Electrical interference may be caused by other equipment (ECG Leads, Stimulators etc.) that are connected to the animal during the experiment. Initially, try removing these peripheral electrodes/devices to determine if they are the source of interference. The user may also try to improve the animal's electrical grounding by using a POAG grounding cable (SP0134) with one end attached to the animal (as close to the heart as possible) while the other end is attached to the grounding plug on the rear of the MPVS Ultra unit/PowerLab.