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Lameness Grading Dogs

In this study, 19 consecutive dogs arriving at a canine physical therapy office on a randomly selected day were videotaped by a third year physical therapy student with no canine experience. This was a double blind process, where neither the student nor the clients were aware of why they were being filmed. Two videos were taped. The first video was from a lateral viewpoint and the second video was from a cranial/caudal viewpoint. Each video filmed the dogs walking 140 to 150 feet on a smooth surface.Each video was numbered, transferred to a CD, and sent to 5 canine-certified physical therapists and 5 general practice veterinarians with the scale described as below:

In conclusion, the veterinary profession continues to be primarily subjective in analysis of canine gait and lameness. The 0 to 5 scale does not appear to be a valid form of gait analysis for most individuals to utilize to show changes in gait or to use as an outcome measure. It can be, however, moderately valid to utilize when charting progress of an individual dog by one practitioner. A more valid universal, objective lameness analysis scale would be beneficial so that physical therapists and veterinary professionals can accurately document changes in lameness with confidence in the objectivity of their observations.

In previous studies, several types of lameness scales were compared over a period of time and the lameness score of each dog in the study could have changed. In an attempt to limit variables, this study did not compare different gait samples over a period of time and did not attempt to compare different types of lameness scales to each other. The idea behind the study was that, even if lameness scoring varied from person to person, if the intra-rater reliability scores were high, at least documentation of a single medical professional would be reliable in showing changes in lameness over time. This hypothesis proved to be false in this study. It is possible that orthopedic-trained veterinarians may have scored higher in both intra-rater and inter-rater reliability than general practice veterinarians. It is also possible that additional training in scoring may have increased the intra and inter-reliability scores for all participants.
From therapeutic exercise to manual techniques, carts and assistive devices, we offer a variety of physical therapy services and home care plans. So whether its rehabilitation, strengthening, pain relief, athletic conditioning, or weight loss, our methods will help your pet learn how to reorganize his/her body movements into more efficient, pain-free patterns.Intra-rater reliability and inter-rater reliability were zero to moderate. The highest intra-rater correlation was .84 and the lowest was .26. And the median was .47 when all 10 evaluators were considered. The physical therapist group intra-rater reliability was a moderate .58 and score correlation in the veterinarian group was a low .37 correlation. Inter-rater reliability was based on the number of dogs that everyone in the group scored identically. Among the physical therapists, the score correlation was a low .16, and among the veterinarians, the correlation was zero.It is our mission to bring educated, experienced, qualified professional physical rehabilitation to the animal world; improving the quality of life and positive psychological effects for pets and their owners. A third study evaluated the agreement between numerical rating scales (NRS), VAS, and force plate gait analysis in dogs. In this study, three veterinarians with orthopedic training rated lameness utilizing the NRS and VAS before surgery, at 4 weeks and at 8 weeks post surgery. Inter-reliability was low with no significant relationships between any observer’s scores and force plate data except in extreme lameness. (Quinn MM 2007) And a fourth study comparing numerical gait analysis with force plate analysis before and after induced lameness in normal dogs showed a low correlation between scores obtained from vets with orthopedic training and veterinary students and the force plate analysis. (Waxman AS 2008) Among the types of canine gait assessment tools available, use of the force plate is clearly the “gold standard.” However, because of financial, time, and space constraints, most veterinary and animal physical therapy professionals do not have the luxury of utilizing a force plate to analyze the majority of their patients’ gait patterns. In an attempt to create more objective and universal communication between medical providers and in an attempt to document progress in rehabilitation, several lameness scales have been created and utilized. The visual analogue score (VAS), the 0 to 5 lameness scale and the 0 to 4 lameness scale are a few of the more frequently utilized scales in an attempt to describe lameness and changes in gait of canine patients. The purpose of this study was to evaluate the intra-reliability, inter-reliability, and validity of veterinarians and physical therapists utilizing a numerical 0 to 5 lameness scale to assess lameness in dogs.

The physical therapists and veterinarians returned the score sheet. In 6 to 8 weeks, they received another CD with identical videos in a different order. They scored each video again and returned the score sheets.
Stride length & duration: Evaluate walk and trot for stride length symmetry and duration of stance; shortened stride, decreased stance time, and stilted gait indicate lameness and can help localize if asymmetric. A complete history and thorough orthopedic examination (including specific techniques) can help localize the lameness and determine further diagnostics. Download this algorithm to diagnose lameness in your canine patients. Stance & posture: Look for externally rotated limb, shifting weight off ≥1 limbs, sitting with ≥1 hindlimbs extended (ie, sit test), elbows abducted, and hindlimb adducted.

Limb tracking: Look for limb crossing the center line during straight line walk or trot, circumduction of limb, wide-based in forelimbs/hindlimbs, and asymmetry of limb tracking.JAMES L. COOK, DVM, PhD, DACVS, DACVSMR, is director and founder of the Comparative Orthopaedic Laboratory and William & Kathryn Allen distinguished professor in orthopaedic surgery at University of Missouri School of Medicine and College of Veterinary Medicine. He is cofounder of Be The Change Volunteers, dedicated to building schools in developing countries. Dr. Cook has more than 120 publications, has received numerous awards, including America’s Best Veterinarian, and has overseen 3 biomedical devices through FDA approval to human clinical trials. Dr. Cook earned his bachelor of science from Florida State University before earning his DVM and PhD from University of Missouri.

