Equine GI Surgery Flashcards
what is GI tract surgery in horses mostly related to?
signs of colic (abdominal pain)
what is GI surgery in horses occasionally for?
exploratory laparotomy or laparoscopy for subacute or chronic conditions or signs (e.g. weight loss, suspected masses, peritonitis)
what is the aim of a colic work up?
establishing whether a horse requires surgery or not
what is colic surgical decision making based on?
pain clinical exam findings rectal exam stomach tube abdominoscentesis blood work ultrasound
what findings on a colic work up would indicate there may be a need for surgery?
pain despite analgesia absence of faeces tachycardia poor MM colour reduced or no gut sounds distention or displacement of LI or SI increased PCV, TP and lactate positive reflux on NG tubing discoloured or turbid peritoneal fluid
what HR is classed as tachycardia in horses?
> 60 bpm
how much fluid on NG tubing is classed as abnormal / indicative of surgical colic?
more than 5L net
what is the likely cost of colic surgery?
around 4-8k
what sort of colic cases often result in high bills?
those that are unsucessful
what may be required up front to secure colic surgery?
substantial payment
what issues around transport are there associated with colic surgery?
where will the surgery be done and how will the horse get there
what is the prognosis for surgical colic cases?
hard to tell pre surgery
duration of signs and severity of systemic disturbance will give clues
what may aid in telling the prognosis of colic surgery cases?
duration of signs
severity of systemic disturbance
are complications following colic surgery common?
yes - owners should be made aware from the outset
what is key about preparation of a horse for colic surgery?
time is critical as it is an emergency so swift and efficient preparation is important
what is involved in the preparation of the horse for colic surgery?
jugular IV catheter placement decompression of stomach with NG tube administration of analgesia / antimicrobials IV fluids clip abdomen remove shoes and tape feet wash out mouth
what is the role of a jugular IV catheter?
administration of medication
IVFT
anaesthetic induction
what size IV catheter is used for an adult horse?
usually 14G
why should horses have their stomach decompressed prior to colic surgery?
cannot vomit and so refluxing will prevent gastric rupture of the stomach by decompressing
what may cause horses to reflux fluid on passage of an NG tube?
if there is obstruction or ileus of the SI
what does presence of reflux do?
helps diagnosis
when should horses stomachs be decompressed?
prior to anaesthesia induction
how will horse be restrained for passage of an NG tube?
stocks
twitch
sedation (Xylazine)
where is the NG tube passed through in the nose?
ventral meatus to avoid ethmoidial turbinates
why should the horses head be flexed when placing an NG tube?
allow passage of the tube into the oesophagus rather than the trachea
what will the horse do as an NG tube is advanced into the oesophagus?
swallow
how can correct placement of NG tube in the oesophagus be confirmed?
observe the left hand side of the neck for end of tube advancing in oesophagus to confirm correct placement
what should be done if spontaneous reflux doesn’t occur when an NG tube is passed?
establish siphon by attaching funnel to end of tube and pouring in a measured amount of water from a jug and then lowering the end of the tube into a bucket to collect and measure what comes out
why is IV fluid therapy needed when preparing a horse for colic surgery?
stabilise cardiovascular system and support circulation
when can the abdomen be clipped?
may be started before induction or left until horse is anaesthetised
what is the risk associated with clipping the abdomen before horses and anaesthetised?
may be safety issue if horse is painful and actively colicking
why do horses shoes need to be removed and their feet taped before surgery?
avoid trauma and damage to the recovery box
what must be done with the horses mouth before induction?
washed out to prevent debris being pushed into trachea at intubation
what must happen after induction when preparing a horse for a laparotomy?
Move from recovery box to table with hoist place urinary catheter clip abdomen (fine clip also) cover legs and feet drape prep skin in sterile manner lay out surgical colic kit
what position are horses usually placed in for exploratory laparotomy?
dorsal recumbancy
what must happen as well as placing a urinary catheter in male horses?
suture prepuce
what incision is made for an exploratory laparotomy?
ventral midline
what surgical kit is needed for colic?
check kit list
surgeons will have differing preferences
what are the main steps involved in surgical treatment of colic?
opening and exploration of the abdomen identification of lesion correction of displaced or entrapped intestine decompression of distended viscera resection if needed and anastomosis closure of abdomen recovery from anaesthesia
what are the main types of intestinal obstruction?
simple
functional
strangulating
describe simple intestinal obstruction
lumen only obstructed
vasculature ok so intestine is minimally compromised
what is the prognosis of simple intestinal obstruction?
good
what is an example of a simple intestinal obstruction?
pelvic flexure impaction
what causes a functional intestinal obstruction?
failure of peristalsis (e.g. ileus) leading to distention
what can cause functional intestinal obstruction?
grass sickness
post op complication of ileus secondary to distention
what happens during a strangulating intestinal obstruction?
compromise of vasculature leading to death (ischemia) of intestine
veins become obstructed causing oedema of gut wall
release of endotoxins into circulation
systemic compromise and shock
later secondary problems
what can cause strangulating intestinal obstruction?
pedunculated lipoma
large colon volvulus
what causes endotoxaemia in strangulating intestinal obstruction?
