What does that mean? Mush and other strange animal commands

One thing a writer does is to spend a lot of time thinking about words.  Although some words have a very clear etymology, others have a somewhat more murky and mysterious history.  Today I was thinking about some words that probably don't even belong in the English language.

I often spend far too much time thinking about ridiculous things. Sometimes, I have trouble remembering why I was even thinking about a particular thing, but there is usually some logical progression from one thought to another that brought me to pondering.

Today it was just a woman walking her dog down the pedestrian trail.  The dog was a Siberian Husky, which got me thinking to whether or not a sled and dogs was a viable transportation alternative in the winter.  I decided that as long as there was snow, we could easily go through town on the pedestrian trail.  The problem would be parking.  When I got to town, where would I park a dog sled?  Would I need insurance in case the dogs bit a passerby?

That got me to thinking about the word "Mush!", which as we all know, is what sled drivers say to the dogs to make them go, or at least they do in the movies.  So, why "mush"?  I thought perhaps it was an Inuit word that we just mispronounce, but no.  It's actually a corruption of the French command "Marchons!" which means, "Let's Go!" or words to that effect.  Marchons became just "mush" over a period of time.  Of course, then I wondered why all the early sled dog drivers were French, but that's a question for another day. Then I began to wonder about horses and the odd things we say to them.

I really found myself perplexed by the phrase "Giddy up".  It took quite a lot of googling to come up with more than "that's what you say to a horse to make it go".  Finally, I did find the etymology of the phrase, which was originally "Get thee up" in the olden, ancient days before we stopped saying all our consonants.
That wasn't nearly as interesting as the meaning of "mush" but it was a more difficult answer to find.

Basically, it seems that when we talk to animals, we don't use proper English and we don't think they'll notice.

Now, back to the dog sled.  I wonder if dog food is more expensive than filling the car's gas tank...