Equine Pathology Flashcards
1
Q
Adv of open castration
A
- Simple
- Quick
- Excellent drainage
- Can be done standing
- Best when incomplete sterility
2
Q
Disadv of open castration
A
- Higher risk of complications
- H+ - testicular a. most sig source
- Infection
- Eventration (hernia) - rare but serious
3
Q
Adv of closed castration
A
- Reduced incidence of H+ + infection, eventration of intestine
- More suitable for older horses (large vessels - ligature provides extra haemostasis
4
Q
Disadv of closed castration
A
- Inc expense of sterile environment + GA
- Implant (ligature) can act as focus for infection
- No drainage
- No visual check for what’s inside parietal tunic
5
Q
Adv of semi-closed castration
A
- Reduced incidence of H+ + infection, eventration of intestine
- More suitable for older horses (large vessels - ligature provides extra hemostasis
- Allows inspection inside parietal tunic
- Better ligament placement = reduced risk of H+
6
Q
Disadv of closed castration
A
- Inc expense of sterile environment + GA
- Implant (ligature) can act as focus for infection
- No drainage
- Inc surgical complexity
7
Q
Indications of GA
A
- Horse not well handled
- Pony too small
- Testes too small or difficult to palpate
- Closed/semi-closed castration - theatre
- Older/large horses + donkeys/mules
8
Q
Local anaesthesia
A
- Recommended for GA castration
- Crucial for standing castration
9
Q
Castration patient selection
A
- Age - spring of yearling year, can be done before weaned, considerations if older, 1 - 2 y/o
- Handleable/temperament - on CE + palp
- Palpation - two testis, scrotal/inguinal hernia?
- Tetanus vacc (first two)
- Donkeys, mules; draft breeds (inc risk of eventration - consider closed/semi-closed)
10
Q
Cryptorchids
A
- = Rigs
- Complete abdo
- Partial abdo (testis in abdomen, epididymis in inguinal region)
- Inguinal (‘high-flanker’)
- Not present (congenital monorchid) = rare
11
Q
Cryptorchid Dx
A
- Palpation
- Sedation + deep palpation, feeling right up into inguinal ring
- US - inguinal -> transabdominal / transrectal - between inguinal ring + kidney
- Static tests - serum Anti-Mullerian Hormone (AMH) - inc
(Serum oestrone sulfate + testosterone (not recommended) static test) - Dynamic testing - if inconclusive AMH results = hCG stimulation test (pre + post testosterone) - testosterone levels inc
12
Q
H+ - CS
A
- Acute blood loss - assess subject (horse blood vol should be 9% BW) - demeanour, HR/pulse, MM/CRT
- Haematology - PCV, transfusion if PCV < 20%
- Steady drop/stream = less than a drop per second for excessive period of time, > 15 min = make active intervention for H+
13
Q
Swelling + oedema
A
- Common post-op (castration)
- +/- Seroma infection
- Exercise crucial
14
Q
Seroma
A
- Common w/ open castration
- Pocket of serum (tinged w/ blood) fills scrotum after Sx
15
Q
Scrotal infection
A
- Common in open castration - determine temp, demeanour, dull/inappetant
- Closed castration - less common - more concerning due to lack of physical drainage, pos presence of implant (ligature)
16
Q
Iatrogenic penile trauma (castration)
A
- Root of penis mistaken for testis -> emasculation of root of penis (usually closed castration, cannot see)
17
Q
Incomplete castration
A
- Cannot see what you’re emasculating in closed castration
- Young foal colts have relatively large gubernaculum - mistaken for testes
- Partial abdo cryptorchids
- Inexperienced surgeons
18
Q
Septic funiculitis (‘Scirrhous Cord’) (castration complication)
A
- Chronic non-healing inflam that keeps recurring + forms discharging sinus tract
- Palpable thickening
- Uncommon
- Not pyrexic when chronic
- Failure of appropriate antimicrobials = Dx, AB don’t work as well)
