Answer: In most cases local anaesthesia is used to remove sensation from a relatively restricted and superficial part of the body. The local anaesthetic (otherwise known as a local analgesic) in the form of drug solution, is injected either around the sensory never endings of an area, or around the nerves which receive sensation from that area (the litter is referred to as nerve blocking). As a result, the transmission of sensations, including pain, from that area to the brain is temporarily prevented, and the animal is unaware of interferences to that region of its body.
Spinal anaesthesia is seldom practiced on cat, but this technique produces complete blockage of the lower spinal nerves to produce a total lack of sensation, and paralysis in the posterior part of the body.
In all types of local anaesthesia, however, the animal still remains conscious and therefore subject to fear when it observes what is going on around it. It is also able to move. For these reasons, it is unsuitable for any surgical procedures which involve the deeper structures of the body, or where sudden movement could produce severe damage (e.g. near the eye). It is also not appropriate for lengthy procedures, or if the animal resents being restrained.
As a consequence local anaesthesia in the cat is usually employed only for desensitization of the skin prior to the removal of small growths, or fro injection into deeper structures to facilitate certain procedures. For example it is useful fro desensitization of the skin before emergency drainage of the bladder, using the needle inserted through the abdominal wall, in cases of urethral obstruction.
