TECHNIQUE

Local Anaesthesia of the Teat in Ruminants

Summary Information
Type of technique Health & Management / Ruminants Pain Management / INDIVIDUAL Technique:
Synonyms and Keywords See also: Perineal Nerve Block in Ruminants
Description Anaesthesia of all or part of the teat, used for surgical operations on the teat. 

Teat cistern infusion:

  • Under adequate physical restraint and sedation, milk out the teat cistern. (B342.16.w16, J234.12.w2)
  • Cleanse the teat orifice thoroughly using alcohol. (B342.16.w16, J234.12.w2)
  • Place a tourniquet (e.g. narrow gauze bandage or suture material) at the base of the teat. This prevents milk from entering the teat cistern and diluting the local anaesthetic. (J234.12.w2)
  • Place a teat cannula in the teat and through this infuse 8 to 10 ml (J234.12.w2) 3 to 5 ml (J234.11.w3) about 10 ml (B342.16.w16) of local anaesthetic solution (2% lidocaine) through the streak canal into the teat cistern. (J234.11.w3, J234.11.w3)
  • Analgesia of the mucosa of the teat cistern should occur in five to ten minutes. (B342.16.w16, J234.12.w2)
  • Milk out the local anaesthetic solution once time has been allowed for analgesia to develop. (B342.16.w16, J234.12.w2)
  • Remove the tourniquet. (B342.16.w16, J234.12.w2)
  • Analgesia should remain for about 90 minutes. (J234.12.w2)

Ring block:

  • Thoroughly cleanse the whole teat and teat base. (B342.16.w16, J234.12.w2)
  • Ensure appropriate restraint of the cow. (B342.16.w16)
  • Place an elastic band around the base of the teat if desired, to prevent diffusion of local anaesthetic into the udder. (B342.16.w16)
    • Do not place a tourniquet if a supernumerary teat is being removed. (B342.16.w16)
  • Insert a 2.5 cm 25 gauge needle into the skin and muscularis layer of the teat, transverse to the direction of the teat, dorsal to the area at which analgesia is required. (B342.16.w16, J234.12.w2); at the junction of the teat and the udder. (J234.11.w3)
  • Inject local anaesthetic solution in a ring pattern around the teat. (J234.12.w2)
    • Each insertion of the needle should take place through an area which has already been desensitized. (B356.2.w2)
    • Inject a total of 4 to 6 ml 2% lidocaine (B342.16.w16, J234.12.w2); a volume of 10 ml 2% lidocaine should be sufficient. (J234.11.w3)
  • Following injection, massage the solution into the tissues. (B342.16.w16)
  • Analgesia develops distal to the tourniquet in about 10 minutes and lasts for about two hours. (B342.16.w16)

Inverted V-block:

  • Thoroughly cleanse the whole teat and teat base. (J234.12.w2)
  • Insert a 2.5 cm 25 gauge needle into the skin and muscularis layer of the teat dorsal to the area at which analgesia is required. (J234.12.w2); 1.5 cm 25 gauge needle (B342.16.w16)
  • Inject a total of 4 to 6 ml of 2% lidocaine in an inverted V-shape enclosing the area in which analgesia is required (e.g. site of a laceration). (B342.16.w16, J234.12.w2)

Intravenous regional anaesthesia of the teat:

  • Restrain the cow, preferably recumbent. (B342.16.w16)
  • Place a tourniquet (e.g. narrow gauze bandage or suture material) around the base of the teat. (B342.16.w16)
  • Into any superficial vein distal to the tourniquet, using a 2.5 cm 22 to 25 gauge needle, inject 5 to 7 ml of 2% lidocaine. (B342.16.w16)
  • Provide digital pressure and gentle massage over the injection site to prevent formation of a haematoma. (B342.16.w16)
  • Analgesia develops in the area distal to the tourniquet within three to five minutes. (B342.16.w16)
  • Analgesia persists until the tourniquet is removed. (B342.16.w16)
  • Remove the tourniquet once the operation is completed; sensation returns in five to ten minutes once the tourniquet has been removed. (B342.16.w16)

Regional nerve blocks may also be used:

Perineal nerve block:

  • Restrain the cow.
  • At the ischial arch, about 2.0 to 2.5 cm lateral to the midline on both sides, inject 5.0 to 7.0 mL of 2% lidocaine solution into the subcutaneous and subfascial tissues. (B342.16.w16, J234.12.w2)
Appropriate Use (?) Teat cistern infusion:
  • To provides anaesthesia of the mucosa and submucosa of the teat cistern. (J234.11.w3, J234.12.w2)

