Biomechanical comparison of standing posture and during trot between German shepherd and Labrador retriever dogs.

It is widely accepted that canine breeds stand and move differently. The prevalence of various musculoskeletal disorders such as hip and elbow dysplasia is also different between breeds. German shepherd dog (GSD) and Labrador retriever dog (LRD) are two large breeds with different conformations that have high prevalence of these disorders. This study quantifies the movement and standing posture of twelve healthy GSDs and twelve healthy LRDs to identify biomechanical similarities and differences that may be linked to sub-optimal hip and elbow mechanics. A pressure walkway and a motion capture system obtained measures of kinetics, kinematics and conformation during standing and trot. During standing, LRDs carry a greater percentage of the weight on the forelimbs (69%±5% vs. GSDs: 62%±2%, p<0.001) and their body Centre of Pressure (CoP) is located more cranially (p<0.001). GSDs had a greater pelvic tilt (79°±8 vs. 66°±9°, p = 0.004), more flexed stifles (44°±9° vs. LRDs: 34°±10°, p<0.05) and hocks (58°±11° vs. 26°±9°, p<0.01) and more extended hips (-10°±11° vs. 30°±12°, p<0.001). During trot, the GSDs' CoP had a longer anterior-posterior trajectory (151%±22% vs. LRDs: 93%±25% of the withers height, p<0.001). Stride parameters and loading of limbs were similar when normalised to the size and weight of the dog, respectively. The LRDs had a more extended thoracolumbar angle (p<0.001) and a less flexed lumbosacral angle (p<0.05). The LRDs' hip remained flexed during trot whereas the GSDs' hip joint was less flexed during swing (p<0.001) and more extended in late stance and early swing (p<0.001). In conclusion, the LRDs and GSDs differ in the way they stand and move and this would result in different loading pattern of the joints. Further investigation is required to determine the extent to which biomechanical differences are linked to musculoskeletal problems presented clinically.

Distraction index and Norberg angle to distinguish dysplastic and non-dysplastic hips based on FCI score.

OBJECTIVE: Radiographic hip scoring according to the Fédération Cynologique Internationale (FCI) and PennHIP (Pennsylvania Hip Improvement Program) method was performed with the purpose to compare the PennHIP and FCI results as well as coxofemoral joint laxity by correlation of Norberg angle and distraction index measurements. MATERIALS AND METHODS: A total of 167 dogs of various breeds presented for official screening examination in a veterinary teaching hospital in Germany were included. Using receiver operating characteristic analysis, the best Norberg angle and distraction index cut-off values to distinguish between dysplastic and non-dysplastic groups based on FCI grades and to distinguish between lax and tight hip joints according to the PennHIP proposal were calculated. RESULTS: More than one third (38.2 %) of dogs that passed the breeding criterions according to FCI (grades A and B) were in the half of the population with lax hip joints and should not be used for breeding according to the PennHIP proposal. A cut-off value for the distraction index of 0.44 with sensitivity of 82.7 % and specificity of 84.2 % was superior to the best cut-off value for the Norberg angle at 101.8° with sensitivity of 82.7 % and specificity of 71.9 % to discriminate between non-dysplastic joints (A, B) and dysplastic joints (C, D, E). CONCLUSIONS AND CLINICAL RELEVANCE: Our results show a limited impact of laxity on the FCI grading. Breeding selection processes that are based on the FCI method could profit by an additional and complementary use of the distraction index.

Comparison of Rotation Force to Maintain Acetabular Ventroversion after Double Pelvic Osteotomy and 2.5 Pelvic Osteotomy in a Canine Cadaveric Model.

OBJECTIVE: The aim of this article was to compare the force required to maintain the acetabular ventroversion after double pelvic osteotomy (DPO) and modified triple pelvic osteotomy (2.5PO). METHODS: Unilateral DPO (group A) and unilateral modified DPO (group B = 2.5PO) were performed on cadaveric canine pelves (n = 10/group). The twisting moment required to maintain fragment position for DPO and 2.5DPO was compared. RESULTS: Mean twisting moment for the DPO group [5.92 N/m ± 2.59 (range, 2.61-12.17 N/m)] and the 2.5PO group [2.11 N/m ± 0.93 (range, 0.63 -3.85 N/m)] was significantly different (p < 0.01). CONCLUSION: Dorsal cortex osteotomy of the ischium decreases the acetabular segment rotation force. Decreased force may facilitate acetabular rotation during DPO procedure.

