Signs of overexertion or heat exhaustion in dogs include excessive panting, drooling, and apparent fatigue. Dogs may also show disinterest in continuing exercise, seek shade or cooler surfaces, and exhibit signs of confusion or disorientation. In more severe cases, vomiting, diarrhea, or collapse can occur. Immediate steps should be taken to cool the dog down if these symptoms are observed, including moving them to a shaded or air-conditioned area, providing water, and applying cool (not cold) water to their body. Veterinary attention should be sought if symptoms persist or worsen.