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By Diana Bocco

Change of any kind—like disruptions to routine or a new home—can bring about a lot of stress for dogs. "Dogs become accustomed to a routine and changes increase stress—even if the change is for the better," says Dr. Julie Brinker, a full-time shelter medicine veterinarian at the Humane Society of Missouri. "However, if the change is an improvement in the dog’s situation, the body’s stress response will return to its normal status much sooner."

Some other common stressors may include loud noises (anything from thunderstorms to fireworks to construction), boarding or kenneling, and even travel. Meeting new family members (whether people or animals) can also cause stress in dogs, Brinker says. "They have to figure out if the new arrival is a friend or enemy, then they have to learn how to get along with it.”

If your dog is stressed for a long period of time, you might start noticing changes in his health or behavior, some of which can lead to serious problems if not addressed quickly and properly. Here are six ways stress can affect your dog.

Loss of Appetite

Any type of stress can cause a loss of appetite, but prolonged stress can cause weight loss from decreased food intake, Brinker says. "This is dangerous for all dogs, but even more so for those that started out medically compromised. For example, dogs that are underweight, young, experiencing other medical problems, or eating a poorly balanced diet.”

In addition, some dogs suffering from stress may start chewing or even eating non-food objects. "This can include obsessively chewing toys, doors, and window sills, or licking themselves, even to the point of injury," Brinker says.

Weakened Immune System

When dogs are stressed, the body releases the hormone cortisol as part of the fight-or-flight mechanism. Cortisol helps the body respond to a stressful event—for example, by directing blood flow to the muscles—but when stress becomes a chronic problem, cortisol also causes problems, such as a weak immune system. According to Emmy Award-winning veterinarian Dr. Jeff Werber, "With stress and, ultimately, immune suppression, dogs are unable to fight off infection or disease. So it’s important to minimize dogs’ stress levels; otherwise, over time, a mild problem can potentially become a major problem."

A good example of this is demodectic mange, a skin disease caused by mites. "Demodectic mites live on the skin of almost every dog without causing harm," Werber says. "However, when the body becomes stressed, the mites multiply in certain parts of the skin, causing an obvious infection." Demodectic mange is also commonly diagnosed in puppies, in large part due to their immature immune systems.


In stressful situations, the body also releases adrenaline, another fight-or-flight hormone. Like cortisol, adrenaline can help a dog survive an immediate threat. For example, adrenaline increases heart rate and blood pressure, but these temporary benefits also come with downsides. "Adrenaline causes a decrease in blood flow to the intestines and stomach, which can result in diarrhea in many dogs," Brinker says. Stress-induced diarrhea often comes on suddenly and is typically not accompanied by other symptoms (no fever, no vomiting).

Behavioral Problems

The aforementioned fight-or-flight response actually involves four Fs: Fight, Flight, Freeze, and Fidget, according to Brinker. "Most dogs will try to run away from something that scares them, but if they aren’t able to escape, or if they have learned that aggression can get them out of a situation, they may behave aggressively instead," she says. “Freezing happens where a dog spends a few extra moments deciding whether they want to fight or flee."

Finally, fidgeting is perhaps the most common reaction we see in dogs who are stressed. "Fidgeting is a way for dogs to work off their excess energy without running away or attacking something," Brinker says. "They may pace, pant, shake their body, lick or scratch themselves, yawn, dig, or do another behavior that doesn’t quite make sense in a particular situation."

Exacerbate Illness

For dogs who are already sick, stress can slow the healing process, according to Werber. "Cortisol has an anti-healing effect," he says. "That’s why we try not to use corticosteroids [medications that act like cortisol in the body], because they slow down the healing process; cortisol affects our ability to fight disease." In addition, disease increases stress in dogs, creating a vicious cycle that is hard to break out of, Werber says.

Issues with Urination 

Stress very often causes inappropriate urination in pets. A clear example of this is urination that occurs in response to fear. The immediate release of stress hormones will relax the bladder sphincters and urination will occur, Brinker explains. "Defecation and anal gland expression may also occur,” she says. “In the wild, urination, defecation, and anal gland expression are all defensive mechanisms that (hopefully) might make a predator back away and give a stressed animal the opportunity to escape a scary situation."

Chronic stress can also lead to changes in a pet’s urinary habits, but so can a long list of medical problems. If your dog develops any unusual symptoms, it’s best to consult with your veterinarian before assuming that stress alone is to blame.

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