Because there is no single certification process for dog training, anyone can call himself a dog behaviorist. A credible behaviorist has a PhD in animal behavior, animal psychology or another related field. However, many trainers use this title without truly earning it.
Education Level
Do your research before deciding on a dog behaviorist. Though they may be advertised as dog behaviorists, they may have no more education in animal behavior than you do. Visit their web sites and look at their credentials. Dog trainers should advertise their experience and credentials. Those that don't probably don't have much.
Decide on your training needs and look for a suitable education level. If you have basic training needs, most trainers can provide you with this. If your dog is showing aggressive or anxious behaviors, look for someone with more experience or a higher education level. Depending on the severity of the problem, you may need a PhD. Ask the trainer what experience he or she has with your particular problem. Some trainers specialize in certain behavior problems and have the appropriate experience, even without a PhD.
Since there are very few PhD level dog trainers, there are other certification programs available as well, some better than others. Look up the accreditation agency and find out the requirements. The most well-accepted certification is currently the Certified Pet Dog Trainer (CPDT) certification, which requires 500 hours of training and a test based on training knowledge.
Ask the trainer about continuing education as well. Training methods change frequently, so your trainer should be attending seminars and reading books to keep up-to-date.
Training Methods
Discuss training methods with your potential trainer. Dominance-based methods are being widely disproved through scientific research and a movement is being made toward positive training based in current research. Ask specific questions about which training methods are used in certain situations and why those methods should be used.
Many trainers advertise themselves as positive when they aren't. If your trainer requires you to use a piece of equipment such as a shock collar, prong collar or choke chain, they are not using the most up-to-date method. As such many positive trainers may not understand the methods, though they are advertising their "scientifically-based methods."
Other Considerations
In the end, choosing a dog behaviorist may depend partially on personality matches. No matter how much education she has, don't choose a trainer with whom you are uncomfortable. For your training program to be successful, you must understand and believe in the chosen methods. If you don't, you won't be motivated to work with your dog.
There are hundreds of dog trainers of differing education levels and philosophies. Don't limit your search to the first person you find. Consider your budget, philosophy and educational needs. Check out the Animal Behavior Society or Council of Certified Pet Dog Trainer (CCPDT) web sites to begin your search with qualified professionals.