlier.

CONCLUSIONS

Significant kinematic changes were detected between clinically sound dogs with radiographic lumbosacral changes and dogs with no radiographic abnormalities.

CLINICAL RELEVANCE

Kinematic data from clinically sound dogs can be used for comparison with data from dogs with gait disturbances associated with orthopedic or neurologic disease or changes associated with therapy.

Assessment of Decompressive Surgery in Dogs with Degenerative Lumbosacral Stenosis Using Force Plate Analysis and Questionnaires

OBJECTIVE

To evaluate the long-term outcome after decompressive surgery in dogs with degenerative lumbosacral stenosis (DLS), using force plate analysis (FPA) and owner questionnaires.

STUDY DESIGN

Prospective clinical study.

ANIMALS

Dogs with DLS (n=31) and 24 clinically normal Labrador Retrievers.

METHODS

FPA was performed before surgery (31 dogs) and at 3 days, 6 weeks, 6 months (each, 31 dogs) and >or=1.5 years (12 dogs) after surgery. Peak vertical forces (Fz(+)), braking (Fy(+)), and propulsive forces (Fy(-)), and the corresponding impulses were determined. Questionnaires were completed by the owners before and at 6 months and >or=1.5 years after surgery.

RESULTS

Fy(-) of the pelvic limbs and the ratio pelvic/thoracic of Fy(-) (P/TFy(-)) were significantly smaller in dogs with DLS than controls. Fy(-) and P/TFy(-) decreased significantly 3 days after surgery, and increased during 6 months follow-up, but with long-term follow-up the values remained the same and were smaller than controls. From questionnaires there was a significant improvement after surgery compared with function before surgery. Most owners were satisfied with outcome after surgery.

CONCLUSIONS

Propulsive forces of the pelvic limbs in dogs with DLS are impaired and are partially restored by decompressive surgery.

CLINICAL RELEVANCE

Owner's questionnaires illustrate that decompressive surgery restores function as perceived by owners whereas FPA continues to show impaired propulsive forces for the pelvic limbs.

Relationship of Tibial Plateau Slope to Limb Function in Dogs Treated with a Lateral Suture Technique for Stabilization of Cranial Cruciate Ligament Deficient Stifles

OBJECTIVE

To evaluate the effect of a lateral suture technique (LST) on tibial plateau angle (TPA) measurement and to compare TPA with functional outcome in dogs treated for cranial cruciate ligament (CrCL) rupture with LST.

STUDY DESIGN

Prospective clinical study.

SAMPLE POPULATION

Dogs (n=34) with unilateral CrCL instability.

METHODS

All dogs had lameness examination, survey stifle radiographs, and force plate analysis before and at 6, 12, 24, and 48 weeks after surgery. Radiographic osteoarthritis (OA) scores and lameness scores were assigned using previously reported methods. Preoperative radiographs were performed in all dogs, and postoperative serial radiographs were performed in 6 dogs for measurement of TPA. Differences in TPA measurements were evaluated with a random effects repeated measures model. The significance of LST on TPA measurement was established in 6 dogs and the effect of TPA on vertical impulse, peak vertical force, progression of radiographic scores, and lameness score were analyzed by general linear models in all dogs. Differences were considered significant if P<.05.

RESULTS

Significant differences were not noted between pre- and serial postoperative measurements of TPA. A significant correlation was not established between TPA and postoperative vertical impulse, peak vertical force, lameness score, or radiographic OA scores.

CONCLUSIONS

TPA values were unchanged after LST and TPA does not affect outcome measures in dogs treated with LST.

CLINICAL RELEVANCE

TPA has no predictive value on clinical outcome in dogs treated with LST for stabilization of CrCL deficient stifles.

Evaluation of Pentosan Polysulfate Sodium in the Postoperative Recovery from Cranial Cruciate Injury in Dogs: A Randomized, Placebo-Controlled Clinical Trial

OBJECTIVE

To evaluate the efficacy of pentosan polysulfate (PPS) for improving the recovery period and mitigate the progression of osteoarthritis (OA) of the canine stifle after extracapsular stabilization of cranial cruciate ligament (CCL) injuries.

STUDY DESIGN

Randomized, blinded, placebo-controlled clinical trial.

ANIMALS

Dogs (n=40) with unilateral CCL instability.

METHODS

Each dog had an extracapsular stabilization of the stifle with or without partial meniscectomy. Dogs were divided into 4 groups based on preoperative radiographic assessment and whether a partial meniscectomy was performed. Dogs were randomly assigned to either (3 mg/kg) PPS or placebo treatment in each group, and then injected subcutaneously weekly for 4 weeks. Lameness, radiographic changes, biological marker concentration in blood and urine, and ground reaction forces (GRFs) were collected preoperatively, and at 6, 12, 24, and 48 weeks. Data were analyzed within and between groups using repeated measures ANOVA; P<.05 was considered significant.

RESULTS

No adverse reactions to PPS were reported. Thirty-nine dogs completed a minimum of 24-weeks follow-up and 33 dogs completed 48 weeks. All dogs clinically improved after surgery without differences in lameness score, vertical GRFs, or radiographic progression. Grouped and evaluated only by initial radiographic score, PPS-treated dogs improved significantly faster in braking GRFs than placebo-treated dogs. In dogs with partial meniscectomies, urine deoxypyridinoline, and serum carboxy-propeptide of type II collagen were significantly increased at 6 weeks in placebo-treated dogs compared with PPS-treated dogs.

