
Food refusal

A dog that’s sufficiently stimulated usually enjoys its food even if what’s on offer isn’t its preferred meal. Some dogs are fussier with what they’ll eat. These animals are likely to be even pickier and perhaps even refuse food altogether if they are bored. Conversely, a well-exercised, mentally-stimulated dog will be hungrier and more likely to eat what it’s given.
Lip licking

Lip licking is one of the earliest signs of a stressed dog. Of course, dogs may experience stress for many different reasons, but one possibility is a lack of mental stimulation. A lip licking dog may also yawn even when it is clearly not tired.
Poor recall

Dogs may have poor recall for several reasons. The most obvious is a lack of training. However, if you’ve put in the training hours and your dog is still reluctant to come when called, it’s time to consider other possibilities. If your pet isn’t getting enough stimulation it will attempt to provide its own – and not recalling to you may be part of this.
Jumping up

Although sometimes tolerated or even encouraged in young, very small or particularly cute dogs, jumping up is not usually regarded as a positive trait in canines. Sometimes a dog may jumps up because it’s excited to see you and sometimes it may do so because you haven’t trained it not to. However, some dogs jump up simply because they are not getting enough mental stimulation.
Counter surfing

It’s easy to write off a particular dog as an incorrigible food thief. And, while it’s true that some breeds – labradors and dalmatians, for example – are more notable food thieves than others – it’s usually possible to train a dog not to take food without permission. Dogs that persist in counter surfing may be doing so as a result of a lack of stimulation.
Yawning

Yawning is the second of the early behavioral stages of a stressed dog. It differs from yawned caused by tiredness as it’s not typically followed by the dog settling down to sleep. Instead, the animal may pace around, whine or engage in destructive behavior. This is the dog’s way of asking for something stimulating to do.
Barking

Easily one of the most annoying behavioral traits, an insufficiently stimulated dog is also often a bark-y dog. Stopping your dog from barking can be challenging and require both persistency and consistency. However, if the barking is primarily due to lack of stimulation, giving the dog more appropriate outlets – for example, more exercise and some scent work – may limit the barking.
Chasing cars

Even a dog that’s never allowed out by itself can develop a car chasing habit. If your dog lacks sufficient stimulation and you have a garden that fronts a road, you may notice him chasing cars along your boundary. Try to distract him with a different sort of game, and reward the desired behavior using a clicker and a food treat.
Escape artist

Escape artist dogs are stressful to own. The worry that they may end up under a car or disappear and never return home is ever-present. Consequently, it’s a behavior you must address. Making your boundary very secure is the first step. The second is to look at why your dog is running off. Rule out boredom by giving him plenty of exercise and brain games.
Pawing

Although they obviously can’t speak, dogs have plenty of other ways of communicating. Barking and whining are obvious but some communication methods, like pawing, are very physical. Pawing can be annoying and even painful. While it’s not to be tolerated, remember your dog is trying to tell you something – and it could be that he’s bored.
Over-eating

As a rule, dogs eat what is in front of them. It’s your responsibility to judge how your dog needs. However, some owners over-feed to compensate for something lacking in the dog’s life – and this missing element may be stimulation. However, a fat dog is rarely a truly healthy dog. It’s far better to find ways other than over-feeding to keep your dog happy.
Chasing wildlife

Many dogs have a strong prey drive. In some breeds, it’s almost impossible to train this drive out of them. However, even with these dogs – but especially with other dogs who may be chasing squirrels because they’re bored – you can redirect the dog’s energies into something more appropriate. Try fetch and retrieve games, “flirt” poles, or even canine sports like canicross.
Whining

Whining can be incredibly annoying. Consequently, it’s one of the most powerful weapons in a dog’s communication arsenal. Sometimes, you’d probably do almost anything to stop or block out the noise – perhaps, provide extra food or shut the dog in a different room. However, a far more effective, long-lasting tactic is to consider why the dog is whining. What is he saying? Is he bored?
Digging

Many dog owners have sad tales of beautiful borders and carefully-tended vegetable gardens destroyed by a dog with busy paws. Although close supervision and fencing both go a long way towards curtailing the problem, perhaps you find out why your dog likes digging. If it’s that he doesn’t have anything better to do, could you give him suitable alternatives?
Hunting

