Why Is My Puppy Misbehaving All Of A Sudden? (Answered By Trainer)

Why Is My Puppy Misbehaving All Of A Sudden

There are many reasons a puppy might misbehave. If they have not been getting enough training, mental stimulation, or exercise, they might put their energy into being naughty instead of behaving.

However, even if you have been doing everything right raising your puppy, it is normal for them to start misbehaving all of a sudden; including biting, barking, and getting into or chewing things. It is incredibly frustrating when your perfect puppy changes their behavior overnight, but there are several reasons why they might start acting out all of sudden. 

From around 5 months to 18 months, puppies and adolescent dogs often go through a rebellious teenage phase (yes, just like humans!). They are testing their boundaries and seeing if they can be pushed. This phase, along with fear periods, sudden stressors, and tiredness can lead puppies to start misbehaving all of a sudden.

How do you determine the cause of your puppy misbehaving all of a sudden?

Understanding some basics about a puppy’s mental and physical development as well as external factors that could affect your puppy’s emotional state are good places to start when trying to figure out why your puppy is misbehaving all of a sudden.

They could be testing boundaries, being temporarily extra sensitive to new things, or being overstimulated and over-exercised! Once you know why your puppy is misbehaving, you can start looking at solutions to help get them through the rough phases and recondition their behavior so you get your happy, confident puppy back!

Reason 1: Rebellious Teenage Phase

It is natural for puppies to test boundaries. If your puppy is misbehaving all of a sudden, they could be going through their “rebellious teenage phase.” Owners who have worked hard to train their puppies to stay out of the kitchen, chew a toy instead of their arms, and have daily nap time in the crate might suddenly notice their puppies start to test what behaviors they can get away with.

It is normal for puppies and young dogs between the ages of 5 months and 18 months to start testing your rules by misbehaving all of a sudden. It is part of the maturing process and an important time to stay consistent; continue training your dogs and shaping the behaviors you do want.

Reason 2: Fear Periods

Have you noticed that your confident puppy becomes nervous around loud noises like thunder seemingly overnight? Or have they suddenly become frightened of strangers and started barking at them? What might seem like the puppy misbehaving all of a sudden could be your puppy going through a fear period.

While this phase is a normal part of puppy growth and development, fear periods can cause a sudden behavior change in your puppy. If this little French Bulldog was not so easily startled by the older dogs outside previously, he could be going through a fear period.

Puppies often go through their first fear period from ages 8 weeks to 11 weeks. This is the time when a puppy adjusts to a new home, and the adjustments of learning a new routine and new rules can be stressful. They are likely to seem to misbehave because they are still in a brand new place, are stressed, and do not know any better.

But from 6 months to 14 months (note this can coincide with the adolescent rebellion phase!), their behavior might change from being a perfect puppy to misbehaving all of a sudden.

A puppy who seems to start barking at the mailman out of nowhere might not be misbehaving but is barking out of fear. They are letting you know that their emotions are fragile and they need your help and support to work through this fear period.

Reason 3: Sudden Changes To Lifestyle

Has your puppy started misbehaving all of a sudden because of changes to your lifestyle? Was there a big move, or maybe you had a baby? Even simple changes like you started going to work an hour early or you changed their food can affect your puppy. Sudden lifestyle changes can be stressful for a puppy, and since they are still learning to process emotions, it could cause them to start misbehaving all of a sudden.

Puppies are sensitive and enjoy structure and routine. While they are still physically growing and mentally developing, a sudden change, especially coupled with a fear period, can stress them out enough that they start acting out. Dogs, in general, like predictability, and a sudden change can be extremely upsetting, especially for a still-developing puppy, causing them to start misbehaving all of a sudden.

Reason 4: Your Puppy Is Over-stimulated

Have you ever seen a toddler refuse to nap, and scream themself into a full-blown tantrum before suddenly nodding off to sleep? Well, puppies do this too. Instead of wanting to take a nap or cuddle, they might start misbehaving all of a sudden. Did you take them on a longer walk than usual after letting them play with the neighbor’s dog?

That puppy is going to be more tired than normal, and if he is still learning to relax, his exhaustion might turn into crazy zoomies and sudden misbehaving. Exercise needs to be carefully monitored with young puppies anyway since too much exercise can be hard on their still-growing bones and joints.

A puppy can be tired from both too much physical exercise and too much mental stimulation. A trip to the hardware store, followed by socializing at the elementary school to pick up your kids, and ending the day training at a puppy kindergarten class is a lot of mental stimulation for a puppy.

Their brain might be completely fried, but the body is still energized, so they start attacking your legs or getting into the trash. Puppies are still developing emotionally and physically and need both mental and physical breaks, or they might start misbehaving all of a sudden.

Reason 5: Boredom

If your puppy is older and more mature, they might not be overstimulated but bored! Puppies, particularly puppies that are high-energy working breeds, might need to start having a bit more exercise, training, and socializing. They are misbehaving because they are feeling rebellious and bored, and pushing your boundaries is a good way to entertain themselves. They might even push other dog’s boundaries, like the bored and maybe tired Labrador puppy in this video.

Another cause of boredom is pro-longed downtime, for example, a puppy recovering from surgery. After my border collie was spayed, it was only two days before her energy returned and she was bouncing off the walls and terrorizing my old dog again. I had to buckle down on her mental games to wear her out, and then encourage her to take long naps in her crate in-between training sessions.

