Why Your Dog Barks at Nothing: Common Reasons for the Behavior

My spotted Cattle Dog, Lilac, often sleeps on a rug in front of a glass door. She also frequently leaps up to stand inches from the glass to bark…at what? Startled, I jump up, too. Is there a car coming up the driveway or a fox near the chicken coop? Half the time, I can’t detect whatever it is that now has my other dog, Willy, barking with her. What’s gotten into them? Read on to learn why dogs so often bark at seemingly nothing.

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Why do dogs seem to bark at nothing?

Dr. Aimee Warner, the resident veterinarian at Waggel, says barking that seems random to us comes from dogs’ acute sensory awareness. “Dogs perceive their environment through different sensory channels than humans because their perceptive abilities operate on a different scale,” Warner explains. “The environmental cues that remain invisible to human perception might be highly significant to dogs.”

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Most common reasons for random dog barking 

They smell something in the environment.

A dog’s sense of smell is incredibly powerful — up to 100,000 times more sensitive than a human’s, Warner says. They smell people coming down the sidewalk before they see them. “Dogs may bark when they detect scents that are undetectable to humans, such as other animals or unfamiliar smells or odors,” she says. 

Dogs gather information and detect danger through their noses, so it makes sense when they bark at unfamiliar and potentially dangerous smells. “They will bark to alert those around them that something is near,” says Sally Grottini, a certified service and therapy dog trainer (specializing in obedience and behavior), who is a former AKC evaluator. “They can also detect medical issues in humans, so they may bark when a person is about to have a seizure or a possible blood sugar drop.”

They hear a noise that we can’t hear.

Long before I hear the sound of thunder, I find Willy hiding under the bathroom sink. That’s because dogs’ hearing encompasses a range of frequencies and distances that exceed human capability, Warner explains. “Distant sirens, high-pitched electronic devices, or the sounds of rodents in the walls can make dogs bark,” Warner says. If it’s rodents, your dog could be doing you a favor. 

They see something in low light that we can’t.

As if you need more evidence of your dog’s superpowers, Grottini points to their night vision. “Dogs have reflective tissue beneath their retina that allows them to see things in the dark that humans may not see,” she says. “They also have a larger pupil size than humans, [which] allows them to constrict and control the amount of light coming into the eye. The more light that enters, the better they see at night.” 

Dogs’ power to detect motion up to half a mile away makes them valuable in police and military work and home protection. “The natural protective instincts of dogs lead to barking when they detect potential threats,” Warner says. 

They may be having some cognitive dysfunction.

This applies mostly to older dogs. As some dogs age, Grottini says, they develop cognitive dysfunction similar to human dementia. “This may cause them to bark or whine,” she says. They may become lost in once-familiar places. They may not recognize their owners, and there is an increase in fear and anxiety due to what they cannot remember as normal.” Warner says age-related disorientation can lead to nighttime barking, hallucinations, and confusion that requires veterinary care.

They might be feeling anxious or bored.

Barking is one way dogs communicate. Maybe they can’t reach their favorite toy under the couch. Or maybe they’re standing over a toy, looking up at you, and barking. “Dogs bark when they want your attention because they’re bored and want you to play,” Grottini says. 

Whether they’re understimulated, isolated, or anxious, barking helps dogs release excess energy, Warner explains. Left unaddressed, it can get worse and cause problems for people nearby, especially if you live in an apartment building or a densely populated neighborhood.

Eunice Arauz, owner of the pet supply company Pets Avenue, says barking can be managed with a balanced routine including socialization and sufficient mental and physical stimulation. “Simply adding interactive toys, daily exercise, or puzzle feeders could reduce unnecessary barking and keep your dog more focused. However, if the barking is persistent or seems unusual, you may want to consider contacting a vet or a behaviorist to rule out any serious, underlying issues,” Arauz says. 

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How do you help your dog learn proper barking habits?

Excessive barking occurs for a number of reasons. Stopping it requires some detective work and follow-through. Warner says that you should first identify the cause of the barking. Like Arauz, she recommends mental and physical exercise to expend your dog’s energy. Next, practice rewarding silent behavior and teaching a “quiet,” “leave it,” or “no bark” cue. Redirecting your dog’s attention can also be effective. “The goal is to shape barking into proper communication channels, since barking serves as a natural canine-communication method,” Warner says. 

Lora Shaw, the vice president of operations at Pet Palace Resort, suggests counter-conditioning. That involves exposing your dog to a particular sound and giving them a treat when they don’t react. “You could also consistently play some sort of background music in the house to help drown out those other potential outside sounds that might trigger your pet. Either way, your dog is trying to alert you to something that they find important,” Shaw says. 

Grottini refers to the infamous mailman syndrome: A dog who barks when they see the mail carrier approaching will bark more loudly until the carrier leaves. “The dog doesn’t know that the [carrier] is going to leave after [they] deliver the mail,” Grottini says. “The dog thinks barking made this threat leave, and so barking works for the dog. And they’ll continue to do it.” 

To interrupt this cycle, teach them a “leave it” cue. “Keep in mind that dogs will always respond to their instincts, and if you want them to stop doing something, you must train them,” Grottini says. 

Other strategies for keeping your dog quiet include finding your dog a companion if you’re away from home for long stretches and pulling a shade over windows to conceal activity outside. Bark collars are controversial and should only be used in extreme cases with help from a certified applied animal behaviorist (CAAB or ACAAB) or a certified professional dog trainer (CPDT). 

How do you know if random barking is a medical issue that needs attention?

Abnormal barking accompanied by confusion or unusual behavior may warrant veterinary examination, Warner says. “The barking behavior of dogs changes due to physical pain along with sensory impairment and neurological conditions, as well as cognitive age-related problems,” she says. 

Conversely, Grottini says, contact your vet if your dog stops barking at something that normally gets their attention. If their bark sounds hoarse or strained, they may have a throat issue. Sometimes, a dog in pain will growl and bark as you approach because they don’t want to be touched. “Pacing, panting, lip licking, sleep pattern differences, and changes in appetite are other signs to watch for as well,” Grottini says. 

Bottom line 

• Barking is a natural form of canine communication with obvious and sometimes not-so-obvious reasons.

• Dogs’ keen senses help them pick up on distant sounds and smells that signal danger. When it’s excessive and you wonder how your dog can bark nonstop, take a deep breath and try to remove yourself from earshot. 

• If you give your dog attention when they’re barking, you’re just rewarding their unwanted behavior. 

• Enlist a vet or behaviorist to pinpoint the reason for your dog’s barking and help you train a “quiet” or a “leave it” cue.