VMS3010 Large Animal Field Surgery PDF 2024

VMS3010 VETERINARY MEDICINE 1 Large Animal Field Surgery PROFESSOR PETER COCKCROFT  LEARNING OBJECTIVES Describe the requirements for producing aseptic surgical conditions in the field. Explain the limitations of field surgery evaluate when surgery in a theatre or referral is indicated. D...

VMS3010 VETERINARY MEDICINE 1 Large Animal Field Surgery PROFESSOR PETER COCKCROFT  LEARNING OBJECTIVES Describe the requirements for producing aseptic surgical conditions in the field. Explain the limitations of field surgery evaluate when surgery in a theatre or referral is indicated. Describe surgeon preparation in relation to field surgery and how to achieve this. Illustrate these principles using examples of common surgical procedures. 2 TOPICS Risks and benefits Regulations Common in field surgical procedures Case study Preparation for field surgery – managing risk Antimicrobial therapy Patient care General principles 3  BENEFITS AND RISKS OF FIELD SURGERY Benefits Convenience Cost Animal remains on farm Biosecurity Handlings facilities Stress of handling Risks Increase risk of infection Limited resources Health & safety Limited assistance 4  C O N S I D E R AT I O N S Cost/benefit – value of animal, cost of procedure and aftercare, slaughter value if the animal can be transported Safety – animal, surgeon, others Welfare Anaesthesia – local, regional, general Fluid therapy Antibiosis Aftercare - fly control, access to food and water, isolation box, re-introduction to herd/pen Analgesia – NSAID, limit movement, support Informed owner and signed consent form 5  ECONOMICS Ask the owner what the animal is worth alive or at slaughter Some indicative prices Horses – £1000-upwards Dairy and beef cows £1000-£1500 Bulls £1000-£5000 (can be much higher) Breeding ewe £100-£200 Rams £300-£5000 Gilts £250 - £300 (in pig £400-00) Boars £500-1000 Alpacas £200-£2,500 (can be much higher) 6 WEIGHT OF LARGE ANIMALS Horse 500-600 kg (depends on breed) Adult dairy cow 600-700Kg (depend on breed) Ewe 60-80 kg (depended on breed) Sow 250-300 kg Alpaca -60-80Kg 7 R E G U L AT I O N S – C AT T L E With Surgical castration veterinary surgeon only Presentation Name | Date | Version 0.0 8 R E G U L AT I O N S - S H E E P Presentation Name | Date | Version 0.0 9  R E G U L AT I O N S - P I G S Regulations Tail docking The procedure may only be carried out where measures to improve environmental conditions or management systems have first been taken to prevent tail-biting, but there is still evidence to show that injury to pigs’ tails by biting has occurred. The method used must involve quick and complete severance of the tail. An anaesthetic and additional prolonged analgesia must be administered where the animal is aged 7 days or over. Tooth reduction (tooth clipping) The procedure must consist only of the uniform reduction of the corner teeth by either grinding or clipping to leave an intact smooth surface. The procedure may only be carried out where measures to improve environmental conditions or management systems have first been taken to prevent tail-biting and other vices, but there is still evidence to show that injury to sows’ teats or to other pigs’ ears or tails by biting has occurred. The procedure may only be carried out on an animal that is aged not more than 7 days. Presentation Name | Date | Version 0.0 10  R E G U L AT I O N S - P I G S Tusk trimming The procedure may only be carried out where there is evidence to show that it is necessary to prevent injury to other animals or for safety reasons. Castration The method used must not involve the tearing of tissues. An anaesthetic and additional prolonged analgesia must be administered where the animal is aged 7 days or over. DEFRA -Code of practice for the welfare of Pigs (2020) The Mutilations (Permitted Procedures) (England) Regulations 2007 (2) Tail docking, or castration, of pigs may only be carried out by a veterinary surgeon or, where the animal is aged not more than 7 days, by a person experienced in performing the techniques involved and who is either a person responsible for the animal or a person employed or engaged by such a person to attend to the animal. 