Most puppies have a lot of energy and get bored easily, but a high-energy puppy like my border collie or a husky (or any other high-energy breed) might need extra mental and physical playtime as they get older.

Reason 6: Health Issues

Puppies and dogs often mask their injuries by misbehaving all of a sudden. Maybe the barking and biting are a result of your puppy being injured (or just sore from a particularly long walk?).

If you cannot rule out your puppy suddenly misbehaving because of a developmental stage, being overstimulated, or boredom, it is worth the peace of mind to talk to your veterinarian about the problem. If your puppy is sick or has an injury, the veterinarian can help diagnose and treat the problem.

What Can You Do About Your Suddenly Misbehaving Puppy?

Puppies grow up fast and do not be surprised if you notice behavior regressions including them misbehaving all of a sudden. Once you have identified the source of your puppy suddenly turning into a monster, there are several ways you can change their behavior.

From the day you bring home your puppy, keep a consistent schedule, work on training, crate train, and meet your puppy’s physical needs; if you start early, the behavioral regressions are usually much easier to recondition.

Keep A Consistent Schedule 

Most puppies grow out of their rebellious teenage phase as long as you stay consistent with training and their daily schedule. Your puppy is testing boundaries and you need to show that you can be trusted to keep a steady routine and rules.

Life does happen: you might need to go on a sudden business trip or have family come stay with you, causing your puppy to misbehave all of a sudden. However keeping up with training, exercise, and socializing will help them work through this phase and mature into a confident adult dog that can cope with unexpected life changes. Just remember that even with a consistent schedule, some behaviors can still regress but that’s a normal part of development. 

Working Through Fear Periods

It is important to work through fear periods with your puppy. If you do not help your dog overcome these issues, it could turn into a bigger problem when they are adults. Be patient and work on reconditioning your puppy to react differently to scary stimuli, even if it did not frighten them before. Barking at strangers might seem like they are misbehaving all of a sudden, but they might be frightened, and they need your guidance.

Allow your dog to give themself space from what they are afraid of, then reward and praise them when they look to you for help. You are training them to trust you, and this helps calm them down and make being around scary things easier. Do not make a big deal about the scary stimuli and keep your training sessions short. By keeping sessions short, you ensure your puppy is successful before their little puppy brains become overly stimulated.

Training and Mental games

If your puppy is recovering from an injury, going through their rebellious teenage phase, or simply bored, there is a good chance they will start misbehaving all of a sudden. Try adding some more training and mental games to their routine. You can start increasing the difficulty of their obedience training by adding distance to their stays or teaching more advanced tricks. Feeding your puppy’s meals with interactive toys and puzzles is also a fun way to teach them to entertain themselves.

There are many different games you can play with your puppy if they are misbehaving all of a sudden, including hide-and-seek, shaping games, and playing with toys. Not only will these games out your puppy’s brain, but they also strengthen your bond with your puppy and build up their confidence.

Crate Training

Whether or not your puppy is misbehaving, crate training is an important tool for puppy-rearing. It helps build a routine, encourages potty training, keeps your puppy safe, and creates a space for them to relax. It is also a good tool if your puppy starts misbehaving all of a sudden. Downtime is a crucial part of a puppy’s routine, and you want them to be comfortable in their crate. Never use the crate as a punishment, but redirect them with a long-lasting chew treat in their crate to encourage them to nap and take a break from misbehaving all of a sudden!

Train A Different Behavior

Is your puppy suddenly zooming around the house and knocking over furniture? Are they starting to attack your legs or trying to herd you? Try to reinforce a different and more appropriate behavior. Redirect them to a squeaky toy, or send them to their crate with a tasty chew. By reconditioning the behavior, you are teaching your puppy to make better choices and help recondition them to not misbehave.

Check out how this puppy automatically offered the more appropriate behavior of sitting when they were caught misbehaving!

Structured Exercise

Puppies need to be able to self-regulate their exercise; otherwise, they can get overly tired and possibly damage their developing bones and joints. A short walk around the neighborhood, playtime in the backyard, or visiting another puppy friend is going to a better option than a 10-mile run.

A run will not only make your puppy over-tired, but they might act out and misbehave all of a sudden because they are sore. Growing pains are common in puppies, especially for big breed dogs like Great Danes, so shorter, structured exercise will help them self-regulate and protect their growing joints. 

Should You Worry If Your Puppy Starts Misbehaving All Of A Sudden?

If you have ruled out a medical concern, you should not worry about your puppy misbehaving all of a sudden. It is normal development for puppies to push boundaries and go through fear periods. However, you should take immediate action and help your puppy work through the behavior positively. If you allow your puppy to continue attacking your legs or barking at strangers, these bad habits can carry into adulthood. 

Always get help from a certified trainer or veterinarian if your puppy starts misbehaving all of a sudden and you are feeling overwhelmed with your puppy’s new behavior.

In Conclusion

Raising a puppy is a lot of work, but with the correct knowledge and understanding of puppy development, you can handle all the little roadblocks that might pop up. This includes your puppy misbehaving all of a sudden.

It can be frustrating when your puppy is in its teenage rebellious phase, or when you see their confidence regress because of a fear period. However, with patience and training, your puppy can easily bounce back to their confident self and grow into a well-rounded adult dog.

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