Evaluation of Ground Reaction Forces and Limb Symmetry Indices Using Ground Reaction Forces Collected with One or Two Plates in Dogs Exhibiting a Stifle Lameness.

OBJECTIVE: The aim of the study was to evaluate the efficiency and consistency in the collection of ground reaction forces using one or two force plates from dogs with stifle lameness. ANIMALS: Twenty-two client-owned dogs with unilateral stifle lameness were used. METHODS: In a prospective study design, data were collected at a single time point using both one- and two-plate collection methods. Ground reaction forces collected included peak vertical force, vertical impulse and associated symmetry indices. Additionally, time required to obtain valid trials and the total number of trials were also recorded for both one-plate and two-plate collections. Linear mixed models were used to analyse differences in peak vertical force, vertical impulse and symmetry indices between the collection methods. A paired-T test was used to compare trial number and time of trial collection. The significance threshold was p < 0.05. RESULTS: It took significantly longer to collect valid trials using one-plate both in time (16.1 ± 8.0 minutes vs, 8.0 ± 4.3 minutes with two plates) and number of trials (33.8 ± 14.8 trials vs. 16.4 ± 8.8 trials with two plates) (p < 0.0001). There was no difference in peak vertical force or vertical impulse data between collection methods. Neither the peak vertical force symmetry indices nor the vertical impulse symmetry indices were significantly different between one- and two-plate collection techniques. CONCLUSION: The total time and number of trials needed to collect valid trials in dogs with stifle lameness were minimized through the use of two force plates. However, there was no significant difference in the ground reaction force or symmetry index values collected between the two systems.

Inappropriate Secondary Erythrocytosis in a Dog With Renal Sarcoma.

A 7-year-old mixed breed dog was evaluated for erythrocytosis with an initial hematocrit of 82.3%. Abdominal ultrasound revealed a 6 cm mass on the cranial pole of the right kidney. Daily therapeutic phlebotomies were performed, reducing the hematocrit to 54%. The dog underwent a right nephroureterectomy, recovered without complications, and was discharged 3 days after surgery. Histopathologic evaluation revealed a completely excised grade II soft tissue sarcoma. The preoperative erythropoietin level was 7.00 mU/mL (RI 1.90-22.90 mU/mL) and the 3-day postoperative erythropoietin level was 0.99 mU/mL, supporting a diagnosis of inappropriate secondary erythrocytosis due to the renal tumor. Secondary erythrocytosis resulting from renal soft tissue sarcoma is rare. Confirmatory testing with erythropoietin levels can assist in the diagnosis of secondary erythrocytosis. Erythropoietin levels that are normal or increased in the face of erythrocytosis indicate a source of inappropriate erythropoietin production.

Use of a platelet-rich plasma-collagen scaffold as a bioenhanced repair treatment for management of partial cruciate ligament rupture in dogs.

Dogs are commonly affected with cruciate ligament rupture (CR) and associated osteoarthritis (OA), and frequently develop a second contralateral CR. Platelet rich plasma (PRP) is a component of whole blood that contains numerous growth factors, which in combination with a collagen scaffold may act to promote bioenhanced primary repair of ligament. This study tested the hypothesis that treatment of partial stable CR stifles with an intra-articular collagen scaffold and PRP would decrease the disease progression, synovitis and risk of complete CR over a 12-month study period. We conducted a prospective cohort study of 29 client-owned dogs with an unstable stifle due to complete CR and stable contralateral stifle with partial CR. All dogs were treated with tibial plateau leveling osteotomy (TPLO) on the unstable stifle and a single intra-articular application of PRP-collagen in the stable partial CR stifle. Dogs were evaluated at the time of diagnosis, and at 10-weeks and 12-months after treatment. We evaluated correlation between both development of complete CR and time to complete CR with diagnostic tests including bilateral stifle radiographs, 3.0 Tesla magnetic resonance (MR) imaging, and bilateral stifle arthroscopy. Additionally, histologic evaluation of synovial biopsies, C-reactive protein (CRP) concentrations in serum and synovial fluid, and synovial total nucleated cell count, were determined. Results indicated that a single application of PRP-collagen in partial CR stifles of client owned dogs is not an effective disease-modifying therapy for the prevention of progression to complete CR. Radiographic effusion, arthroscopic evaluation of cranial cruciate ligament (CrCL) damage, and MR assessment of ligament fiber tearing in partial CR stifles correlated with progression to complete CR over the 12-month follow-up period. We determined that the best predictive model for development of complete CR in PRP-collagen treated partial CR stifles included variables from multiple diagnostic modalities.

