SAS: Exam 2

Respiratory Surgical Considerations

• Pre op: Min restraint, ± cooling, rapid ET intubation

• Rx: Oxygen, butorphanol, acepromazine

  • Extreme anesthetic risk

• Risk: High risk, induction + recovery, examine upper airway at induction

Respiratory surgical procedures

• Normal lung volume: R → 58%, L → 42%

• Partial Lung Lobectomy: SM Focal lesion at peripheral ½ to 2/3 of lung lobe : neoplasia, granuloma, bulla, biopsy

• Dogs can tolerate removal up to 58% (compensate with hyperinflation, alveolar enlargement, capillary thinning)

• Intercostal thoracotomy, remove with a normal margin 

• Complete Lung Lobectomy: (LG) abscess (large purulent), trauma, torsion, large/multifocal neoplasia/bulla, idiopathic

  • Right cranial and middle are most common

  • Intercostal thoracotomy or median sternotomy  

  • Remove lung at pedicle and ligate artery/bronchus/vein

    • DO NOT untwist before removing  

Brachycephalic Obstructive Airway Syndrome (BOAS)

• Et: compressed face, stenotic nares, elongated soft palate, everted saccules ( → Laryngeal collapse), hypoplastic trachea

• Sig: young, brachycephalic breeds

• Cs: stertor(low), stridor(high), gagging, coughing, exercise intolerance, collapse, dyspnea

• Dt: CBC/Chem, rads, airway exam under single anesthetic episode

• Tx: 

  • Stenotic Nares: Cartilage resection/anastomosis or amputation

  • Elongated Soft Palate: staphylectomy/palatoplasty

    • 1-3mm beyond epiglottis - needs to be cut @ tonsil level, watch for laryngeal edema

  • Everted Laryngeal Saccules: temporary extubation, resection, bleeding stops w/ ET tube

    • Prolapse of mucosa lining, inhibit airflow

    • 1st stage of  laryngeal collapse

  • Hypoplastic Trachea: none

    • Tracheal diameter : thoracic inlet <0.2

  • Laryngeal Collapse: laryngectomy or permanent tracheostomy

Laryngeal collapse

• Due to chronic upper airway obstruction/airway resistance

• 3 stages

  • I – everted laryngeal saccules

  • II – I + collapsed cunieform cartilages (red)

  • III – I + II + collapsed corniculate cartilages (green)

• TX: Laryngectomy, Permanent tracheostomy

Laryngeal Paralysis

• Et: arytenoid cartilages fail to abduct (recurrent laryngeal n. & Cricoarytenoideus dorsalis muscle)

• Congenital, idiopathic, trauma, systemic dz, iatrogenic

• Sig: Lg breeds - unilateral then progresses to bilateral

• Cs: progressive signs, inspiratory stridor, voice change, exercise intolerance, cough/gag, anxiety, collapse

• Dt: BW, Rads, neuro exam, laryngeal exam under light anesthesia(ready to do sx)

  • Abduction of arytenoids and vocal folds on inspiration

• Tx: unilateral arytenoid lateralization (reduce obx and resistance) tie back 

  • Prognosis is  good, life-long aspiration risk, heat intolerance, Progression of polyneuropathy – if GOLPP is present

Lung Lobe Torsion

• Et: chronic resp dx, chylothorax, trauma, thoracic Sx, neoplasia, idiopathic

• Sig: deep, narrow chest dogs - pugs

• Cs: right cranial & middle congestion & consolidation - most common

• Tx: complete lobectomy 

  • DO NOT untwist lobe

Diaphragmatic Hernia

• Et: trauma, pressure gradient disruption, genetic

  • abdominal organs migrate into thorax, liver is #1

  • Peritoneopericardial d. hernia (PPDH) → congenital

• Sig: Cocker spaniel, Weimaraner, Himalayan, DLH

• Cs: shock(acute), dyspnea(chronic), exercise intolerance, ADR 

  • Congenital is asymptomatic

  • Tears → weakest areas: muscle

• Dt: thoracic rads (#1), US, CT

• Tx: Sx (8-16w if congenital) (trauma: be ready for anything)

  • abdominal explore, identify hernia, reduce contents, close defect (absorbable 3-0 PDS, simple continuous, dorsal → ventral), remove air

    • Caution of adhesions

    • Do not close the pericardial sac (genetic) 

  • Risk: re-expansion pulmonary edema, abdominal compartment syndrome, ARDS

    • Do NOT manually re-expand lungs, do not close pericardial sac

Lymphadenomegaly

• Palpable - when enlarged

  • Maxillary, Accessory axillary, Cervical, Femoral, Retropharyngeal, Sublumbar (L7), Mesenteric

