BCC Exercise Study
Dr. Sue Taylor (Western College of Veterinary Medicine - Saskatoon, Saskatchewan Canada) has evaluated normal border collies and border collies with BCC during and following participation in a strenuous exercise protocol during the springs/summers of 2010 and 2011. Dogs that chase a ball were evaluated with a 10 minute ball retrieving protocol and dogs that worked stock were evaluated with a 10 minute sheep herding exercise protocol consisting of a series of outruns and fetches of 3 sheep in an outdoor pen. Exercise was halted immediately (before 10 minutes) at the first sign of any lameness, weakness, in-coordination, extreme exhaustion or mental confusion.
BCC affected dogs participating in this phase of the study were intense and physically fit and ideally had experienced at least 2 episodes of collapse with exercise. They were thought to be fairly severely affected by BCC, so that they were likely to show signs with 10 minutes or less of intense exercise. Muscle biopsy, chest radiographs, cardiac ultrasound and ECG were performed to eliminate other common medical and cardiac causes of exercise intolerance.
Dogs with BCC have normal physical, orthopedic and neurologic examinations at rest. Dogs with BCC and normal Border collies develop alterations in rectal temperature, hematologic, biochemical, blood gas and acid base parameters that are very similar to those previously described in normal exercising Labrador retrievers. No abnormalities have been detected in serum electrolytes (sodium and potassium), blood sugar, blood cortisol, ability to ventilate, or heart rhythm that can explain the collapse in dogs with BCC. Dogs with BCC and normal Border collies all develop very high body temperatures (often >41.7C, >107F) after 10 minutes of strenuous exercise, but they cool down quickly when exercise is halted. Normal and BCC affected dogs are negative for the dynamin 1 mutation causing EIC in Labrador Retrievers. Thus far no differences between the normal dogs and the dogs with BCC have been identified except that the dogs with BCC exhibit gait and mentation abnormalities. Dogs with BCC remain abnormal for 5 to 30 minutes, but then recover completely with no residual lameness or muscle stiffness or discomfort.