Equine 3 - colic Flashcards
what are the clinical signs of colic?
- flank watching (early sign)
- rolling
- kicking abdomen
- hunched posture
- pawing
- recumbent
- sweating
- increased resp rate
- restlessness
what extra-abdominal conditions can manifest in a similar way to colic
- fractured leg
- sweet itch
- pyelonephritis
- urinary tract disease
- choleliths
- laminitis
- pneumonia
- any pleural pain
- cardiac dysrhythmias
what diseases can lead to visceral and parietal pain
- strangulating lesions
- distension of regions of GIT (food, gas, impaction)
- traction on the mesentery
- intestinal ischaemia
- abnormal intestinal motility (grass sickness)
- mucosal inflammation particularly serosa
list the types of colic in descending order of prevalence
- spasmodic/undiagnosed
- surgical
- Flatulent
- pelvic flexure impactions
- other impaction
- colitis (uncommon)
what percentage of colic cases can be managed medically in the field
80-85%
what percentage of colic cases require surgery
7-8%
what are the causes of medical colic
- EGS
- spasmodic/flatulent
- colitis
- parasitic (cyathostomes)
- large colon and ileal impactions
what causes of colic may be managed medically or surgically
left and right colonic displacements
what causes of colic must be managed surgically
large colonic volvulus SI strangulation (many subgroups)
what does a major body system assessment involve in a colic case
- GIT - bororygmi listened for in four quadrants
- CVS - hypovolaemia and dehydration
what may very loud or the absence of borborygnmi indicate
loud: spasmodic/flatulent colic or diarrhoea, unlikely to be surgical
absence: poorer prognosis.
what parameters are used for assessing hypovolaemia
HR - increased CRT - prolonged mm colour - pale pulse quality - weak lactate - high USG - high (+RR and temp)
what parameters are useful for assessing dehydration
mm - tacky
eyes - sunken
skin - tents
what are the relevant questions when taking a colic history
- age
- duraton of colic (when last seen normal)
- recent management changes
- worming
- previous colic history
- stereotypies
What restraint may be used for rectal palpation
- stocks (often unavailable)
- sedation with A2A
- nose/neck/ear twitch
- position against wall
- lift front leg
- around stable door
- IV buscopan or diluted lidocaine per rectum to reduce risk of tearing
describe safe entry for rectal palpation
- gloves
- lubricant
- fingers in cone shape
- stay ventral when entering rectum
- extend arm (short sleeves)
what are the normal findings in rectal palpation
Aorta dorsal midline
caecum on the right
left kidney and caudal edge of the spleen on the left with nephrosplenic ligament
pelvic flexture runs left to right at the pelvic inlet ventrally
small colon in faecal balls present
bladder - may be large if colicing and don’t want to urinate
repro tract in mares
should not feel the SI
what may a strangulating SI lesion feel like on palpation
Distended SI 4-6cm diameter often RHS but may be anywhere
if gas distended the taenial bands will roll over. can follow its course.
what does a LI displacement feel like on palpation
tight taenial bands
pelvic flexure in wrong position
left dorsal displacement - piece of large colon through nephrosplenic ligament dorsal to ventral
right dorsal displacement - right bands and no pelvic flexure
what does a pelvic flexure impaction feel like on palaption
primary - doughy, smooth surface, large
secondary - firm balls of ingesta
where is the most common site for rectal tears due to palpation
near the pelvic inlet involving the peritoneal rectum. dorsal and longitudinal.
how are rectal tears detected
always check glove for blood
what is the immediate treatment for any rectal tear
A2A sedation butylcsopolamine lidocaine per rectum epidural anaesthesia \+/- ketamine
how is rectal tear severity assessed
bare-armed rectal
palpate circumferentially from anus cranially
remove faeces
determine size, grade, position
discuss with owner - don’t accept liability
ask senior vet for help
describe a grade 1 rectal tear
Mucosa +/- submucosa involvement. heals without treatment. can give antibiotics, faecal softeners and diet modification for 5-7 days
describe a grade 2 rectal tear
Muscle layer involvement, mucosa and submucosa intact. very unusual, rarely causes a problem
describe a grade 3 rectal tear
Two types
a. only the serosal layer remains intact
b. only the fat filled mesorectum or the retroperitoneal tissues remain intact
bacteria leak through causing peritonitis relatively quickly.
describe a grade 4 rectal tear
disrupts all layers of the rectal wall. may be grade 4 from the outset or progress from grade 3. gross faecal contamination of the peritoneal cavity and rapid overwhelming SIRS and septic shock.
what are the first aid measures for grade 3 or 4 rectal tears
pack rectum with cotton wool retained in a stockinet bandage from anus to cranial to the tear or use gamgee
suture anus closed (purse-string) to retain packing
broad spectrum bactericidal antibiotic e.g. gentamycin.
