The use of transcranial magnetic stimulation in the evaluation of Doberman pinschers with cervical spondylopathy

This thesis is an investigation of transcranial magnetic stimulation (TMS) in the evaluation of Doberman Pinschers with cervical spondylopathy and to assess the integrity of the cervical spinal cord in affected large-breed dogs by correlating the motor evoked potentials (MEPs) with the neurological status. Transcranial magnetic stimulation was performed with a standard technique in 10 healthy large-breed dogs, 14 non-Doberman large-breed dogs with cervical spinal cord disease confirmed by myelography and 11 Doberman Pinschers with cervical spondylopathy. Latencies and amplitudes were measured from the evoked potentials recorded from the extensor carpi radialis, flexor carpi ulnaris and tibialis cranialis muscles. Results indicated that tibialis cranialis muscle was the only reliable muscle to detect a significant difference of mean latencies and amplitudes between normal dogs and Dobermans with cervical spondylopathy. Transcranial magnetic stimulation was observed to be more reliable in the evaluation of the descending motor tracts in affected non-Doberman dogs versus Dobermans with cervical spondylopathy. Reference parameters were established for healthy large-breed dogs and a linear relationship was found between latencies and body length. A linear equation was formulated to correct latencies based on different body lengths.; In the second part of the study, the 25 large-breed dogs (14 non-Doberman dogs and 11 Doberman Pinscher dogs) with cervical spinal cord disease were allotted into three groups based on their neurological status: (1) neck pain alone, (2) ambulatory with ataxia in all limbs, (3) non-ambulatory. Latencies and amplitudes were recorded from the tibialis cranialis muscle and the results were correlated with the neurological status. There was a significant difference between the mean latencies and amplitudes of each of the three categories and the control population, but no significant difference was found among the categories. There was however a linear association when the mean latencies and amplitudes were correlated with the severity of the neurological status: the more impaired the neurological status, the more prolonged the latencies and the more decreased the amplitudes. Regardless of their neurological status, large-breed dogs with cervical spinal cord disease have impaired MEPs when compared to normal dogs following TMS. Even in dogs with neck pain alone, there was impairment of the functional integrity of the cervical spinal cord.