Effect of contact time on variance of ground reaction forces during force platform gait analysis of a heterogeneous sample of clinically normal dogs.

OBJECTIVE To develop contact time (ConT) and withers height-normalized relative ConT (ConT*) for force platform gait analysis of dogs. ANIMALS 29 healthy client-owned dogs. PROCEDURES Height at the most dorsal aspect of the shoulders (withers) was measured with a framing square. Dogs were trotted across a force platform at their preferred velocity with controlled acceleration (± 0.5 m/s2). Ranges of ConT and ConT* centered on the population mean ConT were created. Variance effects on ground reaction forces (GRFs) for 4 thoracic limb and 4 pelvic limb ConT and associated ConT* ranges were examined. Efficiency of trial capture and effects of velocity ranges on GRF variance were determined. RESULTS Individual dogs had the greatest effect on GRF variance for thoracic and pelvic limbs. Narrow ConT and ConT* ranges had few significant effects on GRFs but were inefficient at capturing trials. The ConT ranges of 0.22 to 0.29 seconds and 0.19 to 0.25 seconds for thoracic and pelvic limbs, respectively, provided the most efficient rates of trial capture with the fewest significant effects on GRFs. Compared with ConT and ConT* ranges, relative velocity ranges had higher efficiency and smaller GRF variance effects. CONCLUSIONS AND CLINICAL RELEVANCE Dogs of various morphologies have differing limb velocities. Use of ConT as a surrogate for limb velocity may improve GRF data quality. We identified ConT and ConT* ranges associated with low GRF variance. However, relative velocity ranges captured data more efficiently. Efficient capture of data may help avoid worsening of lameness during gait analysis of dogs.

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

OBJECTIVE To determine variance effects influencing ground reaction forces (GRFs) in a heterogeneous population of lame dogs during trotting. ANIMALS 30 client-owned dogs with thoracic limb lameness and 31 dogs with pelvic limb lameness. PROCEDURES GRFs, velocity, height at the dorsal aspect of the scapulae (ie, withers), and shoulder height were obtained. Each dog was trotted across a force platform at its preferred velocity. Variance effects for 12 velocity and associated relative velocity (V*) ranges were examined. RESULTS Individual dog, velocity, V*, and limb significantly influenced GRFs. Withers height V* ranges were associated with small variance in GRFs, but all absolute and V* ranges were associated with significant effects for all 4 limbs and both types of lameness. Significant changes in lame limb GRFs and velocity in ipsilateral trials in dogs with thoracic limb and pelvic limb lameness were evident with trial repetition. Withers height V* range of 0.55 to 0.93 captured a large proportion of trials (> 90%) in dogs with thoracic limb or pelvic limb lameness, with limited effects on peak vertical force and vertical impulse. CONCLUSIONS AND CLINICAL RELEVANCE Trial repetition caused alterations to GRFs and subject velocity that may have confounded assessment of lameness, which supported the concept that a priori selection of a velocity or V* range for force platform gait analysis should use a range that captures valid trials efficiently while minimizing GRF variance. These ranges typically would span the preferred velocity of subject dogs, such as withers height V* of 0.55 to 0.93.

Radiographic and magnetic resonance imaging predicts severity of cruciate ligament fiber damage and synovitis in dogs with cranial cruciate ligament rupture.

