There are 28 veterinary schools in the United States, and the competition for admission is often quite keen. You should be aware that they generally prefer students from their own states or the states that contract with them due to local unavailability of veterinary schools. Very limited quotas are reserved for non-residents with figures varying from school to school.
As in allopathic and osteopathic medicine, grade point average and test scores are critical factors of the application. Most veterinary schools accept the GRE only as the required standardized test (Purdue is one of them) but you should check to see what your preferred schools' requirements are, using a site such as Petersons. The GRE is offered year-round at Prometric Test Centers and at many universities.
Currently, US veterinary schools require all candidates to submit their applications through VMCAS; it is always advisable to check the school's policy regarding this matter. Just as with medical schools, personal interviews are a must. Likewise, relevant internships and summer experience are virtually required by most veterinary schools. In fact, schools expect significant extracurricular work experience with animals, preferably under the guidance of a veterinarian. While deadlines for application range from October to December, you are strongly encouraged to apply in early summer.
Pre-professional preparatory curricula vary; however, they all generally include at least 2 semesters of general biology, 2 semesters of general and organic chemistry each, 2 semesters of physics, 2 semesters of English, 1 semester of statistics, and various courses in biological, behavioral, and other sciences. Note that different veterinary colleges have considerably different pre-professional course requirements. Make sure your workload matches or exceeds the minimum of the schools to which you intend to apply.