I almost had to face the same thing a couple of weeks ago...my dog was hit by a car and I don't know how he got home...his leg had a massive gash all the way down and you could see everything. They couldn't even stitch it...so it had to heal from the inside out and I've been changing his dressing every day at home and a couple of days ago he started putting the leg down.
I am so sorry...but I agree with you...no way did something bite that dog that caused that much damage...I think the dog may have been hit by a car (could he get out?), or in a fight with a stray...the "critters" invading probably came after the wound and they can set in at a very high rate when it's hot.
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It's gonna be a hootenanny.
Or maybe a jamboree.
Or possibly even a shindig or lollapalooza.
Perhaps it'll be a hootshinpaloozaree. I don't know.