The effects of the toxin on a horse’s nervous system causes muscles to spasm. As a result, symptoms include the third eyelid closing and permanently pricked ears. The classical description of tetanus is lockjaw because, essentially, the jaw is locked shut.
In an infected horse you may see the tail being held up, which is indicative of these muscles being in spasm. In advanced cases, tetanus can prevent the horse from breathing because muscles around the ribcage spasm and restrict its movability, making it difficult for the horse to breathe. The heart may also be negatively affected. Both can cause death.
Facial spasms mean an infected horse will not be able to eat as normal