mod 2 Anesthesia Anesthesia means loss of sensation and reflex response by using an agent which depress the activity of the nervous system either locally or generally By dr.Abd-Elbasit

The importance of anesthesia in veterinary practice 1- Relief of pain from acutely inflammed area. 2- Surgical interference without pain. 3- Diagnosis of obscure cases of lameness

The subjects of anesthesia 1- Local anesthesia 2- Regional anesthesia 3- Tranquillization & sedation 4- Narcosis 3- General anesthesia

Local anesthesia Def. Loss of sensation in a limited body area through transient paralytic action on sensory nerve and nerve endings. Types: I- Topical or surface anesthesia. II- Infiltration anesthesia.

Local anesthetic agents 1- Procaine hydrochloride (Novocaine) 2- Lidocaine (xylocaine,lignocaine ) 3- Ophthaine, Novasine 0.5-1% in form eye drops. 4- Ethyl chloride spray 5- Mepivacaine

Procaine hydrochloride 1- It presents as white powder 2- It used as freshly prepared watery solution.. 3- It causes local vasodilatation and poorly absorped from the the surface of the mucous membranes or skin so it is not used for topical analgesia. 4- It is less toxic than cocaine and completely detoxicated by the liver. 5- It used for induction of local infiltration anesthesia & epidural analgesia. 6- Its analgesic effect begin 10 minutes after injection and continue for 60 – 90 minutes. 7- To prolong its effect, Epinephrine is added in concentration 1/ 100,000 to its solution.The addition of the vasoconstrictor is contra indicated in extremities.

Lidocaine ( xylocaine, lignocaine) 1- It is more potent than procaine and has the ability to pentrate the tissues and absorped by the surface of mucous membranes 2- It is used as topical anesthetic in form jell or ointment. 3-It is commonly used for induction of local infiltration & epidural anesthesia. 4- It used in concentration 1-2%. 5- It does not causes local vaso dilatation.

Mepivacaine 1- it is more potent than procain 2- It used in concentration 1-2 % for infiltration and nerve block anesthesia. 3- It is less toxic 4- It does not couse local vasodilatation.

The mode of action of the local anesthetics It acts by interference with transmission of impulses by preventing the increase in membrane permeability of the nerve cell to sodium ions. It acts by interference with transmission of impulses by preventing the increase in membrane permeability of the nerve cell to sodium ions.

The toxicity of local anesthetics 1- Local damage of the tissues due to high concentration or direct intraneural injection 1- Local damage of the tissues due to high concentration or direct intraneural injection 2-Systematic toxicity due to over dosage or direct intravenous injection manifested by direct myocardial depression, severe hypotention, cardiac arrest, convulsion and respiratory failure. 2-Systematic toxicity due to over dosage or direct intravenous injection manifested by direct myocardial depression, severe hypotention, cardiac arrest, convulsion and respiratory failure.

Surface anesthesia 1- Freezing of the superficial layer of the skin by ethyl chloride spray, carbon dioxide snow or ice 1- Freezing of the superficial layer of the skin by ethyl chloride spray, carbon dioxide snow or ice 2- Application of lidocaine ointment on painful eczematous area. 2- Application of lidocaine ointment on painful eczematous area. 3- Instillation of the eye by local anesthetic solution as xylocain 2%. 3- Instillation of the eye by local anesthetic solution as xylocain 2%. 4- Intrasynovial anesthesia 4- Intrasynovial anesthesia

Instillation anesthesia Indications 1- Examination of the eye. 2- Removal of the foreign bodies. 3- Conjunctival scraping. 4- Removal of hypertrophied glandsof the third eye lid. 5- Subconjunctival injection.

Topical anesthetics for instillation 1- Lidocaine 2-5 % 2- Proparacaine 0.5 % 3- Tetracaine 0.5 % 4- Butacaine 0.5 % These topical anesthetics gives 15 minutes aneshesia after single instillation and 2hrs. Anesthesia after 3-5 series of instillations with one minute intervales. These topical anesthetics gives 15 minutes aneshesia after single instillation and 2hrs. Anesthesia after 3-5 series of instillations with one minute intervales.

Intrasynovial anesthesia Indication Indication 1- diagnosis of lameness caused by joint disorder. 1- diagnosis of lameness caused by joint disorder. 2- To relief pain caused by arthritis 2- To relief pain caused by arthritis

The technique of intrasynovial anesthesia 1- Preparation of the site of arthrocentesis for aseptic injection. 2- Insertion of the injectable needle intra-articularly 3- Aspiration of the excessive synovial fluid to prevent excessive dilution of the local anesthetic. 4- Injection of local anesthetic dose 5-10 ml.according to the size of joint. 5- The onset of the effect begin after 10 minutes & persist for 60 minutes.

Intra articular injection of radiocarpal & intercarpal joints

Infiltration anesthesia I- Types 1- Linear infiltration. 2- Field infiltration.

Indications of infiltration anesthesia 1- It is indicated with or without sedation for surgical interference in ruminant animals for examples; Rumenotomy, Ceasarean, Removal of neoplasm, Cyst or Fibrosed bursa (Fibrous bursitis )and surgical treatment of hernia 2- Surgical operation require standing position such as Medial pattler desmotomy

Technique of infiltration anesthesia I- Linear type 1- Preparation of the area to be anesthetized for aseptic interference 2- Define the intended line of the incision by one of the following methods; A- Scratching of the skin by the tip of the injectable needle. B- Intradermal injection of 1 ml. of local anesthetic at both ends of the line to make blebs. C- Using of Surgical marker.

II- Field type In this type the local anesthetic is infiltrated at the periphery of the operated area in form circle, Quadrilateral, Triangle or Inverted L by the same technique of linear infiltration. In this type the local anesthetic is infiltrated at the periphery of the operated area in form circle, Quadrilateral, Triangle or Inverted L by the same technique of linear infiltration.

Infiltration anesthesia