Steer clear of snappy eye catching lines and think from within of why you want to be received at their univeristy. You need it to be sincere and from you ! But Yes a striking first line makes them read on i agree.
Definately do not start it as 'From an early age' or 'Ever since i was young' etc - everyone does this ! The first sentence should be about why you would like to study your chosen subject and why you would be suitable to study at university. Ask yourself why is this? What motivates you to study veterinary medicine? This is what needs to be in your introductory section.
Good luck.
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