• Et: infection, inflam, neoplasia, systemic dx

  • Size does not correlate with disease

• Cs: 

  • Painful: suppurative lymphadenitis → infection

  • Non-painful: lymphoid neoplasia

  • Fixed: metastatic neoplasia, fungal

  • Normal Palpable: Mandibular, superficial cervical, axillary (C), popliteal, superficial inguinal, tonsils (visible)

  • Abnormal if Palpable: Maxillary, accessory axillary, cervical, femoral, retropharyngeal, sublumbar, mesenteric

Lymph Node Surgical Procedures

• #1 FNA!!: bacti, fungal, neoplasia, culture, staging, tx planning

  • screening tool, cellular only, specific but not sensitive

• Needle (Tru-Cut) biopsy: Lg accessible LN

  • Lg bore (14-16g), aseptic, core sample (small)

    • Only be done in areas that allow it - no important organs/BV near

• Incisional (wedge/removal) Biopsy: small LN, tricky location

  • Stabilize node, wedge excision, close capsule(H. mattress)

• Lymphadenectomy Excisional (LN removal): smaller node, evaluate for metastasis - does not prevent mets

  • Full dissection, ligate vessels

• Sample Preservation: Neoplasia (formalin fixed), Bacti (fresh), Fungal (fresh/frozen), impression smears - cytology

Splenomegaly

• Anatomy:

  • Gastrosplenic ligament - left side 

  • Celiac artery → Splenic artery → pancreas → Left gastroepiploic a. → Short gastric aa

• Diffuse: Congestion

  • Splenic torsion, RHF, GDV, drugs, infection, Immune mediated, lymphoma

• Focal: Nodular regen, hematoma, trauma, neoplasia

Splenic Torsion “acute abdomen”

• Et: spleen twists on pedicle, congestion, necrosis

  • splenic artery and vein

• Sig: Lg-breed dogs

• Cs: shock(acute), anorexia, V/D, pain, enlarged spleen, hemoglobinuria(chronic), VPCs

• Dt:

  • Rads: abnormal location, mass effect, gas bubbles, comma-shaped spleen

  • US: variable echotexture, dilated vessels, thrombi

• Tx: splenectomy DO NOT untwist, Unasyn 

  • necrotic debris → emboli risk

Splenic Neoplasia

• Et: VERY common!

  • Non-neoplastic: hematoma, lipoma, myelolipoma

  • Benign: hemangioma, fibroma

  • Malignant: hemangiosarcoma HSA (#1), fibrosarcoma, liposarcoma, MCT

• Sig: Lg-breed dogs

• Cs: shock, mass, enlarged abdomen, fluid wave, lethargy, pain, vomiting, PCV on free fluid - determine blood, VPCs

• Dt: Abd rads (mass effect, effusion, metastasis), US (mixed echotexture, cavitated lesions, enlarged spleen), biopsy

  • Xray chest for mets!

• Tx: splenectomy

Splenic Surgical Procedures

• FNA: percutaneous, cheap, easy

  • concern for diffuse dz, avoid cavitary lesions

    • Ddx: infection, mast cell, lymphoma 

    • non-diagnostic for neoplastic masses (blood back)

• Excisional Biopsy: diffuse dx, small/focal mass, culture, histopath

  • Sx incision → sample → capsule sutured closed, direct pressure hemostasis

    • NOT really done, just remove the entire thing at once

• Splenectomy: Neoplasia, trauma, IM dz

  • Classic: dissect & ligate/divide all hilar vessels; protect short gastric a.

  • Alternate: Abdominal exploration, isolate, ligate splenic a. & v. distal to pancreatic branch/short gastric aa. / L gastroepiploic

    • quicker, best for no adhesions

  • Complications:

    • Hemorrhage

    • Resist this temptation to break down adhesions

Operative Considerations for the Spleen

• Rx: Blood transfusion(depends), Oxygen(natural anti-arrhythmic), fluids → Crystalloid/colloid fluid support

• Monitor: ECG: ventricular arrhythmias (ECG), coagulation (PT/PTT)

Patient Assessment - oncology

• History

• Visual inspection

• Mass palpation

• Evaluate:

  • Gross appearance

  • Consistency

  • Size

  • Mobility

• Palpation of regional lymph nodes

• Secondary effects of a tumor present

Fine Needle Aspiration - Oncology

• Cytological evaluation - Cells

• Definitive diagnosis:

