Although there are obvious differences between the human brain and the canine brain, there also seem to be striking similarities in the way canine brains and human brains process emotional information when viewed with neuroimaging techniques. This would imply that the canine brain is just as susceptible to damage, chemical imbalance, and emotional trauma as our brains are. Although many behavioral issues can be changed through proper exercise, diet, and training, some dogs, like some humans, may need additional help to control their actions and reach their full potential.

Dogs, like people, may develop mental disorders and diseases that require medication along with behavioral therapy to correct.

The behaviors that indicate a mental disorder may be fairly typical behaviors taken to an extreme, like excessive tail chasing or overeating, or they may be behaviors that are completely out of character, such as inappropriate elimination in a previously house-trained animal.

Types 

Anxiety disorders - Dogs can develop inordinate amounts of anxiety in response to certain situations. The most common anxiety disorders in canines include separation anxiety, social anxiety, and noise anxiety. 

Attention Deficit Hyperactivity Disorder ADHD - Also known as hyperkinesis in dogs, dogs who develop this disorder are often excitable puppies before becoming hyperkinetic adult dogs. Regular high-energy dogs are sometimes mistakenly diagnosed as ADHD, but in the non-hyperkinetic dog, prescription stimulants will worsen the problem rather than helping to correct it.

Canine Cognitive Dysfunction Syndrome - This is the canine version of Alzheimers or Dementia, and as such generally doesn’t occur until your dogs quite advanced in age.

Depression - Dogs, like people, can develop depression due to circumstances, such as the death of a friend, or a move to a new home, or due to chemical imbalances in the brain

Obsessive-Compulsive Disorder OCD - Sometimes referred to as Canine Compulsive Disorder (CCD) in dogs, this disorder results in repeated frenetic behaviors which can be difficult to control. Although this disorder can be exacerbated by stress and boredom, it is genetic at its core. The CDH2 gene on the canine chromosome 7 indicates a dog with a high likelihood of developing Canine Compulsive Disorder. 

Phobias - Dogs can develop phobias and irrational fear responses to specific sounds, smells, or signs. 

Post Traumatic Stress Disorder PTSD - An anxiety disorder that develops after a terrifying or traumatic event. Events such as a violent assault, natural disasters, accidents, or military combat can trigger PTSD in canines.

The causes of mental imbalance in dogs are a combination of nature and nurture. Possible causes could include: 

Genetic predisposition - Certain breeds of dog may have a slight predisposition to develop some of these disorders. Dobermans, for instance, have a higher than average chance of developing an obsessive disorder known as flank sucking as well as narcolepsy.

Physical disorders - Some physical illnesses will cause symptoms that look like those mental disorders. Thyroid problems may instigate hyperkinetic behavior, and itchy skin from allergies may be to blame for obsessive chewing and licking.  

Developmental factors - Improper socialization early in life can cause some of these disorders, like social anxiety, to appear, as can trauma during the dogs prenatal or neonatal development stage.

Environmental factors - This is particularly relevant for disorders like PTSD and depression. Traumatic accidents, the loss of an owner or a friend, and violent physical attacks can all trigger depression and in some cases PTSD.

When you bring your dog into the veterinarian’s office to address a behavior related problem, she will take a behavioral history. Information needed for a complete behavioral history would include anything known about the breed, sex and age of the canine. It is also useful for your veterinarian to know how long these symptoms have been occurring and at what frequency they have been happening. Information about the duration of episodes and how your dog behaved once the episode was over can also be quite useful in diagnosing the underlying disorder as well.

Your dog’s doctor will also want to know if there have been any recent changes to your pet’s medications or diet. In order to determine if there is a medical component to the behavior, a physical examination will be completed,  including ordering a complete blood count, biochemistry profile, and urinalysis. As thyroid disorders can often cause behavioral and mood changes the blood levels of thyroxine concentrations may also be measured. In some cases, such as in the case of hyperkinesis, the final diagnosis is determined by the reaction to the treatment. Clinically hyperactive dogs are rare and can be differentiated from other causes by their responses to stimulant medications.

In some cases, mental issues can become unmanageable with training methods alone. These acute cases of anxiety may be either chemically or environmentally induced. Your veterinarian may prescribe psychiatric medications. Although a few medications in this category are relatively fast acting, most of them require six to eight weeks before substantial improvement is seen. The most commonly used psychiatric medications for canines include: 

Medications given for psychological imbalances will take several weeks before their effectiveness is known, and it is essential that your veterinarian knows all of the other medications your dog is on. Many antidepressants and antianxiety medications have contraindications with certain pain medications, antihistamines, and even herbal treatments such as St. John’s Wort or Kava Kava. Medications alone are rarely effective in eliminating challenging problem behaviors, and changes to both your pet’s exercise levels and diet are often helpful in reducing problems. Further behavioral training will help your pet to become a happier and healthier individual.