• View in gallery

    Illustration of the stair and ramp equipment from the lateral aspect (A) and from above (B) that depicts the dimensions of the steps and ramp used to evaluate the kinematics of the TL during descending exercises for 8 healthy dogs and location of the video camera used to capture the movement of the dogs. In panel B, the gray box represents the 70 × 50-cm platform at the top of the stairs, and the black box represents the 124 × 50-cm ramp that was placed over the steps during the ramp exercise.

  • View in gallery

    Mean peak extension, peak flexion, and ROM for the shoulder (A), elbow (B), and carpal (C) joints of the left TL for 8 orthopedically normal dogs during descent of stairs (white bars) or a ramp (black bars) with a 35% slope and during a trot across a flat surface (gray bars). Each value represents the mean for 5 successful trials from each of 8 dogs (ie, 40 trials). A successful trial was defined as one in which the dog completed the task by moving in a straight line at a consistent velocity without stopping, hesitating, or changing stride and without exaggerated head or body movements. *Values linked with brackets differ significantly (P < 0.016 [Bonferroni adjustment for pairwise comparisons]).

  • View in gallery

    Representative photographs depicting the elbow joint angle (arrow) of the left TL of various dogs while at a trot across a flat surface (A) and descending stairs immediately before initiation of a stride (toe off; B) and during midstride (C). Dogs maintained a natural stride when trotted across a flat surface, which allowed the elbow joint to achieve its maximum extension at the end of the stance phase immediately before toe off (A); however, when dogs descended stairs, the rise of the previous step limited the extent of TL retraction and prevented the elbow joint from achieving maximum extension (B). Notice that peak flexion of the elbow joint occurred as the dog lifted the limb to clear the edge of the step soon after toe off (C). The elbow joint angle is depicted in each photograph for comparison purposes.

  • 1. Millis DL, Ciuperca IA. Evidence for canine rehabilitation and physical therapy. Vet Clin North Am Small Anim Pract 2015; 45: 127.

  • 2. Canapp S, Acciani D, Hulse D, et al. Rehabilitation therapy for elbow disorders in dogs. Vet Surg 2009; 38: 301307.

  • 3. Fischer S, Nolte I, Schilling N. Adaptations in muscle activity to induced, short-term hindlimb lameness in trotting dogs. PLoS One 2013;8:e80987.

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  • 4. Weigel JP, Millis D. Section V, Chapter 24. In: Millis DL, Levine D, eds. Canine rehabilitation and physical therapy. 2nd ed. Philadelphia: Elsevier-Saunders Health Sciences, 2014;420427.

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  • 5. Carr JG, Millis DL, Weng HY. Exercises in canine physical rehabilitation: range of motion of the forelimb during stair and ramp ascent. J Small Anim Pract 2013; 54: 409413.

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  • 6. Millard RP, Headrick JF, Millis DL. Kinematic analysis of the pelvic limbs of healthy dogs during stair and decline slope walking. J Small Anim Pract 2010; 51: 419422.

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  • 7. Durant AM, Millis DL, Headrick JF. Kinematics of stair ascent in healthy dogs. Vet Comp Orthop Traumatol 2011; 24: 99105.

  • 8. Buchner HH, Schildboeck U. Physiotherapy applied to the horse: a review. Equine Vet J 2006; 38: 574580.

  • 9. Holler PJ, Brazda V, Dal-Bianco B, et al. Kinematic motion analysis of the joints of the forelimbs and hind limbs of dogs during walking exercise regimens. Am J Vet Res 2010; 71: 734740.

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  • 10. Richards JD, Holler P, Bockstahler BA, et al. A comparison of human and canine kinematics during level walking, stair ascent, and stair descent. Wien Tierarztl Monatsschr 2010; 97: 92100.

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  • 11. Williams RJ, Nankervis KJ, Colborne GR, et al. Heart rate, net transport cost and stride characteristics of horses exercising at walk and trot on positive and negative gradients. Comp Exerc Physiol 2009; 6: 113119.

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  • 12. Kim J, Rietdyk S, Breur GJ. Comparison of two-dimensional and three-dimensional systems for kinematic analysis of the sagittal motion of canine hind limbs during walking. Am J Vet Res 2008; 69: 11161122.

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  • 13. Grainger J, Wills AP, Montrose VT. The behavioural effects of walking on a collar and a harness in domestic dogs (Canis familiaris). J Vet Behav 2016; 14: 6064.

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  • 14. Mier CM. Accuracy and feasibility of video analysis for assessing hamstring flexibility and validity of the sit-and-reach test. Res Q Exerc Sport 2011; 82: 617623.

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  • 15. Dartfish Customer Care. Extracting data from video. Available at: support.dartfish.com/selfpaced/en/HTML/003EN_Datatables/index.html. Accessed May 9, 2016.

  • 16. English AW. Functional analysis of the shoulder girdle of cats during locomotion. J Morphol 1978; 156: 279292.

