Some of the online programs might be good, and some are absolutely useless. As far as I know, all of them require that you do hands on work through a local veterinary hospital to complete the program.

I've worked with two people who completed online courses at Penn Foster, and found both of them to be shockingly unprepared for basic function in any capacity. One graduate in particular was holding my small female dog in her lap and pointed to her sagging rear nipples (she'd had a litter before I got her) and asked if those were her testicles. When I explained that she was a female those were her nipples, she said "Oh, I've never seen a boy dog underneath before". This was only one of a great many gaps in her knowledge, and yet she had successfully completed the course was, on paper at least, a Veterinary Assistant.

Now...I expect not all online programs are worthless, but I can't say I've been impressed with Penn Foster, by any means.

Good luck with the job. It will make you more misanthropic than you ever thought possible, but there are some wonderful experiences involved too.