One of our ewes ended up with a fat face yesterday. Not sure if a snake (copperhead, rattlesnake or some other kind) or a spider bite her. She was pretty swelled up. We brought her and her daughter back to a stall for the day and night. She looks much more normal this morning.
So, what do we do for a swollen face? We keep a tube of charcoal that has electrolytes mixed in it. A few squirts of this will help to bring the swelling down fairly quickly (usually). Just be careful not to squirt too much in the mouth of the animal (like we did!) and cause them to choke a little bit on the goop!
Back in our CA days, we dealt with Mojave green rattlesnake bites on some of our dogs. We read about a home treatment that we saw work real quickly. Administer butter and whole milk to the dog (or other animal) - as much as they will eat and drink. Our little Chihuahua, Mini, got bit one time and was massively swollen. Within just about 30 minutes of eating butter and drinking milk, she looked almost normal.
Anyway, here is a pic of the ewe that we found yesterday: