Dog bit wild garter

[dieselbaby]

Hi everyone, I'm new to the forum, and a new snake caretaker. This afternoon while i was out moving livestock panels our dog found a garter snake, she bit and shook the snake, and i intervened on the snakes behalf as i like these snakes. I have spent all afternoon reading the forum, and here is a little background, the snake has a puncture wound from where the dog bit it, and it bled some, but we got it cleaned up, and polysporin put on the wound. The bleeding has stopped and the snake appears alert and has tongue flicking, and readily hisses at us. He/she isnt moving around a whole bunch since i am assuming he/she is in pain but when he/she does move around the movement seems normal.

I have he/she in i believe a 20 gallon aquarium with a canopy and florescent light, now i know this will need to be replaced with mesh and a heat lamp but that will have to wait til payday. The inside temp is 77F uniformly, i will try and bring that temp up a bit on at least one side. I have provided a hide, and a large dish of water, and in half of the aquarium, i have plain white papertowels, but for the other half i have fresh picked grass. He/she prefers the grass side. I put the grass in for padding for the injury.

My question is how often should i be changing out the grass to keep it fresh and clean, and is grass okay to use at least til he/she heals? I plan to catch some earthworms later on this evening for our new friend. I am going to try and post a picture of our new friend in hopes someone can tell me what kind of garter snake we have here, also our area is northwestern Ontario, Canada.

Thank you in advance for any advice.
Judy