Effects of postmyelographic removal of metrizamide in dogs

Using a paired crossover trial, the effects of postmyelographic removal of metrizamide injected via the cerebellomedullary cistern were studied in 16 normal dogs. Each animal received a routine and a withdrawal myelogram. Seizure activity, changes in spinal evoked motor potentials and body temperature were measured following each myelogram. The amount of metrizamide removed was determined by densitometrically analyzing radiographs of cerebrospinal fluid/metrizamide aliquots recovered during the withdrawal procedure. There was a significant decrease in the number of seizures for withdrawal versus nonwithdrawal myelography (p < 0.01). The mean amount of metrizamide withdrawn per dog was 29% of the total injected