  • AGASCA

  • Lymphoma

  • Melanoma

  • Mast cell tumor

• Supportive information

Biopsy - Oncology

• Obtain a diagnosis → skip FNA (Oral, airway)

• Need to know tumor behavior

  › Degree of local invasion

  › Metastatic potential - tumor grade (high/low)(1-4)

  › Biologic activity - histamine release

• Pre- or postoperative

  • Pre: helps plan surgery

  • Post: obtain clean margins

• Never for TCC, intestinal cancer → remove mass fully then biopsy

Biopsy procedure - oncology 

• Incisional/TruCut: Removal of part of the tumor

  • Requires a second surgery, seeding

    • Fixed masses

• Excisional: Remove entire tumor with normal tissue

  • a single procedure

  • Small, movable skin masses

  • Internal organs: intestines, spleen, liver

Tumor Staging

• Diagnostic process

  • evaluate for progression/extent of disease

• BW, UA, Bio chem

• Xray → 3 views

• US - abdomen

• LN aspiration

  • Enlarged nodes

  • Draining/sentinel LN (popliteal drains the foot)

• MRI, CT

Surgical Principles - oncology

• 1 and done

  • Excise all neoplastic tissue

• Aggressiveness (surgical ‘dose’) - common to leave some

  • › Intralesional (debulking) - leave some behind (airway)

    › Marginal - edge, peripheral to pseudocapsule, Lipoma, common w/o biopsy

    › Wide - clean margins

    • Solid masses, 1-2 facial planes deep, margin of normal tissue excised

      › Radical - amputation, entire tissue

      • splenectomy, mammary chain

• better to leave a wound open … than tumor cells remaining

• Resection:  “dirty” margins

  • Have to go Deep and lateral

Surgical technique - oncology

• Sharp dissection → scalpel blade is best

  • Gentle tissue handling

  • Hemostasis

    • Prevent release of tumor emboli  → ligate vein 1st

• Minimal handling of tumor itself

  • Use appropriate suture → monofilament (PDS)

• Lavage, Avoid drain

• Change instruments, gloves, drapes for closure 

  • limit contamination / seeding

• Post removal biopsy!!!

  • Allows for margin assessment

  • Dictates adjunctive treatment plan

    • radiation, chemo, 2nd sx

Lymph Nodes

• Palpate regional lymph nodes

  • › Enlargement

    › Symmetry

    › Degree of fixation

• Size does not indicate metastasis!!!

• Biopsy: if Tx dictates or concerned about mets!

• Lymph nodes are a poor barrier to disease

Palliative Therapy / Surgery

cancer is not curable

• Improve quality of life

• Examples:

  • Upper airway obstruction

  • Non-resectable mass

  • Bone tumor, amputation not possible

  • Hemoabdomen

• Debulking → Rarely acceptable

  • Follow up w/ radiation

• Vascular access points → chemo

• Feeding tubes

• Pain management

Prophylactic Surgery

• Ovariectomy/ovariohysterectomy “spay”

  • › Mammary neoplasia

    › Ovarian/uterine neoplasia

• Orchidectomy “neuter”

  • › Testicular neoplasia

    › Perianal neoplasia

    › Prostatic neoplasia

• Rectal polyp

  • Often transform into malignancy

CNS Surgical Considerations

• relies on oxygen and glucose!!

• BP: blood flow constant if MAP = 50–160 mmHg in CNS

  • Trauma ↑ ICP → ↓ local blood flow

• Metabolic: blood flow adjusts to metabolic demand - local blood flow will decrease w/ trauma

  • Sensitive to PaCO₂: ↑ CO₂ → vasodilation → ↑ ICP

    • hypoventilation, Increases blood flow

    • Remember: anesthesia, trauma

• Cs: hemorrhage (1), edema (1), demyelination (2), necrosis (2), inflam (2)

  • Spine: paraspinal pain/defect, limb neuro deficits

  • Head: anisocoria, abnormal pupils, nystagmus, mentation change, bleeding (nose/ear/eye), Cushing response, herniation

• Tx: only do diagnostics once stable → Xray/CT/MRI

  • Rx: Head elevated, fluids, oxygen, opioids, Mannitol (x3), Dexamethasone (once), neck brace

  • Sx: subdural hematoma, depressed skull fx, spinal stabilization 

    • Craniectomy: ↓ ICP 15%

    • Durotomy: ↓ ICP 65%

• Prog: deep pain nociception caudal to lesion is good

  • guarded when DPS absent

    • Schiff-Sherrington: T13-L1 stiff front, floppy back

Mechanisms of Trauma

• 1º damage

  • › Mechanical trauma

    › Axonal injury

    › Hemorrhage

    › Edema

• 2º biochemical effects

  • › Demyelination

    › Neuronal and glial cell necrosis

    › Inflammatory response

Anatomy of the disk (IVDD)

