So I called my vet to discuss my horse's diet and told her everything I fed them. We agreed they get too much so I've worked all that out. She mentioned that the only common supplement horses in our area tend to need is Selenium and Vitamin E. I am happy to provide Vitamin E for my horses even though it's expensive - I know how wonderful it is.
But I'd never really looked into selenium before. I went out and purchased one of those salt licks with selenium mixed in. My mare happily licked it up for a little while - my pony just pawed at it until it was a big pile of dust and didn't eat any.
Then I looked it up. Apparently it's got a very small window of safety for horses between being deficient and being toxic. I suppose I should call my vet on this - but how do I know if my horses actually need this - being so dangerous I don't want to risk it. Aside from obviously a blood test. Is providing a selenium salt lick free choice a safe thing to do? Can it potentially cause toxicity? I'm beginning to wonder if I need to go take it out of their stalls now... Is it worth the risk?