Symmetry: Examine for above signs plus for loading (ie, pad flare), joint angles, swing phase duration and distance, pelvic excursion (ie, hip hike), turning (eg, circles, figure-8 patterns), and ascents and descents.
An important advantage of the PSW is that GRFs of all limbs are directly measured during each passage over the walkway. Thus, the PSW is minimally time-consuming for routine use in a busy clinical setting, and comfortable for patients, as all measurements can be obtained from relatively few gait cycles [22]. Because measurements of all limbs are performed simultaneously, data for calculation of symmetry indices (SIs) will also be directly available. SIs represent standardized comparisons of GRFs obtained from different individual limbs and results in a specific, sensitive, suitable and reliable assessment of unilateral limb dysfunction [19]. Thus, in patients with unilateral limb dysfunction, use of SIs eliminates the need to normalize data between subjects because the affected limb is compared to the clinically normal contralateral or ipsilateral limb [23]. OA is a chronic, progressive condition often affecting multiple joints and even though one specific limb is often more severely affected, contralateral or ipsilateral limbs might also be affected in clinical patients. Consequently, studies of SIs obtained by the PSW in canine OA patients are needed before the PSW can be recommended for routine clinical use in the diagnostic work-up of canine OA patients. Otherwise, the diagnostic performance of the PSW may be overestimated [24] with the risk of OA patients undergoing unnecessary testing [25]. A stepwise evaluation of diagnostic tests is generally recommended and often includes investigation of precision (i.e. the closeness of the measurements to each other) and overlap performance (i.e. the ability to differentiate diseased dogs from clinically healthy dogs) [26].Diagonal, fore:hind, and left:right symmetry indices (SI) were obtained from the Tekscan pressure-sensitive walkway system. SIs were calculated across right thoracic limb (RF), left thoracic limb (LF), right pelvic limb (RH), and left pelvic limb (LH). SI (1) was calculated as simple ratios, whereas SI (2) was obtained by calculations modified from Schnabl-Feichter et al., 2018 [30], respectively.

The following parameters were obtained from the system’s gait analysis software: Stance time, swing time, stride time, stride length, stride velocity, stride acceleration, peak vertical force, vertical impulse, and maximum peak pressure. To evaluate precision, 10 dogs were chosen randomly among those of the clinically healthy dogs, whose owners had no trouble bringing their dog back for an additional visit.
Even though calculation of SIs is generally recommended [27] and extensively used for data presentation in canine PSW studies, SIs can be calculated in several different ways [8, 12, 15, 27, 29] and it is still not clear how gait symmetry is most optimally evaluated [12]. In the present study, several different symmetry indices were therefore calculated and compared in order to suggest recommendations of specific SIs for use in future PSW studies of OA in dogs.Fig 3 illustrates the calculated left:right SIs of maximum peak pressure (Fig 3A–3E) and vertical impulse (Fig 3F–3H) in dogs with different grades of lameness (1–3) on various limbs. Reference intervals for SI (1) and SI (2) are shown as horizontal lines, and was obtained from clinically healthy dogs as described above. A larger proportion of the higher grades of lameness was detected using SI (1) LF/RF, but none of the left:right SIs were found to be useful in the detection of all grades of lameness in dogs with OA (Table 5).

Means (μ) with 95% confidence intervals [CI], standard deviations (SD) and ranges of intra-analytical coefficient of variations (CV) for 8 different parameters measured in 21 dogs with osteoarthritis using the Tekscan pressure-sensitive walkway system.No significant differences were observed when comparing recordings in each direction (Fig 1, p = 0.52–0.99). High precision was observed, with intra-analytical CVs of 1.0–6.5% and inter-analytical CVs of 2.4–7.7%, respectively (Table 1). Sixteen male and 25 female clinically healthy dogs were included in the study. All dogs were medium or large breed dogs; 12 Labrador Retrievers, 6 Golden Retrievers, 2 Flat-coated Retrievers, 2 Border Collies, 2 German Shepherd dogs, 5 Crossbreed dogs, and 1 dog of each of 12 various breeds. The mean age was 4.0 years (range 2.0–6.9, SD 1.4) and the mean weight was 27.2 kg (range 15.2–38.8 kg, SD 6.8). Table 1 shows means, SDs and ranges of CVs of each kinetic parameter measured in clinically healthy dogs. Vertical impulse and maximum peak pressure were measured using the Tekscan pressure sensitive walkway in 21 lame dogs comparing intra-analytical coefficient of variations (CV) based on measurements of the most severely clinically affected, ipsilateral, contralateral, and diagonal limbs, respectively.Reference intervals calculated from measurements of 41 healthy dogs are presented as horizontal lines. Parametric intervals for SI (1) were calculated as the mean±2sd, whereas nonparametric intervals for SI (2) were calculated using the 2.5% and 97.5% percentiles, or the 95% percentile, as appropriate.

As previously mentioned, the nature of OA could be another influencing factor. Whereas gait SIs are specific, sensitive, suitable and reliable to assess unilateral limb dysfunction (8), clinical OA commonly affects more than one joint. In the present study, OA dogs were divided in groups based on the most severely affected limb, but OA affecting more than one joint could potentially result in dysfunction of more than one limb, thus influencing calculated SIs.

In the present study several SIs were compared in order to make recommendations for calculations of specific SIs in future studies of osteoarthritis. Because of the large overlap between SIs calculated in the two groups of dogs, the system and analysis used here cannot be recommended for identifying clinical OA patients with low to moderate grade lameness. However, studies in other groups of orthopedic patients using SIs obtained by the Tekscan PSW will still be relevant and the potential use in longitudinal studies of OA patients may also be an interesting field for further investigation. As larger proportions of OA dogs were detected using SI (1) LF/RF for vertical impulse (Table 5), this specific index might be useful in such studies.
The calculated means and standard deviation listed in Table 1 are based on 6 walkway measurements of each limb of 41 clinically healthy dogs. Temporal characteristics and measured vertical ground reaction forces are listed in the present file.Narrow 95% CIs and low SDs were calculated for each PSW variable (Table 1) indicating that it should be possible to establish narrow reference intervals for each parameter in clinically healthy dogs. However, local validation of such intervals should be considered on an institutional level.