11 WHEN TO REFER Presentation Name | Date | Version 0.0 12 COMMON SURGICAL PROCEDURES EQUINE With the number of equine hospitals and practices with surgical facilities, there are very few indications for doing equine surgery in field. In field surgery in equines: Routine castration (cryptorchids should be referred). Stitch ups. Other emergency procedures. Presentation Name | Date | Version 0.0 13  C O M M O N S U R G I C A L P R O C E D U R E S C AT T L E » Left displaced abomasum correction » Right displaced abomasum correction » Caesarean section » Exploratory laparotomy/rumenotomy » Displaced/torsion of caecum » Open castration » Closed castration » Disbudding/dehorning » Digital amputation » Enucleation » Wound repair 14 CALF DISBUDDING 15 C A L F C A S T R AT I O N 16 C L AW A M P U TAT I O N 17  COMMON SURGICAL PROCEDURES SHEEP » Caesarean section » Open castration » Laparotomy » Wound repair 18  S U RG I C A L P RO C E D U R ES A L PA C A S Castration Tooth root abscess Fractures Wound repair Anti-tetanus Beware cervical injuries 19  IN-FIELD SURGICAL PROCEDURES PIGS » Castration – Commercial boars prior to slaughter or pet pigs » Hernia repairs » Caesarean » Digital amputation Aftercare – beware mixing with other pigs Thermoregulation Pet pigs – often done at the practice Vietnamese Pot-Bellied, Kune Kune, Gloucester Old Spot, and the Tamworth. Ovaro-hysterectomy Entropion 20  CASE STUDY » List the drugs and equipment you would take to perform a Caesarean section in a cow on farm 21  DRUGS » Local anaesthetic » NSAIDs » Oxytocin » Dopram » Xylazine » Antiobiotics Injectable Topical 22  EQUIPMENT Sterile surgical kit Buckets Suture material Sterile gown Sterile drapes Face masks Needles Head light Syringes Clippers plus brushes to clean blades, lubricant oil Chlorhexidine / povidone-iodine Animal technician/nurse Scalpel blades Calf resuscitator Sterile swabs Sterile gloves Arm length gloves Presentation Name | Date | Version 0.0 23  IN FIELD BASICS » Lighting » Protection from the weather » Tables » Water supply » Additional help 24 P R E PA R AT I O N F O R F I E L D S U R G E RY Animal restraint and making environment safe Administer systemic antimicrobials Administer systemic NSAIDs Local anaesthesia Clip the surgical site Clean surgical site Surgical scrub of site with Chlorhexidine/Iodine (gloved -remove) Sterile prep of surgical site with antiseptic/ alcohol (gloved - remove) Surgical hand washing, gowning and gloving Open surgical kit 25  RESTRAINT Cattle Pigs Crush, Swing gate Snare Head restraint – head rope Sedation Sedation Horse Casting – ropes Halter Alpacas Sedation Twitch Chute Stocks Casting - kushing with ropes Sedation Holding 26  P R E PA R AT I O N F O R F I E L D S U R G E R Y: MANAGING RISKS » Isolate the animal. Remove others from the pen/field. » Physical restraint. » Crush » Swing gate » Casting. » Chemical restraint. » Sedation. » Tail immobilisation. » Tying or bandaging. » Prioritise human safety. 