- Absorbable suture can be focus of infection - avoid ligatures in non-sterile Sx
19
Q
Peritonitis (castration)
A
- Rare
- Abdo pain/colic signs
- Pyrexia
- V dull
- Weight loss
- Dx = abdominocentesis (high cell count + turbid appearance)
20
Q
Evisceration of omentum (castration)
A
- Through inguinal hernia
- Open castration
- Rare
- Not Sx emergency
- Dx = appearance
21
Q
Evisceration of SI (castration)
A
- Through inguinal hernia
- Open castration
- Rare but serious
- Fatal w/o Sx Tx (36 - 87% success)
- Draft breeds + standardbreds
22
Q
Standing Sx indications
A
- Castration
- Laparoscopy - ovariectomy; cryptorchidectomy
- URT - ventriculotomy; vocal fold resection, tieback (laryngoplasty)
- Sinus Sx
- Dental Sx
- Orthopaedic Sx - non-displaced Fx, DSP (dorsal spinous process) resection), arthroscopy
23
Q
Laparoscopic Sx indications (standing)
A
- Cryptorchidectomy
- Ovariectomy
- Granulosa cell tumour removal
- Abdominal exploration
- Nephrosplenic space closure
24
Q
Indications for ovariectomy
A
- Behavioural
- Colic/abdo pain
- GCT
25
Q
Granulosa cell tumour (GCT)
A
- Often secretory -> inc testosterone, inc inhibin
- Stallion-like behaviour, anoestrus or continuous oestrus, normal cycling = rare
- Enlarged ovary per rectum
- Dx - US - accum large pockets of fluid, biochemically same as CSF; inhibin hormone test
26
Q
Difficulties w/ non-laparoscopic ovaraiectomy
A
- Haemostasis
- Post-operative pain
- Prolonged wound healing
- Evisceration
27
Q
Abdominal exploration indications
A
- Recurrent colic
- Palpable abdo mass
- US findings
28
Q
Contra-indications of abdo exploration
A
- Acute colic
- Intestinal distension - may need to resect intestines, difficult to do laparscopically
29
Q
URT laser Sx
A
- Vocal cordectomy/ventriculectomy - due to laryngeal hemiplegia
- +/- Laryngoplasty
- Incisional benefits
30
Q
Colic post-op complications
A
- Discomfort
- Prolonged hospitalisation
- Expense
31
Q
Post-op colic complications
A
- Intestinal obstruction - like kink in water pipe hose
- Blockage at anastomosis
- Ileus (gut stasis)
- Adhesions
- Displacement
- Failure of adaptation
- Inc risk following large colon volvulus > 360 degrees
- 50% times more likely to develop after Sx = most common post-op complication
32
Q
Surgical site wound infection
A
- Painful
- Inc risk of hernia formation
- Prolonged hospitalisation
33
Q
Post-op incisional herniation
A
- Wound suppuration
- HR = inc, endotoxaemia - ischaemic bowel in abdo, leaking endotoxins, absorbed by circulation, going into bloodstream, effect of endotoxin = systemic -> inflam, affects healing of abdo wall
- Median time to appear = 57 d
34
Q
Predispositions of colic
A
- Horses that have had an episode of colic
- Crib-biting/windsucking behaviour
35
Q
Post-op ileus
A
- 10 - 20%
- 80% cases survive
- Onset post-op = 24 h
- Intestines fills up w/ fluid from upper GIT - no motility - becomes life threatening when SI fluid backs up in stomach, cannot be sick, pressure built up in stomach -> rupture -> release of fluid into peritoneal cavity = death, pass stomach tube to decompress stomach
- CS - dull + depressed, inc HR, inc PCV, inc TP, gastric reflux
- Inc PCV - endotoxaemia (inhibits GI motility), fluid into SI -> distension
- Dx - US - distended gut, swirling food in lumen, normal intestines would not be as empty
- Pedunculated lipoma strangulation - 3 x more likely
36
Q
Arthroscopy
A
- Dx - visualisation of joint - ST structures, cartilage lesions
- Therapeutic - OCD/chip Fx; synovial sepsis
- Remove bone fragments
- Debridement of intra-articular ST injuries
- Assist in repair of articular Fx with internal fixation
- Debride or inject subchondral bone cysts
(Tenoscopy = within tendon sheath; bursoscopy within a bursa)
37
Q
Orthopaedic arthroscopy intra-operative general anaesthesia risks
