So don't just list what you saw or did! Explain clearly what you learnt or anything you realised about yourself - 'Whilst spending a week lambing, I realised I work well under pressure in a fast paced environment and despite being tired and cold can still make good decisions'.
You must explain early on, and very clearly, why you want to be a Vet. It might sound obvious, but many people don't do this as they assume that the fact they are applying for this degree course is enough proof - it isn't. The most important thing here is not to waste space listing names of places you've been to. It wastes valuable word space! So instead of 'I went to The Mill Equine Veterinary Centre say 'I went to an equine veterinary centre'.
Avoid anything that sounds like 'I have always loved animals' or 'I want to combine my love for animals with my interest in science'. Don't use silly words/phrases like 'zeal 'plethora 'I relish' and 'it piqued my interest'. Don't mention an operation or treatment you observed, without explaining why you are mentioning it! Throughout this section, you should be commenting on how this has helped you reflect on life as a vet, the reality of farming and animal rescue work etc.
Do not get 'clever' and try to make this part 'grab' the reader. The admissions tutors will have read plenty of personal statements that say the same thing. This isn't an entertaining short-story, its an explanation for why you are applying for Vet Med and why you want this as a career. If you know where you want to apply, make sure you have a look on the websites for any specific advice on what they want to see in your personal statement as different universities may have different things they want you to include.