Dogs bark for various reasons, from boredom, because they want attention or they might be fearful or excited. Some dogs, due to their breed, don’t bark as much as others. For example, Basenjis are very quiet tempered and almost never bark. This doesn’t mean they are completely silent, and they will howl or whine on occasion, but are usually just not very vocal.
If you have a dog that usually barks from time to time and he suddenly stops, there might be a reason to be concerned. Sometimes, dogs who have just been brought into a household from a shelter situation, won’t bark much initially. Unless they are a naturally reserved breed, they will likely become more vocal as they get used to their new surroundings.
Also, it’s possible that a shelter or rescue dog could have undergone a surgical procedure called “debarking” in which their vocal cords are trimmed. These dogs can still bark but they can’t bark very loudly.
Of course, most professionals would not recommend this procedure. Sometimes, dogs have been trained not to bark. Unfortunately many times this means the dog was forced into a collar that punished him for barking or he was abused and became fearful of barking.
If your previously healthy dog suddenly quits barking or has trouble barking, it’s possible he could be suffering from a vocal cord strain, usually caused by too much barking. Otherwise, sudden silence on the part of your dog may mean he is in pain or otherwise not feeling well. If you can’t identify an immediate cause for his silence, a veterinary consult is in order.