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  • 18. Marsolais GS, McLean S, Derrick T, et al. Kinematic analysis of the hind limb during swimming and walking in healthy dogs and dogs with surgically corrected cranial cruciate ligament rupture. J Am Vet Med Assoc 2003; 222: 739743.

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  • 19. Bockstahler BA, Henninger W, Müller M, et al. Influence of borderline hip dysplasia on joint kinematics of clinically sound Belgian Shepherd dogs. Am J Vet Res 2007; 68: 271276.

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  • 20. Burton NJ, Dobney JA, Owen MR, et al. Joint angle, moment and power compensations in dogs with fragmented medial coronoid process. Vet Comp Orthop Traumatol 2008; 21: 110118.

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Kinematic analysis of the thoracic limb of healthy dogs during descending stair and ramp exercises

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  • 1 University Centre, Hartpury College, Gloucester, GL19 3BE, England.
  • | 2 University Centre, Hartpury College, Gloucester, GL19 3BE, England.
  • | 3 University Centre, Hartpury College, Gloucester, GL19 3BE, England.

Abstract

OBJECTIVE To compare the kinematics of the thoracic limb of healthy dogs during descent of stairs and a ramp with those during a trot across a flat surface (control).

ANIMALS 8 privately owned dogs.

PROCEDURES For each dog, the left thoracic limb was instrumented with 5 anatomic markers to facilitate collection of 2-D kinematic data during each of 3 exercises (descending stairs, descending a ramp, and trotting over a flat surface). The stair exercise consisted of 4 steps with a 35° slope. For the ramp exercise, a solid plank was placed over the steps to create a ramp with a 35° slope. For the flat exercise, dogs were trotted across a flat surface for 2 m. Mean peak extension, peak flexion, and range of movement (ROM) of the shoulder, elbow, and carpal joints were compared among the 3 exercises.

RESULTS Mean ROM for the shoulder and elbow joints during the stair exercise were significantly greater than during the flat exercise. Mean peak extension of the elbow joint during the flat exercise was significantly greater than that during both the stair and ramp exercises. Mean peak flexion of the elbow joint during the stair exercise was significantly greater than that during the flat exercise.

CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that descending stairs may be beneficial for increasing the ROM of the shoulder and elbow joints of dogs. Descending stair exercises may increase elbow joint flexion, whereas flat exercises may be better for targeting elbow joint extension.

Abstract

OBJECTIVE To compare the kinematics of the thoracic limb of healthy dogs during descent of stairs and a ramp with those during a trot across a flat surface (control).

ANIMALS 8 privately owned dogs.

PROCEDURES For each dog, the left thoracic limb was instrumented with 5 anatomic markers to facilitate collection of 2-D kinematic data during each of 3 exercises (descending stairs, descending a ramp, and trotting over a flat surface). The stair exercise consisted of 4 steps with a 35° slope. For the ramp exercise, a solid plank was placed over the steps to create a ramp with a 35° slope. For the flat exercise, dogs were trotted across a flat surface for 2 m. Mean peak extension, peak flexion, and range of movement (ROM) of the shoulder, elbow, and carpal joints were compared among the 3 exercises.

RESULTS Mean ROM for the shoulder and elbow joints during the stair exercise were significantly greater than during the flat exercise. Mean peak extension of the elbow joint during the flat exercise was significantly greater than that during both the stair and ramp exercises. Mean peak flexion of the elbow joint during the stair exercise was significantly greater than that during the flat exercise.

CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that descending stairs may be beneficial for increasing the ROM of the shoulder and elbow joints of dogs. Descending stair exercises may increase elbow joint flexion, whereas flat exercises may be better for targeting elbow joint extension.

Physical rehabilitation can increase the likelihood of a successful recovery after injury.1,2 Restoration and maintenance of normal movement minimize the need for compensatory movement and the potential for injury elsewhere.3 Specific exercises can be used to maintain or increase ROM and muscle strength to ensure clinically normal joint mechanics.4 For example, the rehabilitation program for a dog with an elbow joint disorder may include stair and ramp exercises to increase ROM initially, but those exercises can also be used to increase strength and challenge the balance and proprioception of the affected limb.2

The use of steps or ramps in rehabilitation programs for dogs is well documented.4–6 Ascending steps or ramps (ascending exercises) increases the ROM for the shoulder, elbow, carpal, hip, stifle, and tarsal joints and strengthens the muscles used to propel the dog forward and upward.5,7 Ascending or descending steps or ramps is commonly recommended for rehabilitation programs for human patients, but to our knowledge, the application and efficacy of descending steps or ramps (descending exercises) in rehabilitation programs for dogs have not been investigated. More evidence is required to ensure informed practice to support the effects and use of steps and ramps in veterinary rehabilitation programs.8

Understanding the biomechanical effects of descending exercises in healthy dogs is necessary to promote evidence-based practice through the establishment of baseline ROM for various joints and is vital for veterinarians and physiotherapists to ensure that the exercises prescribed as part of rehabilitation programs are accurate and facilitate patient recovery. In dogs, the kinematics of the TL have been described during ascending exercises,5 and the kinematics of the PL have been described during both ascending7 and descending6 exercises. Descending exercises increase the ROM of the limbs and challenge balance and proprioception,4,9 which makes them useful for the treatment of various conditions at various stages of rehabilitation to promote and restore clinically normal function.10 It is believed that, in dogs, the TL is mainly responsible for braking momentum on a downhill slope.5 The kinetic load increases in the TLs of horses trotting on downhill slopes, which supports the theory that the TL is responsible for braking momentum during descending excercises5,11; however, that theory has yet to be investigated in dogs. Therefore, the purpose of the study reported here was to compare the ROM of the joints of the TL of healthy dogs during descent of stairs and a ramp with those during a trot across a flat surface (control), exercises that are routinely recommended for HEPs.