Left:right SIs are based on measurements of maximum peak pressure and vertical impulse obtained from the Tekscan pressure-sensitive walkway system. SIs were calculated across right thoracic limb (RF), left thoracic limb (LF), right pelvic limb (RH), and left pelvic limb (LH). SI (1) was calculated as simple ratios, whereas SI (2) was obtained by calculations modified from Schnabl-Feichter et al., 2018 [30].
Averaged data of all clinically healthy dogs from the 3 recordings obtained in each direction of travel were plotted together with the averaged data from all 6 recordings (both directions) for visual assessment of any possible difference. Differences between directions of travel were assessed by paired t-tests.Canine patients are commonly presented in small animal veterinary practice with lameness of various degrees and causes. A thorough gait examination plays a key role in the investigation of these patients, and various lameness scoring scales have been recommended for a standardized grading of lameness in clinical practice [1, 2]. However, grading of lameness is a subjective discipline, and individual observers seem to develop unique scoring scales [3, 4].

Plots of Maximum peak pressure (A-D) and Vertical impulse (E-H) in 12 dogs with osteoarthritis (OA) with thoracic limb lameness (A-B and E-F) and 9 dogs with pelvic limb lameness (C-D and G-H), respectively. Measurements obtained from the Tekscan pressure-sensitive walkway system are presented as diagonal, fore:hind, and left:right symmetry indices (SI), respectively. SIs were calculated across right thoracic limb (RF), left thoracic limb (LF), right pelvic limb (RH), and left pelvic limb (LH) as simple ratios (SI (1), A,C,E,G) and as indices modified from Schnabl-Feichter et al., 2018 (SI (2), B,D,F,H), respectively.
The study was based on the following hypotheses: The Tekscan PSW will be useful for diagnostic purposes in dogs with OA, showing high precision and indisputable overlap performance. Direction of passage over the walkway will not influence the results and calculation of specific SIs can be recommended in future studies of OA in dogs.A wider range of intra-analytical CVs were observed in dogs previously diagnosed with OA (Table 2) compared to the clinically healthy dogs (Table 1). This increased variability was not restricted to the most severely affected limb but was observed for all limbs of dogs with OA (Table 3).In veterinary practice, a thorough gait examination is essential in the clinical workup of any orthopedic patient, including the large population of dogs with chronic pain as a result of osteoarthritis. The traditional visual gait examination is, however, a subjective discipline, and systems for kinetic gait analysis may potentially offer an objective alternative for gait assessment by the measurement of ground reaction forces. In order to avoid unnecessary testing of patients, a thorough, stepwise evaluation of the diagnostic performance of each system is recommended before clinical use for diagnostic purposes. The aim of the study was to evaluate the Tekscan pressure-sensitive walkway system by assessing precision (agreement between repetitive measurements in individual dogs) and overlap performance (the ability to distinguish dogs with lameness due to osteoarthritis from clinically healthy dogs). Direction of travel over the walkway was investigated as a possible bias. Symmetry indices are commonly used to assess lameness by comparing ground reaction forces across different combinations of limbs in each dog. However, SIs can be calculated in several different ways and specific recommendations for optimal use of individual indices are currently lacking. Therefore the present study also compared indices in order to recommend a specific index preferable for future studies of canine osteoarthritis. Forty-one clinically healthy dogs and 21 dogs with osteoarthritis were included in the study. High precision was demonstrated. The direction of travel over the walkway was excluded as a possible bias. A significant overlap was observed when comparing ground reaction forces measured in dogs with osteoarthritis compared to clinically healthy dogs. In some affected dogs, symmetry indices comparing contralateral limbs differed from clinically healthy dogs, but in general, the overlap performance was insufficient and, consequently, general use of this method for diagnostic purposes in dogs with osteoarthritis cannot be recommended.

Plots of left:right symmetry indices (SIs) of maximum peak pressure (A-D) and vertical impulse (E-H) in 21 dogs with osteoarthosis (OA) and 41 clinically healthy dogs obtained from the Tekscan pressure-sensitive walkway system (PSW). Dogs were divided in groups by the visual grade of lameness (0–5) of left (L) or right (R), thoracic (fore—F) and pelvic (hind—H) limb, respectively. SIs were calculated as simple ratios (SI (1), A,C,E,G) and as indices modified from Schnabl-Feichter et al., 2018 (SI (2), B,D,F,H), respectively. Using data from the clinically healthy dogs, parametric reference intervals were calculated for SI (1) as mean±2SD, whereas non-parametric reference intervals were calculated for SI (2) using either the 2.5% and 97.5% percentiles or the 95% percentile, as appropriate. Calculated reference intervals are presented as horizontal lines.
Coefficients of variation calculated for repeated measurements of vertical impulse and maximum peak pressure in 21 dogs with osteoarthritis. In Table 3 precision is compared across limbs affected by osteoarthritis compared with contralateral, ipsilateral and diagonal limbs.Client-owned dogs with and without previously diagnosed OA were recruited by email contact to the staff of the department and by social media contact to the public. The study was performed at the University Hospital for Companion Animals, University of Copenhagen, Denmark during 2018 and 2019. The study protocol was approved by the institutional ethical committee at Departmen
t of Veterinary Clinical Sciences, University of Copenhagen, Denmark (approval number 2017–1). In the study dogs were walked over the pressure sensitive walk-way in loose leash by an experienced handler in a stress free environment. All dogs were allowed to acclimatize to the room and were subsequently walked across the walkway to become comfortable with the surroundings, the PSW, handler, and leash. No dogs were forced to walk on the walkway and the study did not result in any kind of animal sacrifice. Written consent was obtained from the owners.

