I have a few friends from HPU Shimla and according to them, there is no specific syllabus for Zoology entrance. The question of the last few years can be helpful in analyzing the paper pattern. There is no specific syllabus mentioned but the courses generally comprise the topics from the UG degree. So it is definitely recommended to study the UG books and it would be really helpful if you could get previous papers.

There are some books that can be useful such as Arihant’s entrance test book for MSc.