Canine hip dysplasia: A natural animal model for human developmental dysplasia of the hip.

Developmental dysplasia of the hip (DDH) in humans is a common condition that is associated with hip pain, functional limitations, and secondary osteoarthritis (OA). Surgical treatment of DDH has improved in the last decade, allowing excellent outcomes at short- and mid-term follow-up. Still, the etiology, mechanobiology, and pathology underlying this disease are not well understood. A pre-clinical animal model of DDH could help advance the field with a deeper understanding of specific pathways that initiate hip joint degeneration secondary to abnormal biomechanics. An animal model would also facilitate different interventional treatments that could be tested in a rigorous and controlled environment. The dog model exhibits several important characteristics that make it valuable as a pre-clinical animal model for human DDH. Dogs are naturally prone to develop canine hip dysplasia (CHD), which is treated in a similar manner as in humans. Comparable to human DDH, CHD is considered a pre-OA disease; if left untreated it will progress to OA. However, progression to OA is significantly faster in dogs than humans, with progression to OA within 1-2 years of age, associated with their shorter life span compared to humans. Animal studies could potentially reveal the underlying biochemical pathway(s), which can inform refined treatment modalities and provide opportunities for new treatment and prevention targets. Herein, we review the similarities and differences between the two species and outline the argument supporting CHD as an appropriate pre-clinical model of human DDH. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1807-1817, 2018.

Etiopathogenesis of Canine Hip Dysplasia, Prevalence, and Genetics.

First identified in 1935, canine hip dysplasia is thought to be the most common orthopedic condition diagnosed in the dog. It is most prevalent in large and giant breed dogs, with a complex polygenic mode of inheritance, and relatively low heritability. External factors including caloric intake when growing have a significant effect on phenotypic expression. Initial joint laxity progresses to osteoarthritis due to subluxation and abnormal wearing. Selective breeding programs to attempt to decrease prevalence have shown modest results so far.

Vertical forces assessment according to radiographic hip grade in German shepherd dogs.

OBJECTIVE: To investigate the correlation between radiographic hip grade and kinetic parameters in German shepherd dogs. METHODS: Dogs were distributed into five groups of eight dogs each according to hip grade (A, B, C, D or E). Dogs were submitted to clinical evaluation and kinetic analysis. Five valid passages were analysed using data collected from a pressure walkway. Peak vertical force, vertical impulse and stance phase duration were evaluated at velocity (1 · 2 to 1 · 4 m/s) ±0 · 1 m/s(2) acceleration. Kinetic data between groups were compared. RESULTS: In pelvic limbs, mean peak vertical force decreased progressively from grade C (mild) to grade E (severe) hip dysplasia. The vertical impulse was decreased in groups C and E compared to groups A, B and D; stance phase duration did not differ significantly between groups. CLINICAL SIGNIFICANCE: Mean peak vertical force was lower in dogs with severe hip dysplasia compared with mildly dysplastic dogs. These results suggest that hip dysplasia degree can affect lameness severity.

Comparison of body weight distribution, peak vertical force, and vertical impulse as measures of hip joint pain and efficacy of total hip replacement.

OBJECTIVE: To determine whether there is a difference between the ability of peak vertical force (PVF), vertical impulse (VI), and percentage body weight distribution (%BW(dist) ) in differentiating which leg is most affected by hip joint pain before total hip replacement (THR) surgery, and for measuring changes in limb use after THR surgery. STUDY DESIGN: Prospective clinical study. ANIMALS: Dogs (n = 47). METHODS: Ground reaction force (GRF) data were collected using a pressure-sensitive walkway the day before THR surgery and at ∼3, 6, and 12 months postoperatively. PVF and VI expressed as a percentage of body weight (%PVF, %VI), and %BW(dist) were recorded. Regression models performed separately for each outcome were used for statistical analysis. RESULTS: When comparing limb use between the affected limb (AP) and the nonaffected limb (NP) preoperatively, differences between limbs were statistically significant when evaluated using PVF (P = .023), VI (P = .010), and %BW(dist) (P = .012). When evaluating the magnitude of absolute and percentage change difference in AP limb use preoperatively versus postoperatively, differences were statistically significant when evaluated using PVF (P < .001 and P = .001, respectively), VI (P = .001 and P < .001) and %BW(dist) (P < .001 and P < .001). CONCLUSION: There appeared to be no difference in the sensitivity of VI, PVF, and %BW(dist) for evaluating limb use before and after THR.