The measurement system consisted of 4 Tekscan Medical #3140 sensors with a resolution of 1 sensel/cm incorporated in to a 1.95 m long by 0.45 m wide PSW, which was protected by a 3 m by 0.6 m cover throughout the study. Pressure data from activated sensels were transmitted to a computer running Tekscan software (Walkway 7.66) for conversion to vertical forces, enabling calculation of kinetic and temporal characteristics for each limb. All forces were normalized to body mass. The system was equilibrated to 75 Hz on a daily basis and the 4 sensors were calibrated using a phantom mass weighing 21.6 kg on a weekly basis. Data obtained from the PSW was subsequently exported to Microsoft Excel.
From these calculations a SI (1) of 1 and a SI (2) of 0% would represent perfect paired limb symmetry. Symmetry indices were calculated for two parameters: maximum peak pressure and vertical impulse. Calculated SIs for dogs with OA were plotted graphically and compared with references for clinically healthy dogs. Using data from the clinically healthy dogs (S3 File), parametric reference intervals were calculated for SI (1) as mean±2SD, whereas non-parametric reference intervals were calculated for SI (2) using either the 2.5% and 97.5% percentiles or the 95% percentile, as appropriate.Accurately designed and reported studies of diagnostic performance are necessary for safe implementation of diagnostic tests for general clinical use [39] and further evaluation of the diagnostic performance of the PSW in dogs is still needed, before the PSW can be recommended for routine diagnostic workup in canine orthopedic patients. The present study represents some of the important initial steps recommended for thorough evaluations of a diagnostic test [26]. Based on the large overlap between mildly to moderately lame dogs previously diagnosed with OA and clinically healthy dogs, further validation of the diagnostic performance in this group of patients is, however, not recommended.

The calculated means and standard deviation listed in Table 2 are based on 6 walkway measurements of each limb of 21 dogs with osteoarthritis. Temporal characteristics and measured ground reaction forces are listed in the present file.

The aim of the present study was to assess the diagnostic performance of the Tekscan PSW (Tekscan I-Scan model 5101E VH4, Evolution) by evaluating the precision in clinically healthy dogs and in dogs with lameness due to OA, and the overlap performance differentiating dogs with low and moderate grades of lameness caused by previously diagnosed OA from clinically healthy dogs. In previous studies, factors such as different handlers, leash side [27] and cover type [28] have been shown to influence GRF results obtained by PSW. In the present study, direction of travel over the PSW was investigated as another potential source of bias.Fig 1 is based on walkway measurements obtained from clinically healthy dogs. Measurements of stance time (1A), vertical impulse (1B), and maximum peak pressure (1B) are presented in this supplementary file comparing data obtained from different legs of 41clinically healthy dogs walking in different directions.

To support the visual gait examination, ground reaction forces (GRFs) conducted by individual steps in canine locomotion can be measured using systems for kinetic gait analysis [5]. Force plate analysis is considered the gold standard for GRF measurements [5]. Single or multiple force plates placed in walkways or under treadmill belts are valuable tools for diagnostic kinetic gait analysis in both clinical and research settings [6]. Pressure measurement systems are another group of equipment for kinetic gait analysis. These systems consist of multiple pressure sensors and enable visualization of pressure distribution for individual paws as well as quantification of pressure, forces and temporal characteristics during gait [6]. A more in-depth review of kinetic gait analysis instruments has been published by Gillette et al. [6]. One group of commercially available pressure measurement systems is the pressure-sensitive walkway system (PSW), which permits sensitive and objective gait analysis by conversion of pressure measurements to GRFs [7]. Such systems are considered to be reliable and simple methods for evaluating, quantifying and monitoring lameness in dogs [8] with high diagnostic sensitivity and specificity [9]. The diagnostic potential of PSW has been shown to be comparable to force plate gait analysis [10], which itself has been shown to be superior to traditional visual gait examinations in regard to precision and reliability [11]. The diagnostic performance of PSW and force plate gait analysis has been extensively studied in clinically healthy dogs [12–17] and dogs with various causes of moderate or severe grades of lameness, e.g. dogs with hip dysplasia [7], cranial cruciate ligament rupture [8, 18, 19], experimentally-induced stifle arthritis [3], external fixation of tibial osteotomy [4], myelopathies [20], and various other orthopedic disorders [9].
Several of the SIs calculated in dogs with low- to moderate-grades of lameness and a previous diagnosis of OA were contained within the SI reference intervals based on measurements in clinically healthy dogs (Fig 2), and differing SIs were only observed in low proportions of dogs with OA (Table 4). However, more deviation from the healthy dogs were observed, when comparing left:right SIs to diagonal and fore:hind indices (Fig 2 and Table 4), respectively, indicating higher diagnostic sensitivity for the left:right SIs.

Means (μ) with 95% confidence intervals [CI] and standard deviations (SD) for 8 different parameters measured in 41 clinically healthy dogs by the Tekscan pressure-sensitive walkway system. The range of coefficients of variation (CVs) based on 6 passages of 10 dogs on the same (intra-analytical CV, CV1) and 2 different days (inter-analytical CV, CV2), respectively are also included in the table.
All dogs with OA were filmed while standing and walking for later visual gait analysis by the same author (JM). Based on clinical examinations and visual gait analysis, dogs were divided into 4 groups depending on the localization of the most severely affected joint; left thoracic (fore) limb (LF), left pelvic (hind) limb (LH), right thoracic (fore) limb (RF), and right pelvic (hind) limb (RH), respectively. Lameness was scored on an ordinal visual analogue scale from 1–5 defined as; no visual lameness (grade 0), mild lameness with minimal head/pelvic movements (grade 1), moderate lameness with normal stride length and partial weight bearing (grade 2), moderate lameness with reduced stride length and partial weight bearing (grade 3), severe lameness with minimal use of limb (grade 4), and non-weight bearing lameness (grade 5) [1, 2]. Data from 10 clinically healthy dogs were used to assess precision using coefficients of variation (CVs) calculated from 6 successive runs on the same day (intra-analytical CV) and averages of 6 successive runs on 2 separate days (inter-analytical CV), respectively. Fig 3 is based on left:right symmetry indices (SIs) of Maximum peak pressure (A-D) and Vertical impulse (E-H) measured in 21 dogs with osteoarthritis (OA) and 41 clinically healthy dogs, respectively. Dogs were divided in groups by the visual grade of lameness (0–5) of left (L) or right (R), thoracic (fore—F) and pelvic (hind—H) limb, respectively. SIs were calculated as simple ratios (SI (1), A,C,E,G) and as indices modified from Schnabl-Feichter et al., 2018 (SI (2), B,D,F,H). Using data from the clinically healthy dogs, parametric reference intervals were calculated for SI (1) as mean±2SD, whereas non-parametric reference intervals were calculated for SI (2) using either the 2.5% and 97.5% percentiles or the 95% percentile, as appropriate.

