Risk factors associated with canine obesity include the amount of walking a dog receives. The aim of this study was to investigate the relationships between canine exercise requirements, socio-demographic factors, and dog-walking behaviors in winter in Calgary. Dog owners, from a cross-sectional study which included a random sample of adults, were asked their household income, domicile type, gender, age, education level, number and breed(s) of dog(s) owned, and frequency and time spent dog-walking in a usual week. Canine exercise requirements were found to be significantly (P < 0.05) positively associated with the minutes pet dogs were walked, as was the owner being a female. Moreover, dog walking frequency, but not minutes of dog walking, was significantly associated with residing in attached housing (i.e., apartments). Different types of dogs have different exercise requirements to maintain optimal health. Understanding the role of socio-demographic factors and dog-related characteristics such as exercise requirements on dog-walking behaviors is essential for helping veterinarians and owners develop effective strategies to prevent and manage canine obesity. Furthermore, encouraging regular dog-walking has the potential to improve the health of pet dogs, and that of their owners.

Objective: To investigate the effect of exercise during yearling sales preparation on the risk of interruptions during training in Thoroughbred racehorses. Animals: 114 Thoroughbred racehorses. Procedures: Information regarding the daily exercise of yearlings during sales preparation was obtained prospectively from a convenience sample of stud farms. Yearlings were followed to entry into race training, and subsequently, daily training information was recorded until the end of the racing season. Competing-risks survival analysis was used to model time from entry into race training to voluntary training interruption (no known condition or disease identified) and time from entry into race training to involuntary training interruption (due to presence of a condition or disease) occurring before the first trial (practice race for education). Total hand walking time and mechanical walker time accumulated during sales preparation were the main exposures of interest. Results: 82 of 114 (71.9%) horses had an interruption before the first trial; 65 (79%) interruptions were voluntary, and 17 (21 %) interruptions were involuntary. Increased total hand walking time was significantly associated with decreased risk of voluntary interruptions, whereas longer cumulative distances at a canter were significantly associated with decreased risk of involuntary interruptions. Conclusions and Clinical Relevance: Results identified an association between early exercise during sales preparation and decreased risk of voluntary interruption and increased risk of involuntary interruption during training of 2-year-old Thoroughbred racehorses. Further investigation into the effects of early exercise on racing performance is needed, but results have indicated that there may be an opportunity to modify early exercise programs.

Objective: To assess joint kinematics in dogs with osteoarthritis of the hip joints during walking up an incline or down a decline and over low obstacles and to compare findings with data for nonlame dogs. Animals: 10 dogs with osteoarthritis of the hip joints (mean ± SD age, 6.95 ± 3.17 years; mean body weight, 34.33 ± 13.58 kg) and 8 nonlame dogs (3.4 ± 2.0 years; 23.6 ± 4.6 kg). Procedures: Reflective markers located on the limbs and high-speed cameras were used to record joint kinematics during walking up an incline or down a decline and over low obstacles. Maximal flexion, extension, and range of motion of the hip joints were calculated. Results: Osteoarthritis of the hip joints reduced extension of both hip joints and flexion of the contralateral hind limb, compared with flexion of the lame hind limb, during walking down a decline. Walking up an incline resulted in decreased extension of the stifle joint in both hind limbs of osteoarthritic dogs; extension was significantly decreased for the lame hind limb. During walking over low obstacles, maximal flexion of the stifle joint was increased significantly for the contralateral hind limb. Maximal flexion was increased in both tarsal joints. Conclusions and Clinical Relevance: Osteoarthritis of the hip joints led to complex changes in the gait of dogs, which involved more joints than the affected hip joint alone. Each exercise had specific effects on joint kinematics that must be considered when planning a rehabilitation program.

Objective: To determine the influence of intensified training and subsequent reduced training on glucose metabolism rate and peripheral insulin sensitivity in horses and identify potential markers indicative of early overtraining. Animals: 12 Standardbred geldings. Procedures: Horses underwent 4 phases of treadmill-based training. In phase 1, horses were habituated to the treadmill. In phase 2, endurance training was alternated with high-intensity exercise training. In phase 3, horses were divided into control and intensified training groups. In the intensified training group, training intensity, duration, and frequency were further increased via a protocol to induce overtraining; in the control group, these factors remained unaltered. In phase 4, training intensity was reduced. Standardized exercise tests were performed after each phase and hyperinsulinemic euglycemic clamp (HEC) tests were performed after phases 2, 3, and 4. Results: 10 of 12 horses completed the study. Dissociation between mean glucose metabolism rate and mean glucose metabolism rate-to-plasma insulin concentration ratio (M:I) was evident in the intensified training group during steady state of HEC testing after phases 3 and 4. After phase 4, mean glucose metabolism rate was significantly decreased (from 31.1 ± 6.8 μmol/kg/min to 18.1 ± 3.4 μmol/kg/min), as was M:I (from 1.05 ± 0.31 to 0.62 ± 0.17) during steady state in the intensified training group, compared with phase 3 values for the same horses. Conclusions and Clinical Relevance: Dissociation between the glucose metabolism rate and M:I in horses that underwent intensified training may reflect non-insulin–dependent increases in glucose metabolism.

