Simon C. Roe

Evaluation of Client‐Specific Outcome Measures and Activity Monitoring to Measure Pain Relief in Cats with Osteoarthritis

BACKGROUND There are no validated systems for measuring pain from osteoarthritis in cats. HYPOTHESIS Owner subjective assessments and an activity monitor (AM) can be used to detect pain in cats with osteoarthritis and to assess efficacy of treatments. ANIMALS Thirteen cats older than 10 years old, with owner-assessed decreases in activity, painful arthritic joints, and clinically normal blood work were included and evaluated for 3 weeks. METHODS A collar-mounted AM measured activity and a client-specific outcome measure (CSOM) questionnaire characterized the severity of impairment. Overall global quality of life was also evaluated for each treatment. In weeks 2 and 3, meloxicam (0.1 mg/kg, day 1; 0.05 mg/kg, days 2-5) or a placebo was administered in a blinded, randomized, cross-over manner to test the assessment systems. RESULTS The cats had a median of 4 arthritic appendicular joints. Activity counts for the week when cats (complete data on activity; n=9) were administered meloxicam were significantly higher than at baseline (P = .02) but not after placebo (P = .06). Baseline activity counts were not significantly different from placebo (P = .6). The CSOM data (n=13) showed that owners considered their cats to be more active on meloxicam compared with baseline (P = .001) and placebo (P < .004), and more active on placebo than at baseline (P < .01). Global quality of life improved significantly with meloxicam (P < .042). CONCLUSIONS AND CLINICAL IMPORTANCE Both an AM and a CSOM system can detect behavior associated with pain relief in cats that are arthritic. Objective activity data might allow subjective assessment systems to be validated for use in clinical studies.

Amantadine in a Multimodal Analgesic Regimen for Alleviation of Refractory Osteoarthritis Pain in Dogs

BACKGROUND Nonsteroidal anti-inflammatory drugs (NSAIDs) do not always provide sufficient pain relief in dogs with osteoarthritis (OA). HYPOTHESIS The use of amantadine in addition to NSAID therapy will provide improved pain relief when compared with the use of nonsteroidal analgesics alone in naturally occurring OA in dogs. ANIMALS Thirty-one client-owned dogs with pelvic limb lameness despite the administration of an NSAID. METHODS The study was randomized, blinded, and placebo controlled with parallel groups (days 21-42). On day 0, analgesic medications were discontinued. On day 7, all dogs received meloxicam for 5 weeks. On day 21, all dogs received amantadine (3-5 mg/kg once daily per os) or placebo for 21 days, in addition to receiving meloxicam. Assessments were performed before the study and on days 7, 21, and 42. Primary outcome measures were blinded owner assessments of activity using client-specific outcome measures (CSOM) on days 0, 7, 21, and 42. Data were analyzed by a mixed model approach. RESULTS For CSOM activity, there was a significant time by treatment effect (P=.009). On the basis of the planned post hoc t-tests of postrandomization means, there was a significant difference between treatment groups on day 42 (P=.030), with the amantadine group being more active. CONCLUSIONS AND CLINICAL IMPORTANCE In dogs with osteoarthritic pain refractory to an NSAID, physical activity is improved by the addition of amantadine. Amantadine might be a useful adjunct therapy for the clinical management of canine osteoarthritic pain.

Item generation and design testing of a questionnaire to assess degenerative joint disease-associated pain in cats