We used clinical examination and visual gait analysis by an experienced orthopedic surgeon as the golden standard for assessment of lameness and pain in dogs. However, the visual analogue lameness scale may not be the most optimal comparison variable for future PSW studies [3]. In the present study lameness was graded by the same experienced orthopedic surgeon, taking into account that an individual observer seems to have an individual unique lameness scoring scale [4]. However, grading of lameness is a subjective discipline and low agreement between visual assessment of lameness and GRFs has previously been demonstrated in force plate studies, unless investigated dogs were severely lame [3]. Higher agreement might be expected in PSW studies compared to measurements obtained by force plate gait analysis because higher sensitivity and specificity of measurements of GRF could be expected using the PSW [10, 22, 38]. However, these assumptions remain to be confirmed.
Means with 95% confidence intervals (CI) and standard deviations (SD) were calculated for each parameter. D’Agostino & Pearson normality tests were used to confirm that kinetic data from clinically healthy dogs followed a normal distribution. Differences between ipsilateral and contralateral limbs in clinically healthy dogs were assessed by paired Student’s t-tests.The Tekscan PSW measures ground reaction forces in clinically healthy dogs with high precision and the results are not influenced by the direction of passage over the walkway. However, the study showed a large overlap of measured ground reaction forces in mildly to moderately lame dogs with OA compared to clinically healthy dogs. Even though one specific symmetry index was more useful in the detection of lameness compared to other calculated indices, the SIs obtained from most dogs with OA were contained within the reference intervals obtained from clinically healthy dogs. Based on the present study, the system and analysis used here cannot be recommended as a diagnostic test for detection of abnormal gait in dogs with OA. Before data collection, dogs were weighed on an electronic scale. All dogs were allowed to acclimate
to the room and were subsequently walked across the walkway to become comfortable with the surroundings, the PSW, handler, and leash. All dogs were led at the right side in a loose leash by one of four experienced handlers, and leash side was kept constant during the study. Following acclimatization, 6 successive valid recordings were obtained for each dog while they walked the PSW, with 3 recordings in each direction of travel. A trial was considered valid when all 4 limbs fully contacted the PSW and the dog walked straight forward without stopping, hesitating, or having overt head movements. Velocity was controlled at 0.9–1.1 m/s. If velocity differed from these limits, the trial was repeated in order to ensure the same velocity in all patients allowing comparison of parameters across different individual dogs. 
The study showed an acceptable analytical performance of the Tekscan PSW regarding precision. Lower CVs were found in the present study, compared to previous PSW and force plate studies, showing CVs up to 14–30% [27, 31–33], even though higher CVs were observed in dogs with OA compared to clinically healthy dogs. Handlers, leash side, cover material, and velocity were kept constant in the present study to avoid unnecessary influence, as previously recommended by other authors [13, 27, 28]. In contrast to a smaller pilot study [34], the results were not influenced by the direction of travel (Fig 2).Dogs were included as clinically healthy if the owner reported absence of lameness or other diseases, if there were no signs of local or systemic illness on a thorough clinical examination, if they presented with no visually detectable lameness, and if there was absence of abnormal findings on a thorough orthopedic examination. Other inclusion criteria were age between 2–7 years old, body mass of 15–40 kg, and body condition scores of 4–6. Dogs were not included as healthy if they received any medication or if they had a history of orthopedic disorders e.g. fractures or cruciate ligament rupture.

Whereas most diagonal and fore:hind SIs obtained from OA dogs were contained within the reference SIs, the left:right SIs subjectively tended to show more variation. The authors would like to acknowledge Dr J. Bøjesen and Dr P.S. Christensen for collection of data from dogs with OA. Dog owners participating in the study are also acknowledged. Twelve male and 9 female dogs with previously diagnosed OA were included in the study. All dogs were large breed dogs (10 Labrador Retrievers, 6 Golden retrievers, 2 German Shepherd dogs, 1 American Bulldog, 1 American Staffordshire Bull Terrier, and 1 Rottweiler) with a mean age of 9.3 years (range 3.6–13.6, SD 2,4) and a mean weight of 36.3 kg (range 27.2–48.5, SD 5,9). The distribution of the most severely affected limbs was: RF (n = 7), RH (n = 5), LF (n = 5), and LH (n = 4). Primary joints involved were the hip (n = 9), elbow (n = 10) and interdigital (n = 2) joints, with additional involvement of either contralateral or ipsilateral hip/ elbow and metacarpo- or metatarsophalangeal joints, based on clinical and radiographic examinations. The visual grading scores of lameness varied from low (Grade 1, n = 10 and grade 2, n = 7) to moderate (grade 3, n = 4). Table 2 shows means, SDs and ranges of CVs of each kinetic parameter measured in dogs presented with lameness and previously diagnosed OA.A large overlap between SIs calculated for clinically healthy and OA dogs was observed (Figs ​(Figs22 and ​and3)3) and SIs only differed from clinically normal dogs for a limited number of dogs with OA (Tables ​(Tables33 and ​and4).4). Possible influencing factors could be breed, age, and weight differences between included dogs with and without OA, as well as lameness severity and multiple joint involvement. Each group contained a mixture of breeds and was considered broadly representative of the general population of large breed dogs presented to our practice. However, breed variation has been described [15, 17, 35] and even though Labrador and Golden Retrievers were the dominant breeds in both groups of dogs, several other breeds of dogs were included, not necessarily with comparable GRFs. Differences in age and weight distribution between groups could be other influencing factors. The dogs with OA were older than the clinically healthy dogs. Age variation of GRF variables has been proposed to explain variation between dogs [35], but studies specifically addressing this question are lacking. Unfortunately, the high incidence of OA in the older dog population [21] could make it challenging to find reference dogs with a comparable age distribution but without clinical or subclinical OA. The included dogs with OA had higher body mass compared to the group of clinically healthy dogs. Differences in body mass could result in morphological variation and variation in preferred velocity, and these are other factors previously shown to affect GRFs [23]. In humans, obesity is a well-known risk factor for developing OA [36] and obesity and overweight are common in dogs with OA [37]; finding reference dogs with a comparable weight distribution, but without clinical or subclinical OA might also be challenging. Subclinical osteoarthritis in the clinically healthy dogs included in our study was not excluded radiographically, and could represent a possible bias. However, clinical lameness and pain were systematically ruled out by thorough clinical examinations and owner histories, thus minimizing the practical importance of this potential source of bias. Further studies are needed in order to investigate whether reduced heterogeneity of the included dogs could result in less overlap of SIs between groups, e.g. by defining breed-specific reference intervals.

