also this specifically for dogs that might have chewed on the battery.. just like your friends dog case

http://www.petfinder.com/journal/index.cgi?article=943

Dogs are most commonly affected because they chew and puncture the battery casing. If the battery is chewed into pieces and the fluid swallowed, or if the battery case is cracked, allowing fluid to leak out, burns can occur in the mouth and esophagus. If the fluid leaks onto the skin, dermal burns can occur.

Did He, Or Didn’t He?
If battery fluid has been ingested, the tips and sides of the tongue will usually appear red and raw, or will have a whitish-gray appearance due to dead skin. The dog will generally drool heavily and may vomit. He may be quiet or may whimper or cry due to pain. Although many animals will stop eating because of oral pain, some dogs will continue to eat, but may chew slowly and carefully. The dog may appear to have difficulty swallowing. These signs often are delayed and may not appear for up to 12 hours.

If a dog ingests a battery, it’s important to know what kind it is and if it was ingested whole or chewed into pieces. When a battery is missing, and it is not known if the dog actually ingested it, an X ray will show if pieces of the battery are in the stomach.

When ingestion is recent, the most important initial treatment is to dilute the corrosive fluid. Small quantities of milk—based on the weight of the animal—can be given. Large amounts may cause diarrhea. Vomiting should not be induced without consulting a veterinarian, because if the dog vomits the corrosive fluid, the damage to his throat can be significantly increased.

If pieces of the battery are present in the stomach, surgery may be required to remove the battery and prevent further leakage of the fluid. An intact battery, on the other hand, may obstruct the intestine, requiring surgical removal. Sometimes, if the battery is intact, a high-fiber “bulking” diet may aid in passage of the battery.

Dogs who develop clinical signs will require veterinary care consisting of antibiotics, pain medications, medication to protect the stomach and intestines and special diets. A veterinarian may recommend that a dog’s throat be examined endoscopically to access the damage to the esophagus. If severe scarring occurs, the dog may have difficulty eating and swallowing later on.


petco source:

Battery acid is a particularly nasty chemical for your pet to come across. Most dogs know better than to lap battery acid up with their tongues, but if some falls in their fur, the gut reflex is to clean. Many animals have permanently lost the tips of their tongues from cleaning battery acid off their fur. Battery acid does as much damage to a dog as it would to a human.

Symptoms of battery acid poisoning include abdominal pain; bloody vomit; refusal to eat because of a sore mouth; shock; lip, mouth and tongue burns that look like patches of grayish-yellow discoloration; or a bad smell issuing from the mouth due to dying tissues.

Battery acid poisoning is very severe and an extreme emergency. Rush your pet to an emergency facility or vet. If your pet is conscious, give him milk of magnesia or vegetable oil to dilute the poison, 1 tablespoon per 10 pounds of weight. If his skin is burned, flush with lots of cold water. DO NOT INDUCE VOMITING! Battery acid is caustic.

Dispose of any old batteries, and never leave them lying around your garage. If your dog rubs against a battery, the acid may get on his fur. Also, many dogs like to crawl underneath cars to explore and possibly nap. This is a highly dangerous area, especially if your dog is a large one. Their fur can become coated with all sorts of unpleasant substances, like battery acid. Train your dog not to go under a car. Yell, scold him firmly, spray him with water or throw soft objects at him when you see him under the car. It sounds mean, but the benefits to your dog's health are worth it.