A
- Haemarthrosis - articular bleeding into joint cavity
- Obstruction of view by synovial villi
- Extrasynovial extravasion (leakage) of fluid
- Iatrogenic damage to articular cartilage
- Intrasynovial instrument breakage
- Intrasynovial foreign material - intrument broken off
39
Q
Fx that involve conservative Tx
A
- Pedal bone, non-articular
- Ileal wing - uncommon, box rest/keep stable for time, detect on US
- Incomplete long bone e.g. tibia
- Accessory carpal bone
40
Q
Fx that involve Sx removal of bony fragments
A
- Splint bone (distal)
- Carpal chips
- P1 extensor process
41
Q
Fx that involve Sx repair
A
- Mc/Mt condyle
- P1 sagittal
- Carpal/tarsal slab
- Olecranon
- Common in racehorses
42
Q
Fx that involve euth
A
- Comminuted
- Open/contaminated
- Transverse long bone/large horse
45
Q
Tarsal arthrodesis
A
- Fusion of bone to joint
- Osteoarthritis of TMT + DIT, not responding to medical therapy
46
Q
Impingement/overriding of dorsal spinous processes
A
- Kissing spines - processes/ligament formation between spinal processes
48
Q
Periosteal transection
A
- Angular limb deformity non-responsive to conservative Tx (hoof trimming, corrective shoes)
- Early in life during active growth phase - before 2 m/o
49
Q
Tendon repair
A
- Partial or complete severance of flexor tendon (extensor tendons managed conservatively)
- Repair only attempted if severance cleaned
54
Q
4 stages of wound healing
A
- Inflam (6 - 48 h, swelling, oedema, erythema, most sore) - Haemostasis - reflex vasoconstriction (first 5 - 10 min) -> vasodilation -> haemostatic plug, prevents further fluid loss, dies to form scab -> sloughs off eventually
- 1). Inflam phase - migration of leucocytes into wound - neutrophils + monocytes + production of pro-inflam mediators
- 2). Debridement phase (7 - 10 d) macrophages remove clot + debride necrotic tissue, pus produced
- 3). Proliferative/fibroblastic phase (repair) - pink tissue = new granulation tissue, edges forming
- Growth factors stimulate fibroplasia (to contract wound), angiogenesis, epithelialisation -> modify ECM -> granulation tissue (combo of new capillaries, fibroblasts + connective tissue) -> 2 - 3 w
- 4). Maturation phase (v v long time, regain full strength + elasticity) - hair follicles
- Restoration of skin integrity - wound w/ new tissue
55
Q
Mechanisms of wound healing/closure
A
- Wound contraction (of myofibroblasts) - reduction in wound size
- Granulation - new capillaries, fibroblasts + connective tissue, surface for epithelialisation
- Epithelialisation - side-to-side healing of epithelium - on top of fibroblasts, at margin of granulation
- First intention - suture - bring edges together, soon after problem, clean wounds/clean-contaminated, no tension or dead space, before granulation, minimal scaring
- Second intention - granulation healing, wound contraction + re-epithelialisation, unsuitable for closure, severe contamination + devitalisation + tissue loss, AB needed, allow gap to fill up w/ granulation tissue, slower, more tissue scarring
57
Q
Synovial sepsis
A
- Synovial cavities w/ thin soft tissue coverage of joints/tendon sheaths/bursae
- Dx - sudden, onset severe lameness, v painful, synovial fluid sample, turbid synovial fluid (high protein content, inc WBC), synovial WBC > 20 x 10^9/L; protein > 20 g/L, egress of injected sterile fluid (communication of synovial cavity/joint capsule + wound)
- If untreated -> sepsis -> severe pain -> articular cartilage destruction - non-treatable, infective, OA
58
Q
Proud flesh formation
A
- Exuberant granulation tissue - continued proliferating
- Deforms wound
- Grows beyond wound edges
- Looks like sarcoid
- Slice/debride off
59
Q
No wound contraction below carpus/tarsus
