Experimental Mutism in Dogs

Reports of experimental mutism in the literature have been confined chiefly to investigations in which cats were used as the experimental animal.¹⁻⁷With one exception,⁷the lesion responsible for this phenomenon has been reported to be in the region of the periaqueductal gray matter. In 1944, Bailey and Davis⁸reported on similar lesions in the monkey, but no comment appears in their article as to whether or not the animals were mute. Although mutism has been reported in humans,⁹⁻¹⁵the individuals described were different from the above experimental animals as regards the location of pathologic processes and type and magnitude of neurologic deficits. Accordingly, the present investigations were undertaken to discover if lesions similar to those in the cat would result in mutism in another species, specifically the dog. Until recently, the use of dogs in experiments involving the accurate placement of lesions or electrodes has