OBJECTIVE To determine the items (question topics) for a subjective instrument to assess degenerative joint disease (DJD)-associated chronic pain in cats and determine the instrument design most appropriate for use by cat owners. ANIMALS 100 randomly selected client-owned cats from 6 months to 20 years old. PROCEDURES Cats were evaluated to determine degree of radiographic DJD and signs of pain throughout the skeletal system. Two groups were identified: high DJD pain and low DJD pain. Owner-answered questions about activity and signs of pain were compared between the 2 groups to define items relating to chronic DJD pain. Interviews with 45 cat owners were performed to generate items. Fifty-three cat owners who had not been involved in any other part of the study, 19 veterinarians, and 2 statisticians assessed 6 preliminary instrument designs. RESULTS 22 cats were selected for each group; 19 important items were identified, resulting in 12 potential items for the instrument; and 3 additional items were identified from owner interviews. Owners and veterinarians selected a 5-point descriptive instrument design over 11-point or visual analogue scale formats. CONCLUSIONS AND CLINICAL RELEVANCE Behaviors relating to activity were substantially different between healthy cats and cats with signs of DJD-associated pain. Fifteen items were identified as being potentially useful, and the preferred instrument design was identified. This information could be used to construct an owner-based questionnaire to assess feline DJD-associated pain. Once validated, such a questionnaire would assist in evaluating potential analgesic treatments for these patients.

Kinetic evaluation of normal walking and jumping in cats, using a pressure-sensitive walkway

The kinetic parameters of the limbs of 23 normal, client-owned cats were evaluated by encouraging them to walk and jump normally on a pressure-sensitive walkway. Each cat was encouraged to walk across the walkway five times over a period of 30 to 45 minutes (by using food, toys, the owners presence and a purpose-built tunnel) at a target speed of 0·6 m/s (and an acceleration of less than ± 0·1 m/s2). They were then encouraged to jump on to the walkway from a height of 1 m five times at five-minute intervals. The kinetic parameters of peak vertical force (pvf) and vertical impulse (vi) were measured for each limb (the forelimbs only for the jumps), and expressed as a percentage of bodyweight (pvf%bw and vi%bw/s). Fifteen of the 23 cats satisfactorily completed three to five walks and two to five jumps that could be analysed. There were no significant differences between the pvf or vi of the left and right limbs, but both parameters were significantly greater for the forelimbs than the hindlimbs (P<0·001) for the walking data. The mean (sd) pvf%bw for the forelimbs and hindlimbs were 48·2 (6·0) and 38·3 (4·0), respectively, and the mean vi%bw/s were 16·9 (3·2) and 13·3 (2·8). Jumping down generated significantly greater pvf (P<0·01) and slightly greater vi than during walking; there were no significant differences between the left and right forelimbs. The mean pvf%bw was 148·9 (16·4) and the mean vi%bw/s was 18·1 (4·3).

Reliability and discriminatory testing of a client-based metrology instrument, feline musculoskeletal pain index (FMPI) for the evaluation of degenerative joint disease-associated pain in cats

The objective of this study was to test the readability, reliability, repeatability and discriminatory ability of an owner-completed instrument to assess feline degenerative joint disease (DJD)-associated pain (feline musculoskeletal pain index, FMPI). Readability was explored using four different formulas (Flesch, Fry, SMOG and FOG) and the final FMPI instrument was produced. To assess the instrument, client-owned cats that were defined as normal (normal group) or as having DJD-associated pain and mobility impairment (pain-DJD group) were recruited. A total of 32 client-owned cats were enrolled in the study (normal, n=13; pain-DJD, n=19). Owners completed the FMPI on two occasions, 14days apart. Internal consistency (reliability) and repeatability (test-retest) were explored using Cronbachs α and weighted κ statistic, respectively. Data from the two groups were compared using analysis of covariance (controlling for age) to evaluate discriminatory ability. The FMPI was constructed with 21 questions covering activity, pain intensity and overall quality of life. It had a 6th grade readability score. Reliability of the FMPI was excellent (Cronbachs α>0.8 for all groupings of questions in normal and pain-DJD cats) and repeatability was good (weighted κ statistic >0.74) for normal and pain-DJD cats. All components of the FMPI were able to distinguish between normal cats and cats with DJD (P<0.001 for all components). This initial evaluation of the FMPI suggests that this instrument is worthy of continued investigation.