Objective: To determine the effects of exercise on the distribution and pharmacokinetics of technetium Tc 99m medronate (99mTc-MDP) following intra-articular (IA) injection in horses. Animals: 5 horses. Procedures: 1 antebrachiocarpal joint (ACJ)/horse was assigned to the exercised group (n = 5), and the contralateral ACJ was evaluated in the nonexercised group (5) after a minimum washout period of 7 days. Following IA injection of 99mTc-MDP (148 MBq), blood and scintigraphic images of the carpus were obtained at 5, 10, 15, 20, 25, 30, 45, 60, 90, 120, 240, 360, 480, 600, 720, and 1,440 minutes. Plasma and scintigraphic radioactivity were determined over time, and pharmacokinetic parameters were generated via noncompartmental and compartmental analyses. Each horse was monitored via physical and lameness examination and ACJ synovial fluid analysis before injection and at days 1, 2, 3, and 7. Results: Lameness was not observed. Mean ± SD synovial fluid WBC count increased at day 1 (exercised, 721 ± 234 cells/μL; nonexercised, 948 ± 223 cells/μL), but returned to baseline at days 3 and 7 Mean time to maximum plasma radioactivity was earlier in the exercised group (16.00 ± 2.35 minutes) than the nonexercised group (43.75 ± 3.64 minutes). Linear regression of the scintigraphic radioactivity-time curves revealed a greater negative slope in the exercised group within the first 25 minutes. There was no difference in absorption or elimination rate constants in a 2-compartment model. Conclusions and Clinical Relevance: IA injection of 99mTc-MDP was safe and effective for evaluating synovial solute distribution. Exercise significantly increased early transfer of 99mTc-MDP from the ACJ into plasma, although absorption and elimination rate constants were not affected. Exercise may affect synovial clearance and withdrawal times of medications administered IA.

Objective-To investigate whether submaximal aerobic exercise in dogs is followed by activation of all phases of coagulation as has been reported for humans. Animals-9 healthy Beagles. Procedures-30 minutes before dogs were exercised, a 16-gauge central venous catheter was placed in a jugular vein of each dog by use of the catheter-through-the-needle technique. Samples were collected before exercise, after running on a treadmill (6 km/h for 13 minutes), and at 60 minutes. Platelet activation was evaluated with platelet morphology indices (mean platelet component, mean platelet volume, and number of large platelets) provided by a laser-based hematology system. Platelet function was assessed in hirudin-anticoagulated whole blood with an impedance-based aggregometer with collagen as the agonist (final concentrations, 0, 1.6, 3.2, 5, and 10 micrograms/mL). Prothrombin time, activated partial thromboplastin time, and concentrations of fibrinogen, factor VIII, antithrombin, protein C, protein S, and fibrin D-dimer were determined automatically. Kaolin-activated thromboelastography variables R (reaction time), K (clot formation time), angle alpha, maximal amplitude, and G (clot stability) were measured in recalcified citrated whole blood. Results-Exercise resulted in a significant decrease in mean platelet volume and the number of large platelets but did not change the mean platelet component, which reflected platelet activation as well as platelet function. Secondary and tertiary coagulation did not change significantly, nor did thromboelastography variables. Conclusions and Clinical Relevance-Aerobic exercise resulted in a decrease in the number of large and thus most likely activated platelets but otherwise had no major impact on coagulation in dogs.

Objective: To describe and measure histologic features of midcarpal joint cartilage defects in Thoroughbreds and evaluate the influence of early conditioning exercise on defect development. Sample: 24 midcarpal joints from twelve 18-month-old Thoroughbreds. Procedures: Midcarpal joints from 12 horses (6 exercised spontaneously at pasture only and 6 given additional conditioning exercise beginning at a mean age of 3 weeks were evaluated. Gross cartilage defects were assessed histologically. Third and radial carpal bones were categorized with regard to the presence or absence of calcified cartilage (CC) abnormalities at the dorsoproximal and dorsodistal articular surfaces, respectively; histomorphometric assessment and statistical analysis were conducted for the third carpal bone. Results: Number and severity of defects did not appear different between exercise groups. Nine third or radial carpal bones had thickened CC with microcracks, matrix and osteochondral junction changes, and increased vascularity, without histologic changes in the hyaline cartilage. Third carpal bones with CC abnormalities had significantly thicker CC (452 vs 228 μm) than did those without CC abnormalities in the evaluated region. However, in the same region, there were no significant differences in hyaline cartilage thickness (681 vs 603 μm), vascular channel area in the subchondral bone (624,894 vs 490,320 μm2), or number of vascular channels (15.9 vs 18.0). Conclusions and Clinical Relevance: Early exercise did not appear to influence the distribution or severity of cartilage defects in the midcarpal joint. Calcified cartilage abnormalities beneath the undisrupted hyaline cartilage in the dorsoproximal aspect of the third carpal bone may represent the first changes in the pathogenesis of midcarpal osteochondral disease.