For all dogs several different symmetry indices were calculated, in order to investigate whether one specific index should be preferred in future PSW studies of dogs with OA. Diagonal (LF versus RH and RF versus LH), fore:hind (LF versus LH and RF versus RH), and left:right (LF versus RF and LH versus RH) SIs for each parameter were calculated, using 2 different approaches. Symmetry index (1) was calculated as simple ratios of measurements obtained by each limb, whereas SI (2) was calculated by the following equation modified from Schnabl-Feichter et al., 2018 [30]:
Stance time (A), vertical impulse (B) and maximum peak pressure (C) measured in 41 clinically healthy dogs using the Tekscan pressure-sensitive walkway system. Following acclimatization, 6 successive valid recordings were obtained for each dog, with 3 recordings in each direction from sensor I to IV. Fore:hind symmetry of the stance time measurements was visually observed (A), whereas the vertical impulse (B) and maximum peak pressure (C) were asymmetric because of the increased weight load on the thoracic limbs compared to pelvic limbs in clinically healthy dogs. Left: right symmetry was visually observed for all parameters (A-C).Data obtained from clinically healthy dogs in the present study were comparable to previous studies showing symmetric data when comparing contralateral thoracic or pelvic limbs and significantly more weight bearing on the thoracic limbs compared to pelvic limbs [29]. Fig 2 is based on symmetry indices calculated from measurements of maximum peak presure (A-D) and vertical impulse (E-H) of different legs in dogs with osteoarthritis. 2 different symmetry indices (SI1 (A, C, E, G) and SI2 (B, D, F, H)) are compared in 12 dogs with thoracic limb (A, B, E, F) and 9 dogs with pelvic limb lameness (C, D, G, H), respectively. Osteoarthritis (OA) is a condition affecting up to 20% of the adult dog population [21] and is a common cause of low-grade clinical lameness in dogs [2]. To the authors’ knowledge, clinical OA patients have previously been included in canine PSW studies to a very limited extent, thus motivating for further investigation in the field.

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You can almost certainly identify a forelimb lameness. How are you with hind limb lameness? What about when multiple limbs are affected? Can you make an educated guess at a diagnosis from watching a dog walk, trot and stand? How are you at doing all of this, along with an effective orthopaedic examination, within the time-confines of a busy practice?

Drawing on many years of experience, including examining hundreds of dogs with objective gait-analysis tools such as force platforms and motion-capture cameras, in this session Ben will break down canine gait analysis into simple, repeatable steps.

Exercising him on different surfaces will improve his CP, as on a slightly uneven surface he will receive increased afferent feedback from his foot to his brain signalling how he should place his foot. Start by exercising him on flat, firm, non-slip surfaces and progress him to grass, bark chippings and sand, which will be the most challenging surface.
Practising functional activities in a controlled environment will boost the animal’s confidence to carry out these activities in the home environment. If the animal has stairs to negotiate in the home or other places he visits this activity should be practiced under supervision.

This consists of a small control box, with wires leading to electrode pads. It is used to reduce pain by transmitting small electrical pulses to the affected area via the electrode pads.Secondary osteoarthritis develops resulting in new bone growth at the destroyed cartilage sites, and the formation of fibrous tissue within the joint space as an attempt to provide joint stability.

If the patient has undergone joint surgery full ROM of the joint is neither desirable nor essential in the early stages. However, full ROM should be maintained in all the other joints of the affected limb.