NSAIDs
refer to surgical facility
PTS if cannot refer (speak to boss beforehand)
describe the method of NG intubation
tube into ventral meatus
flex horse’s neck
tube into oesophagus - check by watching left side of neck, negative pressure if suck on tube, horse swallows with passing, release of gas once in cardia
what is the normal volume of fluid recovered from NG intubation
1-2L. normal volume of stomach is 6-8L so some leeway e.g. if just had a large drink
what is the cut-off volume of fluid recovered for the lesion to be considered surgery
> 5L
what is the normal colour and total solids of fluid from a peritoneal tap
straw coloured
TS <20g/l
why might there be red cells in peritoneal fluid
iatrogenic - starts straw coloured then turns red
serosanguinous fluid due to red cell diapedesis usually secondary to ischaemic bowel. expect a lot of fluid
what causes increased cellularity of peritoneal fluid
septic peritonitis
what causes peritoneal fluid to be green/brown coloured?
GI rupture
check in case of incorrect needle placement (into the intestine)
what may be seen on peritoneal cytology
neutrophils - inflammation
ruptured viscous - inflammatory cells with intracellular bacteria (45-60mins after rupture). ingeseta present but this will not differentiate from GIT tap.
what lab parameters can be used to assess hydration
PCV
TP
Lactate
blood gas
how is lactate interpreted
produced in cells due to anaerobic respiration therefore sensitive marker of hypovolaemia. normal <2
how may PCV and TP change
hypovolaemia - increase (haemoconcentration)
haemorrhage/bleed/PLE - decrease
stress/exercise - increase due to splenic contraction
shire - 25% normal
TB - 40-45% normal
if disease causes reduction then animals becomes hypovolaemic then may look normal. check lactate.
What are possible tests used in a colic investigation
- palpation per rectum
- NG intubation
- peritoneal tap
- basic bloodwork. often send some if referring a horse so ready to run once there
what factors are used to assess clinical state/degree of pain
degree of tachycardia (higher = more hypovolaemic)
any faeces passed (none/mucoid = reduced transit)
mentation (obtunded = reduced blood to the brain)
pain - difficult to assess
response to analgesia
what parameters are used to assess CVS status
HR (28-44)
pulse quality
CRT
mm colour
- red = congestion. hyperdynamic phase of hypovolaemic shock)
- white = decompensated hypovolaemic shock. deaeth inevitable
how is borborygmi graded
0 - no sound. strangulation or torsion
1 - reduced. requires knowledge of animal
2 - normal. depends on diet. louder on grass than hay
3 - hear without stethoscope. spasmodic colic or diarrhoea
grade each quadrant
what additional procedures may be used in a colic investigation
abdominal ultrasonography - rectal - little use - transabdominal useful for LDD and EFE (other SI lesions). generally in clinic. radiography - sand impaction in foals endoscopy
what parameters may indicate that a case of colic can be managed medically
mild pain responsive to analgesia HR < 60 CRT <3 mm normal colour borborygmi present normal peritoneal fluid lactate <2 PCV/TP normal for breed <3-5L recovered from NG intubation mildly abnormal rectal findings dependent on disease
what parameters may indicate that a colic case needs surgical management
severe pain, less likely to respond to analgesia (breed dependent) HR >60 CRT 3-4s mm dark red, congested absent borborygmi peritoneal fluid serosanguious with protein >30g/l lactate >2 PCV/TP outside reference range >5L recovered from NG intubation rectal findings obviously abnormal
which conditions managed medically don’t fit the normal presentatio n
grass sickness - HR>60 anterior enteritis - severely hypovolaemic and large volume of NG reflux (common outside UK) colitis - severely hypovolaemic peritonitis - high HR, hypovolaemic spasmodic colics - can be very painful
when may a surgical condition not present in the expected way?
epifloic foramen entrapment - SI trapped cranially on RHS (normal rectal findings)
ponies and donkeys - very stoic, may not show pain
what are the indications for referral of a colic case?
