But the fact that there are many names for this condition sort of obscures the fact that there can be any one – or more – of many underlying causes. So, if you’re horse is unfortunate enough to get this annoying condition, it’s important that you take immediate action.
Skin is the largest organ in the horse’s body. I think it’s a very underrated and underappreciated organ. So did the late, great, Allen Sherman, and he even wrote a song about it.
There’s nothing about the skin of the pastern that’s fundamentally different from the skin of any other part of the horse. The biggest differences, I suppose, are that the hair in the pastern tends to be longer than the hair in most other parts of the horse’s body. Long hair tends to hold moisture, as anyone who has dried their hair through a variety of different hairstyles over the years knows and wet is, well, wet.
Anyway, when the skin of the horse’s pastern gets scraped/wet/damaged, etc., it reacts just like the skin on any other part of the horse’s body. It gets red, it gets swollen, it gets crusts and goo (exudate, if you must) on it; the skin of the pastern gets rather nasty-looking. If it doesn’t get treated – if the infection becomes chronic – chronic changes start to happen. The skin gets thicker. Red, angry-looking granulation tissue can form. The skin can start to scale, and crust. Fairly quickly, the skin can start to scar.
But even though most “scratches” cases look a lot alike, in fact, underlying the problem can be any one of a number of causes. It shouldn’t be any real surprise that many infections have both bacteria and fungi involved, I mean, if you culture your horse’s stall, or his environment, you’re always going to find those; it’s a smorgasbord of infectious agents down there. Fungi and bacteria can live on your horse’s skin with no problem – it’s when they get in the skin that the issues start.
In some horses, especially the draft breed, skin parasites can be a big problem. So, you’ll occasionally see one of these big guys with infections caused by mites (Chorioptes equi, for example), or by infections from parasites that live in dead or decomposing material (the agent is Pelodera strongyloides). In fact, draft breeds seem rather prone to developing skin infections of the pastern in general. Nobody is entirely sure why, although the big feathers that they typically carry on their lower legs certainly help keep things nice and wet. Some folks even surmise that there may be a genetic component to draft horse pastern dermatitis.
Of course, there are also lots of other, non-infectious, agents that can cause the pastern to flare up. These things can result in a horse that looks very much like he’s got a skin infection, when he really doesn’t. So, for example, if there’s chemical irritant that gets on the skin (tea tree oil is one that I’ve seen), or if your horse is allergic to something (neoprene is one that that I’ve seen), or if he’s sensitive to the sun (I’ve seen that a few times, usually because of something that the horse has eaten), or if there’s been some trauma (I’ve seen lots of those), or if there’s been some sort of weird immune reaction (only seen a couple of those), you’re horse can look very much like a horse that has scratches. Of course, if you treat him like a horse that has scratches, and he doesn’t have scratches, he’s not going to get better. That’s why, if the skin of your horse’s pastern looks inflamed and awful, and if you think that your horse has scratches, you should think about calling your veterinarian out to take a look. If he does have scratches, he’s going to need something for it – if he doesn’t have scratches, he’s going to need something else.
Still, even though there are some weird causes of horses developing chronic pastern skin problems, most of them respond pretty well to some pretty basic management strategies. Mostly, you want to keep the area clean and dry, which, admittedly, can be a bit of a trick in wet pastures. Curiously, it also seems to be a bit of a problem in dry southern California, but this happens mostly when horses get bathed and then are put away wet into stalls bedded in bug-laden pine shavings. Even so, if you can cut the hair around your horse’s pasterns, keep the pasterns relatively clean, and at least dry them off once in a while (or always, before you put him back in his stall), you’ll go a long way to preventing a scratches problem. Spreading a petrolatum based ointment on the skin can help with drying and cracking, too.