I was watching "A Most Mysterious Murder" the other night, a delightful little british series that re-enacts real crimes in history -- not famous ones, just ones that held a bit of infamy in their day for having never been solved -- and attempts to deduce who perpetrated the crime and why. Well, the very first episode (The Death of Charles Bravo -- Google it and you'll come up with loads of informative articles and sites about the circumstances of the murder) hinges on a bottle of antimony being used by a groom on the horses in the yard. The stable-boy is rubbing his horse down with a rag soaked in the stuff to, as he describes, make their coat healthy and shiny. I immediately was interested -- I love looking up old remedies for horse care -- and you can well imagine my surprise when not a few minutes later the narrator explained how antimony is, in fact, a deadly poison. You should watch the movie if you want to know the rest of the story (and if you love murder-mysteries and documentaries, this should be right up your alley), however I was incredibly intrigued by this substance that was ostensibly as poisonous as arsenic (if not more so), but in wide-spread use on horses. Inquiring minds need to know.
So, I spent the week studying old veterinary remedy texts dating from the mid-1700s to the very early 1900s (I love you, Google books) and have discovered that the poison was indeed used to improve a horse's coat and condition, amongst a myriad of other uses. As excerpted from The Pharmaceutical Journal, Fourth Series, Volume 12, January - June 1901: "Their action has never been understood, that is to say their modus operandi, their effects, are visible enough and despite the uncertainty of their action in human practice and the abandonment of these forma of antimony by the medical profession, they are found to assist markedly in producing a good coat, a soft thriving skin, in horses when mixed with sulphur and other simple ingredients. That the peculiar silkiness of the hair is due to antimony is demonstrable and only one other agent is there which can produce a like effect - arsenic." Now there is no mention anywhere of the stuff being rubbed directly onto the skin of any animal. In fact, it was also known to be quite caustic and also used in cases of canker and thrush in an external application to the frog of the hoof. For coat conditioning, it was always to be ingested, either ground to a fine powder or made into a liquid solution, but I imagine that the dramatic elements of the movie needed a more insidious looking application of the stuff. But they preserved the overall reasoning behind using the poison, for an improved coat. I read several texts that indicated that the hair of such animals would veritably sparkle.
And while very extremely poisonous to humans, antimony was given in much larger doses to horses without ill effect. Though in large enough doses it does still kill. Interesting how in small doses poisons can sometimes produce appealing effects (at least to a human eye). However, it must be noted that an other common use of antimony, in tartar emetic, was as a wormer. It is easy then to draw the conclusion that dosing with antimony would simply kill off the worms in a horse, thereby improving the horse's overall constitution, fatten him up a bit and put a healthy shine on the coat.