General Surgery

Question 1

What equipment and set ups should be considered for surgery in zoo animals?

Describe the use of approximation sutures in zoo species.

What considerations need to be kept in mind when closing a surgery in a zoo animal?

What peioperative medications should be considered and when should they be given?

Answer 1

Fowler 7 Ch 17 - Fundamentals of Zoo Animal Surgery

INTRODUCTION

• Important to use necropsies to become familiar with tissues and anatomy
• Surgical Area- 2 surgery rooms (one for small animal one for large animal)
• Occasionally field surgery is still an option for zoo animals. May be a good choice for large mammals or patients requiring short duration anesthesia.
  
  • useful to have: good light source, anesthesia machine, oxygen tank, stretcher, surgical table
• Relevant instrument packs: microsurgery pack (very small patients), small-medium animal pack, large animal pack. (see tables 17-1, 17-2, 17-3)
• Electrocautery and suction are valuable equipment that should also be included
• A diversity of retractors is recommended
• Stapling devices, surgical lasers, vessel sealing systems can decrease surgical time and increase efficiency
• Laparoscopic surgery is becoming increasingly popular: prevents major surgical wound dehiscence but requires special training and is not indicated for all procedures.

APPROXIMATION SUTURES AND DEAD SPACE OBLITERATION:

• Approximation suture (anchoring and walking sutures used for apposition) is needed in most cases to close tissue in order to diminish tension on wound suture and limit dead space.
  
  • drain usage is often limited due to monitoring and removal requiring another anesthesia.
  • force applied by panniculus muscle and thick skin is challenging in some species (ex: large felids)
  • May be impossible to use bandages and need protective effects and support for the tension and suture line
  • Obliteration of dead space prevents seroma formation and speeds healing.
• When the use of drains is indicated but not feasible, must leave open space to drain in dependent area.

CLOSURE TECHNIQUES:

• Keep orientation of tension lines running parallel when suturing. Tension line orientation can be determined by noting a tissue’s resistance when manipulated.
• Prolonged isolation must be avoided when dealing with hierarchized groups, as reintegration may be a problem. The use of intradermal sutures may be best (but not good with high tension areas)
• In large species and for large incisions the suture must be divided into smaller sections, thus preventing total suture loss if wound dehiscence.
• Precautions must be taken with external knots, drains, or protective bandages, particularly for felines and primates (licking, nibbling, grooming)
• With high tension areas approximation sutures can be used in combination with tension-relieving sutures (mattress).
• Near-far-far-near suture pattern provides high tensile strength and good tissue apposition.
• If skin suture with external knots is selected and a second anesthesia is not practical, a non-absorbable monofilament suture must be used.

PERIOPERATIVE MEDICATION

• Tissues must have an appropriate antibiotic concentration at the time of surgery, thereby boosting the efficiency of preventing bacterial colonization, which is an aim of aseptic surgery.
• If you must proceed to surgery immediately, then IV administration is preferable.
• Analgesia is justified to prevent discomfort and pain after surgical intervention
• Administration of drugs in restraint cages post-operatively must be avoided, as this will place greater stress over the sutures and may lead to dehiscence.

Question 2

What are some commonly used minimally invasive surgical techniques used in zoological medicine?

What are some advantages of minimally invasive surgery in wildlife?

What are some risks associated with these techniques?

Answer 2

Fowler 8 Ch 72 Minimally Invasive Surgery Techniques

Intro

• Minimally invasive surgery (MIS) such as laparoscopic cholecystectomy and appendectomy are used routinely in human medicine
• Rapid recoveries and minimizing post op pain
• Many possible implications in vet med as well, especially in animals where post op care is challenging

Overview

• Laparoscopy and coelioscopy
  
  • Endoscopic procedures in the abdomen or coelom
  • Most widely recognized and best reported MIS technique in zoo and wildlife medicine
• Thoracoscopy
  
  • Endoscopic procedures of the chest
  • Improved visualization
  • Reduced need for chest drains and other intensive post op care
  • Few reports in zoo species to date
• Arthroscopy
  
  • Few reports published in wildlife species despite widespread use in domestic animals
  • Has been reported in giraffe, camels, alpaca, and llama
  • Much potential for use in hoofstock
• Percutaneous surgical interventions
  
  • Interventional procedures include interventional radiology, interven- tional cardiology, and ultrasound-guided procedures
  • Pacemaker has been reported in a gorilla
• Other endosurgical techniques
  
  • Other rigid and flexible endoscopic modalities can be used
  • Rhinoscopy has been used to remove nasal polyps in chimps
  • Endoscopy combined with fluoroscopy can be used for things such as urethral stenting as well as tracheal stenting

Current knowledge

• Cognitive bias in wildlife MIS
  
  • MIS being less invasive does not mean that it’s always better than open surgery, or that surgery is always the best option
  • All options should be considered
• Potential advantages of MIS in Wildlife
  
  • Post op care and monitoring in wildlife is challenging, as well as activity restriction
  • May facilitate more rapid return to their normal enclosure
  • More waterproof for aquatic species like pinnipeds
  • Minimal to no clipping for species that rely on their fur for insulation
  • Decreased risk of contamination in suboptimal operating conditions

Specific risks of MIS

• Safe laparoscopic access
  
  • The greatest risk is in achieving safe access/entry at the start of the procedure
  • Access may be open (a small incision into the abdomen, followed by port placement); blind (blind entry into the abdomen with a sharp trocar, normally after blind insertion of a Veress needle to insufflate the abdomen); or optical (using a laparoscope to assist entry, either with or without prior abdominal insufflation with a Veress needle).
  • Species prone to abdominal adhesion formation are at higher risk
  • The author’s preference is a modified open approach through the caudal umbilical scar, an exception being pinnipeds, in which blind access after insufflation with a Veress needle is recommended
  • In reptiles and amphibians, paramedian or lateral approaches are favored
  • Other ports can then be placed with laparoscopic visualization
• Other MIS-Specific risks
  
  • Inadvertent bowel injuries during laparoscopy - less likely to be seen during the surgery due to delayed signs from less significant inflammatory response
  • Especially true when using cautery
  • “Out of sight” injuries ie injuries that occur behind the tip of the endoscope
  • Thermal injuries from electrosurgical instruments may also not be visualized
• Endoscope selection
  
  • Tradeoff between smaller wound size and light transmission/image quality as well as size of biopsies if applicable
• Environmental impact of disposable instruments
  
  • Many single use instruments can be resterilized and reused

Clinical applications of MIS in wildlife

• Diagnostic laparoscopy
  
  • Ex laps and organ biopsies can be especially useful when advanced imaging modalities are not available
• Operative laparoscopy
  
  • Available instrument design/size may not be applicable to all species
  • However multiple different surgeries can be successfully performed
  • The author performed a ventriculoperitoneal shunt on a black bear with hydrocephalus
• Reproductive management
  
  • Laparoscopic sterilizations (vasectomies, tubal ligations, OVH, castration on cryptorchids) have been helpful