He / she should be physically strong to handle animals, have stamina for long working hours and have manual dexterity to perform on the job, often enduring outdoor working condition in diverse setting.
You can refer book for Veterinary Field Assistant by Indian Author.
Book Name-Essentials Of Veterinary Pharmacology & Therapeutics
Author Name-by Harpal Singh Sandhu
Price-Rs.950 (approximately)
Link : http://www.amazon.in/Essentials-Veterinary-Pharmacology-Therapeutics-2nd/dp/9327228243/ref=lp_4149706031_1_2?s=books&ie=UTF8&qid=1493878872&sr=1-2