I found a video that discusses the early symptoms of heat stroke in dogs and I tried to watch the video but it took a long time to load and there was an advertisement about pet insurance before the main video clip. Synptoms to look out for were excessive panting, redness around the eyes, weakness, irritability, vomiting, and finally, collapse. They suggested giving cool water to drink, not cold, as cold water may make the dog vomit. In a mild case of overheating you could sponge the dog down with a cool wet towel and have her lie in front of a fan. In a case of seriously dangerous heat stroke, where she has greyish gums and a blue tongue, they said you would place her in a cool bath and call the vet.
I also came across an article by Lori Verni with good tips for keeping a dog cool in summer. I was interested that it said not to remove your dog's natural insulation by clipping the fur too short - we haven't clipped Penny at all because I had been told the coat insulates and also prevents sunburn. Penny doesn't seem to have that hot double coat that some breeds have.
Another tip was to remove bedding from the bottom of a crate so the dog can lie on the cooler bottom. Penny's crate is available for her but she always tends to lie on the floor near the crate if she is hot - often, upside down to expose her belly to the air. I know myself when I'm trying to grab some sleep on an unbearably not night I will often lie splayed out rather than curled up, so I think I know how she feels!
Champlain Islander, has hot weather tips also. One section discusses whether to clip your dog's coat in summer and says
Many people clip or shave their dogs in the summer time with the logic that less hair will allow for a cooler canine. However, Dr. Karen Campbell, a veterinary dermatologist at the University of Illinois Veterinary Teaching Hospital in Urbana, Ill., explains that clipping your dog may be counterproductive. The canine coat is designed to hold heat near the body in the winter, but also to insulate against the heat from the sun in the summer. Leaving your dog's hair coat intact will actually provide a cool microenvironment for your pet. Your pet's fur also helps act as a sunscreen to protect its skin from ultraviolet radiation. Yes, dogs can get sunburn as well.
Dr. Campbell does concede that a dark-colored dog will get a lot hotter in the summer due to his color (dark colors absorb more heat energy from the sun). If you do own a dark-colored dog it may be beneficial to clip it despite the loss of the insulating properties of their hair coat.
One thing is for certain, dogs that are outside in the summer heat should be properly groomed. Dr. Campbell reminds us that a matted coat will trap moisture on the skin providing an excellent environment for skin infections or even worse problems.