I recently patched up the deteriating mobile goat shelter, resulting in the above monstrosity.
I originally built The Mobile Goat Shelter Mark I in April of 2016, using mostly 2x2s and OSB. A pair of lawnmower wheels let it roll, and a retractable handlebar let you lift one end and drag the shelter. I was proud of the reactable handle, although I wish I'd made it just a little bit longer so that the wall of the shelter didn't bite my heels when I dragged it.
The mobile shelter was actually built for the pigs we had at the time: Shakin' Bacon and Piggly Wiggly (named for their neurological disorder of Congenital Tremor (Myoclonia Congenita), or “shaking head syndrome”). Every few days we'd move their pen so that they had a fresh patch of grass to dig up, and they needed a shelter that was easy to move, but not so flimsy that they could knock it down, like a board leaning on T-posts which we'd been implementing.
After the pigs were butchered, the goats got a lot of use out of it, and for a while it even ended up as a straw-filled dog house next to the rabbit pen.
Starting earlier this year we've been rotating the goats and sheep in a mobile pen behind the new house. After the critters have eaten down a patch, we move their fence panels over, along with the mobile shelter. (This has cut down on our feed costs!) We then water where they just were, and then the grass grows back so that it can be grazed again. (It's a form of sustainabile agriculture.)
Or rather I should say my wife has been doing all that. She's been managing the mobile critters while I handle other responsibilities. A couple of months ago however, one of the lawnmower wheel rails fell, and last month half of the no longer retractable handlebar fell off. OSB is probably the worst material you can use to build an outdoor structure that you want to last more than a few years, so the roof developed a huge hole too. I'm surprised more things haven't fallen off already.
Using 3-inch screws and lumber scraps meant for firewood, I attached some new wheels. These are old bicycle wheels from the pile of bikes that came with the old farmhouse when my wife took posession of it. I put the handlebar back together but had to make it permanently extended, and I used the outer wrapping of a water heater to cover the roof. It's not perfect, but it will still provide the critters with shelter from the sun and the rain.