Effect of electromyography on serum creatine kinase values in clinically normal dogs and horses

The effect of needle electromyography (EMG) on serum creatine kinase (CK) activity was determined, using clinically normal dogs (males and females; n = 8) and horses (females; n = 8). All animals appeared normal on EMG evaluation. Serum CK was measured before and 4, 24, and 48 hours after EMG. Except for a single 24-hour sample in a dog, the animals did not have abnormally increased serum CK activity after EMG. For dogs and horses, mean values were increased, but within normal range at 4 and 24 hours and returned to base-line values by 48 hours after EMG. For dogs, but not for horses, these CK increases at 4 and 24 hours were significant (P less than 0.05). Most dogs and horses, without neuromuscular disease, did not have serum CK activity above the normal range after EMG.