CONCLUSIONS

PPS administered after stabilization of the cruciate deficient stifle may prove to be a useful adjunctive treatment option, although further studies are necessary to substantiate this claim.

Association between subjective lameness grade and kinetic gait parameters in horses with experimentally induced forelimb lameness

OBJECTIVE

To evaluate the association between subjective lameness grades and kinetic gait parameters and assess the variability in kinetic parameters in horses with experimentally induced forelimb lameness.

ANIMALS

32 horses.

PROCEDURES

Forelimb lameness was induced in each horse via injection of lipopolysaccharide into 1 metacarpophalangeal joint (40 experimental trials). Subjective lameness grading and 13 kinetic gait parameters (force plate analysis) were assessed before (baseline) and at 12, 18, and 24 hours after lipopolysaccharide injection. While horses were trotting, kinetic gait analysis was performed for 8 valid repetitions at each time point. Repeated-measures analyses were performed with 8 repetitions for each kinetic parameter as the outcome, and lameness grades, time points after lipopolysaccharide injection, and repetition order as explanatory variables. Sensitivity and specificity of kinetic parameters for classification of horses as sound or lame (in relation to subjective lameness scores) were calculated. Between- and within-horse variabilities of the 13 kinetic parameters were assessed by calculation of coefficients of variation.

RESULTS

Subjective lameness grades were significantly associated with most of the kinetic parameters. Vertical force peak and impulse had the lowest between- and within-horse coefficients of variation and the highest correlations with subjective lameness grade. Vertical force peak had the highest sensitivity and specificity for lameness classification. Vertical force peak and impulse were significantly decreased even in horses with mild or unobservable lameness.

CONCLUSIONS AND CLINICAL RELEVANCE

Among the kinetic gait parameters, vertical force peak and impulse had the best potential to reflect lameness severity and identify subclinical forelimb gait abnormalities.

In vivo effects of carprofen, deracoxib, and etodolac on prostanoid production in blood, gastric mucosa, and synovial fluid in dogs with chronic osteoarthritis

OBJECTIVE

To evaluate in vivo activity of carprofen, deracoxib, and etodolac on prostanoid production in several target tissues in dogs with chronic osteoarthritis.

ANIMALS

8 dogs with chronic unilateral osteoarthritis of the stifle joint.

PROCEDURE

Each dog received carprofen, deracoxib, or etodolac for 10 days with a 30- to 60-day washout period between treatments. On days 0, 3, and 10, prostaglandin (PG) E2 concentrations were measured in lipopolysaccharide-stimulated blood, synovial fluid, and gastric mucosal biopsy specimens; PGE1 concentrations were measured in gastric mucosal biopsy specimens; and thromboxane B2 (TXB2) was evaluated in blood.

RESULTS

Carprofen and deracoxib significantly suppressed PGE2 concentrations in blood at days 3 and 10, compared with baseline, whereas etodolac did not. None of the drugs significantly suppressed TXB2 concentrations in blood or gastric PGE1 synthesis at any time point. All 3 drugs significantly decreased gastric synthesis of PGE2 at day 3 but not day 10 of each treatment period. All 3 drugs decreased synovial fluid PGE2 concentrations in the affected and unaffected stifle joints at days 3 and 10.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicate that carprofen and deracoxib act in vivo on target tissues as COX-1-sparing drugs by sparing gastric PGE1 and PGE2 synthesis and production of TXB2 by platelets. Etodolac also appears to be COX-1 sparing but may have variable effects on COX-2 depending on the tissue. In gastric mucosa and synovial fluid, there were no significant differences in PG production between compounds at recommended concentrations.

Evaluation of changes in vertical ground reaction forces as indicators of meniscal damage after transection of the cranial cruciate ligament in dogs

OBJECTIVE

To determine whether decreases in peak vertical force of the hind limb after transection of the cranial cruciate ligament (CrCL) would be indicative of medial meniscal damage in dogs.

ANIMALS

39 purpose-bred adult male Walker Hounds.

PROCEDURE

The right CrCL was transected arthroscopically. Force plate measurements of the right hind limb were made prior to and 2, 4, 10, and 18 weeks after transection of the CrCL. Only dogs with > or =10% decreases in peak vertical force after week 2 were considered to have potential meniscal damage. Dogs that did not have > or =10% decreases in peak vertical force at any time point after week 2 were assigned to group 1. Group 2 dogs had > or =10% decreases in peak vertical force from weeks 2 to 4 only. Group 3 and 4 dogs had > or =10% decreases in peak vertical force from weeks 4 to 10 only or from weeks 10 to 18 only, respectively. Damage to menisci and articular cartilage was graded at week 18, and grades for groups 2 to 4 were compared with those of group 1.

RESULTS

The percentage change in peak vertical force and impulse area was significantly different in groups 2 (n = 4), 3 (4), and 4 (4) at the end of each measurement period (weeks 4, 10, and 18, respectively) than in group 1 (27). The meniscal grade for groups 2 to 4 was significantly higher than for group 1. A > or =10% decrease in peak vertical force had sensitivity of 52% and accuracy of 72% for identifying dogs with moderate to severe medial meniscal damage.

CONCLUSIONS AND CLINICAL RELEVANCE

In dogs with transected or ruptured CrCLs, force plate analysis can detect acute exacerbation of lameness, which may be the result of secondary meniscal damage, and provide an objective noninvasive technique that delineates the temporal pattern of medial meniscal injury.