Materials and Methods

Animals

All study procedures were reviewed and approved by the University of the West of England Hartpury Ethics Committee. A convenience sample of 8 healthy dogs was selected from a local dog-training club with 50 members. The owners of all dogs provided informed consent prior to enrollment of their pets into the study. Each dog was considered healthy and orthopedically normal on the basis of results of a physical and orthopedic examination.

Instrumentation

The left TL of each dog was instrumented with 5 polystyrene markers for 2-D kinematic evaluation to provide accurate and repeatable data for measurement of joint angles, velocity, and stride length in the sagittal plane.12 The markers were 15 mm in diameter and were attached with adhesive tape to the skin after the hair was clipped, when necessary. For each dog, a marker was placed at the proximal aspect of the spine of the scapula, greater tubercle of the humerus, lateral epicondyle of the humerus, lateral aspect of the ulnar carpal bone, and lateral aspect of the head of the fifth metacarpal bone. The same Association of Chartered Physiotherapists Category A–certified veterinary physiotherapist (NLK) placed all markers on each dog.

Experimental design

Each dog underwent 2-D kinematics evaluation of the left TL for each of 3 conditions or performed exercises (descending stairs, descending a ramp, and trotting over a flat surface). To ensure the results were externally valid, the equipment used was designed to mimic conditions dogs commonly encounter in their home environments. The stairs consisted of 4 steps that had a height of 17.7 cm, depth of 25.4 cm, and width of 50 cm (Figure 1).5 There was a 70 × 50-cm platform at the top of the stairs. For the ramp exercise, a solid plank (50 × 124 cm) was placed over the steps, resulting in a ramp with a 35° slope. The flat exercise consisted of trotting the dog in a straight line over flat ground for a total distance of 6 m, of which the central 2 m were within the data collection area. A video cameraa was positioned perpendicular to the equipment (stairs or ramp) at a distance of 2.5 m and in line with the back support for the second step to record the movements of all dogs for kinematic analysis.

Figure 1—
Figure 1—

Illustration of the stair and ramp equipment from the lateral aspect (A) and from above (B) that depicts the dimensions of the steps and ramp used to evaluate the kinematics of the TL during descending exercises for 8 healthy dogs and location of the video camera used to capture the movement of the dogs. In panel B, the gray box represents the 70 × 50-cm platform at the top of the stairs, and the black box represents the 124 × 50-cm ramp that was placed over the steps during the ramp exercise.

Citation: American Journal of Veterinary Research 79, 1; 10.2460/ajvr.79.1.33

To ensure that the exercises were representative of an HEP, each dog was led by its usual handler (generally the owner) with its usual leash and collar or harness.13 Each dog was required to complete a minimum of 10 trials for each exercise (stairs, ramp, and flat). Dogs with prior agility experience appeared more confident on the equipment (ramp) and tended to slow their descent toward the bottom of the ramp, whereas dogs without agility experience tended to descend the stairs and ramp slowly and began to jump to the ground from the second step or middle of the ramp with increasing repetitions. Consequently, only trials in which the dog completed the task by moving in a straight line at a consistent velocity without stopping, hesitating, or changing stride and without exaggerated head or body movements (ie, successful trial) underwent kinematic analysis.12

Video analysis

Videos were transferred to kinematic softwareb for analysis. For the left TL, 1 stride (defined as the period from when the last toe on the designated limb left the ground [ie, toe off] to the next toe off; generally for the stride obtained most perpendicular to the camera) was analyzed from each successful trial. The anatomic markers were used to define the angles for the shoulder, elbow, and carpal joints. The angle for the shoulder joint was defined by the markers at the proximal aspect of the spine of the scapula, greater tubercle of the humerus, and lateral epicondyle of the humerus. The angle for the elbow joint was defined by the markers at the greater tubercle of the humerus, lateral epicondyle of the humerus, and lateral aspect of the ulnar carpal bone. The angle for the carpal joint was defined by the markers at the lateral epicondyle of the humerus, lateral aspect of the ulnar carpal bone, and head of the fifth metacarpal bone. For each successful trial, the angles of the shoulder, elbow, and carpal joints were measured and tracked frame by frame for the entire stride as described.14 Briefly, measurements were obtained every 0.03 seconds and automatically recorded into a data table.5 For each trial, peak flexion (smallest angle), peak extension (largest angle), and overall ROM (peak extension – peak flexion) were determined for the shoulder, elbow, and carpal joints. For each dog, 5 successful trials for each exercise were selected for statistical analyses, and the means for peak flexion, peak extension, and ROM for the shoulder, elbow, and carpal joints were calculated as described.5

Velocity was determined by use of premeasured markers (ie, step depth for the stair and ramp exercises and ground markers for the flat ground exercise) to calibrate distance on the videos and was reported in meters per second.15 It was calculated as the distance traveled by the TL during 1 stride for each trial. The mean velocity was then calculated for the 5 trials selected for evaluation for each exercise.

