"We're not trying to move bones we're trying to send information into the joints," he told the Herald on Sunday. "I'm trying to make the body more aware."
Keenan has a post-graduate diploma, focusing on the treatment of animals, from Parker College of Chiropractic in the United States.
He estimated about 30 of the hundreds of qualified chiropractors in New Zealand would have this post-grad training.
Dogs and cats are his bread and butter, but he has also carried out adjustments on cows, horses and, once, even a duck.
Chiropractic care is used in conjunction with medical care from a vet, says Keenan whose wife is a practicing veterinarian.
Although some vets are suspicious of his methods, he says sceptics should be satisfied because animals won't fall for a placebo."I can't convince an animal to get better - it either does or it doesn't."