release of endotoxins into the circulation and peritoneal cavity due to oedema of intestinal wall that leads to increase in mucosa permeability
what results from endotoxaemia?
systemic compromise and shock
what is the prognosis of strangulating intestinal obstruction?
increasingly poor after 6-8 hours
what secondary problems may occur from strangulating intestinal obstruction?
laminitis
what does strangulating intestine look like?
goes from maroon to purple and then black as blood supply is compromised
what is the effect of SI strangulating obstructions on more proximal structures?
effect of a simple obstruction with distention as gas and fluid cannot pass the obstruction
what can be the result of prolonged distention of SI?
ileus
what will the intestine be like distal to strangulating obstruction?
appear relatively normal
what are the specific conditions that may lead to SI strangulating obstructions?
pedunculated lipomas
herniation (epiploic foramen, inguinal, mesenteric defects)
intussusceptions
how is an SI resection performed?
isolate affected (devitalised) segment with bowel clamps at either end
ligate blood vessels supplying the affected segmant
resect
what materials are used for anastomosis of the small intestine?
sutures or staples
what must be closed to prevent SI herniation once surgery is over?
defect in mysentery that comes from the SI resection
what must be checked about the SI and mysentery anastomosis?
patent lumen and integrity (no holes or leaks)
once anastomosis has been performed and checked what should be done with the small intestine?
lavage and remove packing
decompress remaining bowel
replace in abdomen
do simple or functional SI obstructions often require surgery?
no - can usually be managed medically
how may simple / functional SI obstructions be managed surgically?
decompression of SI
possible enterotomy to remove obstruction
no resection or anastomosis required as non-strangulating so blood supply is not compromised
what is the prognosis for SI simple obstruction?
good once resolved
what are the risks associated with strangulating SI lesions involving resection or anastomosis?
contamination leading to peritonitis
endotoxic shock
ileus
post op adhesions
what is the prognosis of survival to one year of strangulating SI obstruction treated with resection and anastomosis?
~50%
what are the main causes of colic due to the large intestine?
displacement
large colon torsion
enteroliths (uncommon in UK)
what are the common LI displacements?
left dorsal
nephrosplenic ligament
right dorsal
what is the most common reason for LI colic?
displacement
what happens during colonic displacement?
colon becomes distended with gas or fluid due to continued fermentation in the presence of obstruction
becomes displaced from normal anatomical position
what is involved in the surgical management of colonic displacement?
recognise nature of displacement
decompression of distended bowel with needle
correction of displacement
what may be necessary if colonic distention is due to fluid or food?
evacuation of the colon via a pelvic flexure enterotomy
are colonic resections often performed?
no - technically challenging and rarely necessary
what is colopexy?
anchoring of colon to body wall with sutures
when may colopexy be performed?
non-athletes to prevent recurrence of displacement
what is the most critical problem affecting the horses large colon?
large colon volvulus
why is large colon volvulus the most critical problem affecting the horses large colon?
is commonly a strangulating obstruction with ischemia of a huge section of the horses GI tract
where may volvulus of the large intestine occur?
sternal flexure or close to the attachment of the right ventral colon to the caecum
what is the result of large colon volvulus?
great deal of gas distention within affected colon
what is the cause of large colon volvulus?
unknown
what animals are usually affected by large colon volvulus?
larger horses
brood mares around 90 days post foaling
what is the onset of colic like in patients with large colon volvulus?
sudden and high degree of pain
describe the colon on rectal exam of patient with large colon volvulus
enlarged and very evident
is abdominal distention seen with large colon volvulus patients?
yes - often marked
why is there often high HR and poor peripheral perfusion in patients with large colon volvulus?
mucosal ischemia leading to endotoxaemia and rapid deterioration of systemic status
what is needed to correct large colon volvulus?
surgery to correct issue with removal of ischemic colon if necessary
what is the prognosis of large colon volvulus linked to?
directly related to the time that elapses between onset of condition and surgery
why are survival rates of large colon volvulus so much higher veterinary facilities near brood mare farms?
due to reduced transport time which means prognosis is much improved
what is involved in the post-op care of abdominal surgery patients?
clinical exam and colic check every 2 hours initially then every 4 analgesia antimicrobials IVFT belly bandage monitor for complications regular blood sampling for PCV, TP and lactate NG tubing as needed
how often do colic cases need a full clinical exam?
every 2 hours initially increasing to every 4 when stable
what are the main post-op complications of colic surgery?
endotoxaemia ileus jugular thrombophlebitis incisional infection further obstruction anastomosis leakage peritonitis adhesions
when is endotoxaemia especially seen?
post strangulating obstructions
what can endotoxaemia lead to?
SIRS
laminitis
when is ileus often seen in post op colic cases?
prolonged SI distention and/or toxaemia
what must be monitored during the post op period?
pain pyrexia GI system CVS incision catheter feet respiratory system
what should be monitored in the post op period with regards to pain?
behavioural signs of colic
heart rate
specific signs (peritoneal, incisional, MSK)
how can pyrexia be monitored in the post op period?
rectal temp
how can the GI system be monitored in the post op period?
reflux through NG tube will show blockage
faecal output
gut sounds
appetite
how can the CVS be monitored in the post op period?