PROM exercises are performed to maintain or improve joint ROM, and to prevent joint inflammation and stiffness. PROM exercises are especially important in recumbent animals that may already have established osteoarthritis and associated pain, stiffness and reduced ROM in the affected joints.
Ensure that if the patient’s trunk is positioned in sternal recumbency and the patient has a support at his lateral thorax so he is not weight-bearing excessively or unevenly through his elbow joints. Ensure the elbows are equally abducted to prevent uneven weight-bearing, which could result in pressure sores. If the affected limb is positioned uppermost an adductor wedge or internal rotator wedge should be placed between the limbs to prevent muscle imbalance – for instance, weak gluteals versus tight adductors. Aim to use the adductor wedge to place the affected limb in a neutral position as this will be most likely tolerated by the patient.For animals with multiple trauma to several limbs a fully body sling and mobile hoist may be necessary to assist mobilisation. The body sling supports the animal’s trunk, whereas the hoist supports the animal’s bodyweight; the hoist is slowly moved forwards and the animal can move his limbs without taking very much of his body weight. The owner can be taught how to carry out the limb-lifting exercises at home. The owner could also have the patient walk in figures-of-eight or in circles to challenge balance. Start with wide figures-of-eight and circles, and then progress by making them smaller. When assessing muscle mass compare with the unaffected contralateral limb for muscle mass symmetry. A standard tape measure can be used to measure the circumference of muscle bulk. Again, try to be systematic to ensure accuracy. For example, when measuring pelvic limb muscle bulk try to measure in standing, measure at the thickest point – this usually corresponds to the level of the muscle belly. Try to have a landmark – say in the pelvic limb the greater trochanter of the femur – where the two ends of the tape measure should meet and record the measurement. A difference of more than 1 cm would be considered significant. It is good practice to measure three times and take the average measure from the three readings and record this average reading in the notes. Animals should be on a loose lead at walk and trot to observe for anatomical symmetry (normal gait pattern). Animals should be observed in a straight line towards, and then a straight line away from the observer. Pay particular attention to how the animal turns to both the left and right side – this may show reluctance to transfer weight onto the affected limb, or that the animal has issues with balance. The observer should then view the animal moving from both left and right sides. Subtle lameness may not readily be observed at walking pace; however, at trot the animal will only have one thoracic limb and one pelvic limb in contact with the ground, and these limbs will be placed under greater pressure meaning a lameness may be easier to detect. Active-assisted (using a sling) exercises in a controlled environment are an excellent way to reduce gait abnormalities. As the patient is challenged by the exercises (weaving cones/cavaletti poles) he will not be able to compensate by mobilising on three limbs and therefore will commence with gentle weight-bearing, which is desirable at this stage of the rehabilitation programme.Consider the use of electrotherapy such as a class IV K-Laser™, if available, to reduce pain and inflammation within the joint and control scar tissue, which may reduce ROM. Lumbar spine pain and stiffness can be treated with mobilisations. Start gently with grade II for pain relief, then progress to grade III to improve mobility and reduce stiffness. The animal is usually recumbent for the PROM exercises with the affected limb(s) uppermost. (However, the exercises can be performed in standing with the patient supported.) If the animal has undergone joint surgery this joint should be isolated and gently moved through its pain-free range in all anatomical planes. This joint would then be supported and the other joints in the affected limb would be moved through full ROM in all anatomical planes. PROM exercise three sets of 10 repetitions for each joint twice a day is considered to be effective.The animal will be reluctant to fully weight-bear through the affected limb; at rest, toe touch weight-bearing is often evident; the animal may also adopt various strategies to reduce weight-bearing in stance and will often position the affected limb in a cranio-medial plane. Late-stage rehabilitation can commence at 6 weeks postoperatively following a satisfactory check-up from the veterinary surgeon, who may take survey radiographs at this stage to check healing. Rehabilitation goals will be to continue to strengthen the muscles of the affected limb. The patient may be full weight-bearing (FWB) on the affected limb at this stage. To maintain joint ROM at the hip, stifle and tarsus joints. All joints are flexed, and then extended. Rotation of the limb is avoided, with one hand supporting at the medial stifle joint. Note that the limb is not gripped and no pulling of the limb occurs; the distal hand pushes the limb into flexion, then the proximal hand, which is medial and anterior to the stifle joint, pushes the limb into extension.Stretches are performed to maintain or increase muscle length. These are usually performed passively by an operator for recumbent patients, or in patients that have undergone surgery.

Hydrotherapy using a UWT can also be used to strengthen the extensor muscles as the patient places his limb in the stance phase and pushes through the limb and enters the swing phase. As the patient progresses a faster belt speed will encourage longer strides and greater activity in the extensor muscle groups.
Cold therapy aims to control and minimise inflammation postoperatively or following acute injury. The body responds to injury by triggering an inflammatory reaction in the cells. The normal inflammatory phase in healthy tissues is approximately 72 hours. This is the period of time when cold therapy is recommended to minimise the inflammatory response.

The principle of heat therapy is to vasodilate local blood vessels thus increasing blood flow to the local area to promote healing. Increased cellular activity results in an increase of oxygen and nutrients delivered to the cells.
Changes in muscle length can occur quickly in: (i) recumbent animals; (ii) patients that have recently undergone surgery when they may not be moving limbs through their full ROM; or (iii) an animal that is non-weight-bearing for a period of time, when the flexor muscles will become short and tight, and the opposing extensor muscle groups will become weak.

A combination of glucosamine hydrochloride, chondroitin sulphate, manganese and ascorbate is a commonly used nutraceutical in osteoarthritic small animals (Hulse, 1998). The use of these nutritional supplements is supported by clinical studies investigating the treatment of osteoarthritis (Leeb et al., 2000).
Apply bilateral laser treatment to the hips, to reduce pain; the power and time (duration) of treatment will depend on the patient’s skin colour, bodyweight and stage of condition (acute or chronic).

Also consider the owner’s ability
and commitment to carry out the rehabilitation programme, plus environmental factors. The owner may work full time and have other family commitments. The rehabilitation home exercise programme should fit in with the animal’s needs and the owner’s time restrictions. Do not advise a rehabilitation home exercise programme that takes any more than 30 minutes twice daily to ensure owner compliance. Environmental factors to consider would include: are there other animals in the house, and are there stairs in the house that the patient needs to use?
The unit consists of a control panel and an electronic waterproof pad that can be placed under the affected area to be treated. It is a non-invasive treatment and as such is usually well tolerated by the patient. It is especially useful for treatment in arthritic patients and uses pulsed magnetic therapy to reduce pain and inflammation. PEME can be used in both the acute and chronic phases of disease. Pulsed magnetic therapy has been used in the assistance of bone healing.

