That is fucking horrible, I hope your little guys makes a full recovery! Mydog (German shepherd/malamute mix) is friendly but Im also always aware it could snap for whatever reason. I always make it a habit to also bend down and pet the other dog too, when my dog goes over to say hi. I don't know if theres any factual evidence but I found it makes them more at ease and if anything happens I can step between, I also really love dogs