Surgery Flashcards
What are the advantages of open castration?
Testicular/vaginal tunics entered and reflected, allowing palcement of ligatures directly onto vascular cord and ductus deferens, minimising chance of ligature slippage or loosening
What are the disadvantages of open castration?
- Indirect opening into peritoneal cavity created (however under aseptic technique, infection should not be a major issue)
- Operation time slightly longer
Describe the method for open castration
- Incise skin and subcut tissue on prescrotal midline
- Advance one testicle towards incision
- Incise speratic fascia to reach parietal vagina tunic
- Fenestrate spermatic fascia, place clamp across ligament of tail of epididymis
- Divide ligament and fascial attachments above clamp
- Wipe spermatic cord with gauze sponge to retract fascial layers
- Double or triple clamp, ligate testicular vein and artery together proximally to animal, ligate ductus deferens
- Place second encircing ligature around vascular cord and ductus deferens
- Transect cord between 2 haemostatic clamps
- Release cord under control of thumb forceps
- Observe for haemorrhave, replace within tunic
- Repeat with second testicle
- Dense fascial layers apposed with interrupted or continuous suture, subcut tissues with simple interrupted or continuous absorbable sutures, intradermal or subcuticular sutures placed instead of skin sutures, or close skin in routine fashion
Describe semi-closed castration
- Same as open, except that the vaginal tunic is ligated at the end of the procedure
- Commonly used in rodents
- Vaginal tunic cut proximally then closed using 3-0 or 4- absorbable suture
How can herniation of abdominal contents into the tunic following semi-closed castration be avoided?
Minimise the size of the tunic before closure
What are the advantages of closed castration?
- Vaginal tunics not entered
- Reduced risk of bleeding from incised vaginal tunics
- Rapid, easy
- Reduced risk of infection as there is no opening into peritoneal cavity created
- No possibility of seeding local wound with tumour cells as tunics and testicle remain in tact
What are the disadvantages of close castration?
- No tension must be placed on spermatic cord during clamping or ligation
- Extra care when placing ligatures since vessels supplying testicles are indirectly ligated
- More risk of catastrophic bleeding if ligatures are not secure
Describe the method for close castration in the dog
- Pre-scrotal midline incision
- Advance testicle towards incision
- Do not incise tunic
- Push testicle out of wound
- Hold scrotum in place under drape, pull testicle firmly up to break down spermatic fascia and gubernaculum and expose at least 8cm of cord
- wipe spermatic cord with gauze sponge to retract fascial layers and strip loosely adhered fat
- place 3 clamps on cord
- Ensure cord is loose so vessels are not under tension
- Flatten cord with finger, separate cremaster from vessels
- Apply transfixing encircling ligature closest to proximal clamp around spermatic cord
- Pass needle through cord, around vessels, 2 throws on vessels side, 4 on other side
- Transect cord 0.5cm distal to transfixing ligature
- Release cord under control of thumb forceps, observe for haemorrhage, replace within wound
- Close subcut tissue with simple interrupted or continuous absorbable sutures
- Can place intradermal sutures or route percutaneous sutures
What are the advantages of cruciate mattress sutures?
- Quick to place
- Allows for good skin apposition and control of tension across the wound
What are Ford Interlocking sutures used for?
Closure of skin incisions in farm animal species
What is cytology?
The study of cell number and type in a tissue mass or fluid accumulation, to investigate it’s cause
What can be gained from cytological examination?
- Differentiation of different fluids
- Differentiation of types of inflammation
- Detect presence of neoplasia (and indicate type)
What are the advantages of cytology?
- Sampling is quick, safe, inexpensive
- Can often be safely retrieved from lesions near vulnerable structures in conscious animals, so anaesthesia and surgical biopsy is unnecessary
- Quick results
- Little equipment and limited skill for sampling
- Simple blood stain and microscope can give idea of pathological process
How might false negatives in the detection of neoplasia occur in cytology?
- Poor exfoliation of neoplasm
- Failure to sample tumour tissue
- Extensive necrosis/inflammation present hiding tumour cells
- Neoplasm may not be well differentiated enough to allow accurate diagnosis
How might false positives in the detection of neoplasia occur in cytology?
- Dysplasia can mimic neoplasia and may occur in inflammatory diseases
- e.g. mesothelial cells can develop atypical morphology and proliferative changes caused by inflammation, revert back to normal if irritant is removed
Describe fine needle capillary sampling
- FNA with no suction
- No syringe attached
- Cells drawn into needle via capillary action
- Less traumatic to cells
- Less likely to draw blood and dilute sample
Describe fine needle aspirates
- Minimal suction
- used in cysts or failed FNCS
- Need to ensure are not applying suction pressure when removing the needle from the animal
- Some risk of cell destruction
List the different sampling techniques for cytology
- FNA and FNCS
- Lavages
- Thoraco/abdominocentesis
What are lavages/washes in cytology?
- Using sterile saline, cells washed from nasal, bronchoalveolar and urinary bladder mucosae
- Retrieved by immediate aspiration of the lavage fluid
Outline abdomino/thoracocentesis
- Small amount of fluid is normal, usually too little for collection except in horses
- Marked hypoproteinaemia is common pathological cause of excess body cavity fluid
- May use needle alone, needle with syringe or needle with a 3-way tap
Outline transtracheal lavage
- Catheter passed through wide gauge needle in a conscious dog
- Fluid flushed into airway and quickly aspirated
- Smears made from centrifuged sediment
Outline bronchoalveolar lavage
- Fluid lavaged through catheter which has been passed through endo-tracheal tube in anaesthetised animal
- Can be done using a bronchoscope
What is the advantage of using a bronchoscope in cytological sampling?
Can visualise lesion and directly remove cells from it using a small brush
What 4 basic tests are applied to fluid samples?
- Gross appearance
- Total protein content
- Nucleated cell count (TNCC)
- Cell type/s content (sediment smear under microscope)