Students wishing to enter this field would do well to learn as much as they can about animals, especially animal psychology, either through formal course work or independent study. Interviews with animal trainers and tours of their workplaces might be arranged to provide firsthand information about the practical aspects of this occupation.

Volunteering offers an opportunity to begin training with animals and learning firsthand about the tasks and routines involved in managing animals, as well as training them. Part-time or volunteer work in animal shelters, pet-training programs, rescue centers, pet shops, or veterinary offices gives potential trainers a chance to discover whether they have the aptitude for working with animals. Experience can be acquired, too, in summer jobs as animal caretakers at zoos, aquariums, museums that feature live animal shows, amusement parks, and for those with a special interest in horse racing, at stables.

Many animals are capable of being trained. The techniques used to train them are basically the same, regardless of the type of animal. Animal trainers conduct programs consisting primarily of repetition and reward to teach animals to behave in a particular manner and to do it consistently.

First, trainers evaluate an animal's temperament, ability, and aptitude to determine its trainability. Animals vary in personality, just as people do. Some animals are more stubborn, willful, or easily distracted and would not do well with rigid training programs. All animals can be trained at some level, but certain animals are more receptive to training; these animals are chosen for programs that demand great skill.

One of the most familiar examples is the seeing-eye dog, now usually called a companion animal for the blind. These dogs are trained with several hundred verbal commands to assist their human and to recognize potentially dangerous situations. The dog must be able to, without any command, walk his companion around obstacles on the sidewalk. The companion dog must be able to read stoplights and know to cross at the green, and only after traffic has cleared. The dog must also not be tempted to run to greet other dogs, grab food, or behave as most pet dogs do. Very few dogs make it through the rigorous training program. The successful dogs have proved to be such aids to the visually impaired that similar programs have been developed to train dogs for people who are confined to a wheelchair, or are hearing impaired, or incapable of executing some aspect of a day-to-day routine where a dog can assist.

Animal trainers teach an animal to obey or perform on command or, in certain situations, without command, by painstakingly repeating routines many times and rewarding the animal when it does what is expected. In addition, animal trainers feed, exercise, groom, and generally care for the animals, either handling the duties themselves or supervising other workers. In some training programs, trainers come in and work with the animals; in other programs, such as the companion animal program, the animal lives with the trainer for the duration of the program.

Trainers usually specialize in one type of animal and are identified by this type of animal. Dog trainers, for example, may work with police dogs, training them to search for drugs or missing people. The programs to train drug-detecting dogs use different detection responses, but each dog is trained in only one response system. Some dogs are trained to behave passively when the scent is detected, with a quiet signal given to the accompanying police officer that drugs have been detected. The signal can be sitting next to the scent, pointing, or following. Other dogs are trained to dig, tear, and destroy containers that have the drug in them. As one animal trainer from U.S. Customs and Border Protection pointed out, these dogs may be nightmare pets because they can destroy a couch in seconds, but they make great drug-detecting dogs. The common breeds for companion dogs and police dogs are German shepherds, Rottweilers, and Labrador retrievers.

Some dog trainers train guard dogs to protect private property; others train dogs for performance, where the dog may learn numerous stunts or movements with hand commands so that the dog can perform on a stage or in film without the audience hearing the commands spoken from offstage. Shepherding dogs are also trained with whistle or hand commands because commands may have to be given from some distance away from where the dog is working.

Dogs have countless roles for which they are trained, partly because of the variety of breeds available and partly because of their nature to work for approval. Even pet dogs may be trained by animal trainers who work with owners to teach the dog routine commands that make walking the dog safer and easier, or break the dog of destructive or dangerous habits.

Horse trainers specialize in training horses for riding or for harness. They talk to and handle a horse gently to accustom it to human contact, and then gradually get it to accept a harness, bridle, saddle, and other riding gear. Trainers teach horses to respond to commands that are either spoken or given by use of the reins and legs. Draft horses are conditioned to draw equipment either alone or as part of a team. Show horses are given special training to qualify them to perform in competitions. Horse trainers sometimes have to retrain animals that have developed bad habits, such as bucking or biting. Besides feeding, exercising, and grooming, these trainers may make arrangements for breeding the horses and help mares deliver their foals.

A highly specialized occupation in the horse-training field is that of racehorse trainers, who must create individualized training plans for every horse in their care. By studying an animal's performance record and becoming familiar with its behavior during workouts, trainers can adapt their training methods to take advantage of each animal's peculiarities. Like other animal trainers, racehorse trainers oversee the exercising, grooming, and feeding of their charges. They also clock the running time during workouts to determine when a horse is ready for competitive racing. Racehorse trainers coach jockeys on how best to handle a particular horse during a race and may give owners advice on purchasing horses.

Police horse trainers work with police horses to keep them from startling in crowds or responding to other animals in their presence. As with the police dogs, these animals require a very stable, calm personality that remains no matter what the situation the animal works in. Police officers who work with animals on a routine basis develop strong attachments to the animals.

Other animal trainers work with more exotic animals for performance or for health reasons. The dolphins and whales at the Shedd Aquarium in Chicago, Illinois, for example, are trained by marine mammal trainers to roll over, lift fins and tails, and open their mouths on command, so that much veterinary work can be done without anesthesia, which is always dangerous for animals. These skills are demonstrated for the public every day, so they function as a show for people, but the overriding reason for training the dolphins is to keep them healthy. Other training elements include teaching dolphins to retrieve items from the bottom of their pool, so that if any visitor throws or loses something in the pool, divers are not required to invade the dolphins' space.

Animal trainers work with hunting birds, training them to fly after an injury, or to hunt if the bird was found as a hatchling before a parent had trained it. Birds that are successfully trained to fly and hunt can be released into the wild; the others may remain in educational programs where they will perform for audiences. It is, however, illegal to keep any releasable hunting bird for more than one year in the United States.

Each species of animal is trained by using the instincts and reward systems that are appropriate to that species. Hunting birds are rewarded with food; they don't enjoy petting and do not respond warmly to human touch, unless they were hand-raised from hatching by humans. Dogs, on the other hand, respond immediately to petting and gentle handling, unless they were handled inappropriately or viciously by someone. Sea mammals respond to both food and physical contact.

Some animal species are generally difficult to train. Sea otters are extremely destructive naturally and do not train easily. African elephants are much more difficult to train than Asian elephants, and females are much more predictable and trainable than the larger males. Most circus elephants are Asian because they are much easier to handle. Captive elephants, though, kill more handlers and keepers than every other species combined.