Poor little Sprout...
I think he might have mites. I did notice a tiny patch of missing hair above his eye when I purchased him two weeks ago, but didn't think too much of it, especially as the hair grew back within days.
But the evidence is unmistakable now. This is his coat the day after he came to live with us:
This is his coat now:
He's a raggy looking little critter now! And the surprising this is that Liam, who shares a cage with him, is perfect! Beautiful, thick, wavy coat. I think it says a lot about the quality of the start to life Liam had versus Sprout. Sprout was sold WAY too early, so missed out on the immunity boost he would have gotten from suckling. It also explains why he didn't gain as much weight as his sister Sparrow in the last weigh in. (she's fine by the way, which is a little odd!).
So all of the pigs got dosed up with the appropriate amounts of revolution for kittens/puppies medication. Guinea Lynx has an awesome website with information on the treatment of mites in guinea pigs. I was able to use their calculations to get my drug doses right. Technically Sprout and Sparrow are a little too small to be dosed, but it needs to be done before the poor little guy gets any worse!
So fingers crossed he'll be feeling a lot better soon.