Top ten Hot Weather Tips from the ASPCA website:
In summertime, the living isn’t always easy for our animal friends. Dogs and cats can suffer from the same problems that humans do, such as overheating, dehydration and even sunburn. By taking some simple precautions, you can celebrate the season and keep your pets happy and healthy.

1. A visit to the veterinarian for a spring or early summer check-up is a must; add to that a test for heartworm, if your dog isn't on year-round preventive medication. Do parasites bug your animal companions? Ask your doctor to recommend a safe, effective flea and tick control program.
2. Never leave your pet alone in a vehicle—hyperthermia can be fatal. Even with the windows open, a parked automobile can quickly become a furnace in no time. Parking in the shade offers little protection, as the sun shifts during the day.
3. Always carry a gallon thermos filled with cold, fresh water when traveling with your pet.
4. The right time for playtime is in the cool of the early morning or evening, but never after a meal or when the weather is humid.
5. Street smarts: When the temperature is very high, don’t let your dog standing on hot asphalt. His or her body can heat up quickly, and sensitive paw pads can burn. Keep walks during these times to a minimum.
6. A day at the beach is a no-no, unless you can guarantee a shaded spot and plenty of fresh water for your companion. Salty dogs should be rinsed off after a dip in the ocean.
7. Provide fresh water and plenty of shade for animals kept outdoors; a properly constructed doghouse serves best. Bring your dog or cat inside during the heat of the day to rest in a cool part of the house.
8. Be especially sensitive to older and overweight animals in hot weather. Brachycephalic or snub-nosed dogs such as bulldogs, pugs, Boston terriers, Lhasa apsos and shih tzus, as well as those with heart or lung diseases, should be kept cool in air-conditioned rooms as much as possible.
9. When walking your dog, steer clear of areas that you suspect have been sprayed with insecticides or other chemicals. And please be alert for coolant or other automotive fluid leaking from your vehicle. Animals are attracted to the sweet taste, and ingesting just a small amount can be fatal. Call your veterinarian or the ASPCA Animal Poison Control Center at (888) 426-4435 if you suspect that your animal has been poisoned.
10. Good grooming can stave off summer skin problems, especially for dogs with heavy coats. Shaving the hair to a one-inch length—never down to the skin, please, which robs Rover of protection from the sun—helps prevent overheating. Cats should be brushed often.

Bonus tip: Please make sure that there are no open, unscreened windows or doors in your home through which animals can fall or jump.

Signs of Heatstroke: 

1.  heavy panting and salivating

2.  warm dry skin

3.  rapid pulse

4. dizziness

5.  vomiting

6. deep red or purple tongue

7. losing consciousness

8. glazed eyes