The main veterinary relevance is muscle relaxation during anaesthesia. You can happily go through life without using these drugs, but if you do use them, you must know what you are doing.
Myaesthenia gravis is a rare disease of dogs where the number of receptors for acetylcholine is reduced: this may be congenital (Jack Russel terriers) or acquired (autoimmune). The usual treatment is to give anticholinesterases (pyridostigmine) to increase the amount of acetyl choline or immunosuppressant drugs if appropriate. Some toxins will interfere with acetylcholine synthesis or release, causing muscle weakness.
Malignant hyperthermia is a condition which is only common in pigs, where excitation is uncoupled from contraction, and the muscles go into spasm.
Used in anaesthesia to relax the skeletal muscles.
Animals 
be unconscious before use. These drugs paralyse all the skeletal muscles - the animal lies still but these drugs have no effect on consciousness. Among other effects the animal is unable to breathe and must be ventilated.
Do not use these drugs if facilities for artificial ventilation are not at hand. These drugs will rapidly kill animals in a particularly nasty way if used incorrectly. They are not drugs for beginners.
There are two main classes:
depolarising (non - competitive) blockers
non - depolarising (competitive) blockers
diagram