Ring block:

  • Appropriate for most procedures carried out on the teat. (J234.11.w3) e.g. repair of lacerations or fistulas, removal of warts, teat removal associated with gangrenous mastitis, opening of obstructed teats, removal of fistuli and supernumerary teats. (B342.16.w16)
  • Simple to perform. (B342.16.w16, J234.11.w3)
  • Does not interfere with healing. (J234.11.w3)

Inverted V-block:

  • Surgical procedures on the teat such as repair of lacerations or fistulas, or wart removal. (B342.16.w16, J234.12.w2)

Intravenous regional anaesthesia of the teat:

  • For most surgical procedures on the teat. (B342.16.w16)
Notes General notes for local anaesthesia:
  • The analgesic technique chosen should be decided based on the procedure to be undertaken, the facilities available and the skills of the practitioner. (J215.7.w1)
  • Standard aseptic techniques should be practiced when performing local analgesia, including surgical preparation of the skin and sterile injection techniques. (J215.7.w1)
  • Aspiration to check for blood should be carried out prior to injection, to avoid inadvertent intravenous injection. (J215.7.w1)
  • Hyaluronidase may be added to local anaesthetic solutions to increase tissue permeability and thus decrease the time to onset of analgesia and reduce the volume of local anaesthetic solution required; it will also reduce the duration of analgesia. However it is questionable whether it is needed other than with procaine hydrochloride solution, since other local anaesthetic agents, such as lidocaine, penetrate tissues adequately. If used, then 150 turbidity reducing units (TRUs) of hyaluronidase may be added per 25 mL of 2% lidocaine. Note: Use of hyaluronidase is NOT a substitute for accurate placement of local anaesthetic solution, since the tissue fascial planes will still act as barriers. (B342.16.w16)
Complications/ Limitations / Risk Physical restraint and/or sedation is required in addition to the local anaesthesia before any operation is carried out on the teat, both for the safety of the surgeon and to maintain asepsis. (J234.12.w2)
  • The cow is restrained standing for minor procedures, otherwise in lateral or dorsal recumbency. (J234.11.w3)

Note: Local anaesthetic solution with added vasopressors (adrenalin or noradrenaline) should NOT be used for analgesia of the teats as they may produce sufficient circulatory compromise of the teat to result in tissue necrosis and sloughing. (J215.7.w1)

Teat cistern infusion:

  • The muscularis and skin layers of the teat are not anaesthetised by this procedure. (J234.12.w2)

Intravenous regional anaesthesia of the teat:

  • Adequate restraint, preferably with the animal recumbent, is essential. (B342.16.w16)
  • Aseptic technique is essential. (B342.16.w16)

Perineal nerve block:

  • Technically more difficult than local infiltration. (B342.16.w16)
Equipment / Chemicals required and Suppliers
  • Fine gauge needle (23-25 gauge) (B342.16.w16, J234.11.w3)
  • 2% lidocaine. (B342.16.w16, J234.12.w2)
    • Note: Local anaesthetic solution with added vasopressors (adrenaline or noradrenaline) should NOT be used for analgesia of appendages such as the teats as they may produce sufficient circulatory compromise of the appendage to result in tissue necrosis and sloughing. (J215.7.w1)
  • Syringe.
  • Narrow gauze bandage or suture material to make a tourniquet. (B342.16.w16)
Expertise level / Ease of Use Procedure should only be undertaken by an individual with appropriate clinical training and practical experience; this would usually be a veterinarian or someone with advanced veterinary technician training.
  • These blocks are simple to perform. (B342.16.w16)
Cost/ Availability
  • Inexpensive. (B342.16.w16)
Legal and Ethical Considerations In some countries there may be legislation restricting the use of this type of technique to licensed veterinarians. For example in the UK: "The Veterinary Surgeons Act 1966 (Section 19) provides, subject to a number of exceptions, that only registered members of the Royal College of Veterinary Surgeons may practice veterinary surgery." (see: LCofC1 - RCVS Guide to Professional Conduct 2000 - Treatment of Animals by Non-Veterinary Surgeons).
Author Dr Debra Bourne MA VetMB PhD MRCVS (V.w5)
Referee Graham Bilbrough MA, VetMB, CertVA, MRCVS (V.w69)
References B342.16.w16; J215.7.w1, J234.11.w3, J234.12.w2, LCofC1 

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