The heat can make your dog sick, especially if they don't have access to water. If your dog was outside in the heat and is acting lethargic, it may be dehydrated. You'll need to get water to it quickly. Here are the four steps you should take immediately, to help re-hydrate your dog.
Offer Fresh Water
You need to offer your dog plenty of fresh water. Unfortunately, dehydration often makes it difficult for pets to consume water. In fact, if your pet is dehydrated, it may vomit the first few times you offer water to it. Place a bowl of water in front of your pet. If it won't drink the water, soak a wash cloth in the water and squeeze the cloth into your pet's mouth. Continue doing this until your dog drinks the water willingly.
Add Some Incentives
If your dog just doesn't seem thrilled with plain water, try adding ice cubes or even low-fat chicken broth to the water. Your dog may be more willing to drink the additional water if there is a bit of flavoring or cool ice added.
Bring on the Electrolytes
Depending on the length of time without water and the temperature outdoors, your dog may be suffering from severe dehydration. If your dog's mouth and eyes are dry, you may want to add some electrolytes to the water. Fill the water bowl with half water and half sports drink to increase your dog's electrolyte levels. Encourage your dog to drink until it shows signs of rehydration—moist eyes, nose and mouth, along with increased energy.
Get to the Vet
If your pet refuses to drink water and becomes increasingly lethargic, meaning it's unable to move or it is falling asleep, you'll need to get to the veterinarian as soon as possible. Severe dehydration can lead to kidney failure. Your pet may require IV fluids to fully recover. Be sure to let the vet know what measures you took while at home.
If your pet was left outside without access to water, even if accidentally, you'll need to work fast to rehydrate it. The safety measures above will help you rehydrate your dog so that it can recover completely. To prevent the situation from occurring again, you may want to install a drip watering system on an outside water faucet. The drip system will allow your pet to receive water whenever it licks the faucet.