Equine 4 - colic Flashcards
where is the large colon attached to the body
- caecum
- right dorsal colon
(right ventral colon attached to right dorsal and caecum)
list the order of sections of the large intestine following from the caecum
cauceum RVC sternal flexure LVC pelvic flexure LDC diaphragmatic flexure RDC transverse colon descending colon
which sites are predisposed for impaction
the 180 degree bends - especially the pelvic flexure
what does SCOD stand for
simple colonic obstruction and distension - all forms of large colon disease except those causing vascular obstruction
what are the risk factors of SOCD
windsucking/crib-biting stabling 24 hours a day history of travel in past 24 hours recent change in exercise program absence of use of moxidectin/ivermectin in previous 12months increasing hours in stable history of colic less regular dental care
describe a primary pelvic flexure impaction
flexure pushes back into pelvic inlet
build up of ingesta causing it to feel doughy
describe a secondary pelvic flexure impaction
occurs secondary to sequestration of fluid in the small intestine so none makes it to the colon. will feel very hard due to lack of fluid
what may be the primary causes of secondary PF impaction
ileal impaction
anterior enteritis
equine grass sickness
other strangulating lesions if chronic
how is primary PF impaction treated
NG intubation of fluids - 6L every 30-60mins (no proof that paraffin is better)
alternative - provide analgesia and wait for passage
can remove ingesta surgically if too painful
what is a key disadvantage to using paraffin in NG intubation
if administered down the trachea accidentally it will kill the horse as it prevents gas exchange
how is a left dorsal displacement (nephrosplenic entrapment) felt on rectal exam
can’t feel left kidney or spleen or feel displaced spleen
how is a simple left colon displacement felt on a rectal exam (retroflexion of pelvic flexure)
cannot feel flexure
how is right dorsal displacement felt on a rectal exam (colon moves between caecum and body wall)
feel horizontal taenial bands of colon on right side rather than vertical band of caecum
what are the clinical signs of colon displacement
- abdominal distension (especially on left for LDD)
- reduced gut sounds
- varying degrees of pain (LDD > RDD)
- usually cardiovascularly stable - HR normal/slightly high, PCV and lactate normal
how are colon displacements treated and what is the prognosis
medical initially as gut is still functioning surgery if pain becomes unmanageable prognosis good (but some predisposed to recur)
what is a large colon volvulus
entire colon twists around the long axis involving both dorsal and ventral colons usually site of right dorsal and ventral colon. signs depend on degree of rotation
describe an 180 degree large colon volvulus
mild pain
often present like a displacement
not ischaemic or vascularly compromised so manage medically and hope it untwists
describe a 270 degree volvulus
usually complete rotation but no vascular compromise
what are the clinical signs of a volvulus over 270 degrees
severe, uncontrollable pain
vascular compromise - tachycardia, dehydration, congested mm
abdominal distension
rectal - distended, tympanitic, oedematous LI, abnormal position, tight taenial bands
describe a volvulus over 360 degrees
complete obstruction and vascular compromise
why do horses with 360 degree volvulus lose a significant proportion of circulating blood volume and cardiovascular compromise
venous occlusion but blood still pumped in until it reaches a point of arterial occlusion which traps the blood. Enters submucosal space then get fluid sequestration and protein loss . pressure on the diaphragm also worsens CV compromise
what causes SIRS in colon volvulus
dying gut allows bacterial toxins to pass through the gut wall.
how are colonic torsions treated
midline laparotomy incision
exteriorise (30-40kg - may perform enterotomy at pelvic flexure to reduce weight from ingesta but blood remains)
untwist
euthanase if bowel is non-viable
colon resection rarely performed in UK - difficult due to congestion and mural oedema
how are horses managed post-op after correction of a colonic volvulus
same as for SI surgery
care over hydration and serum protein
may require plasma transfusion
list particular complications after colonic volvulus correction
SIRS
diarrhoea/colitis
laminitis due to septic shock
hypoproteinaemia
what is the prognosis for colonic volvulus correction
360 - poor. directly related to CV status before surgery , higher risk of post-op colic
how are caecal diseases diagnosed
rectal examination
describe caecal impactions
often seen in orthopaedic patients following box rest
failure of treatment may lead to rupture
often not diagnosed until late in disease - only mild pain early on
describe caecal intussusception
usually younger horses
high association with tapeworm burden
feel some change if not the intussusception itself
name types of caecal disease
impactions
intussusceptions
local infarction
involvement in large colon torsions (apex in twist)
what is the prognosis for caecal diseases
poor unless there is no ischaemia or only focal ischaemia of the caecal apex
list some diseases of the small colon
- strangulated by lipomas
- impaction (may be presumptive in ponies too small to rectal)
- intussusception
what is the prognosis for small colon surgery
excellent compared to other LI lesions
what anatomical landmarks would you expect to feel in a normal horse rectal
clockface 12 - aorta 11 - left kidney, nephrosplenic ligament, caudal border of spleen 7 - pelvic flexure 6 - uterus if female 3-5 - caecum NOT small intestine
what pharmacological agents may make a rectal exam safer
IV buscopan
lidocaine per rectum
ketamine per rectum
sedation - A2A
what are the landmarks for abdominocentesis in a horse
most dependent part of the abdomen
midline
5cm caudal to xiphoid
US to detect fluid pockets
what are the immediate treatment options for nephrosplenic entrapment
phenylephrine then lunging - causes spleen to contract to help dislodge the colon. lunging aids dislodging
rolling - drop onto right side, rolled into sternal then onto left
what are the surgical treatment options for nephrosplenic entrapment
nephrosplenic space ablation
large colon colopexy
large colon resection
