Urban search and rescue (USAR) dogs provide an important service in search, patrol, and explosive detection in urban and natural disasters. These dogs are exposed to stressful and dangerous conditions that can lead to dehydration and electrolyte imbalances. Oral electrolyte and carbohydrate supplementation decreases electrolyte disturbances and improves endurance in other animal species. A field study was performed to determine the effect of oral electrolyte supplementation on performance and electrolyte balance of USAR dogs performing moderate-intensity work. Nine Pennsylvania Task Force 1 USAR dogs were randomly assigned to water or electrolyte replacement solution (Electramine, Vitae Inc., Breckenridge, CO) on two separate training days, one in winter and one in summer. There was no clinically significant or repeatable improvement in plasma electrolyte composition or performance in electrolyte-supplemented dogs. Although other electrolyte formulations must be tested to determine potential benefits, the overall benefits of electrolyte supplementation do not seem to outweigh the expense and burden of including these replacement fluids in USAR gear.