And I'm thinking injuries from deep snow would be more from pulled or strained muscles in the legs, shoulders and back from having to pull oneself up and out as opposed to injuries from jumping onto a firm surface or landing wrong or too hard causing damage to the growth plates as they may be forced to meet before nature intended, and then causing uneven growth in the affected bones making the dog potentially lame or worse for life.
IMHO, anytime a dog struggles as in a panic situation there is increased danger of some injury happening. I've had mine get tangled in briar bushes and start to really freak out, and of course I'm thinking of eyes getting poked out by branches and/or thorns and a zillion other horrible images. So they have learned when in a situation to wait for me to help them, to not struggle and make things worse, except when falling off the pier into the water, they've actually been so relaxed and confident that I was coming to get them that they stop swimming... but not for too long...
