About 40 percent of American households have at least one dog, according to The Humane Society of the United States. But as the costs of dog-bite litigation spirals — costing insurers $351.4 million in 2006, according to the Insurance Information Institute — some insurance companies are refusing to write coverage for owners of certain breeds.

While there might not be an industry-wide "blacklist" of breeds, it's probably best to check with your agent before you buy one of these breeds that account for the greatest number of dog-bite fatalities:

• Pit bull
  
• Rottweiler
  
• German shepherd
  
• Husky
  
• Malamute
  
• Doberman pinscher
  
• Chow chow
  
• Great Dane
  
• Saint Bernard
  

Some home insurers have lists of breeds and crossbreeds they will not insure; other insurers consider such breeds on a case-by-case basis, or charge more for certain "biting" breeds such as pit bulls. Some home insurers require dog owners to sign liability waivers for dog bites.

In Michigan and Pennsylvania, it’s illegal for home insurance companies to deny coverage simply because a home has a dog of a particular breed.

Some companies don't discriminate by breed. "We believe that there are good dogs and bad dogs within every breed, just as we believe that there are responsible and irresponsible owners," says Phil Supple of State Farm.

Dan Hattaway, an underwriting consultant for State Farm, says the company doesn't even track how many of its home insurance policyholders own dogs. Policyholders do have to answer questions about dogs on the application, however. Specifically, the company wants to know if a dog has ever bitten anyone or if it has been trained for attack purposes.

If the dog has bitten someone, State Farm will want to know the circumstances surrounding the bite. "We'll want to ascertain if it's ever likely to happen again — if precautions have been taken to prevent it," says Hattaway. Other factors the company looks at are the seriousness of the injury and whether the attack was provoked or unprovoked.

Considering each case individually

Hattaway gives this example: An Irish setter gives birth to a litter of puppies. She and the puppies are on the back porch. Some friends come over with their little boy to look at the puppies. Under the supervision of the insured, everything is fine. Everyone goes inside, and parents tell the boy that it’s time to leave the dog alone with her puppies.

"Well, the adults got to talking about adult things and the little boy, unnoticed, decides he's going to go out and pet the puppies. He got bit," says Hattaway. "When State Farm followed up on the claim, we found that the insured had had the female spayed. She wasn't going to have any more puppies, and she showed no further aggressive tendencies." Because the dog's owner had taken steps to make sure that a similar incident would not occur, State Farm continued his coverage.

Some companies will ask, "Do you own a vicious dog?" on home insurance applications. Any previous dog-bite claims will show up on your claims history, which insurers check before issuing a policy. Like State Farm, some insurers will consider whether an attack was provoked or unprovoked.

Insurers are most concerned about unprovoked dog attacks. If your dog has an unprovoked attack in its history, most insurers will cancel or refuse to renew an existing home insurance policy, decline your application for a new one, or attach an exclusion for the dog to the policy. The exclusion means the insurance policy would not cover any liability claims caused by the dog, making you personally responsible for any medical bills or lawsuits stemming from your dog's actions.

Prevention is the best medicine

The best way to make sure your home insurance won't get canceled because of your dog is to make sure your dog won't bite anyone.

Dan Hattaway of State Farm outlines ways to make sure a dog won't bite the hand that pets it: "Socialize the pet with people and other animals outside the household," he says. Training it to obey your commands — whether on your own or with the help of obedience school — will also lessen the chances your dog will strike out on its own. Keep your dog healthy; if your dog is in pain, it's more likely to lash out. Obey leash laws, even on your own property.

The Centers for Disease Control and Prevention says that 50 percent of dog bites occur on the dog owners property. Spaying and neutering a dog can also improve its disposition, especially with male dogs.

Don't put your dog in situations where it will be threatened or teased. Hattaway notes 60 percent of dog-bite victims are children, who might not be aware that their behavior is threatening to dogs. "Most importantly, be alert to signs that your dog is having a problem," says Hattaway. If your dog is agitated or appears threatened, take the necessary steps to calm it down.

If there's a bite

If your dog bites someone, respond right away. Restrain or confine your dog immediately. Then do whatever you can to help the victim, whether that means calling 911 or driving them to the emergency room.

Once the victim is taken care of, you might have to contact the local authorities to report the dog bite. You should then call your homeowners insurance company, especially if there are medical costs involved. Be sure to cooperate with your insurance company. No doubt, the adjuster will want to investigate the circumstances surrounding the incident.

Take steps to make sure a similar incident doesn't happen. That might mean building a fence around your yard or sending your dog to obedience school. When all else fails, a certified animal trainer might help.