By Diane LarattaAfter watching several episodes of a popular TV program about changing a dogís behavior, some folks may believe that there is no such thing as a dog with a temperament so bad that it should be euthanized. After all, if the guy or gal on television can waltz into a home and turn a bad dog into a seemingly wonderful pet, why canít every dog be rehabilitated by any trainer?In my opinion, some dogs are born with a genetic propensity for aggression. They are just plain nasty. They may not start out appearing to be aggressive, but somewhere between 16 and 24 months, they change and their true colors emerge. Weíve seen it in our classes. A delightful puppy sails through puppy kindergarten, does well in beginnerís obedience, and even manages to pass its canine good citizen class. Six months to a year later, we get a phone call from the owner describing a completely different dog. What happened?If the dog did not suffer any abuse, trauma and is healthy, nothing the owner did changed this dog. What happened is that it matured and the genes it inherited are now being exhibited.The owner probably missed the warning signs, as they can be subtle. The dog may have growled a few times and the owner dismissed the behavior, sometimes even calling it ďtalkingĒ instead of what it really was, a warning from the dog. The owner may have made excuses for the dogís increasingly aggressive behavior. Instead of seeking help from an animal behavior specialist, the owner may try to avoid circumstances that make the dog aggressive. I know people who canít walk into their kitchen once they set their dogís food bowl down because the dog gets ďfunnyĒ while itís eating. I know other people who have to stay on ďtheir side of the bedĒ because their dog claimed the other side as its own. It amazes me that people will live with a dog exhibiting this kind of behavior. This type of dog is a ticking time bomb. Given the right trigger, it will bite. Small dogs get away with a whole lot more attitude than the bigger guys. I suppose itís because a small dog is unlikely to severely injury someone, sending them to the hospital. But they can still inflict enough damage to cause pain and require stitches. Small dogs tend to get a lot of pampering and attention. They begin to think theyíre equal to or better than their owners! Let a small dog with aggressive tendencies get to the point that itís running the household, well, letís just say, you have a recipe for disaster. Can an aggressive dog make a good pet? Perhaps ó in certain circumstances. It takes an experienced dog person to deal with this type of dog. The dog can be managed, and this is a lifelong commitment. There is no time that the owner can let their guard down. When guests are in the house, the dog must be crated or put in a place from which he cannot escape and no one can accidentally get to him. Many years ago, I recall a show dog that retired from the show ring after winning many Best In Shows. The dog was sleeping in the foyer when an elderly adult member of the family accidentally tripped over the dog. The result was disastrous. The dog killed the human. A judge ruled that the dog be euthanized. Yes, you guessed it, the owners did not want to do that and appealed the decision. They agreed to have all the dogís teeth pulled and to put the dog in a secure place whenever guests were in the house. Some people will go to any lengths to keep their dog regardless of its temperament. I am not one of those people. I have had dogs euthanized for exhibiting aggressive behavior. It is not something I want to live with, and I donít want to put any one else at risk. How do you avoid buying or adopting a dog with a bad temperament? If youíre buying a purebred dog, go to a reputable breeder. See the parents of the puppy. If they have a good temperament and are living in the breederís home and are well socialized, chances are the pup will have a stable temperament. Adopting a dog presents many challenges. If you are adopting from a good rescue agency, they will have temperament tested any dog prior to putting it up for adoption. But remember, dogs living in humane societies and other rescue agencies are under stress. They may have been stray, living on the street, or they may have been rehomed several times. We donít know what baggage a rescued dog may bring into a home. Be vigilant, cautious, and watch the dogís body language. If youíre gut feeling is that something isnít right, take the dog back as soon as possible. There are many, many wonderful dogs that need a home. Adopt one of them!Diane Laratta owns and operates the Hollowell Academy of Dog Training. Questions regarding training or behavior may be emailed to her at email@example.com.