Muscular Hypertonicity

Scottie cramp is a genetic disease in Scottish terrier dogs characterized by episodes of progressive muscular hypertonicity with associated postural and locomotive difficulties. The episodes are observed during exercise. Results of clinical laboratory tests and gross and histopathological examinations were normal. Telemetered electromyograms (EMG) revealed that the interference pattern from the muscles was of longer duration and higher amplitude during the episode when compared to the preepisode recording. A normal response from the muscle was observed following tubocurarine chloride administration, epidural anesthesia, or electrical stimulation below a procaine nerve block. These data suggest the disease is of central nervous system origin. During an episode when the dog was suspended in a sling, the EMG activity was not continuous. Dorsal root section, lumbar 3, 4, and 5, did not appear to alter the EMG activity during an episode.