Feline Musculoskeletal Pain Index: Responsiveness and Testing of Criterion Validity

BACKGROUND Progress in establishing if therapies provide relief to cats with degenerative joint disease (DJD)-associated pain is hampered by a lack of validated owner-administered assessment methods. HYPOTHESIS That an appropriately developed subjective owner-completed instrument (Feline Musculoskeletal Pain Index-FMPI) to assess DJD-associated impairment would have responsiveness and criterion validity. ANIMALS Twenty-five client-owned cats with DJD-associated pain. METHODS FMPI responsiveness (ability to detect the effect of an analgesic treatment) and validity (correlation with an objective measure) were explored through a stratified, randomized, double blinded, placebo-controlled, crossover 10-week clinical study. Meloxicam was administered to effect pain relief. A linear mixed model, backward stepwise regression, and Pearson correlations were used to assess responsiveness and criterion validity with the assumption that the NSAID would increase activity. RESULTS Positive responses of cats to placebo (P = .0001) and meloxicam treatment (P = .0004) were detected; however, the instrument did not detect any difference between placebo and meloxicam (linear mixed model), even for the high impairment cases. Percent meloxicam target dose administered, temperament, and total baseline FMPI score were covariates that most affected FMPI scores. Controlling for significant covariates, most positive effects were seen for placebo treatment. Positive treatment effects on activity were detected, but only for the cases designated as most highly impaired. CONCLUSIONS AND CLINICAL IMPORTANCE Neither responsiveness nor criterion validity were detected by the inclusion criteria for cases in this study. The data suggest that further work is indicated to understand factors affecting activity in cats to optimize inclusion criteria.

Evaluation of functional outcome after BFX total hip replacement using a pressure sensitive walkway.

OBJECTIVE To evaluate stance phase limb use after cementless (BFX) total hip replacement (THR) in dogs and to relate postoperative radiographic variables to static bodyweight distribution after surgery. STUDY DESIGN Prospective clinical study. ANIMALS Dogs (n=35) that had THR. METHODS THR was performed using the BFX THR technique. Postoperative pain management regimens were similar for all dogs. Standing bodyweight distribution (%BW(distrib)) was measured using a pressure sensitive walkway and radiographs made before surgery and at 3, 6, and 12 months after surgery. Repeated measures models (with backwards-stepping to obtain the final model) were used for statistical analysis. RESULTS Temporally, %BW(distrib) to the operated limb increased (P<.0001; normal by 3 months) and decreased to the unoperated limb (P=.0001) and also increased to the pelvic limbs and decreased to the thoracic limbs. %BW(distrib) to the unoperated limb was significantly less than the operated limb at 3, 6, and 12 months after surgery. Postoperative canal fill and femur flare were significantly negatively correlated with change in %BW(distrib) (estimate=-0.24, P=.0413). CONCLUSION BFX THR results in normal %BW(distrib) to the operated limb by 3 months after surgery. A greater fill of the proximal femur may be associated with a suboptimal outcome. CLINICAL RELEVANCE BFX THR normalizes standing bodyweight distribution dogs with hip osteoarthritis. Objective evaluation of THR outcome and radiographic features may reveal factors that could be improved through changes in prosthesis design or surgical technique.

Expression and Activity of COX-1 and 2 and 5-LOX in Joint Tissues from Dogs with Naturally Occurring Coxofemoral Joint Osteoarthritis

Understanding the neurobiology of pain in naturally occurring models of osteoarthritis (OA) may improve the understanding of human OA pain. Both COX and LOX have been associated with joint pain. This study evaluated COX‐1, COX‐2, and 5‐LOX expression and activity in a naturally occurring canine model of secondary OA. Hip joint capsule with synovial tissue (HJC) and femoral head subchondral bone (FH) was collected from normal dogs and dogs undergoing total hip replacement for coxofemoral joint OA. Tissues were analyzed for COX‐1, COX‐2, and LOX protein, and PGE2 and LTB4. Significantly more COX‐2 protein was present in OA HJC than normal joints (p = 0.0009). There was no significant difference in COX‐1 or LOX protein, although LOX protein was increased (p = 0.069). PGE2 concentration in normal and OA HJC was similar (p = 1.0). LTB4 concentration in OA HJC was significantly greater than normal HJC (p = 0.028). Significantly more COX‐1 (p = 0.0098), COX‐2 (p = 0.0028), and LOX (p = 0.0095) protein was present in OA FH tissue compared to normal FH tissue. There were no differences in PGE2 or LTB4 concentration in normal and OA FH tissue (p = 0.77 and p = 0.11). Together, these data suggest both COX‐2 and 5‐LOX are appropriate targets for the management of pain associated with naturally occurring OA.