A
- Skin cells below do not contain myofibroblasts, cells developed differently on lower limb
- Slow to heal
- Expensive
- If don’t do anything, granulation tissue keeps growing
- Epithelial tissue - keeps granulation tissue in check - use skin graft - provides myofibroblasts + capillaries
- Pinch grafting - tiny piece of skin
60
Q
Sequestrum formation
A
- = Piece of dead bone - necrosis of outer bone cortex
- Wound appears to heal then w - m later, pus, like sinus in skin, pus bursts out
- Involucrum = hole in parent bone
- Periosteal damage often results in sequestrum formation
- Acts as nidus for infection - no blood supply, bacteria won’t be killed by host defence mechanisms
- Wound can heal over top of sequestrum
- Leads to recurrent wound breakdown + discharge
- Dx - radio
- Particularly on distal limb
64
Q
Colic - sand impactions
A
- Inc prevalance
- Peri-urban horses/ponies
- Large impaction of RDC
65
Q
Intestinal displacements
A
- Obstruction outside gut, LI in tight space + compressed from outside + can undergo torsion + volvulus, twist around axis -> inflated + distended intestines
- Right dorsal displacement
- Nephrosplenic entrapment? LDD
- Pelvic flexure retroflexion
- Partial colon torsion
66
Q
Nephrosplenic entrapment
A
- Lower grade colic (pain) compared to strangulation (ischaemic)
- Colon trapped dorsal to spleen
- Gas distension + impaction of trapped colon
- Leads to impaction in ventral colon
67
Q
Large colon torsion
A
- RDD - right dorsal colon - twists/rotates clockwise
- Can cause mucosal oedema following ischaemia - esp at pelvic flexure
- Once blood supply obstructed - get ischaemic necrosis
- Colon = massive SA -> leakage of bacteria from colon into peritoneal cavity -> become sick v quickly
- V painful colic
- Signs of endotoxaemia - changes in mm colour, inc heart rate - know horse requires Sx
68
Q
Intestinal strangulation - ischaemic + stop blood flow
A
- Pedunculated lipoma, most common
- Epiploic foramen entrapment - anatomical hole bordered by ligaments, intestines may slip through, tight hole, venous supply blocked, so arterial supply occluded -> ischaemic -> endotoxaemia
- Mesenteric tears
- Gastro-splenic ligament
- Volvulus nodosus
- Intussusceptions
69
Q
Problems of intestinal strangulation
A
- Ischaemic gut
- Endotoxaemia
- Distension proximally
71
Q
Eosinophilic enteritis
A
88
Q
Compare + contrast jugular vein catheters - teflon vs polyurethane
A
- Teflon = simple, over need, cheap, common, easy to use, but inc irritation, prone to kinking, inc risk of thrombophlebitis
- Polyurethane = less rigid, longer placement time, less irritation, reduces risk of thrombus, but inc contamination risk, difficult to place, more expensive
90
Q
Thombophlebitis - hospitalised horse
A
- Indwelling catheters or venepuncture sites
- Risk factor: Endotoxaemia, septic or non-septic
- CS - heat, pain, swelling, no drainage at the affected site, pyrexia, peripheral venous distension
- Monitor daily - remove catheter if signs of thrombophlebitis
- Investigation - US for thrombus, C&S of catheter tip
- Complications - vegetatie endocarditis
92
Q
Hyperlipaemia
A
- Cause: inadequate food intake (negative energy balance) exacerbated by underlying disease + obesity
- Donkeys and ponies worse affected than horses
- Occurs when the rate of lipolysis from adipose stores exceeds the rate of removal of triglyceride from the plasma
- Excessive fat deposition causes organ dysfunction
- CS - non-specific - depression, anorexia, weakness, ataxia, seizures, signs of liver or other organ failure
- Dx - Blood sample - opaque discolouration of plasma; elevated triglycerides but < 5.65 mmol/L = hyperlipidaemia; elevated triglycerides > 5.65 mmol/L = hyperlipaemia
