Inverse dynamics analysis of the pelvic limbs in Labrador Retrievers with and without cranial cruciate ligament disease.

OBJECTIVES: To quantify net joint moments, joint powers, and joint reaction forces (JRF) across the hock, stifle, and hip joints in Labrador Retrievers with and without cranial cruciate ligament (CCL) disease. To investigate differences in joint mechanics between normal, CCL deficient, and contralateral pelvic limbs. STUDY DESIGN: Cross-sectional clinical study. ANIMALS: Clinically normal (n=14) and CCL-deficient (n=9) Labrador Retrievers. METHODS: Each limb was analyzed separately and classified as normal, CCL-deficient or sound contralateral limb. Kinematic, ground reaction force (GRF), and morphometric data were combined in an inverse dynamic approach to compute hock, stifle and hip net moments, powers and JRF, while trotting. RESULTS: Vertical and braking GRF and JRF were significantly decreased in CCL-deficient limbs. In affected limbs, extensor moments at the hock and hip, flexor moment at the stifle and power in all 3 joints were less than normal. Kinetics also identified a greater joint moment and power of the contralateral limbs compared with normal, particularly of the stifle extensor muscles group. CONCLUSION: Lameness resulting from CCL disease affected predominantly reaction forces during the braking phase and the extension during push-off. A greater contribution of the contralateral limbs to propel the dog forward was identified. CLINICAL RELEVANCE: Reductions in joint motion, loads, and muscle contraction were interpreted as modifications adopted to reduce or avoid painful mobilization of the injured stifle joint. The increased joint moment and power of the contralateral compensating side may correlate with the lameness observed, but also with the predisposition of contralateral limbs to CCL deficiency in dogs.

Noninvasive determination of body segment parameters of the hind limb in Labrador Retrievers with and without cranial cruciate ligament disease.

OBJECTIVE: To determine mass, center of mass (COM), and moment of inertia (ie, body segment parameters [BSPs]) of hind limb segments by use of a noninvasive method based on computerized tomography (CT) in Labrador Retrievers with and without cranial cruciate ligament (CCL) disease and to provide regression equations to estimate BSPs of normal, CCL-deficient, and contralateral hind limbs. ANIMALS: 14 clinically normal and 10 CCL-deficient Labrador Retrievers. PROCEDURES: Bone, muscle, and fat areas were identified via CT. Mass, COM, and moment of inertia were determined on the basis of tissue densities in the thigh, crus, and foot segments. Regression models were developed to determine predictive equations to estimate BSP on the basis of simple morphometric measurements. RESULTS: The thigh and crus of CCL-deficient limbs weighed less than in contralateral segments. Thighs weighed less in CCL-deficient than in normal limbs. The thigh moment of inertia was less in CCL-deficient than in contralateral limbs. The crural COM was located more distally in normal limbs, compared with other limbs. Predictive equations to estimate BSP varied by parameter, body segment, and limb status. CONCLUSIONS AND CLINICAL RELEVANCE: BSPs of the thigh and crus varied with segment and status of the hind limb in Labrador Retrievers with or without CCL disease. Equations to estimate BSP on the basis of simple morphometric measurements were proposed, providing a basis for nonterminal studies of inverse dynamics of the hind limbs in Labrador Retrievers. This approach may offer new strategies to investigate the pathogenesis of nontraumatic joint diseases.

Variation in captopril formulations in pharmacies across Canada.

Captopril, an angiotensin-converting enzyme inhibitor used to manage congestive heart failure in the paediatric population, has limited data on efficacy and safety. Its variety of liquid formulations dispensed by different pharmacies poses a challenge in optimizing captopril dosing in patients. Fourteen tertiary paediatric centre pharmacies across Canada were contacted to decipher the type of captopril formulation they dispense, their recipe and the stability of each formulation. Of the 14 centres surveyed, four dispensed solid tablets, two dispensed either solid tablets or liquid formulations, and eight dispensed extemporaneously prepared liquid formulations. There was also great variety in the solutions used to prepare the liquid formulations. The bioequivalence of these preparations has not been studied. As a result, physicians cannot be certain about the effective dose of captopril. Uniformity is recommended among paediatric pharmacies in Canada when preparing medications such as captopril. Proper testing of the stability and bioequivalence of medications is recommended.