Canine hip and elbow dysplasia in UK Labrador retrievers.

This paper examines the outcomes from recent genetic analyses of hip and elbow scores from British Veterinary Association (BVA)/UK Kennel Club (KC) screening programmes targeted at reducing the prevalence of hip dysplasia (HD) and elbow dysplasia in UK Labrador retrievers. The analyses made use of 25,243 hip scores and 3613 elbow scores. Heritabilities (± standard error) for hip score, analysed on a log scale, and for elbow score were 0.35±0.02 and 0.19±0.04, respectively, with a genetic correlation of 0.41±0.09. For both hip and elbow scores, there was a near perfect genetic correlation between the left and right joint; analysis of hip score showed a predictive benefit of using the total of left and right scores rather than worst score and the benefit of using all component scores rather than their aggregate score. Downward genetic trends were observed in both hip and elbow scores, although the latter was consistent with it being correlated to response to genetic change in hip score. Estimated breeding values (EBVs) offered substantial benefits in accuracy and hence genetic progress when compared to the use of phenotypes for both hip and elbow scores. There are major opportunities for improving selection against elbow dysplasia through the use of bivariate evaluations, although progress against dysplasia would be improved by more widespread elbow scoring. The studies highlighted a number of ways in which data recording for addressing complex traits may be improved in the future. Ongoing advances in genomic technology may be utilised for increasing the rate of genetic progress in selection against HD and for complex diseases in general, through the use of genomic evaluations.

Genetic evaluation of elbow scores and the relationship with hip scores in UK Labrador retrievers.

A linear mixed model analysis of elbow and hip score data from UK Labrador retrievers was used to estimate the heritability of elbow score (0.16-0.19) and to determine a moderate and beneficial genetic correlation with hip score (0.40). A small improvement in the genetic trend of elbow score was observed during the years 2000-2008, equivalent to avoiding only the worst 3-4% of scored dogs for breeding, but close to what may have been anticipated if the current British Veterinary Association-approved guidelines were followed. Calculations suggested that a correlated response to indirect selection on hip score may elicit a greater response than direct selection on elbow score and that the genetic trend in elbow score may be explained as a consequence of the stronger selection pressure that has been placed on hip score. Increases in the accuracy of estimated breeding values for elbow score of 4-7% for dogs with elbow data only and 7-11% for dogs with both hip and elbow score were observed from bivariate analysis of elbow and hip data. A selection index confirmed the benefits of bivariate analysis of elbow and hip score data by identifying increases in accuracy (directly related to the response to selection) of 14% from the use of optimum coefficients compared to use of hip data only. The quantified genetic correlation means that hip score effectively acts as a 'secondary indicator' of elbow score in this breed and the preponderance of hip data means that it acts as a major source of information that may be used to improve the accuracy of estimates of genetic risk for elbow dysplasia.

Genetic evaluation of hip score in UK Labrador Retrievers.

Hip dysplasia is an important and complex genetic disease in dogs with both genetic and environmental influences. Since the osteoarthritis that develops is irreversible the only way to improve welfare, through reducing the prevalence, is through genetic selection. This study aimed to evaluate the progress of selection against hip dysplasia, to quantify potential improvements in the response to selection via use of genetic information and increases in selection intensity, and to prepare for public provision of estimated breeding values (EBV) for hip dysplasia in the UK. Data consisted of 25,243 single records of hip scores of Labrador Retrievers between one and four years old, from radiographs evaluated between 2000 and 2007 as part of the British Veterinary Association (BVA) hip score scheme. A natural logarithm transformation was applied to improve normality and linear mixed models were evaluated using ASREML. Genetic correlations between left and right scores, and total hip scores at one, two and three years of age were found to be close to one, endorsing analysis of total hip score in dogs aged one to three as an appropriate approach. A heritability of 0.35±0.016 and small but significant litter effect (0.07±0.009) were estimated. The observed trends in both mean hip score and mean EBV over year of birth indicate that a small genetic improvement has been taking place, approximately equivalent to avoiding those dogs with the worst 15% of scores. Deterministic analysis supported by simulations showed that a 19% greater response could be achieved using EBV compared to phenotype through increases in accuracy alone. This study establishes that consistent but slow genetic improvement in the hip score of UK Labrador Retrievers has been achieved over the previous decade, and demonstrates that progress may be easily enhanced through the use of EBVs and more intense selection.

The relationship between the size of caudolateral curvilinear osteophyte of the canine femoral neck and the radiographic view.

