I stored a car under a big plastic tarp in my uncle's barn while I was in the service. On the second floor of the barn, right over my car were about 500 chickens. When I came home on leave a year later, holy crap. There was about an innch of solid chicken poop, pee, feed dust, and about everything you could think of that fell thru the cracks in the floor and onto that tarp. Some of the dust got under the tarp and stunk up the car for a bit. If that car had not been covered, I'd have had to junk it.
It was a freshly overhauled, and newly painted 59 Chevy Impala convertible. This was in 1967 and it was just a used car. I drove it for for another few months, while stationed near home and, figuring it would never last there for another 3 years, sold it for $300 before I left for overseas duty for 3 years. My wife wears it in the form of an engagement ring....so it's sorta still with me.
But yeah, storing stuff near animals can be troublesome.
First the floor was sagging (wood, with 18-24" of space under it) so I got worried about driving it in. Same thing happened in the second bay with her Rav4. Then we got more tools, generator, welding cart, bikes, and soon no room to fit the truck in. Then the door broke, and we couldn't lift it up to replace the roller. So it was screwed in place to keep the kids from trying to open it and messing things up. Then she got chickens, and they took over half of the second bay so no room for a car in there anymore. The Massey lifted the door so I could weld in a new roller and open the door again, and weighs far less than the truck so it sits in the barn now. And I deal with scraping windows in the winter. While her newer Pathfinder has remote start from the previous owner. 