• Shock absorption and distribution

• Annulus fibrosus

  • Parallel arrangement of lamellae

    Thicker ventrally

• Nucleus pulposus: Center

• Cartilagenous vertebral end plates

  • Source of nutrients via diffusion

Intervertebral Disk Disease

• Herniation (Hansen Type I) Acute → fast progressive

  • Et: chondroid metaplasia, increased intradisc pressure

  • Sig: chondrodystrophics, 3-5y (TL) T10/11-L6/7 ¾ dogs

    • 8-12y C2/3-C5/6 (Cervical) ¼ dogs

• Cs: Compressive myelopathy, Contusion injury

  • paraspinal hyperesthesia, hunched back, vocalization(cervical), forelimb lameness, ataxia/paresis, plegia

• Dt: CT/MRI (#1), Rads(r/o) (narrowing, wedging, mineralized disc in SITU)

• Tx: percutaneous laser disc ablation(prevent T10/11-L5/6), >4w rest, NSAID, gabapentin, amantadine, ventral slot Sx (C), Hemilaminectomy (TL) 

  • Reoccurrence: 15-20%, increased w/ >5 mineral disks

• Protrusion (Hansen Type II) Chronic → slow progressive

  • Et: fibroid metaplasia,  dorsal annulus weakens, nucleus bulges, TL > cervical

  • Sig: Lg, non-chondrodystrophic, 5-12y older dogs

  • Cs: slow progressive ataxia, pain at lesion, paresis

  • Dt: MRI

  • Tx: Medical(best): NSAID, gabapentin, SX: dorsal laminectomy → decompression #1 goal

Percutaneous laser disk ablation (PLDA)

• Why: IVD herniation, reduce risk of recurrence 

• How:

  • Approach to remove (ablate) the nucleus pulposus

  • Performed from T10-11 thru L5-6

Lumbosacral Disease (Cauda Equina Syndrome)

• Et: L7-S1/3 → spinal cord stops @ L5-6

  • Degenerative: disc protrusion, lig hypertrophy, facet hypertrophy, spondylosis, instability

  • Congenital: stenosis, malformation, transitional vertebrae, end plate OC

• Sig: Lg, middle-aged, working dogs, GSD

• Cs: reluctance to jump, stiff gait, low tail, incontinence, back pain, weakness(non-weight bearing), LMN signs(L4-3)

  • Patellar “pseudohyperreflexia” – exaggerated reflex

    • Sciatic affected, patellar reflex spared

• Dt: rads (spondylosis, narrowed disc), CT, MRI(best)

• Tx: NSAID, gabapentin, 4-6w rest, epidural steroids (MPA protocol: wk 0, 2, 6)

  • SX: laminectomy + discectomy = reoccurrence 1-2y esp. w/ lateral compression 

Cervical Spondylomyelopathy (Wobbler Syndrome)

• Et: cervical vertebral instability/malformation, cord/nerve root compression, disk protrusion → C5/6-C6/7

• Sig:

  • Disc-associated: middle-aged Lg breeds Dobermans; C6-C7 IVD protrusion(ventral); 50:50 single/multi

    • Ligamentum flavum hypertrophy (dorsal)

• Osseous-associated: young giant breeds, Danes; C6-7 Vertebral stenosis; multi sites 80%

• Cs: chronic progressive ataxia, neck pain, proprioceptive deficits, Proliferation of the vertebral arch

• Dt: Rads(r/o), CT(bone), MRI(both) site/severity/parenchymal assessment (#1)

• Tx: Mild cases: restriction, harness, NSAID, gabapentin, good footing

  • Surgical(static): direct decompression (ventral slot, dorsal laminectomy), distraction/stabilization w/ spacers/implants(dynamic)

    • domino effect deterioration → adjacent VB effected

    • Both Sx and Rx equally successful

Atlantoaxial Instability (AA)

• C1-C2

• Et: congenital, dens aplasia, dens hypoplasia, dorsal angulation, ligament laxity, trauma

  • cranial axis(C2) dorsal displacement in relation to C1,  cord compression

• Sig: young, sm breeds

• Cs: neck pain(30-60%), progressive tetraparesis, ataxia, neuro defects(94%)

• Dt: rads (C1-2 misalignment), CT/MRI

  • do NOT flex neck!!