Cruciate ligament rupture (CR) and associated osteoarthritis (OA) is a common condition in dogs. Dogs frequently develop a second contralateral CR. This study tested the hypothesis that the degree of stifle synovitis and cranial cruciate ligament (CrCL) matrix damage in dogs with CR is correlated with non-invasive diagnostic tests, including magnetic resonance (MR) imaging. We conducted a prospective cohort study of 29 client-owned dogs with an unstable stifle due to complete CR and stable contralateral stifle with partial CR. We evaluated correlation of stifle synovitis and CrCL fiber damage with diagnostic tests including bilateral stifle radiographs, 3.0 Tesla MR imaging, and bilateral stifle arthroscopy. Histologic grading and immunohistochemical staining for CD3+ T lymphocytes, TRAP+ activated macrophages and Factor VIII+ blood vessels in bilateral stifle synovial biopsies were also performed. Serum and synovial fluid concentrations of C-reactive protein (CRP) and carboxy-terminal telopeptide of type I collagen (ICTP), and synovial total nucleated cell count were determined. Synovitis was increased in complete CR stifles relative to partial CR stifles (P<0.0001), although total nucleated cell count in synovial fluid was increased in partial CR stifles (P<0.01). In partial CR stifles, we found that 3D Fast Spin Echo Cube CrCL signal intensity was correlated with histologic synovitis (SR = 0.50, P<0.01) and that radiographic OA was correlated with CrCL fiber damage assessed arthroscopically (SR = 0.61, P<0.001). Taken together, results of this study show that clinical diagnostic tests predict severity of stifle synovitis and cruciate ligament matrix damage in stable partial CR stifles. These data support use of client-owned dogs with unilateral complete CR and contralateral partial CR as a clinical trial model for investigation of disease-modifying therapy for partial CR.

The evaluation of limb symmetry indices using ground reaction forces collected with one or two force plates in healthy dogs.

OBJECTIVE: To compare the variability of symmetry indices within and between days when using one and two force plates for data collection. ANIMALS: Seventeen healthy client-owned adult dogs. METHODS: Vertical ground reaction force data were collected in a crossover study design, with four collection sessions on two consecutive days, and then two weeks apart (days 1, 2, 15, and 16) using both 1-plate and 2-plate collection methods. Symmetry indices were calculated for limb pairs using two standard equations (SI1 and SI2). Repeated measures analysis was used to compare symmetry indices data between plate systems and days. Significance was set at p <0.05. RESULTS: There were no significant differences between plate systems for SI1 and SI2. There were no significant differences between data collected on different days and no significant interaction effects between variables. Symmetry indices were consistently larger for ground reaction forces calculated from non-consecutive footfalls. CONCLUSIONS: The use of two force plate systems will minimize variance caused by trial repetition and paired limb variation. When comparing SI1 to SI2, results were not significantly different. However, there were consistently higher mean values for SI1 compared with SI2 and symmetry indices were consistently larger for 1-plate systems compared to 2-plate systems for both symmetry indices.

Metallosis with pseudotumour formation: Long-term complication following cementless total hip replacement in a dog.

CASE DESCRIPTION: A 10-year-old female Belgian Teruven dog was presented to our clinic for total hip revision following a diagnosis of implant (cup) failure with metallosis and abdominal pseudotumour formation. The patient had a cementless metal-on-polyethylene total hip replacement performed nine years prior to presentation. CLINICAL FINDINGS: The clinical findings, including pseudotumour formation locally and at sites distant from the implant and pain associated with the joint replacement, were similar to those described in human patients with this condition. Histopathological, surgical, and radiographic findings additionally supported the diagnosis of metallosis and pseudotumour formation. TREATMENT AND OUTCOME: Distant site pseudotumours were surgically removed and the total hip replacement was explanted due to poor bone quality. The patient recovered uneventfully and has since resumed normal activity. CONCLUSION: In veterinary patients with metal-on-polyethylene total hip implants, cup failure leading to metallosis and pseudotumour formation should be considered as a potential cause of ipsilateral hindlimb lameness, intra-pelvic abdominal tumours, or a combination of both. These clinical findings may occur years after total hip replacement surgery.