- surgery needed
- medical case not manageable in field (IVFT, intensive care)
- chronic EGS
- any client that requests it
what makes up the initial medical management of colic
analgesia - NSAIDs - opioids - ketamine anti-spasmodics A2As (fast action IV, longer IM, unlicensed for colic) fluid therapy exercise
which NSAIDs may be used in colic
any
- phenylbutazone
- flunixin meglumine - some concern about masking surgical cases. lower dose, won’t mask hypovolaemia
- carprofen/meloxicam
which opioids are indicated in colic
buprenorphine - licensed
methadone - SA licence. bolus or infusion
morphine - may use over morphine as better PK/PD for CRIs
NOT butorphanol - poor analgesia
for which colic types are anti-spasmodics particularly useful
spasmodic colic
pelvic flexure impaction - relax colon to help ingesta pass
list some anti-spasmodics
butylscopolamine and metamizole - short acting ~20mins
pethidine - licensed for spasmodic colic but currently unavailable. lasts ~1hr
buprenorphine
(methadone)
what effects with A2As have
- analgesia
- reduced HR unless hypovolaemic
- increased urination
- sedation
- reduced gut motility - may help spasmodic colic
- warn owner regarding cardiovascular collapse due to vasodilation (very rare)
what are the indications for fluid therapy
hypovolaemia - IVFT
pelvic flexure impaction - PO
what are the contraindications for oral fluids
obstruction - torsion, strangulation, ileal impaction
hypovolaemia (won’t be absorbed)
what are the maintenance fluid requirements in adults and foals
adults - 2ml/kg/hr
foals - 5ml/kg/hr
when is exercise indicated in colic
minimal pain e.g. mild, large colonic tympany palpable on rectal
spasmodic colic - if mild pain
LDD and RDD if not too painful/taenial bands not too tight
note: don’t exercise/walk before assessment
what may cause ileus
hypovolaemia lack of feeding excessive handling of gut/trauma during surgery (damage to nerves) long surgery time stress/pain (hypothermia in small animals)
how is ileus diagnosed
no faecal output
absent borborygmi/present with no forward movement
ultrasound
lots of NG reflux
how is ileus managed
generally in clinic rather than field
secondary to peritonitis - reduce inflammation (no pro-motility agent will be of use until neutrophils and toxins reduced)
post op ileus - analgesia, anti-inflammatories, promotility agents
list some pro-motility agents
analgesia (lack of pain promotes motlity even if drug inherently reduces it e.g. opioids)
lidocaine IV - anti-ileus, analgesic and anti-SIRS
metaclopramide IV
erythromycin IM
list some risk factors for colic
change in diet change in housing e.g. box rest poor condition of teeth anti-parasiticides/high worm burden seasonality stable vices/stereotypies previous colic/colic surgery stress age
what is the likelihood of survival from colic
SI strangulating leisons (surgery) - 60-80%
large intestinal displacements - 70-85% (overall), 90% (surgical)
LI torsions - 25-50%. varied due to timing of how soon lesion is corrected. lots of ischaemic bowel –> SIRS
what are the most important predictors of prognosis following colic surgery
SIRS markers
- ischaemic bowel
- serosanguinous fluid
What does palpable small intestine distension indicate the need for
colic surgery
list the three broad categories that SI obstructions can be classed as
- physical - most common
- neurological e.g. EGS
- vascular e.g. infarction due to cyathostome larvae
what is a simple obstruction
partial or complete but no interference of blood supply
what is a strangulating obstruction
obstruction of blood supply to the intestine from the outset
what may cause a simple SI obstruction
adhesions
neoplasia
abscesses
what is the consequence of complete obstruction of the SI in terms of fluid
sequestration of fluid oral to the obstruction in the intestine and eventually the stomach. leads to a reduced circulating volume, increased HR and PCV, end result is hypovolaemic shock
what volume of secretions pass through the SI per day and where is most absorbed?
> 100L, absorbed mostly in the Large intestine
what are the consequences of progressive intraluminal pressure in the SI
hydrostatic pressure in the vasculature leads to loss of protein through the gut wall into the abdomen
impaired blood supply leading to ischaemia
what are the clinical signs of a strangulating SI obstruction
- severe pain
- progressive increase in HR
- progressive deterioration in pulse quality
- congested mm
- increased CRT
- progressive increase in PCV and total protein through haemoconcentration with subsequent hypoproteinaemia
- increased RR
- marked changes in peritoneal fluid
whether a strangulating lesion is venous or arterial depends on what?
