Factors that contribute to variance in ground reaction forces (GRF) include: dog morphology, velocity, and trial repetition. Narrow velocity ranges are recommended to minimize variance. In a heterogeneous population of clinically normal dogs, we hypothesized that the dog subject effect would account for the majority of variance in peak vertical force (PVF) and vertical impulse (VI) at a trotting gait, and that narrow velocity ranges would be associated with less variance. Data from twenty normal dogs were obtained. Each dog was trotted across a force platform at its habitual velocity, with controlled acceleration (±0.5m/s2). Variance effects from twelve trotting velocity ranges were examined using repeated-measures analysis-of-covariance. Significance was set at P<0.05. Mean dog body weight was 28.4 ± 7.4 kg. Individual dog and velocity significantly affected PVF and VI for thoracic and pelvic limbs (P<0.001). Trial number significantly affected thoracic limb PVF (P<0.001). Limb (left or right) significantly affected thoracic limb VI (P=0.02). The magnitude of variance effects from largest to smallest was dog, velocity, trial repetition, and limb. Velocity ranges of 1.5–2.0 m/s, 1.8–2.2 m/s, and 1.9–2.2 m/s were associated with low variance and no significant effects on thoracic or pelvic limb PVF and VI. A combination of these ranges, 1.5–2.2 m/s, captured a large percentage of trials per dog (84.2±21.4%) with no significant effects on thoracic or pelvic limb PVF or VI. We conclude wider velocity ranges facilitate capture of valid trials with little to no effect on GRF in normal trotting dogs. This concept is important for clinical trial design.

Mid-substance rupture of the canine cranial cruciate ligament rupture (CR) and associated stifle osteoarthritis (OA) is an important veterinary health problem. CR causes stifle joint instability and contralateral CR often develops. The dog is an important model for human anterior cruciate ligament (ACL) rupture, where rupture of graft repair or the contralateral ACL is also common. This suggests that both genetic and environmental factors may increase ligament rupture risk. We investigated use of bone marrow-derived mesenchymal stem cells (BM-MSCs) to reduce systemic and stifle joint inflammatory responses in dogs with CR. Twelve dogs with unilateral CR and contralateral stable partial CR were enrolled prospectively. BM-MSCs were collected during surgical treatment of the unstable CR stifle and culture-expanded. BM-MSCs were subsequently injected at a dose of 2x106 BM-MSCs/kg intravenously and 5x106 BM-MSCs by intra-articular injection of the partial CR stifle. Blood (entry, 4 and 8 weeks) and stifle synovial fluid (entry and 8 weeks) were obtained after BM-MSC injection. No adverse events after BM-MSC treatment were detected. Circulating CD8+ T lymphocytes were lower after BM-MSC injection. Serum C-reactive protein (CRP) was decreased at 4 weeks and serum CXCL8 was increased at 8 weeks. Synovial CRP in the complete CR stifle was decreased at 8 weeks. Synovial IFNγ was also lower in both stifles after BM-MSC injection. Synovial/serum CRP ratio at diagnosis in the partial CR stifle was significantly correlated with development of a second CR. Systemic and intra-articular injection of autologous BM-MSCs in dogs with partial CR suppresses systemic and stifle joint inflammation, including CRP concentrations. Intra-articular injection of autologous BM-MSCs had profound effects on the correlation and conditional dependencies of cytokines using causal networks. Such treatment effects could ameliorate risk of a second CR by modifying the stifle joint inflammatory response associated with cranial cruciate ligament matrix degeneration or damage.

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.

CASE DESCRIPTION A 2-year-old 5.2-kg (11.4-lb) neutered male domestic shorthair cat was referred because of a 6-week history of progressive paraparesis. CLINICAL FINDINGS Neurologic examination revealed moderate ambulatory paraparesis with marked spinal hyperesthesia at the thoracolumbar junction. The lesion was localized to the T3-L3 spinal cord segment. Clinicopathologic testing, thoracic radiography, and abdominal ultrasonography revealed no abnormalities to explain the observed clinical signs. Advanced spinal imaging with MRI revealed an extradural right-lateralized mass originating from the L2 vertebral pedicle and causing severe spinal cord compression. TREATMENT AND OUTCOME Surgical decompression was achieved by performance of a right-sided hemilaminectomy at L2. Histologic examination of biopsy samples obtained from the mass revealed an ill-defined zone of mature vascular proliferation extending through the preexisting vertebral bone, consistent with vertebral angiomatosis. After surgical recovery, adjuvant radiation therapy was initiated with a total dose of 48 Gy administered in 16 fractions of 3 Gy each over a 3-week period. Neurologic function rapidly improved to full ambulation with only minimal monoparesis of the right pelvic limb. Results of neurologic and MRI examination performed 26 months after surgery indicated no change in neurologic status or evidence of recurrence. CLINICAL RELEVANCE To the authors' knowledge, this report was the first to describe the long-term outcome for vertebral angiomatosis in a cat. Surgical decompression and radiation therapy provided an excellent outcome in this case. Vertebral angiomatosis should be considered as a differential diagnosis for any young cat with thoracolumbar myelopathy secondary to a mass associated with the vertebral pedicle.

Cranial cruciate ligament (CCL) rupture is one of the most common causes of pelvic limb lameness in dogs. In a CCL deficient stifle, joint lameness develops from cranial tibial translation in relation to the distal femoral condyles. The tibial plateau leveling osteotomy (TPLO) is a well-described surgical procedure that neutralizes tibiofemoral shear force by altering the tibial plateau via a proximal tibial osteotomy, and subsequently restores normal limb function. Current literature for the TPLO was reviewed and used to describe the optimal patient selection and to report clinical outcome with the TPLO in comparison to other surgical options for CCL rupture. The clinical outcomes reported to date, particularly those utilizing objective outcome data, support the TPLO as being able to consistently return dogs to normal limb function with a low risk for long-term morbidity. The TPLO procedure was found to be widely applicable to dogs ranging from small breed to large and giant breed, and does not appear to have some of the limitations that exist with alternative surgical options. This review concludes that the TPLO is an excellent treatment option for any dog with CCL rupture due to the excellent long-term outcome and high rate of owner satisfaction previously reported. Despite these conclusions, it is important to remember that treatment selection for CCL rupture remains dependent on multiple considerations including patient factors, surgeon experience, and costs.