on the drug used. Infiltration or infusion- injection beneath the skin and other tissue layers along the site of an incision before or after a procedure Field block, ring block - injection into soft tissues distant from the actual incision in a pattern that intersects the nerve supplying the surgical site Nerve conduction block - infusion of a small amount of drug or directly adjacent to the sheath of a nerve supplying the surgical site Regional or spinal anesthesia - injection into the vertebral canal, epidurally or into the sub-arachnoid space. To avoid systemic toxicity, care must always be taken not to inject local anesthetics into blood vessels. Topical local anesthetics, such as lidocaine jelly, may be useful for some surgical wounds. Proparicaine may be used as a local anesthetic during retroorbital blood collection from mice. One drop on the eye, wait 10-15 minutes before performing the procedure. An interesting use of local anesthetics is for amphibian and fish anesthesia . Tricaine and benzocaine can be added to water at a dose of from 25-100 mg/L, depending on the depth of anesthesia required. When the fish loses equilibrium (floats belly up) or an amphibian becomes inactive, it can be handled. For longer procedures, intermittent supplementation of anesthetic treated water to the gills or skin may be required. The animal is recovered in fresh water. Phenothiazine and Buterophenone Sedatives These sedatives include acepromazine , chlorpromazine , droperidol ( Innovar-Vet ) and azaperone (Stresnil). These drugs have excellent sedative properties, as well