Spontaneous potentials in skeletal muscle distal to human spinal cord injury (SCI) have been reported in the literature. Two animal models of SCI were studied for the presence of similar potentials. Six rats and two cats with surgical transections of the thoracic spinal cord were followed for 4-6 weeks with serial electromyography. As a control for the effects of anesthesia and serial testing, three intact rats were anesthetized and tested weekly for 4 weeks. In rats with spinal cord transection, spontaneous potentials emerged 4-7 days after surgery and persisted for the duration of the study (28-32 days). Spontaneous potentials were absent in controls at all timepoints. In cats, spontaneous potentials were observed 8 days postinjury and gradually diminished, starting at 2 weeks. Spontaneous potentials therefore occur after SCI in animals as well as in humans. The utilization of animal models will facilitate the understanding of alterations that occur distal to spinal cord lesions and affect the function of lower motor neurons, leading to peripheral denervation after SCI.