Stride length directly affects the ROM for a limb.16 It was defined as the distance traveled by the left TL during 1 stride and was determined for each successful trial. The mean stride length was calculated for the 5 trials selected for evaluation for each exercise.

Data analysis

Because previous studies5–7 that evaluated the kinematics of the TLs and PLs of dogs used only hound-type dogs, leg length data were obtained for and compared among the dogs of the present study to determine whether leg length was homogeneous among dogs. The kinematic software and same premeasured markers used to calculate velocity were used to measure the distance between the anatomic markers on the greater tubercle and lateral epicondyle of the humerus (humeral length) and between the anatomic markers on the lateral epicondyle of the humerus and lateral aspect of the ulnar carpal bone (radial length). Dogs were then separated into 2 groups on the basis of body weight (20 to 22.5 kg [group 1] and 22.6 to 24 kg [group 2]). A Mann-Whitney U test was used to determine whether the humeral and radial lengths varied significantly between the 2 groups and ascertain whether the data would need to be transformed to normalize the respective distributions before further statistical analyses. Results indicated that neither the humeral (P = 0.343) nor radial (P = 1.000) length differed significantly between the 2 groups; therefore, the data did not require transformation.

The mean peak flexion, peak extension, and ROM for the shoulder, elbow, and carpal joints and mean stride length were compared among the 3 exercises (stairs, ramps, and flat) by means of a 1-way ANOVA for repeated measures, and values of P ≤ 0.05 were considered significant. When necessary, pairwise comparisons were performed by use of t tests with a Bonferroni adjustment to prevent type I errors, and values of P < 0.016 were considered significant for those comparisons.17 Mean velocity was compared among the 3 exercises by means of a Friedman test followed by a Wilcoxon analysis with a Bonferroni adjustment for pairwise comparisons; values of P < 0.016 were considered significant for that analysis.

Results

Dogs

The study population consisted of 1 Border Collie crossbred, 2 Labrador Retrievers, 1 Australian Shepherd, 1 Belgian Sheepdog, 1 Labrador Retriever crossbred, 1 Staffordshire Bull Terrier crossbred, and 1 Vizsla crossbred, of which 6 were spayed females, 1 was a neutered male, and 1 was a sexually intact male. The population had a mean ± SD age of 5.5 ± 2.7 years and body weight of 22.3 ± 1.9 kg.

Velocity and stride length

Although the mean ± SD velocity was greatest for the flat exercise (1.45 ± 0.38 m/s), it did not differ significantly from that for the stair (1.01 ± 0.15 m/s) and ramp (1.16 ± 0.31 m/s) exercises. The mean ± SD stride length for the flat exercise (67.00 ± 8.91 cm) was significantly (P = 0.001) greater than that for the ramp exercise (48.99 ± 9.51 cm) but did not differ significantly from that for the stair exercise (56.99 ± 1.87 cm). Interestingly, the mean stride length among dogs was most consistent during the stair exercise, as evidenced by the fact that the SD for that exercise was approximately a fifth than that for the flat and ramp exercises.

Peak flexion, peak extension, and ROM

The mean peak extension, peak flexion, and ROM for the shoulder, elbow, and carpal joints during each of the 3 exercises were summarized (Figure 2). The mean peak extension and peak flexion of the shoulder joint did not differ among the 3 exercises. However, the mean ± SD ROM for the shoulder joint during the stair exercise (50.72 ± 8.45°) was significantly (P = 0.002) greater than that during the flat exercise (36.68 ± 8.55°).

Figure 2—
Figure 2—

Mean peak extension, peak flexion, and ROM for the shoulder (A), elbow (B), and carpal (C) joints of the left TL for 8 orthopedically normal dogs during descent of stairs (white bars) or a ramp (black bars) with a 35% slope and during a trot across a flat surface (gray bars). Each value represents the mean for 5 successful trials from each of 8 dogs (ie, 40 trials). A successful trial was defined as one in which the dog completed the task by moving in a straight line at a consistent velocity without stopping, hesitating, or changing stride and without exaggerated head or body movements. *Values linked with brackets differ significantly (P < 0.016 [Bonferroni adjustment for pairwise comparisons]).