Some breeds of dog are bred for hunting. However, to a greater or lesser extent, most dogs have some instinct for it and may give in to it if they’re insufficiently stimulated. Generally considered as one step up from simply chasing wildlife, it’s a difficult behavior to check. Obedience lessons, strengthening the dog-owner bond and teaching a rock-solid “leave” command can all help.
Humping

There’s nothing like a pet dog enthusiastically humping a guest’s leg or another dog to bring social chit chat to a crashing halt. Although it’s mostly male does, some bitches also hump because it’s as much an attention-seeking behavior as it is hormonal. A bored, over-excited dog is a bad combination in many settings but especially if you don’t want it humping anyone’s leg.
Fur loss

Like people, anxious dogs can develop OCD-like behavior. In dogs, this frequently shows itself as excessive licking, nibbling or scratching at their own fur or skin. You may not clock this as unusual – at least until your pet starts losing fur. Veterinary collars can be a temporary physical solution but, for long term results, look at your dog’s lifestyle to see what’s prompting the behavior.
False pregnancy

Unspayed bitches sometimes have false pregnancies. These can even result in the dog lactating and becoming possessive or protective of puppy-substitutes, such as toys or other small animals. Although false pregnancies are hormonally-driven, the behavior they trigger may be enhanced if the dog also lacks sufficient stimulation in her life.
Destructive in the house

A bored dog is often a destructive dog. Newspapers, clothes, shoes, paintwork, furniture and even walls can all take the brunt of an insufficiently stimulated dog. Crating the dog when it’s not supervised is a practical solution but will not solve the underlying cause. For that, you’ll need to ramp up the exercise, mental games, canine sports or all three.
Fearful

Dogs that don’t have enough to do divert their time and brain space into other activities. Although this is mostly expressed outwardly, in barking, digging or chewing, some dogs turn the problem inwards. A naturally timid animal may become more fearful and less confident about the world, especially if its lack of stimulation partly stems from insufficient real-world interactions.
Dog reactive

Just like people, dogs don’t always get on with other dogs. Some dogs have problems with specific other dogs. Other dogs display antipathy towards all other dogs. The causes of this behavior can be complex but it’s certainly worth considering whether lack of stimulation plays a part.
Eliminating in the house

Once house trained, dogs should not urinate or defecate in the house. There are exceptions, of course – illness, old age incontinence and so on – but, generally, a sudden return to this behavior suggests that something else is amiss. Lack of stimulation, and perhaps also, lack of opportunity to eliminate outside is one possibility.
People-reactive

People-reactivity in dogs is rarer than dog-reactivity. Sometimes it occurs because this is how that particular dog has been trained to behave. Usually, however, it is a consequence of some combination of poor socialisation, a naturally fearful animal, a dog that was castrated too young, and insufficient stimulation.
Racing in circles

Most dogs have plenty of energy. Like small children, they need time and opportunity to release that energy. Exuberant racing around is sometimes seen in a young, happy dog, particularly in high energy breeds, like setters. However, it can also be a hallmark of a bored, insufficiently stimulated dog that doesn’t know what else to do with itself.
Howling

This is one of those behaviors that’s sure to get the neighbors complaining. It’s characteristic of a dog that doesn’t like being left alone and wants everyone to know about it. Essentially, this is separation anxiety. Dealing with the problem requires patience but it’s well worth remembering that a well-exercised, appropriately stimulated dog is more likely to feel tired enough to relax when left alone.
Excessive grooming

Unless too young, old or ill, all dogs groom themselves. Sometimes they groom themselves more frequently: for instance, if they’re muddy after a walk or have burrs stuck in their fur. Sometimes, however, excessive grooming has no obvious physical cause. In these circumstances, it may be prompted by boredom. Ensuring your dog has sufficient stimulation, both mentally and physically, may curb the problem.
Pacing

Perhaps you’ve seen zoo animals pacing their enclosure. Most experts agree that, even in territorial animals, which include dogs, pacing is not “species-typical behaviour”. Instead, it’s probably symptomatic of a stressed animal that’s having difficulty coping with its surroundings. Stress has many causes – and one possibility is insufficient stimulation.
Head weaving

