OK Bob, but read the small print again! This is information from the link you gave us:
Animal Physiotherapy is much more diverse that people imagine. There are many different backgrounds that can lead to a desire to provide physiotherapy for animals. Some of these are:

Veterinary Nursing
Racing – jockeys, retired jockeys, trainers and stable and kennels hands.
Riders - from all equine disciplines, trainers, instructors, yard managers.
Therapists in related fields – massage therapists, chiropractors, osteopaths and hydrotherapists.
Professionals from other walks of life who have a high level of animal knowledge and experience and an unfailing passion for animals.
My comment:
Without an excellent base of knowledge from a related relevant profession or someone with age and experience a course possible in one year of 15 hours a week (more small print about the distance learning and then the rest is there to be read) is not on!
This 16 yr old person must get other qualifications first! She has to be a good rider and deal with horses on a regular basis. I say that as a long qualified physio working with people, as a horse owner still striving to find out how it all works and with an extra swiss qualification in canine and equine physiotherapy done part time on a course open to vets and physios. The amount of movement analysis needed for equine therapy, and that includes horse and rider (one of the main problems of the horse can be faulty training and riding and not just accidents) is vast. A base in human physio is excellent, and then some sort of income likely from the start (i hope ) Or qualifications in the direction of horsemanship, nice but very hard work with long hours. It's also physically demanding with horses, one has to think about doing it aged 50-60 still and also get good qualifications somewhere else to fall back on. Having said that I wouldn't like to stop anyone going for it as it's great working with horses. ("my today": 4°-6° c with rain, dark, miserable, wet stables, dirty horse blankets, smelly clothes in the morning versus 22° nice warm light practice, clean humans in the afternoon.take your choice!)