There is no known affects of too much biotin. It is a water solulable vitamin. Your horse can have not enough biotin, but there is no history of problems caused by an overdose of boitin. A good way to find more information is to Google : horse too much biotin
You can tell when it's been too much
A horse that eats a lot
Yes and thicker and it helps your skin too
First of all, keep in mind that biotin is a substance that is produced naturally in your body. Therefore, when you take biotin, you are not introducing a foreign substance into your body. You are simply adding more of something it already makes. That being said, you might worry about having too much of a good thing. Here are a few things to look out for regarding biotin side effects: it doesnt necessarily make your hair grow faster... it usually makes hair grow in thicker. one side effect that i know of from taking it is it can give you a lot of energy and make it difficult to sleep if you take it later in the day.
if there too little water animal die crops are not growing and if their is too much water flood came
Horses fed excessive alfalfa can have weight issues and can develop large mineral "stones" in the GI tract called enteroliths.
you can die
you get FAT
it can have effects on your memory
You won't be able too speak.
If you get too much calcium you may get calcium deposits on your bones.
I took Biotin and Niacin in an attempt to make my hair grow faster. I have to say, that yes, my hair was thicker and longer over a period of time. Also, my nails grew stronger and faster. HOWEVER. I developed a retinal hemorage in my eye which led to temporary blurred vision. Apparently, too much Niacin and Biotin can alter something with your blood or something like that, especailly if you are on Birth Control too. So be careful and only take a minimal amount.