Problems mean different things to different people, some owners find it very difficult to live with an aspect of their pet's behaviour that other owners may be untroubled by or even find endearing. In recent years there has been an increasing lack of tolerance towards the behaviour of dogs whilst at the same time the opportunities for learning good social behaviour have been limited by attitudes and by legislation. At one time a dog could go anywhere that its owner went, including food shops and restaurants, in much of Europe this remains the case but in the UK dogs are now banned from most shops and many shopping centres, they are unwelcome on some beaches, in many hotels, in some parks and recreational areas and on some parts of the public transport network. Whereas at one time dogs learned to take everyday life in their stride today they may only be exposed to a limited number of experiences and a limited number of people. Early socialisation gives the best opportunity for dogs to learn that the world around them is a normal place full of normal things performing in a normal way. However many puppies never get to be properly socialised and in the case of rescue or second hand dogs earlier experiences may be mainly negative. It is also a fact of modern life that many families are out for much of the day and dogs are left for several hours at a time, this can lead to boredom and anxiety which sometimes results in barking and destructive behaviour. Lack of socialisation or nervousness can lead precipitate aggressive or inappropriate behaviour towards other dogs to towards people, at one time dogs were deemed in law to be entitled to retaliate against bad handling, teasing etc. and it was generally accepted that a dog was allowed "one bite", today dogs have to be and be seen to be whiter than white regardless of incitement, poor treatment and teasing. 
What we can do to help
Graham Everitt is an qualified and experienced behaviourist he deals routinely with amongst others, all the behaviours discussed above. It is wrong to think in terms of good or bad dogs, dogs like people are multi-faceted and what we are really talking about is dogs who exhibit inappropriate or wanted behaviours. A dog that shows aggression to other dogs on a walk may be delight at home and a wonderful member of the family, it is just one aspect of the dog's behaviour that causes concern and the careful application of specific training techniques can usually address the issue. Some "problems" are breed specific and are behaviours that were originally desirable but which are now misplaced in the context of family life or the contemporary world, for example some breeds have a highly developed chase instinct which is well adapted to assisting in the management of livestock but potentially dangerous in the context of traffic. Some breeds have a strong guarding instinct which is valuable in the context of a security role but may be inappropriate in the context of an urban garden, some herding breeds have been bred to bark as a part of the their driving behaviour, this may be wholly appropriate out in the remote country side but far from acceptable in a flat.
Unsociable attitudes to other dogs can be the result of a dogs own nervousness, lack of confidence in the owner or a desire to dominate other dogs. Where dogs exhibit this behaviour owners may walk them in areas where they are less likely to meet other dogs and may be reluctant to let the dog interact with other dogs, the dog may spend much of its time on a lead. Whilst these measures may treat the symptoms of unsocial behavior they also tend to reinforce the underlying problem and further poor manners. We seek to appropriately treat the cause of the behaviour rather than its symptoms. 
Aggression to people or children may be the result of bad experiences in the past, a nervous temperament or an owners failure to apply the principles of an appropriate hierarchy in the home, it can also stem from teasing, inappropriate training techniques, a misplaced guarding instinct, rough handling or an owners nervousness of their own pet. Sometimes, particularly with a rescue dog aggression may stem from the owner over compensating for a dogs previous hardship, this may be misunderstood by the dog and lead to confusion in the dog's mind over its place in the family. Understanding the underlying cause is key to resolving this behaviour. 
A very common problem especially with excitable, friendly dogs. This is training issue rather than a "problem" the behaviour needs to be modified through the application of appropriate training techniques. The problem can typically addressed very successfully in a relatively short space of time. Other factors than training can also aggravate this sort of behaviour. 
Barking usually becomes a problem for the owner if there are issues of nuisance raised by third parties, however it can also be a real annoyance to the owner if it becomes common place in the car or in the home. Destructive and noisy behaviour can stem from a number of causes including anxiety, boredom, loneliness, in addition consistent barking may be due to inappropriate guarding behaviour. 
One area where nothing has changed over the years is the menace posed by dogs to sheep, game and other livestock, a dog may be somewhat less likely to be shot for worrying livestock than in years gone by (although this does still happen) but it remains an absolutely unacceptable behaviour. Such behaviour is often breed dependent and needs expert advice. 
Chasing cars and motorbikes is a very common problem and most often encountered in certain herding breeds, this behaviour is a natural chase response and is best managed by training rather than conditioning. In most cases this behaviour can be controlled and managed successfully in a relatively short space of time. It goes without saying that no dog should be off-lead anywhere near road traffic. 
This is one of the most frequently encountered problems and one that we deal with on a daily basis. Generally this is a training issue which may be aggravated by other factors including breed type. A programme of training as well as an examination and sometimes a modification of the dog/owner relationship is usually successful in resolving this problem over a period of time. 
This is the most common problem and the one we spend most of our time helping our clients to resolve, the good news is that with appropriate patience on the part of the owner and the application of proper training techniques this problem can invariably be resolved in a short space of time. Pulling can be aggravated by a number of other factors including issues in the dog/owner relationship and the breed and type of dog. 