Objective: To determine the effects of clenbuterol, at a dosage of up to 3.2 μg/kg for 14 days, PO, on skeletal and cardiac muscle in healthy horses undergoing treadmill exercise. Animals: 12 healthy horses from 3 to 10 years old. Procedures: Horses were randomly assigned to a control group (n = 6) or clenbuterol group (6) and received either saline (0.9% NaCl) solution or clenbuterol, PO, every 12 hours for 14 days. Horses were subjected to submaximal treadmill exercise daily during treatment. Muscle biopsy specimens were collected before and after treatment for determination of apoptosis. Echocardiographic measurements, serum clenbuterol and cardiac troponin I concentrations, and serum activities of creatine kinase and aspartate aminotransferase were measured before, during, and after treatment. Jugular venous blood samples were collected every 3 days during treatment. Echocardiography was repeated every 7 days after beginning treatment. Response variables were compared between treatment groups and across time periods. Results: No significant effect of clenbuterol or exercise on response variables was found between treatment and control groups at any time point or within groups over time. Conclusions and Clinical Relevance: Results did not reveal any adverse effects of treatment with an approved dose of clenbuterol on equine cardiac or skeletal muscle in the small number of horses tested.

Objective: To investigate forelimb hoof wall strains and shape changes in unshod horses undergoing regular moderate exercise on a treadmill at selected speeds and gaits. Animals: 6 horses of various body types. Procedures: Each horse was exercised on a treadmill (walking, trotting, and cantering, with or without galloping at 12.5 m/s) 3 times a week for 4 consecutive weeks; duration of each exercise session ranged from 10 to 14 minutes. During the 4-week period, the proximal hoof circumference (PHC) and toe angle (TA) of each forelimb hoof were measured weekly with a flexible measuring tape and a hoof gauge, respectively. Forelimb hoof wall strains were measured bilaterally at the toe and each quarter (3 strain gauges) immediately before the first and after the last exercise session. Results: Strain measurements revealed a consistent pattern of deformation of the hoof wall in both forelimbs at all gaits; strains increased during the stance phase of the stride. Strain values were dependent on site and gait. Compared with initial findings, mean TA increased significantly, whereas mean PHC did not, after the 4-week exercise period. A relationship between TA changes and hoof wall strains could not be established. Conclusions and Clinical Relevance: In unshod horses, forelimb hoof wall strains were affected by site and gait, but not by discrete changes in TA; PHC did not change in response to moderate regular exercise. The pattern of hoof loading was consistent despite significant changes in TA.

Objective: To determine whether repeated oral administration of glucose and leucine during the period immediately after intense exercise would increase the release of insulin and thereby enhance glycogen synthesis in horses. Animals: 12 Standardbred horses. Procedures: In a crossover study design, after glycogen-depleting exercise, horses received oral boluses of glucose (1 g/kg at 0, 2, and 4 hours) and leucine (0.1 g/kg at 0 and 4 hours) or boluses of water (10 mL/kg at 0, 2, and 4 hours; control treatment). Blood samples for determination of glucose, insulin, and leucine concentrations were collected prior to and during a 6-hour period immediately after exercise. Biopsy specimens of a gluteus muscle were obtained before and immediately after exercise and at 3, 6, and 24 hours after exercise for measurement of glycogen concentration. Results: When glucose and leucine were administered to the horses, plasma insulin concentration was significantly higher during the 6 hours immediately after exercise than it was when water was administered to the horses. Serum glucose concentration during the 4 hours immediately after exercise was significantly higher when glucose and leucine were administered than the serum glucose concentration when water was administered. Muscle glycogen concentrations did not differ between the 2 treatments during the 24 hours after exercise. Conclusions and Clinical Relevance: Synthesis of muscle glycogen after intense intermittent exercise was not enhanced by oral boluses of glucose and leucine after exercise despite pronounced increases in plasma insulin and serum glucose concentrations.