27 O R G A N I S I N G E Q U I P M E N T A N D A S S I S TA N C E Check you have all the equipment before you start Make sure you can reach it easily Communicate with assistant 28  R E D U C I N G R I S K A S E P T I C P R E PA R AT I O N » Clip the area. » Remove hair which can contaminate the wound. » Remove organic debris attached to coat. » Clippers » Heavy duty clippers to create surgical area. » Surgical clippers to get closer clip at incision site. » Razor blades » Avoid using a razor blade. » Can disrupt epidermis and encourage bacterial colonisation. Presentation Name | Date | Version 0.0 29  REDUCING INFECTION RISK – ASEPTIC P R E PA R AT I O N » Iodine-povidone » Iodine inactivates microbes. » Short kill time (2 minutes), minimal residual activity. » Inactivated by organic debris. » Chlorhexidine. » Reasonable kill time (5 minutes). » Persistent residual effect (binds to protein of the stratum corneum). » Wider range of antimicrobial activity. » Less susceptible to inactivation by organic debris. Both must be diluted to reduce tissue irritation. Both agents perform comparably in the field setting. 30  REDUCING INFECTION RISK – ASEPTIC P R E PA R AT I O N 1. Tail Prep. » Bandage. » Tie to back legs. 2. Initial Clean. » Remove gross organic matter/dirt from skin. 3. Surgical Scrub. » Further removal of dirt and contact time with antiseptic solution. 4. Sterile Prep. » Final preparation of area with sterile swabs, antiseptic/alcohol/sterile saline and wearing sterile gloves. 5. Draping? » Adhesive drapes? » Isolate surgical site from fixtures/crush/surgeon contamination. 31 SURGICAL SCRUB-TECHNIQUE - 32  REDUCING INFECTION RISK – ASEPTIC P R E PA R AT I O N » Surgeon. » Surgical scrub – antiseptic » Dry with sterile towelling » Gowning and gloving. » Sterile kit. » New kit for each procedure. » Within easy reach. » Clean zone – not on the ground, on a stainless-steel tray or clean drape. 33  S T E R I L E S U R G I C A L K I T, G O W N S , G L O V E S A N D MASKS It is important to plan in advance the The surgeon in the field is wearing latex gloves over plastic instruments that will be needed during sleeves. the surgery and possible complication. 34 DRAPES A clean, disposable paper drape covers the animal and is fixed with towel clamp. 35  R E D U C I N G I N F E C T I O N R I S K – M A I N TA I N I N G ASEPSIS » Communication. Briefing of assistants (sterile & non-sterile). Planning & anticipation of problems. » Environment. Operate under cover. No other animals in the pen. Well-restrained animal. » Resources. Equipment on a stable surface, safe distance. 36 REDUCING INFECTION RISK – ANTI-MICROBIAL THERAPY » Recommendations based on human research. » No evidence on ideal course length. » AMs should reach MIC in the target organ by the time of surgery if practically possible. IM drugs must be given 1-2 hours prior to Sx. IV drugs can be given at the time of Sx. 37 REDUCING INFECTION RISK – ANTI-MICROBIAL THERAPY Infection status Non-contaminated (e.g. LDA correction). Contaminated (e.g. Caesarean section to remove a dead calf). Infected (e.g. TRP). Risk of contamination Opening viscera (e.g. Rumenotomy, Typhlotomy or Caesarean section). Decompressing viscera (e.g. Right sided approach to LDA correction). Duration of surgery, environmental hygiene. Patient compliance with procedure. Likely bacteria present G+ organisms from the skin. G- organisms associated with the GIT and Reproductive tract. Anaerobic organisms from GIT & established peritoneal / uterine infections. Resistance/ culture and sensitivity Presentation Name | Date | Version 0.0 38  REDUCING INFECTION RISK – WOUND I N F E C T I O N C L A S S I F I C AT I O N Class Description Clean An uninfected operative wound in which no inflammation is encountered. The respiratory, alimentary, genital, or uninfected urinary tract is not entered. Clean- An operative wound in which the respiratory, alimentary, genital, or urinary tracts contaminated are entered under controlled conditions and without unusual contamination. Contaminated Open, fresh, accidental wounds. Operations with major breaks in aseptic technique. Dirty Old traumatic wounds. Existing clinical infection. Perforated viscera. 