Citation: American Journal of Veterinary Research 79, 1; 10.2460/ajvr.79.1.33

Dogs maintained their natural stride when trotted across flat ground, which allowed the elbow joint to achieve its maximum extension at the end of the stance phase (ie, immediately before toe off); however, when dogs were descending stairs or the ramp, the rise of the previous step or slope of the ramp limited the extent of TL retraction and prevented the elbow joint from achieving maximum extension (Figure 3). Thus, the mean ± SD peak extension for the elbow joint during the flat exercise (132.03 ± 11.49°) was significantly greater than that during both the ramp (113.95 ± 13.24°; P = 0.007) and stair (114.79 ± 11.31°; P = 0.009) exercises, but did not differ between the ramp and stair exercises (Figure 2). The extent of elbow joint flexion was greatest when a dog lifted its TL to clear the edge of the step. Thus, the mean peak flexion of the elbow joint was when the angle was lowest (joint flexed the most) during the stair exercise and the angle was greatest (joint flexed the least) during the flat exercise. Additionally, the mean ± SD peak flexion of the elbow joint during the stair exercise (34.36 ± 3.42°) was significantly greater than that during both the ramp (46.00 ± 10.90°; P = 0.010) and flat (66.23 ± 8.61°; P = 0.001) exercises, and the mean ± SD peak flexion of the elbow joint during the ramp exercise was significantly (P = 0.001) greater than that for the flat exercise. The mean ± SD ROM for the elbow joint during the stair exercise (80.43 ± 8.69°) was significantly greater than that during the ramp (67.95 ± 9.96°; P = 0.010) and flat (65.81 ± 7.48°; P = 0.003) exercises, but did not differ significantly between the ramp and flat exercises.

Figure 3—
Figure 3—

Representative photographs depicting the elbow joint angle (arrow) of the left TL of various dogs while at a trot across a flat surface (A) and descending stairs immediately before initiation of a stride (toe off; B) and during midstride (C). Dogs maintained a natural stride when trotted across a flat surface, which allowed the elbow joint to achieve its maximum extension at the end of the stance phase immediately before toe off (A); however, when dogs descended stairs, the rise of the previous step limited the extent of TL retraction and prevented the elbow joint from achieving maximum extension (B). Notice that peak flexion of the elbow joint occurred as the dog lifted the limb to clear the edge of the step soon after toe off (C). The elbow joint angle is depicted in each photograph for comparison purposes.

Citation: American Journal of Veterinary Research 79, 1; 10.2460/ajvr.79.1.33

Mean peak extension (P = 0.795), peak flexion (P = 0.064), and ROM (P = 0.195) of the carpal joint did not differ significantly among the 3 exercises (Figure 2).

Discussion

Two-dimensional kinematic evaluation is a simple and effective method to analyze therapeutic exercises, such as ascending or descending stairs and ramps, and has been used to evaluate the ROM for joints of healthy dogs and dogs with cruciate ligament–deficient stifle joints,18 hip dysplasia,19 and elbow joint disease.20 In the present study, 2-D kinematics of the left TL of healthy dogs were determined during descent of stairs and a ramp with a 35° slope and during a trot across a flat surface. Results indicated that, compared with a trot across a flat surface (flat exercise), the mean ROM of the shoulder and elbow joints were increased during descent of stairs (stair exercise), mean peak extension of the elbow joint was increased during the flat exercise, and mean peak flexion of the elbow joint was increased during both the stair and ramp exercises.

For the shoulder joint, ROM was the only variable assessed for which a significant difference was identified among the 3 exercises. The mean ROM for the shoulder joint during the stair exercise (50.72°) was significantly greater than that during the flat exercise (36.68°). However, the mean ROM for the shoulder joint during the ramp exercise did not differ from that during either the stair or the flat exercise, which suggested that dogs might have a tendency for more controlled and purposeful movement when descending stairs, compared with their movement when descending a ramp or trotting across a flat surface. For the dogs of the present study, stride length decreased but the mean ROM for the shoulder joint increased during descent of stairs relative to trotting across a flat surface. In horses, stride length increases on a negative gradient of 3.43°.11 However, in dogs, the stride length of the PL does not differ significantly during descent of stairs or a ramp, both of which had a 35° slope.6 Therefore, when quadrupeds traverse negative gradients, stride length may increase to a set point and then decrease as the gradient becomes steeper and the limbs are required to provide braking. In cats, the ROM of the shoulder joint is positively associated with stride length.16 Dogs of the present study were unable to adjust stride length during the stair exercise owing to the dimensions of the steps.6 Consequently, the increase in the ROM for the shoulder joint during the stair exercise, compared with that during the flat exercise (control), appeared to be the result of the TL being extended to reach the next step while the contralateral limb was flexed to allow the body to descend in the direction of movement.

