OK well I've just looked at the packaging and the insert in mine and it doesn't say.
I have always assumed it would keep until its expiry date as it comes in a syringe so isn't exposed to the air. I just pop it in the fridge afterwards, it has to be stored below 25 degC. I only used to use 2ml per shoeing so that would be 5 x 6 weeks, it has still worked after 30 weeks and the horse hasn't dropped dead.
