Every injection carries some risk but tetracycline in general is not a problem if it's not an infection. In a younger animal like your's I'd be more certain it is an infection rather than a catyract (sp?) You're best advice always comes from a vet second from and experienced person who can see it, and third or even further down the list from the internet where we can't see it. Pipestone vet offers a free telephone help line phone number for a phone consultation. ( it's in the sheep basics post)