Usually begin the treatment early to minimise the inflammatory response. If an animal is recovering from surgery and is hypothermic, treatment may be postponed until the patient’s body temperate returns to normal.Another common functional activity that the animal may need to perform is getting in and out of the car. A ramp is recommended for medium to large dogs. If the animal has not used the ramp before he may be reluctant to use it. Always make sure the ramp is firmly secured to the car. Start by practising getting into the car first so he can gain confidence. Practice this several times before attempting using the ramp to exit the car. Like with stair practice he will feel most vulnerable on the descent. It may be useful to have an assistant at the opposite side of the ramp to yourself to give extra reassurance and to assist the patient should he lose his balance.In conjunction with passive exercises to improve ROM and passive stretches to increase muscle length, progressive exercise programmes focused around the assessment findings can be useful adjuncts to achieve short- and long-term goals.Conscious proprioception may be delayed or absent in the presence of a joint effusion, which is often evident in acute cranial cruciate ligament injury.The animal may abduct the limb to alter the direction of ground reaction forces passing through the joint, and if there is fatigue or weakness in the hip flexor muscle groups.Three sets of 10 PROM repetitions are performed on each pelvic limb; there is no hold at the end of full flexion or extension so one repetition of pelvic limb PROM should not take more than one to two seconds. Three sets of 10 repetitions should be completed in 30–60 seconds if the patient is compliant.Observe gait in a quiet area at walk and trot; thoracic limb lameness is often associated with head bobbing. When the animal takes its bodyweight through the painful thoracic limb the head will bob upwards in an attempt to unload the ground reaction force passing through the limb.Hip dysplasia is also seen in humans. However, this is not considered a hereditary condition and is not screened for. The primary cause in humans relates to the size (large) and presentation of the foetus. The incidence is highest in large female babies who develop in a confined space with the hip joint flexed and rotated. All babies are assessed for excessive hip laxity shortly after birth. If hip dysplasia is confirmed the baby is fitted with a special hip brace, which is worn for most of the day for a period of months to correct the hip deformity.Commence balance and proprioceptive exercise training using wobble cushions, wobble boards and cavaletti pole work. Address compensatory postures, which may be associated with trigger points.A wobble cushion can be placed under the patient’s limb. Perpetrations or nudges at the contralateral hip will force the patient’s limb onto the wobble cushion, which is an unstable surface so he will need to use stabilising muscles in the limb to maintain his balance. If this exercise is well tolerated, it can be progressed by incorporating limb lifting of the contralateral pelvic limb whilst the affected limb is balancing on the cushion. This will increase the stabilising muscle strength in the limb and also further challenge his ability to balance. Hold each limb lift for 5 seconds and repeat five times.Positioning aids and supports are used to maintain muscle length and support the weight of the affected limb. The animal may not have full function or control of the affected limb postoperatively. This may be exacerbated by factors such as pain or discomfort, bulky dressings or external fixators.

Hip flexors, hamstrings and adductors are stretched passively. Again avoid any rotation of the joints of the pelvic limb and support the distal limb. Each stretch should be taken into resistance and held for 15 seconds and repeated three times. Stretching should not be painful for the patient. If the patient is very tense gentle warm-up exercises may assist with stretching, or warming the muscles with heat packs pre-stretching may be beneficial. With hip dysplasia, extension and abduction are usually the most uncomfortable movements for the patient, so be aware that full hip extension and abduction may not be possible if the patient has developed secondary osteoarthritic changes around the hip joint.
Tibial osteotomies all aim to eliminate cranial tibial thrust, and provide long-term stability of the stifle joint. Long-term studies are required to provide evidence of each technique’s effectiveness.It is important to evaluate treatment to ensure it is effective. Once a patient has achieved his short-term goals progress him on to improve joint ROM and muscle length in the mid-phase rehabilitation programme, then finally in the late phase of rehabilitation progress him again to improve strength and muscle mass, to rehabilitate him back to his highest level of function.

Each dog was re-evaluated following a 4-day rest period and still exhibited a mild increase in weight-bearing on the affected limb, but these differences were not significant. The author concluded this preliminary study showed positive benefits of TENS application in dogs with osteoarthritic stifle joints. When the TENS machine is set at a frequency of 2–5 Hz this stimulates the body to produce its own pain-easing chemicals, endorphins, thereby blocking the pain signals. As the inflammatory phase passes PROM exercise of the affected joint may be gradually increased within the pain-free range, and with consent from the veterinary surgeon.

Buster is a 12-year-old neutered Labrador. He has a right stifle cranial cruciate ligament rupture and is being referred for physiotherapy. He is overweight at 40 kg, and is currently on a calorie-restricted diet.
The animal will usually choose not to lie on the same side as the affected limb. However, the animal may find it difficult to find a comfortable position in which to rest. In most circumstances the animal will be more comfortable if the affected limb is supported in a neutral position, or slightly elevated in the early stages of recovery, and this will also prevent any muscle imbalances from developing. Folded beds, towels and pillows can be used to maintain the required position. Gentle handling and support of the affected limb and reassuring the animal are essential to aid compliance.

Baseline measures should be taken at the time of the first assessment. Assuming the patient is attending on a weekly basis re-measure outcomes at 6 and 12 weeks.
Various methods can be used to apply heat to the superficial tissues, such as wheat bags and heat discs that can be warmed in the microwave. Alternatively a damp towel can be microwaved, placed in a zip-lock bag and applied to the affected area for 10–20 minutes. This can be repeated every 4–6 hours.If available hydrotherapy using an underwater treadmill (UWT) would be an ideal active exercise for the patient to increase ROM of the joint. Use the buoyancy effect of the water and fill to the level of the patient’s mid-trunk. Start with slow speeds and short duration with plenty of rest breaks, then increase speed and time as the patient progresses.

Mid-stage rehabilitation can commence 14 days postoperatively, following a satisfactory check-up from the veterinary surgeon and suture removal. The aims are to begin to increase joint ROM of the affected limb, and increase muscle length and mass on the affected limb. Begin gentle partial weight-bearing (PWB) exercises to increase function and strength, and prevent secondary compensatory postures and complications from developing.
When assisting with a physical examination try to find a quiet area. Adopt a systematic anatomical approach each and every time. With the animal standing each limb will be lifted in turn to gauge weight-bearing through the limbs. Obviously the animal will be taking least weight through the affected limb, but lifting each limb in turn may give an indication of where the animal is shifting his bodyweight as a compensatory measure. Compensatory measures can often lead to secondary musculoskeletal issues so these should be noted during the physical exam and addressed later.Slings are used to assist the animal when he is mobilising. A variety of slings are available for veterinary use, most commonly used with orthopaedic patients is The Soft Quick Lift™ (Four Flags Over Aspen, Inc.) abdominal sling. This type of sling is useful following pelvic limb surgery, is easy to use, and is usually well tolerated by the patient. If you are using a sling to assist the patient to mobilise, position yourself on the same side as the unaffected limb in line with the pelvic limb. In this position you can tilt the patient slightly onto his unaffected limb and assist with balance if necessary and prevent him from falling.