For the dogs of the present study, the pattern for extension, flexion, and ROM of the shoulder joint during the stair and ramp exercises was similar to the pattern for extension, flexion, and ROM of the hip joint of dogs during descent of stairs and a ramp.6 In that study,6 although the magnitudes of extension (stairs, 123.07°; ramp, 119.64°) and flexion (stairs, 95.9°; ramp, 96.83°) of the hip joint were similar during descent of both the stairs and ramp, the ROM of the hip joint was significantly greater during decent of the stairs than during descent of the ramp. Investigators of that study6 postulated that the significant increase in the ROM of the hip joint during descent of stairs, compared with that during descent of a ramp, was caused by the cumulative effects of small increases in extension and flexion of the hip joint rather than an increase in stride length. The increases in the ROM of the shoulder joints for the dogs of the present study and the hip joints for the dogs of that other study6 during descent of stairs versus a ramp could be associated with avoidance of the prominent edges of the steps. Results of another study9 indicate that when dogs adjust the swing phase of a gait to accommodate changes in the ground surface, the extent of flexion and extension of the more distal joints of both the TL (elbow and carpal joints) and PL (stifle and tarsal joints) increase while the ROM of the shoulder and hip joints remain fairly stable. Interestingly, results of a study5 that investigated the kinematics of the TL of dogs during ascent of stairs and a ramp and trotting across a flat surface indicate that flexion, extension, and the ROM of the shoulder joint are less when ascending stairs, compared with when ascending a ramp or trotting across a flat surface; this fact suggests that the increased ROM of the shoulder joint during ascent or descent of stairs is not solely the result of adjustments to the swing phase to avoid the edges of the steps. We believe that the increase in the ROM of the shoulder joint during the stair exercise for the dogs of the present study was likely associated with the joint transitioning from its ordinary role of increasing stride length to lengthening and shortening the TL to accommodate the step dimensions.

Results of the present study suggested HEPs that include descending stairs might be useful for increasing the ROM of the shoulder joint but may not specifically target flexion or extension of the shoulder joint. Thus, for dogs with tendinopathy of the shoulder joint, in which the ROM of the joint is decreased in all directions because of pain, rehabilitation programs could use descending stair exercises during the subacute phase to maintain the ROM of the joint once activity increases.4 Conversely, descending stair exercises may not be specific enough to improve the ROM of the hip joint in dogs with hip dysplasia because the decrease in the ROM of the hip joint of those dogs has a capsular pattern in which extension and then abduction of the joint become restricted.4

For the dogs of the present study, mean peak extension of the elbow joint during the flat exercise (132.03°) was significantly greater than that during both the ramp (113.95°) and stair (114.79°) exercises; however, mean peak extension did not differ significantly between the ramp and stair exercises. Those results may reflect step-induced limitations to elbow joint movement or the initial caution with which dogs descended the ramp. When trotting across a flat surface, dogs are able to maintain their natural stride, which includes full extension of the elbow joint at the end of the stance phase immediately before toe off. When a dog is descending steps, the rise of the previous step limits the limb from achieving full retraction at the end of the stance phase. In contrast, peak extension of the elbow joint of dogs during ascent of a ramp (156.6°) is significantly greater than that during ascent of stairs (149.0°) or trotting across a flat surface (139.6°).5 The difference in peak extension of the elbow joint during ascent of a ramp versus stairs is believed to be caused by the stair dimensions restricting the stride length of dogs. Interestingly, mean stride length did not differ significantly between the stair and ramp exercises and was actually greater for the stair exercise for the TLs of the dogs of the present study and the PLs of dogs of another study.6 Therefore, from a therapeutic standpoint, trotting across a flat surface would appear to be more effective than stair exercises for increasing elbow joint extension because the natural stride of dogs is unaffected by step dimensions when trotting across a flat surface.

Alterations in the COM affect the mechanics of the walk and trot of dogs, even when traversing a flat surface,21 and changes in the COM to accommodate ascent or descent of various slopes might explain the kinematic differences observed in the limbs of dogs at various gaits over various surfaces.22 When dogs travel downhill, loading forces shift to the TLs,4 and the animals adjust their COM to accommodate this and prevent overbalancing in a forward direction. Consequently, the TLs are placed more cranially when moving in a downhill direction than during normal locomotion across a flat surface to account for a lack of propulsion, which may explain the nonsignificant differences in the mean peak extension of the elbow joint between the stair and ramp exercises of the present study.

Mean peak flexion of the elbow joint differed significantly among all 3 exercises of the present study and was greatest (smallest angle) for the stair exercise (34.36°) and lowest (largest angle) for the flat exercise (66.23°). During the stair exercise, peak flexion of the elbow joint occurred when dogs lifted the TL to clear the edge of the step. Investigators of another study5 suggested that flexion of the elbow joint accounts for the kinematic differences observed in the TLs of dogs ascending a ramp or stairs or trotting across a flat surface. In that study,5 peak flexion of the elbow joint was significantly greater when dogs were ascending a ramp versus stairs, which suggests that lifting of the TL to clear the edge of the steps is not solely responsible for the differences observed in the magnitude of elbow joint flexion between the ramp and stair exercises. Moreover, during stair exercises, it appears that shortening of the limb to clear the edge of the step occurs at the level of the elbow and stifle joints of the TLs and PLs, respectively.