Caudolateral curvilinear osteophyte (CCO), an osteophyte at the site of joint capsule attachment on the caudal aspect of the femoral neck, has been advocated as a radiographic criterion for coxofemoral subluxation. The correlation between the presence of CCO on radiographs (radiographic-CCO), the size of the CCO (CCO index) on three-dimensional computed tomographic (CT) images, and hip evaluation using transverse CT images was assessed in 22 Border Collies. CCOs were detected on the radiographs and CT images of 32% and 100% femurs, respectively. The CCO index correlated significantly with radiographic-CCO, but a large CCO index did not necessarily imply that the CCO was visible on radiographs. Hence, radiographic-CCO findings should be used cautiously in hip evaluation of Border Collies.

The relationship between the size of caudolateral curvilinear osteophyte of the canine femoral neck and the radiographic view

Caudolateral curvilinear osteophyte (CCO), an osteophyte at the site of joint capsule attachment on the caudal aspect of the femoral neck, has been advocated as a radiographic criterion for coxofemoral subluxation. The correlation between the presence of CCO on radiographs (radiographic-CCO), the size of the CCO (CCO index) on three-dimensional computed tomographic (CT) images, and hip evaluation using transverse CT images was assessed in 22 Border Collies. CCOs were detected on the radiographs and CT images of 32% and 100% femurs, respectively. The CCO index correlated significantly with radiographic-CCO, but a large CCO index did not necessarily imply that the CCO was visible on radiographs. Hence, radiographic-CCO findings should be used cautiously in hip evaluation of Border Collies.

Ground reaction force analysis of unilateral coxofemoral denervation for the treatment of canine hip dysplasia.

Coxofemoral denervation has success rates of 90-96% reported retrospectively for palliative treatment of hip dysplasia. The aim of this study was to objectively evaluate ground reaction forces (GRF) in dysplastic dogs after unilateral denervation. Unilateral coxofemoral denervation was performed by means of a previously reported technique on 10 dogs with asymmetric gait. GRF were measured at zero, one and three months. Statistical analysis was performed using repeated measures analysis of variance and paired t-tests, with p< or =0.05. There was a lack of significant difference in mean peak vertical force (PVF) or vertical impulse (VI) in the operated limb (TX) over time. For the unoperated limb (UnTX), mean PVF and VI significantly decreased over time. The dogs were significantly more lame in the TX limb initially and at one month, however, there was no significant difference between limbs by three months. In the UnTX limb, 40% of dogs decreased PVF by >5%, by three months. Over time, there was no significant difference in mean average rise or mean average fall for TX or UnTX limbs. Between limbs, mean rise in the TX limb was significantly less at zero months, but not at one or three months. Decreased compensatory load shifting to the UnTX limb due to procedural efficacy could explain decreases in the UnTX limb. Worsening disease could also explain decreases in the UnTX limb, and may indicate a protective effect denoted by a lack of change in the TX limb. Longer follow-up would be required in improved dogs in order to document continued efficacy.

Freqüência da displasia coxofemoral em cães da raça Pastor Alemão / Frequency of hip dysplasia in German Shepherd dogs

One hundred twenty-three radiographs of German Shepherd dogs (47 females and 76 males) from Military Police of Minas Gerais State were studied from April 2001 to july 2004, with the purpose of establishing the frequency and asymmetry of hip displasia. The radiographs were taken with the animals in the ventrodorsal position, with the limbs parallel and the pelvis symmetric. The average age of the dogs was 33.8±23.5 months-old. The study indicated that 89.4 percent of them had hip dysplasia (91.5 percent of females and 88.2 percent of males), being 6.3 percent unilateral, 17.3 percent bilateral asymmetric, and 76.4 percent bilateral symmetric. The frequency of hip displasia in the studied population was high, indicating the necessity of an efficient control program of the disease.

Comparison of conservative management and juvenile pubic symphysiodesis in the early treatment of canine hip dysplasia.