Evaluation of a Midhumeral Block of the Radial, Ulnar, Musculocutaneous and Median (RUMM Block) Nerves for Analgesia of the Distal Aspect of the Thoracic Limb in Dogs

OBJECTIVE To evaluate a technique for midhumeral peripheral nerve blockade in the dog. STUDY DESIGN Cadaveric technique development; in vivo placebo-controlled, prospective crossover study. ANIMALS Canine cadavers (n=38) and 8 clinically healthy, adult hound dogs. METHODS A technique for peripheral block of the radial, ulnar, musculocutaneous, and median nerves (RUMM block) was evaluated using cadaver limbs. Eight purpose-bred, research dogs were anesthetized; a RUMM block was performed on each thoracic limb. One limb from each dog randomly received 0.5% bupivacaine and the opposite limb was assigned to receive sterile saline solution as a control. After recovery from anesthesia, skin sensation at selected dermatomes was evaluated for 24 hours using a mechanical stimulus. Weight-bearing, conscious proprioception, and withdrawal reflex were also evaluated. One month after initial testing, each dog was reanesthetized and each limb received the opposite treatment. RESULTS Sensory thresholds were significantly increased over baseline measurements when compared with control limbs for all nerves. Complete sensory block was achieved in radial (15/16), ulnar (3/16), musculocutaneous (8/16), and median (11/16) nerves, using a mechanical stimulus of analgesia. Complete simultaneous block of all nerves was only obtained in 1 of 16 limbs. CONCLUSION RUMM block resulted in desensitization of the skin in the associated dermatomes for 4-10 hours. Complete sensory block of the dermatomes supplied by the radial nerve was most consistent. CLINICAL RELEVANCE RUMM block may be an effective technique to provide adjunctive analgesia for dogs undergoing surgery of the distal aspect of the thoracic limb.

Relationship Between Mechanical Thresholds and Limb Use in Dogs With Coxofemoral Joint OA-Associated Pain and the Modulating Effects of Pain Alleviation From Total Hip Replacement on Mechanical Thresholds

OBJECTIVES To compare von Frey mechanical quantitative sensory thresholds (mQSTvF ) between pelvic limbs in dogs before unilateral total hip replacement (THR) surgery; to correlate ground reaction forces (GRF) with mQSTvF ; to assess changes in mQSTvF after THR surgery. STUDY DESIGN Prospective clinical study. ANIMALS Dogs (n = 44). METHODS mQSTvF and GRF measured using a pressure sensitive walkway were evaluated before, and 3, 6, and 12 months after, unilateral THR. Measurements were recorded from the affected (operated) pelvic limb (APL) and the non-operated pelvic limb (NPL). Random effects analysis and forwards stepwise linear regression models were used to evaluate the influence of time since surgery and patient factors on mQSTvF thresholds. RESULTS There were no significant correlations between mQSTvF data and age, bodyweight or the GRF variables. Preoperative mQSTvF measured at the APL and NPL did not differ (P = .909). mQSTvF thresholds increased significantly after 12 months in NPL (P = .047) and APL (P = .001). In addition to time, APL mQSTvF values were significantly affected by sex (higher in males, P = .010) and body condition score (higher in leaner dogs, P = .035) and NPL mQSTvF values by sex (P = .038). CONCLUSION Successful unilateral THR results in decreased central sensitization after 12 months.