Eleven physical therapy programs are now doctoral programs (Ph.D.). The number of required years of schooling varies somewhat from program to program. Three/four years is a typical length. The admission requirements vary from school to school, but typical requirements include a BA/BS degree and the following courses:
General Biology (2 semesters - BIOL 101 and 102)
Anatomy and Physiology (2 semesters - BIOL 341 and 351)
General Physics (2 semesters)
English (1 semester)
Statistics (1 semester)
Psychology (1 semester)
Social Sciences (1 semester).
Many programs require or recommend a semester or year of General Chemistry and a few programs require a semester of Organic Chemistry. To increase the degrees of freedom, some pre-PT students take a year of Organic Chemistry. An applicant also needs to be certified in CPR and have some PT related experience (working as a student athletic trainer is a terrific and appropriate experience to fulfill this requirement). You can also volunteer with a local physical therapist.
The choice of a major is not critical, but with 4 required biology courses (BIOL 101, 102, 341, 351), a biology major should at least be considered.