A.Local anesthesia (analgesia): giving to the animals by the following ways: 1)Topical (surface) application of local anesthesia. 2)Splash block. 3)Intra-articular or synovial block. 4)Intra and sub dermal infiltration. a)Line block. b)Ring block. c)Field block.

a)Intravascular: anesthetic solution is administration by intravenous, intra-arterial, intra-cardiac, or intramedullary (bone marrow) injection. b)Other injectable routes: anesthetic agent is administration by intramuscular, intraperitoneal, intrathoracic, and subcutaneous injection.

1)Should be water soluble. 2)Should be stable in solution and easily sterilized. 3)Should be rapidly absorbed from the tissue. 4)Should be not irritant. 5)Should be not toxic. 6)Should be high potency in low concentration and with rapid onset and long duration.

1)Extracellular fluid → ↑conce. Na and ↓conce. K → Intracellular fluid → ↓conce. Na and ↑conce. K. 2)Cell stimulation → Na ++ passes → Special canal (cell membrane) → Intracellular fluid → action potential. 3)Sodium canal (cell membrane) → phospholipid (internal and external opening) → open only when the Ca ++ combined with the phospholipids.

Local anesthesia solution → prevent Ca ++ - phospholipids binding (inner and outer opening of Na canal in the cell membrane) → prevent Na to pass inside the cell → prevent conduction of nerve impulse → prevent action potential. Toxicity of local anesthesia: The over dosing of local anesthetic lead to signs of toxic effect  Local reaction: The over dose → ischemia → necrosis of the area → itching at the injection site?  Systemic reaction: The over dose of local anesthetic solution → the toxic level in the circulation → peripheral cardiovascular depression, salivation, tremor, excitement, nausea, vomiting, convulsion, coma, and death.

1)Injection minimum dose with low conce. 2)Aspiration before injection to avoid injecting local anesthesia in the blood vessels. 3)Adding of vasoconstrictors as adrenaline. 4)Injection of preanesthetics drug to reduce the dose of the later.

1)Topical or surface application:  Freezing of the superficial layers → analgesia (Ice Ethyl chloride spray, ether spray, and carbonic acid snow).  Local analgesic agents applied directly into the eye (conjunctiva), or mucous membranes (larynx, urethra, nasal passages, ear canal) or skin.  Lignocaine gel, ointments, or spray on the mucous membranes, or the skin.  Local anesthetic creams, may be applied to the skin before intravenous catheterization.

2)Splash blocks: Local anesthetics are dripped onto wounds at the end of a procedure. 3)Intra-articular or synovial block. 4)Intra and sub-dermal infiltration.  Line block.  Ring block.  Field block: circle block, inverted-L or 7 block, or inverted-V block above the incision line.

1)Absence of distortion of the anatomical features in the line of incision. 2)Ischemia of the tissue within the blocked area. 3)Muscular relaxation. 4)Absence of interference with the healing of the wound.