For the dogs of the present study, the overall mean ROM of the elbow joint during the stair exercise (80.43°) was significantly greater than that during the ramp (67.95°) and flat (65.81°) exercises. This was in contrast to results of another study,9 in which the ROM of the elbow joint of dogs did not differ significantly when the dogs were descending a ramp or walking across a flat surface. However, the slope (6.3°) of the ramp used in that study9 was not as steep as the slope (35°) of the ramp used in the present study. Alterations in the ROM of the elbow joint facilitate lengthening and shortening of the TL, and the slope of a ramp is key to the magnitude of those changes.4 When descending stairs, the elbow joint must be flexed sufficiently to allow the TL to clear the edge of each step, whereas when descending a ramp, the elbow joint only needs to be flexed to a magnitude similar to that when the dog is trotting across a flat surface, because the surface of the ramp is unimpeded aside from its downward slope. Conversely, flexion of the elbow joint is greater when dogs are ascending a ramp (110.9°) versus stairs (92.0°) because the TL has to adjust to the uphill surface of the ramp rather than simply clear the edge of a step and because flexion of the elbow joint when ascending either a ramp or stairs is greater than that required for trotting across a flat surface (46.0°).5 Therefore, from a rehabilitation standpoint, although both descending stair and ascending ramp exercises appear to increase the ROM for the elbow joint, the ascending ramp exercise is preferred because it increases the mean ROM for the elbow joint to a greater extent than the descending stair exercise (110.9° vs 80.43°).

The mean peak extension, peak flexion, and ROM of the carpal joint did not differ significantly among the 3 exercises of the present study; however, the mean ROM for the carpal joint was greatest for the stair exercise (115.87°). In another study,5 mean extension, flexion, and ROM of the carpal joint were significantly increased when dogs ascended a ramp versus stairs. Similarly, the mean ROM for the tarsal joint is significantly increased when dogs ascend7 or descend6 stairs versus ascending or descending a ramp or trotting across a flat surface. In regard to descending stairs versus a ramp, it has been postulated that maximum flexion of the tarsal joint occurs when a dog lifts the PL to clear the edge of the step, which is not required during ramp descent, and maximum extension of the tarsal joint occurs when the foot makes contact with the next step.6 In the present study, the mean ROM of the carpal joint during the stair exercise was 8° greater than that during the flat exercise and 18° greater than that during the ramp exercise, which suggested that the movement patterns for the carpal joint may mirror those for the tarsal joint.

Velocity directly affects stride length and may also affect flexion and extension of TL joints,23 particularly the shoulder joint.16 For the dogs of the present study, although the mean velocity did not differ significantly among the 3 exercises, it was greatest during the flat exercise (1.45 m/s) followed by the ramp exercise (1.16 m/s) and slowest for the stair exercise (1.01 m/s), which was similar to the findings of another study.9 For dogs, a velocity of 1.7 to 2.1 m/s is considered acceptable for a trot across a flat surface,5 which is considerably greater than the mean velocity attained for the dogs of the present study during the flat exercise. An increase in velocity may increase the ROM for the joints of the TL. The dogs of the present study were allowed to trot at what appeared to be their natural pace and move on the stairs and ramp at a speed that appeared comfortable, which was considered reasonable because dogs are generally allowed to dictate the pace of exercises that comprise HEPs. During exercise regimens, changes in velocity are affected by challenges to a dog's balance and proprioception, and velocity changes are most frequently observed during obstacle walking, which is considered particularly useful for dogs that need to improve motor control and advanced limb placement.9 However, the fact that, in the present study, the mean velocity was slowest when dogs were descending stairs suggested that a descending stair exercise might also be a beneficial exercise for dogs with impaired balance and proprioception. In practice, dogs should be allowed to adjust their exercise velocity in accordance with their stage of rehabilitation, and dogs with impaired ROM may move slowly during the initial stages of rehabilitation simply because they find the exercises difficult to complete.

Challenges to balance and proprioception can affect the efficacy of stair and ramp exercises.4 When descending stairs or a ramp, dogs must transfer weight from side to side to ensure each limb clears the edge of the step or surface of the ramp. The physical ability, mobility, and neurologic status of each animal should be considered when rehabilitation exercises are prescribed. For example, a dog with an injury that impairs the ROM of the elbow joint may be able to descend stairs, which should help increase the ROM of that joint, but might use compensatory movement to do so during the period immediately following the injury, and an alternative exercise for maintaining or increasing ROM might be more appropriate at that stage of rehabilitation. Both ascending (incline) and descending (decline) exercises require dogs to alter their center of gravity and shift their weight laterally from side to side, which challenge their balance and proprioception.4,24

Stair and ramp exercises can also be useful for increasing the strength, ROM, control, and placement of the PLs24 as well as the TLs. Ascending stair and ramp exercises require the PLs to propel the dog forward and upward, which improves their strength.5 Conversely, descending stair and ramp exercises improve the strength of the TLs by accentuating their braking role through eccentric contraction of protractor muscles.22 However, caution is necessary because eccentric, or negative, work can place too much force on weak muscles and cause or exacerbate an injury.25 We recommend that descending, or eccentric, exercises should only be included in HEPs for dogs when appropriate.