HR
MM
CRT
PCV, TP, lactate and electrolytes
what should you look for when monitoring the incision in a post op colic case?
swelling (some oedema normal, excessive is bad)
pain
discharge
what should you look for when monitoring the IV catheter?
swelling
pain
jugular patancy
what should you look for when monitoring the feet in a post op colic case?
signs of laminitis due to endotoxaemia
movement around box
increased or bounding digital pulses
heat
what should you look for when monitoring the respiratory system in a post op colic case?
auscultation increased RR nasal discharge or cough effects of GA if any aspiration pneumonia
what should be done if there is still significant net reflux on passing a NG tube post op?
nil by mouth
IVFT
muzzle to prevent horse eating bedding
what can the horse be given orally when reflux has ceased and parameters are improving?
small volumes of water that are gradually increased
what depth of water in a bucket should be given if reflux in the horse has stopped and systemic parameters have improved?
5 cm depth
what is the best first solid food for horses following colic surgery?
grass - hand grazing or picked
what may be fed first following colic surgery if grass isn’t available?
small wet mashes of concentrates although less appetising
when is hay introduced to the colic patient post op?
once mash or grass has been well tolerated small handfuls can be introduced and then gradually increased
over how may days should it takes horses to return to normal volumes of food or hay once eating after colic surgery?
3 days
what exercise should be allowed following colic surgery?
box rest for 6 weeks with very short walks in hand to allow grazing and promote gut motility (if temperament allows)
what criteria must be met before a horse can be turned out into a small paddock?
check there are no incisional problems (e.g. breakdown of underlying abdominal wall closure) that may require more prolonged restriction of exercise
how many weeks post op can horses be turned out into a small paddock?
6 weeks
when can ridden exercise resume following colic surgery?
at 3 months if abdominal repair is sound
what are the potential complications of colic surgery that are seen immediately?
endotoxaemia
ileus
when is endotoxaemia most often seen?
post strangulating obstructions
what are the signs of endotoxaemia?
tachycardia tachypnoea pyrexia and then hypothermia hyperaemic MM that become purple and then brown colic signs dullness
how is endotoxaemia treated?
IVFT
Flunixin, Polymixin B and Hyperimmune plasma (anti-endotoxic drugs)
when is ileus most often seen as a complication?
prolonged SI distention and/or endotoxaemia
how is ileus treated?
NG intubation to decompress stomach
IVFT
electrolytes if needed
prokinetics
what fluids are needed in a patient with ileus?
maintenance (2ml/kg/hr)
correction of any dehydration
any losses
what volume of reflux losses should be replaced through IVFT in the horse?
80% of volume refluxed
how often should patients hydration status be assessed post op?
2-4 hourly
what prokinetics may be used in a horse with pot-op ileus?
lidocaine infusion
Erythromycin and Metaclopramide (off licence)
what are the potential short term complications of colic surgery in horses?
laminitis jugular thrombophlebitis peritonitis colitis incisional infection
what is laminitis often secondary to post colic?
endotoxaemia
how may laminitis be prevented in at risk horses?
ice boots
what are the main signs of laminitis?
bounding (increased) digital pulses
heat
foot pain
how is laminitis treated?
frog support
deep bedding
analgesia
how is jugular thrombophlebitis treated?
remove catheter
local anti-inflammatory drugs
thrombolytic such as asprin
antibiotics if infection suspected or known
if a horse develops jugular thrombophlebitis where should the new IV catheter be placed?
not into other jugular - other site if venous access still needed
why should a new IV catheter not be placed in the other jugular vein if there is jugular thrombophlebitis?
to prevent bilateral blockage / damamge
what are the main signs of peritonitis in horses?
colic
inappetance
pyrexia
how is peritonitis treated in horses?
broad spectrum antibiotics
abdominal drainage and / or lavage in some cases
what are the signs of colitis?
pyrexia
colic
diarrhoea
when is colitis often seen post op?
after colon torsion / displacement where colon wall has been compromised
from antibiotic and NSAID use
sudden change in management
how is colitis treated?
intensive nursing
IVFT
analgesia (avoid NSAIDs)
probiotics
what drugs may help with colitis?
Misoprostal (prostaglandin analogue) and sucralfate
probiotics
in how many laparotomy cases does incisional infection occur?
10-15% of cases
when is incisional infection more common?
after second laparotomy
what are the signs of incisional infection?
oedema around incision (large, some local is normal)
pain
drainage of purulent material
how should incisional infection be treated?
antibiotics if horse systemically affected (e.g. pyrexia) - culture and sensitivity
encourage drainage
how long will incisional infection persist for if present?
until suture material resorbs (~6 weeks)
what are the the potential long term complications of colic surgery?
adhesions
what are adhesions?
fibrin forming on intestinal surface with adheres to other areas of intestine
what are adhesions a consequence of?
surgery and general handling of intestines
what can adhesions result in?
further obstruction and colic
what does recurrent significant colic due to adhesions often result in?
euthanasia as owners are reluctant for horse to have surgery when the prognosis would be guarded at best
