If your dog's personality goes from confident to fearful in certain parts of the house, he has probably developed a negative association with some aspect of the room. You can help your dog deal with his fear once you figure out what exactly is causing his sudden behavioral shifts.
Many canine phobias are related to prior traumatic experiences and reinforced negative associations. For example, being cooped up in an animal shelter for months may make something as benign as the smell of certain disinfectants intolerable for your pet because it reminds him of the long, unpleasant ordeal. Whatever the cause, fear develops when your pup connects a certain room to unpleasant sensations, memories or negative feelings, like isolation or competition. A room may be too hot or too cold for your pup most of the time, so he knows that going in there will be uncomfortable. Some dogs are just afraid of new things. Phobias aren't always the result of prior experience. If your dog seems to be afraid of a lot of things, consult a behavioral therapist to discuss remedial training and acclimation strategies.
When your dog steps onto certain hard flooring, it's possible that all the terrible memories of vet office visits are flooding back into his brain. As strange as it may seem, the appearance or texture of the flooring in a particular room can terrify your pup, according to the Merck Manual for Veterinary Professionals. Develop a positive association with the room with treats and encouraging words. Start slowly by beckoning your dog to cross only a small portion of the room to reach the reward. Increase the distance until he's comfortable traversing the entire area.
You may not be able to smell the difference between one room and another, but your dog can. Certain smells, like potent perfume or air freshener, can be offensive to your pet's senses. Remove candles and other scents from the room and see how your dog reacts. Consult a behavioral therapist if your dog is afraid of the sight and smell of other people. Consider having the room tested for mold and other unseen sources of odor. Dogs are able to smell mold spores even when humans can't. In fact, some mold detection companies rely on dogs to find unwanted fungal growth inside houses. The scent of an animal, either dead or alive, inside the wall may also be bothering your pup.
Washing machines, hair dryers and high-pitched sounds are not very pleasant for your pup. Listening to these sounds may cause physical pain or arouse negative memories. Remember, dogs can hear at much higher frequencies than humans. Even if you hear nothing, unplug all of the electronic devices in the room and turn off the lights. Bring your dog into the room and see how he reacts with all of the sound sources disabled. More than a third of pups with noise phobias also suffer from separation anxiety, according to the American Kennel Club Canine Health Foundation.
Your dog's phobia may not have anything to do with the room itself. If the dreaded vacuum cleaner or another offensive object dwells in the area, it might be enough for him to loathe the entire room. If your dog becomes fearful or aggressive when you handle a certain stuffed animal or the fly-swatter, remove the undesirable object from the room and bring him back into the area.