A disadvantage of ramps as exercise modalities in HEPs is the potential for lack of control of the dog's stride length and movement. In the present study, dogs appeared to become more confident during repetition of the ramp exercise and tended to jump from the midpoint to the bottom of the ramp during the latter trials, which could negate the intended effects of the exercise. Therefore, the experience of both the dog and handler should be evaluated prior to prescribing ramp exercise as part of an HEP. We recommend that ramp exercise should be prescribed only for dogs with handlers who are compliant and experienced or trained to ensure that the dog properly executes the exercise and prevent possible detrimental effects or overexcitement.

Results of the present study indicated that descending stair exercise can improve the ROM of the shoulder and elbow joints of dogs, compared with simply trotting across a flat surface. A descending ramp exercise might also be beneficial for rehabilitation of dogs with elbow joint injuries but may not be as effective as a descending stair exercise and may be difficult for handlers to conduct properly in an HEP. Moreover, because a ramp with a 35° slope might not be readily accessible outside of a clinical or rehabilitation setting, the dimensions of the steps used for the stair exercise in the present study were consistent with the dimensions of steps commonly found in many UK households, where HEPs generally take place. Dogs need to remain calm and move in a straight line when traversing stairs or a ramp; therefore, ascending and descending stair or ramp exercises might not be suitable for all dogs. Typically, movement is easier to control on stair exercises than ramp exercises because the stride length is dictated by the dimensions of the steps, whereas dogs can alter stride length voluntarily on a ramp. All HEPs should be regularly reviewed by a physiotherapist to ensure that the prescribed exercises are being performed correctly and consistently and are having the desired effects.9 The healthy dogs of the present study required minimal acclimation to the step and ramp equipment used and frequently attempted to jump down the ramp or over steps as they became accustomed to the exercises. Therefore, during HEPs, owners or handlers must have sufficient control of dogs by use of appropriate restraint (leashes or harnesses) to ensure that the prescribed exercises are performed correctly and do not put the dogs at risk for further injury.

Although stairs are a good functional exercise for dogs, they may not always be present or present as a straight flight in a home. To our knowledge, no studies have been conducted to determine how step or ramp dimensions or slopes affect rehabilitation results for dogs of various sizes. Results of the present study suggested that breed and size may affect the kinematics of the TLs of dogs because fewer significant differences were identified among the 3 exercises evaluated than in other studies.5–7 We believe this was because the dogs of the present study represented multiple breeds of various sizes, which led to large variation and limited the power to detect significant differences. It is also currently unknown what slope or gradient is necessary for stair and ramp exercises to induce a significant increase in the ROM for TL joints. That information could potentially affect development of HEPs, and further research into the effect of various breeds and stair and ramp dimensions on TL kinematics is warranted to expand the existing evidence on which HEPs are based.

Stair and ramp exercises can be used in the rehabilitation of dogs with orthopedic and neurologic disorders and as components of postoperative rehabilitation regimens; however, they should be implemented only at the proper stage of rehabilitation to avoid injury or detrimental effects. To our knowledge, the effects of stair and ramp exercises on lame dogs have not been evaluated, and because those exercises alter the kinematics of both the TLs and PLs, their use for the rehabilitation of lame dogs should be considered carefully prior to implementation to avoid placing unwanted stress on the affected limb. However, if the goal is to increase the weight-bearing capacity of the TLs, descending stair or ramp exercises will increase the weight and forces applied to those limbs and help achieve that goal.22 Those exercises can also be used to strengthen TL muscles and improve balance, motor control, proprioception, and limb placement.

Results of the present study suggested that descending stair and ramp exercises may have therapeutic value in rehabilitation programs for dogs. The TL kinematic results determined for the orthopedically normal dogs of this study during descending stair and ramp exercises can be used as baseline data for comparison with those for other therapeutic exercises and facilitate evidence-based decisions during the development of HEPs to ensure that those programs are as effective as possible. Descending stair exercises should help increase the ROM of the shoulder joint and the flexion and ROM of the elbow joint and may be useful for the rehabilitation of dogs following surgery or orthopedic or neurologic injury. Other effects of descending stair and ramp exercises, such as improvements in balance, proprioception, and TL muscle strength, may also occur, but require further investigation.

Acknowledgments

This manuscript represents part of a thesis submitted by Nadia L. Kopec to Hartpury College as partial fulfillment of the requirements for a Master of Science degree.

No third-party funding or support was received in connection with this study or the writing or publication of the manuscript. The authors declare that there were no conflicts of interest.

ABBREVIATIONS

COM

Center of mass

HEP

Home exercise program

PL

Pelvic limb

ROM

Range of movement

TL

Thoracic limb

Footnotes

a.

HX-WA3 camcorder, Panasonic, Kadoma, Osaka, Japan.

b.

ProSuite Software 8, Dartfish, Fribourg, Switzerland.

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Contributor Notes

Address correspondence to Mrs. Kopec (nadia@nkvetphysio.com).