Signs that a dog is getting too tired or overheated during a walk include excessive panting, drooling, or labored breathing. The dog may also display a decreased pace, seek shade, or stop walking altogether. Other indicators include a bright red tongue or gums, glazed eyes, and increased salivation. In severe cases, signs like vomiting, disorientation, or collapse can occur. Owners should watch for these symptoms, especially in hot weather, and provide water and rest immediately if these signs are observed.