• Tx: 6-8w rest, neck brace, NSAID, gabapentin, Sx A-A fusion (#1)

  • Moderate peri-op mortality

Surgical Considerations for the skin

• Sharp dissection

• Trauma: Dissect deep to subdermal plexus to prevent devascularization 

  • Scalpel < scissors < CO₂ laser < electroscalpel

  • Skin hooks/suture stays < tissue forceps/repeated manipulation

• Healing: 

  • Primary: immediate closure

    • Delayed primary: <3-5d, before granulation

  • Secondary: >3-5 days, after granulation

  • Second intention: granulation + epithelialization

• Tension: 

  • Close parallel to lines: faster healing, less dehiscence

    • Perpendicular = wider scars, delayed healing, “dog ears”

• Excision: First attempt = best attempt 

  • Lipoma: 0 cm margins

  • Mast cell tumor: 1–2 cm

  • High-grade sarcoma: 3 cm

Skin Tension relief Surgery Techniques

• Undermining: Tension relief, simple, max elastic potential

  • separate skin + panniculus from SC tissue

  • Delayed wound healing

• Walking sutures: Tension relief, move skin / tack down, obliterate dead space, distribute tension

  • Stretch skin over defect

  • Use multi rows of suture anchored in fascia and dermis

    • Do not penetrate the skin surface

• Tension Relief Sut: cruciate(skin), horizontal/vertical mattress (fascia/deep tissue), far-near-near-far (support)

  • Limited effect

• Stents & quills: Tension relief

  • red rubbers

Abnormal Wound type closures

• Dog ears: excess skin puckers

  • Excise ellipse or trim excess → scissors

• Circular defects: 

  • Linear: Start at center and close parallel with line of tension

  • Ellipse: 4:1 length:width ratio, eliminates dog ears

  • Combo V: 45° from axis of tension, extra skin is not removed → eye lid masses

• Triangular defects: 

  • Y-closure: Start at points and work inward, horizontal suture at center

  • Rotational flaps: 4:1 length:width ratio, semi circular flap formatted onto defect

• Square/rectangular: start at corners work inward, may use advancement flap

• Fusiform/elliptical: place central suture, bisect segments

• Crescentic: one side is longer than other 

  • close from midpoint, sutures closer on concave side

Skin Grafts

• Transfer of a segment of free dermis and epidermis to a distant recipient site

• Full-thickness (recommended)

  • Epidermis and dermis

• Mesh:

  * Increased surface area

  * Better conformity

  * Fluid drainage

• Critical to graft survival

  • Healthy vascular bed

    Lack of motion

    Contact between the bed and graft

    Lack of infection

Ear Surgical procedures

• Pinna Lacerations: partial thickness vs amputation
  Aural hematoma: longitudinal planar fracture of articular cartilage

  • obliterate dead space (incision+suture, CO₂ laser, steroid infusion)

• Lateral ear canal resection: for otitis externa only / vertical, small lateral neoplasia

  • remove lateral wall of the vertical ear canal

  • New opening is at junction of vertical and horizontal canal

    • must still Medicate ear

• Vertical ear canal resection: confined vertical otitis (normal horizontal)  better cosmetic sx

• Total ear canal ablation TECA + lateral bulla osteotomy BO: chronic otitis, neoplasia

• Ventral bulla osteotomy: cats neoplasia, polyps

  • increased exposure to tympanic cavity and bulla drainage 

  • Cats have two bulla compartments

Tail & Rear Surgery

• Caudectomy (Tail docking): Cosmetic, trauma, neoplasia

  • Puppies 3-5d: local anesthesia

  • Adults: general anesthesia, ligation, V-incision closure

• Episioplasty: Vulvar folds

  • overweight dogs, younger recessed vulva 

• En-bloc resection: Tail folds

  • Bulldogs

  • Redundant skin overlaps a deformed terminal

    caudal vertebrae & prone to 2ndary infections

Foot surgical procedures 

• Onychectomy (Declawing): P3 removal at 3-12m

  • Scalpel, Resco clippers (risk bone left), CO₂ laser

  • Local /ring block to provide additional analgesia

  • Place a tourniquet (Radial neuropathy - limit time)

  • absorbable monofilament sutures

  • Post-op bandage, paper litter

• Dewclaw removal

  • Puppies (3-5d): no anesthesia, silver nitrate

  • Adults: GA, excision (bony vs soft tissue)

• Digit amputation: neoplasia, infection, osteomyelitis, severe trauma

  • 3rd & 4th digits = weight-bearing 

• Footpad lacerations: irrigation, 2-layer closure, padded splint

• Interdigital pyoderma: treat cause first → fusion podoplasty if refractory

  • fuses webbing/space between digits