39  WOUND INFECTION Increased susceptibility to wound infection is related to five basic risk factors. (1) Necrotic tissue – excellent growth medium for bacteria and poor vascularization decreases antibiotic efficacy (2) Phagocytosis and humoral immunity are significantly decreased in damaged tissue. (3) It is difficult to eliminate microorganisms from an infected foreign sutures – surgical excision required (4) Hematoma or blood - Excellent growth medium and, because it clots, interferes with the perfusion of the body’s defense mechanisms. (5) The creation of dead space lends itself to infection because it has no defence mechanism. 40  REDUCING INFECTION RISK – WOUND I N F E C T I O N C L A S S I F I C AT I O N » Field surgeries can’t be considered clean as it is accepted that aseptic technique will always be compromised. » Route of administration. IV or IM achieve tissue concentrations above the MIC most rapidly and reliably. Intra-peritoneal contraindicated. » Licensed products. » Milk and meat withhold. Therapeutic aspects (e.g. spectrum) MUST be considered first. 41  REDUCING INFECTION RISK – ANTI-MICROBIAL THERAPY Surgery Licensed Systemic Antibiotics Non-contaminated abdominal Aminopenicillins (e.g. Ampicillin or Amoxycillin). surgery Penicillin and Aminoglycoside (e.g. Penicillin and Streptomycin). First generation cephalosphorins (e.g. Cephalexin). Tetracyclines (e.g. Oxytetracycline). Potentiated sulphonamides (e.g. Trimethoprim and Sulphadiazine). Anaerobic contamination likely Aminopenicillins (e.g. Ampicillin or Amoxycillin). or infection established Cephalosporins (e.g. Cephalexin). Suspected or known beta- Tetracyclines (e.g. Oxytetracycline). lactamase resistance Potentiated sulphonamides (e.g. Trimethoprim and Sulphadiazine). Potentiated Aminopenicillins (e.g. Amoxycillin and Clavulanic acid). Third generation cephalosporins (e.g. Ceftiofur). Presentation Name | Date | Version 0.0 42 REDUCING INFECTION RISK – ANTI-MICROBIAL THERAPY Surgery Minimum duration Non-contaminated abdominal 0 days surgery (In theatre). Non-contaminated abdominal 3-5 days surgery (On farm). Contaminated or infected (On 5-10 days farm or in theatre). 43  REDUCING INFECTION RISK – ANTI-MICROBIAL THERAPY-TOPICAL » Purpose » Reduce wound contamination post-surgery. » ?Reduce intra-abdominal infection? » Options » Antibiotic spray – tetracyclines or amphenicols. » Anti-septic sprays – aluminium, copper sulphate, chlorhexidine. » Intra-peritoneal antibiotics » Not indicated. » +/- increase risk of adhesions. 44  PAT I E N T C A R E ability of owner to provide appropriate after care facilities to provide after care access to food and water protection from bullying of other animals protection from weather hygiene (faeces/urine) fly control during summer months Isolation – good or bad re-introduction to herd need to milk lactating cow – how will this be done? analgesia NSAID reduce movement support dressing avoid downer cows soft bedding ensure animals are standing periodically turn 3-5 x a day 45  GENERAL PRINCIPLES OF SURGERY 1. Surgical site preparation (clean v sterile) 2. Hair removal 3. Disinfectant 1. Povidone-iodine or chlorhexidine 2. Saline or alcohol 4. Patient surgical site preparation 1. Cleaning and disinfecting 1. Zone 1 - surgical site 2. Zone 2 – around the surgical site 3. Zone 3 - junction of clipped and non-clipped area 5. Drapes – 1. tapes and clips 2. Dispsable v re-usable 46  P R E PA R AT I O N S U R G EO N Hand and arms - Scrubbing Cleaning Disinfecting Sterile gloves Plastic sleeves – washed chlorhexidine plus sterile gloves (intra-abdominal) Gown Mask Head light 47 Resources » Desrochers A, (2005) General Principles of Surgery Applied to Cattle Vet Clin Food Anim 21 (2005) 1–17