OBJECTIVES: To evaluate the efficacy of juvenile pubic symphysiodesis (JPS) in a clinical setting for the early treatment of canine hip dysplasia (CHD), and to identify its indications and contraindications. METHODS: The final degree of CHD using the FCI (Fédération Cynologique Internationale) CHD classification in 5 Grades (A, B, C, D, E) was assessed at skeletal maturity in two homogeneous groups of dogs assessed at the age of 14 to 22 weeks and selected according to their susceptibility to CHD; one group was treated with JPS and one group was conservatively managed. Two hundred seventeen puppies completed the study; 81 were treated with JPS (group 1) and 76 were conservatively managed (group 2). A third group of 60 puppies with normal hips was followed as a negative control group. RESULTS: In group 1, 43.2% of the puppies had regression or a lack of progression of the disease in the final evaluation (Grade A & B), 25.9% had mild CHD (Grade C) and 30.9% had moderate and severe CHD (Grade D & E). In group 2, 23.6% of the puppies did not show any development of the disease (Grade A & B), 21.1% had mild CHD (Grade C) and 55.3% developed moderate to severe CHD (Grade D & E). Further investigation was done by comparing the severity of early signs of susceptibility to CHD with the final FCI Grades at adulthood in both groups. CLINICAL SIGNIFICANCE: The JPS procedure increased the odds of arresting or limiting the progression of CHD in mild to moderate grades of CHD, while it was less effective or ineffective in more severe forms.

Influence of borderline hip dysplasia on joint kinematics of clinically sound Belgian Shepherd dogs.

OBJECTIVE: To detect changes in joint kinematics of clinically sound dogs with or without radiographically detectable borderline hip dysplasia (HD). ANIMALS: 20 Belgian Shepherd Dogs (Malinois; mean +/- SD age, 2.75 +/- 1.32 years) with no clinical signs of HD. PROCEDURES: Kinematic gait analysis was performed in Malinois walking on a treadmill. On the basis of results of radiographic examination for HD and in accordance with guidelines established by the Fédération Cynologique Internationale, dogs were assigned to group 1 (no radiographic signs of HD; 8 dogs) or group 2 (borderline HD; 12 dogs). Ground reaction forces and weight distribution among limbs and differences between groups were evaluated. Maximal sagittal angle during the stance and swing phases, the time at which they were detected, and angle velocities were calculated for joints of the hind limbs. RESULTS: Ground reaction forces revealed no differences between groups. Dogs in group 1 had significant changes (earlier time for maximal flexion of the hip joint and less flexion and less range of motion of the stifle joint), compared with results for dogs in group 2. Maximal angle velocity of the stifle and tarsal joints was significantly lower during the swing phase in group 1 than in group 2. CONCLUSIONS AND CLINICAL RELEVANCE: This study revealed that dogs with borderline HD had altered joint kinematics. Our data provide basic kinematic values for clinically sound and affected dogs and can be used to investigate the long-term effects for subclinical radiographic changes of the hip joints of dogs.

Effects of pelvic positioning and simulated dorsal acetabular rim remodeling on the radiographic shape of the dorsal acetabular edge.

A radiographic study was conducted to evaluate the effect of pelvic rotation and of simulated dorsal acetabular rim (DAR) remodeling on the radiographic appearance of the dorsal acetabular edge (DAE). The DAE is the line connecting the cranial and caudal rims of the acetabulum when viewing a pelvic radiograph made with the dog in the ventrodorsal position with the hind limbs extended. In this study, it was hypothesized that the DAE would change with pelvic rotation and simulated DAR damage. Ventrodorsal radiographs of eight canine pelves were made at 0 degrees, 5 degrees, and 10 degrees of left and right pelvic rotation over its longitudinal axis. These radiographs were repeated following removal of 2, 4, and then 6 mm of bone from the right DAR of each pelvis. The ratio of acetabular width to maximum depth of the DAE was calculated. The area between the DAE and a straight line connecting the cranial and caudal acetabular rims was measured digitally. The DAE depth and area changed with pelvic rotation, and with increasing simulated DAR damage. A linear relationship between the obturator foramina width ratio and pelvic rotation allowed estimation of the degree and direction of pelvic rotation. Equations were developed from the data to assist with the estimation of the amount of DAR remodeling on a clinical radiograph.

Double-blind, placebo-controlled trial of the pain-relieving effects of the implantation of gold beads into dogs with hip dysplasia.

Seventy-eight dogs with pain due to hip dysplasia were studied in a controlled, double-blind clinical trial to evaluate gold bead implantation as a pain-relieving treatment. The dogs were randomly assigned to two groups, 36 in the gold implantation group and 42 in the placebo group. Both groups were treated equally regarding anaesthesia, hair clipping and penetration of the skin with the same type of needle. The gold implantation group had small pieces of 24 carat gold inserted through needles at five different acupuncture points and the placebo group had the skin penetrated at five non-acupuncture points so as to avoid any possible effect of stimulating the acupuncture points. A certified veterinary acupuncturist marked the points, and two surgeons performed the implantations according to a randomisation code made in advance. After 14 days, three months and six months, the owners assessed the overall effect of the treatments by answering a questionnaire, and the same veterinarian examined each dog and evaluated its degree of lameness by examining videotaped footage of it walking and trotting. The treatment was blinded for both the owners and the veterinarian. There were significantly greater improvements in mobility and greater reductions in the signs of pain in the dogs treated with gold implantation than in the placebo group. The veterinarian's and the owners' assessments corresponded well.