When it comes to head weaving, it’s important to separate psychological causes from physical ones. Head injuries, seizures and neurological disorders can all cause abnormal head movement. If you’re sure there’s no physical cause, it’s time to consider a psychological one. Head weaving is atypical behaviour for dogs and indicative of a stressed and possibly under-stimulated animal.
Guarding behavior

Although guarding – of food, toys or even a person – is a natural behavior, which is an essential survival strategy in a wild dog, it’s usually undesirable in pet dogs not bred for guarding duties. It’s less likely than other entries on this list to result from under-stimulation but ensuring that your dog is well-trained and has plenty to do should help counteract the behaviour.
Scavenging on walks

Most dog owners dislike seeing their pets scavenge. As it’s instinctive for a dog to seek out food, no matter where or how revolting it is, you must provide very attractive alternatives. Turning a walk into a training session, with games of hide and seek, scent work and so on, help ensure your dog is too busy and stimulated to scavenge.
Growling

You probably understand what growling means – or, at least, what you’re afraid it means: a dog that’s about to bite. And, sometimes, that’s true. However, dogs rarely progress from calm to growling without first showing other signs of stress, such as lip licking, looking away, and yawning. Stress in a dog has several possible causes, and under-stimulation can certainly play a part.
Afraid of strangers

An under-stimulated dog may also be an under-socialized dog. And an under-socialized dog will frequently appear timid or even frightened around strangers or people it doesn’t know well. Socializing your dog properly, and ensuring it continues to receive social interaction with people and other dogs, will help ensure it isn’t timid, easily frightened or lacking in stimulation.
Fighting with other pets

Bored dogs usually find their own entertainment. If you have more than one dog, your dogs may play together. However, like people, two dogs won’t always get along, and even dogs that are normally friends can have the occasional squabble. Consequently, you can’t rely on them entertaining each other to avoid boredom. Indeed, boredom may even spark a fight.
Hyperactive greetings

If your dog spends long hours alone, you shouldn’t be surprised if you receive a bouncy, hyperactive greeting when you return. It’s your dog’s way of saying, “Oh, I have been bored! Thank goodness you’re back!” Think about ways of entertaining your dog while you’re gone, such as a stuffed kong and leaving the radio playing.
Biting

It’s common for over-stimulated, over-tired puppies to bite. Sometimes they may bite very hard and with considerable ferocity. Try to give as little reaction as possible as squealing, shouting or even pushing them away can provoke the behavior. Instead, tuck your arms out of reach, avoid eye contact and, if you can, turn away from the pup.
Begging

Begging can seem cute, or even a bit of a party piece. If you reward the behavior, the dog will soon learn to associate begging with a treat. Consequently, when he’s bored or otherwise under-stimulated, he may react by begging. Teaching strong obedience commands will both help curb this impulse-based behavior and give him something to do.
Excessive sleeping

A fit adult dog needs 10 to 12 hours sleep in every 24. However, a bored dog with nothing else to do may sleep for much longer than this. Essentially, this is like a person with depression taking to their bed and attempting to sleep away the day. They’re not doing anyone else any harm but, ultimately, it’s not a sign of good mental health.
Separation anxiety

Dogs experience separation anxiety because they are unable to cope with being apart from their owner. In behavioral terms, separation anxiety tends to play out via barking, whining, howling, eliminating inside, and destructive behavior. Exactly what causes separation anxiety varies from dog to dog but, in some cases, this may include under-stimulation.
Over-excitement

It’s all too easy for a dog that generally has very little to do to go from zero to 60 when something even moderately interesting occurs. If possible, the best way to calm a dog like this is to ignore it because reacting to the behavior risks escalating it. Of course, the best solution is to pre-empt the over-excitement and ensure your pet doesn’t reach this state.
Panting

It’s well-known that dogs pant to cool down. However, panting is also included in their behavioral repertoire. Excessive panting may indicate a happy dog, an excited dog or a stressed dog. A happy dog is unlikely to be a bored one but an excited or stressed dog may be in that state because it’s been lacking in stimulation.