
While a lack of proper obedience and socialization training can cause a dog to misbehave, sudden changes in an otherwise well-behaved dog’s demeanor and temperament are usually signs of something wrong.
If you have noticed that your dog is not behaving as well as they usually do, the first step is always to identify the cause. Luckily, we can help! We will list some of the most common reasons dogs begin misbehaving and explain what you need to do next to get your dog’s annoying behavior back on track.
If you are tired of your canine companion’s sudden poor behavior, you have come to the right place!
Why Do Dogs Suddenly Start Misbehaving?
Occasional poor behavior moments should not be considered a serious cause for concern, especially if a dog is still young. That said, typical poor behavior that has started suddenly and without much warning is usually a sign of an underlying issue.
To help you get to the root cause of your dog’s recent changes in behavior, we have outlined the four most common reasons. Read through this list and look for other symptoms your dog displays alongside their recent behavioral changes.
Once you have identified the cause, you can begin to address the unwanted behavior and help your furry friend get back to being the good boy or good girl you know they can be.
1. Lack of Physical Exercise and Mental Stimulation

A lack of mental and physical stimulation is the most common reason dogs begin misbehaving. For the most part, dogs are very energetic and curious animals. If they do not get enough daily exercise, or their days become overly mundane, they can begin acting out.
While many assume that a single walk daily is enough exercise for a dog, this is inadequate for most breeds. Your dog should be getting at least two reasonably lengthy walks per day, especially if they are one of the larger and more energetic breeds.
You should also avoid taking your dog on the exact same route every single time you go for a walk. While this routine might be easy, it can become stale for your dog, especially if those walks are the only time the dog leaves the house.
New and exciting routes can help keep things interesting for your dog and increase the mental stimulation they get each day. You can also try increasing the pace by taking your dog with you on jogs and light bike rides.
Your dog’s lack of exercise and mental stimulation could be unintentional. If you just started a more demanding job, you might be cutting back on the frequency and length of walks you are taking with your pooch, which could also explain why they are now misbehaving.
How can you increase the amount of physical and mental stimulation your dog gets each day?
Increasing the mental and physical stimulation your dog gets daily is pretty straightforward. Try increasing the length and frequency of walks your dog gets per day. Also, try to incorporate new routes into your walks.
You can also consider trips to dog-friendly hiking trails and beaches. Off-leash dog parks are also a great idea, as they offer an opportunity for your dog to socialize and run around, which is excellent for mental stimulation.
If your schedule does not allow you to spend more time with your pooch, you can consider hiring a dog walker. Often, this is an affordable and practical solution that will stop your dog’s sudden changes in behavior.
For more information on the daily exercise requirements for dogs according to their age and breed, consider reading the American Kennel Club’s guide – How Much Exercise Does a Dog Need Every Day?
2. Anxiety and Fear

Just like humans, dogs can suffer from chronic anxiety, which is often related to a fear response. When dogs feel anxious, they can begin displaying various destructive behaviors. In many cases, these anxiety-related symptoms are simply attributed to poor behavior.
Common symptoms associated with chronic anxiety include the following:
- Excessive barking, growling and whining
- Self-destructive behaviors, like biting and scratching their skin
- Destroying furniture, toys, carpets, and other objects
- Urinating and defecating in the house
- Pacing throughout the night
As you can see, many of these symptoms are the same behaviors often labeled as poor behavior in dogs. If you are punishing your dog as a response to behaviors caused by anxiety, you can just make the dog’s anxiety worse.
What should you do if anxiety is causing your dog to misbehave?
Fortunately, there are several ways to treat canine anxiety. You can alter your schedule to spend more time with your dog if fear of abandonment triggers their anxiety.
You can also speak with your veterinarian about anxiety medications and calming treats. There are even dog training classes to help anxious dogs feel more comfortable.
The ASPCA has a helpful guide to anxiety issues in dogs that can help you determine if your dog’s recent behavior is a symptom of anxiety or just a passing phase – ASPCA Separation Anxiety Guide.
3. Lifestyle and Environmental Changes

Most dogs are true creatures of habit, meaning significant changes to their routines and environment can trigger various unusual behaviors.
Moving to a new home can overwhelm a dog and cause undesirable behavior. That said, environmental changes do not have to be as significant as moving to a new house. Something as innocent as introducing a new baby or pet into the home could be a significant enough change in your dog’s life to make them behave differently.
Changes in your schedule could also disrupt your dog’s lifestyle and cause them to misbehave. This is particularly true if you are out of the home for long periods, as it could trigger separation anxiety.
What should you do if lifestyle or environmental changes are responsible for your dog’s sudden changes in behavior?
If your dog reacts poorly to changes in their lifestyle or environment, you must be patient and help them adjust. Reintroducing consistency into your dog’s daily routine will help them adjust.
Try to take your dog on walks at the same time each day. If you have introduced a new baby or pet into the home, try introducing your dog to them gradually and always do so while offering plenty of positive reinforcement. This will help the dog feel less threatened and like their perceived territory is under attack.
A mixture of structure, consistency, and setting firm boundaries should help your dog adjust and put a stop to their recent changes in behavior. Just remember, patience is essential, as is maintaining positivity.
4. Age-Related Cognitive Issues

If you have a dog in its senior life stage, any sudden changes in behavior could be due to age-related cognitive decline. Unfortunately, dementia is reasonably common in senior dogs over the age of 13.
One of the symptoms associated with a type of dementia known as canine cognitive dysfunction is increased aggression. While many assume that their dog has become grumpy in their old age, it is a medical condition that will worsen as the dog grows older.
What should you do if the cognitive decline is responsible for your dog’s sudden misbehavior?
If you encounter behavior issues in your senior dog, booking an appointment with your veterinarian could be worthwhile. They will be able to assess your older dog and determine if their changes in behavior are related to a cognitive issue.
If they diagnose your dog with canine cognitive dysfunction or a similar issue, they can review some of the treatment options you would have at your disposal.
Fortunately, there are quite a few prescription medications and lifestyle changes that can help senior dogs suffering from dementia-like symptoms, including increased aggression and destructive behavior.
For more information about canine cognitive dysfunction and other age-related cognitive behavioral issues, we recommend reading PetMD’s informative guide to neurological problems in dogs –Dog Dementia – Symptoms, Causes, Treatments, and Life Expectancy.