Effect of dorsal hip loading, sedation, and general anesthesia on the dorsolateral subluxation score in dogs.

OBJECTIVE: To determine whether dorsal loading of the pelvis and type of chemical restraint affected the dorsolateral subluxation (DLS) score of dog hips. STYDY DESIGN: In vivo testing of diagnostic method. ANIMALS: Labrador retrievers, Greyhounds, and crosses between both breeds (n = 119 dogs). METHODS: Dorsal load was applied to the hips through a strap that was placed over the hips, and the peak vertical and steady-state vertical, ground-reaction forces exerted on the stifles were measured in the DLS position. The DLS score was measured with their hips under dorsal load and compared with the DLS score without load. For 24 dogs, the DLS score was measured both under chemical restraint (medetomidine) and under general anesthesia. Wilcoxon-signed rank test and paired t test was used to compare effects of dorsal load and restraint method on the left and right DLS hip score, and P <.05 was considered significant. RESULTS: Both stifles together accepted median 15% body weight in the vertical plane in the unloaded steady state. Loading the hips increased the steady-state, vertical ground-reaction force to 34% body weight. At 8 months of age, loading significantly decreased the DLS score from 65% +/- 11% (mean +/- SD) to 60% +/- 12% for left hips and 66% +/- 11% to 63% +/- 13% for right hips. The left hip DLS score was affected by load more consistently than the right hip. In general, loading the hips decreased the DLS score in all breeds by 4% to 6% except for the greyhounds, in which the DLS score was unchanged by dorsal loading. When grouped by their DLS scores, load significantly decreased DLS scores in dogs with unloaded scores greater than 55% (nondysplastic), whereas DLS scores of dogs with unloaded scores between 55% and 45% (dysplastic) and less than 45% did not change significantly with load. Unloaded scores did not change significantly when compared under sedation versus general anesthesia. However, load significantly decreased the DLS score under general anesthesia for the left hip but not for the right hip. CONCLUSIONS: Less than half of the vertical ground-reaction force normally exerted by the hindlegs of a standing dog was sufficient to induce hip subluxation in the DLS position. Although dorsal loading approximately doubled the steady-state, vertical ground-reaction force, the decrease in the DLS score under load was never greater than 6%. Furthermore, the DLS scores of dogs most likely to be dysplastic (based on DLS scores <45%) were not affected by load, whereas load slightly decreased DLS cores of dogs with DLS scores greater than 55%. CLINICAL RELEVANCE: External influences can change the DLS score significantly, but the magnitude of change is unlikely to be of clinical importance, making the method useful as a field screening test for both dysplastic and nondysplastic hips in young dogs.

Evaluation of methods for assessment of pain associated with chronic osteoarthritis in dogs.

OBJECTIVE: To identify variables and evaluate methods for assessing chronic pain in dogs. DESIGN: Prospective study. ANIMALS: 41 dogs with canine hip dysplasia (CHD), and 24 apparently healthy dogs with no history of pain. PROCEDURE: 2 veterinarians evaluated the dogs' locomotion and signs of pain. Owners of dogs with CHD and control dogs answered a questionnaire regarding their dogs' demeanor, behavior, and locomotion (descriptive scales) and assessed pain and locomotion (visual analog scales). Plasma concentrations of several stress-related hormones were determined, and 13 radiologic variables were assessed in affected hip joints. RESULTS: For many of the questions, answers provided by owners of dogs with CHD differed significantly from those of owners of control dogs. Stress hormone concentrations differed significantly between dogs with CHD and controls, but individual variation was too great for them to be of value in pain assessment. None of the radiologic variables examined correlated well with owner or veterinarian pain scores. CONCLUSIONS AND CLINICAL RELEVANCE: Chronic pain could be assessed in dogs with CHD through completion of the study questionnaire by a person familiar with the pet (eg, owner) after receiving appropriate education in its use. Eleven variables were identified as being potentially useful in assessment of chronic pain in dogs.