degree of compression of the blood supply
describe the pathology that occurs with venous strangulating obstruction
- arterial supply unaffected initial so blood still enters
- blood cannot flow out
- rapid mural congestion
- intestine becomes dark red and oedematous
- red blood cells present in all layers diapedese into peritoneal cavity causing serosanguinous peritoneal fluid
- increased mural thickness and luminal distension increases pressure against constricting structure
- pressure eventually exceeds arterial pressure
- no further blood enters the strangulated segment
- mucosa starts to become necrotic within 1 hour (apices of villi initially then crypts by 4 hours)
what proportion of blood supply does the mucosa receive
80%
describe the pathology of arterial strangulating lesion
- pressure on intestinal vessels obstructs veins and arteries from the outset
- cell dead occurs rapidly
- ischaemic changes result in the wall becoming paper thin and easily ruptured
- rapid onset of clinical signs
- shock develops due to necrosis
what aids bacterial multiplication in SI strangulating lesions
mucosal damage –> bleeding into the lumen
what does endotoxins breaching damaged mucosa lead to
SIRS
what does the severity of shock in strangulating SI lesions depend on
- length and diameter of intestine involved (larger area = more endotoxins)
- degree of vascular occlusion
- length of time the obstruction has been in existence
what are the clinical findings in SI obstructions
hypovolaemia and endotoxaemia - tachycardia - congested mm - delayed CRT - increased PCV (>45%) and TP distended loops of SI on rectal and US exam NG reflux (depending on level of obstruction) serosanguinous peritoneal tap
how is the cause of an SI obstruction discovered
laparotomy
what is the average cost of colic surgery
£5000
what are the steps involved in stabilising a patient for colic surgery
- NG decompression
- IV fluids
- NSAIDs
- antibiotics
what surgical technique is used for colic
exploratory midline laparotomy
- correct strangulation
- ingesta removed/milked into caecum
- evaluate intestinal viability
- anastomosis of healthy sections
how much of a horse’s SI can be removed before nutrient absorption is compromised
50% (~9m in typical horse)
describe the post-op care after colic surgery
- maintain hydration status
- gradual re-introduction of water and food
- 5 days NSAIDs and antibiotics
- monitor for complications
- off work for minimum 3-4 months
list some complications following colic surgery
colic recurrence wound suppuration jugular thrombosis ileus incisional hernia formation re-laparotomy diarrhoea laminitis salmonellosis
what is the main cause of colic recurrence following surgery
adhesion formation. most cases within 1 year of surgery
what are the signs and treatment of wound infections after surgery
massive oedema
breakdown of skin margins (linea alba usually holds)
clean regularly, remove crusts and skin sutures
usually resolves in 7-10 days
what are the risk factors for an incisional hernia post-op
wound suppuration post-op higher HR (more severe SIRS) at admission
how are incisional hernias managed
small - conservative
large - mesh repair
how is jugular thrombosis managed
remove catheter
hot pack
+/- DMSO
what are the risk factors for jugular thrombosis
sicker horse
- PCV on admission
- heart rate >60
what is the prevalence, average time to onset and prognosis of post-op ileus
10%
24 hours post-op
50% with post-op reflux survive
what are the risk factors of post-op ileus
PCV
pedunculated lipoma strangulation
what are the common causes of a re-laparotomy
epiploic foramen entrapment
post-op ileus (unless straightforward)
what is the best way to prevent complications
early referral before SIRS causes deranged cardiovascular parameters
what are the most common indications for SI colic surgery
ileal impaction idiopathic focal eosinophilic enteritis epiploic foramen entrapment pedunculated lipoma (grass sickness - exploration)
what may cause an ileal impaction
- physical obstruction of ingesta (milk through to caecum)
- anoplocephala burden
what are the signs of idiopathic focal eosinophilic enteritis
very elevated PCV severe pain reflux difficult to distinguish from SI strangulation - huge numbers of eosinophils
how is idiopathic focal eosinophilic enteritis treated during surgery
milk ingesta through to caecum
administer steroids
what makes up the epiploic foramen
caudate lobe of liver
hepatic portal vein
gastropancreatic fold
epiploic = greater omentum
how does epiploic foramen entrapment occur
small portion of SI may fit through a gap, peristaltic movement draws more in, SI becomes compromised, distended and pressure increases
what are the risk factors for epiploic foramen entrapment
taller horses - not seen in miniatures/donkeys
crib-biting/windsucking
what is a pedunculated lipoma
benign fatty lump which occurs in the mesenteric window. gravity draws the lump out on a stalk. eventually becomes heavy enough to wrap around the SI and strangulate it
in which horses are pedunculated lipomas most common
geldings > mares
ponies > horses
what lesions can cause strangulation
pedunculated lipoma hernia (internal or external) intussusception volvulus merckel's diverticulum (rare)
why may grass sickness cases be taken to surgery
- chronic forms often present clinical signs similar to strangulated SI
- no obstruction at surgery then take a biopsy and euthanase horse
- not a surgical disease in itself
