Colic

Both pale and cyanotic membranes indicate need to intravenous resuscitative fluids, as is a prolonged CRT and tacky membranes.

Non-stragulating lesions

Spasmodic colic

Impaction

Displacement

Brief episode of pain of unknown origin that resolves with no/minimal treatment

Feed material in large intestine (ileum possible). Resolves in most cases with isotonic enteral fluid therapy. IV fluid therapy is rarely needed unless there is cardiovascular compromise. Worst cases require surgery.

Enteritis/ileus

infection/inflammation of small intestine causes hypomotility or amotality

Large amounts of nasogastric reflux

intensive medical treatment required

Typhlocolitis

infection/inflammation of large intestine

variable amounts of diarrhoea

intensive medical treatment required

Peritonitis

Infection/inflammation of peritoneum

Fever, depression, mild-moderate colic

intensive medical treatment or surgery

Strangulating lesions

SMALL INTESTINE

LARGE INTESTINE

REFLUX (may be absent), DISTENDED SMALL INTESTINE

Palpable on rectal exam

Visible using ultrasonography

+/- Abdominal distension, impaction or gas accumulation palpable in large intestine, displacement of large intestine palpable, usually no reflux.

Surgical

Volvulus (around the root of mesentery)

Strangulating lipoma

Epiploic foramen entrapment

Inguinal/scrotal hernia

Intussusceptions

Diaphragmatic hernia

Mesenteric rent

Colon torsion

Intussusception

Ileo-caecal

Caeco-colic

Caeco-caecal

When to refer

Any suspicion of strangulating lesion

Small intestinal lesions are best referred

high chance of surgical lesion

medical diseases need intensive therapy

Conditions requiring intensive medical treatment

enteritis/colitis

Non-resolving impactions

may require IV fluids

May require surgery (impaction and displacement)

Must discuss circumstances, finances, insurance, expectations and willingness to agree to abdominal surgery first.

Signs

Moderate-severe pain

Recurrent pain

Pain poorly responsive to analgesia

Indication of cardiovascular compromise (heart rate, capillary refill time, jugular filling)

Severe abdominal distension

Signs of small intestinal lesion

reflux

Palpable/visible SI on rectal/USS

Signs of strangulating lesion

Abdominocentesis

Cardiovascular compromise

When to go to surgery

Diagnostic and therapeutic: only 20-30% of abdomen can be evaluated with rectal exam and USS

strangulating lesion suspected

Non-resolving displacement

Non-resolving impaction

Non-responsive or recurrent pain

Signs

History: severe/progressive pain or no/transient response to analgesia

Physical examination: cardiovascular compromise, severe abdominal distension

Nasogastric intubation >2L reflux

Rectal palpation: distended small or severely distended large intestine

Additional diagnostics

abnormal abdominocentesis

Haemorrhagic, orange, red

Nucleated cell count >5 -70x10^9

Protein concentration >25g/L

Abnormal transabdominal ultrasonographic exam

Distended small intestine on rectal palpation

increased abdominal fluid

Medical

E.g. enteritis/ileus, grass sickness, spasmodic colic, impaction, left dorsal displacement, right dorsal displacement, colitis, typhlocolitis

History

Low grade, intermittent pain

Physical exam

Low heart rate

Normal borborygmi

No cardiovascular compromise

Fever (enteritis/colitis)

Nasogastric intubation

no reflux (<2L)

Rectal palpation

Normal, impaction, mild gas distension of large intestine

Complications and prognosis

Short term (<2-4 weeks)

Anaesthetic complications

Post-operative colic

Post-operative ileus (reflux)

Incisional complications (infection, breakdown)

Thrombosis

Peritonitis

Laminitis

Long term complications (>2-4 weeks)

Recurrent/chronic colic - adhesions

Incisional hernia

Prognosis

Simple medical colic: good around 90%

Non-strangulating surgical colic: good 70-90%

Strangulating small intestinal lesion: good-guarded

without resection 60-80%

with resection 50-70%

Strangulating large intestinal lesion: guarded to poor

Increased respiratory rate (pain, shock)

Abrasions or other signs of trauma from rolling

Profuse sweating (pain, shock)

Icteric mucous membranes (liver disease)

Potentially little haemorrhagic/black reflux (gastric rupture possible)

Tight gaseous distension of large intestine

Response to treatment

Signs of pain controlled with small dose of sedative or one dose of flunixin meglumine/buscopan

No recurrence of colic signs after initial dose

Horse remains comfortable for >12-24 hr

Response to treatment

Large dose of sedative required to examine horse

Little response to flunixin meglumine

Short lived (<1-3h)

Initial physical exam

Is the patient stable + any evidence of discomfort e.g. high rest rate, self-trauma, nostril flaring , trembling, sweating

Mucous membranes

Injected mucous membranes: red and prominent vasculature

hyper perfusion of the vascular bed as a result of increased cardiac output in the early stages of systemic inflammatory response syndrome (SIRS).

Pale mucous membranes

Vasoconstriction when body attempts to maintain perfusion in response to falling cardiac output.

Cyanotic mucous membranes

vessels vasodilate. Seen with serious hypotension and low cardiac output. Change consistent with the later stages of SIRS

Both pale and cyanotic membranes indicate need to intravenous resuscitative fluids, as is a prolonged CRT and tacky membranes.

Icteric membranes

Horse anorexic or hepatic disease or haemolysis

Skint tent

Affected by interstitial fluid volume and prolonged skin tenting indicates dehydration.

Jugular filling time

As horses age the skin loses elasticity and skin tent may be prolong to some extent with normal hydration, some hereditary dermal diseases can also affect skin tenting

Occluding vein should make it visibly distended in about 2 seconds

If prolonged indicates hypovolaemia and the need for IV fluids.

Carefully evaluate cardiovascular and respiratory status

Auscultate for borborygmus

distinguish ileum from intestinal cramping from hyper motile activity

Permission of abdomen may reveal a 'ping' indicating a gas-fluid interface in a viscus, a finding consistent with colonic gas distension and large intestinal ileus

Treatment

NSAIDs (analgesia)

Requires monitoring as repeated doses can lead to complications with gastrointestinal tract and kidney function

Flunixin meglumine (1.1mg/kg IV or PO)**

Firocoxib(0.09mg/kg IV or PO)

Phenylbutazone(4.4mg/kg IV or PO)

Meloxicam (0.6mg/kg IV or PO)

Ketoprofen (2.2mg/kg IV)

Some sedatives also have analgesic properties

note side effects of sedatives when a horse is being evaluated monographically as both alpha2 receptor agonists and opioid drugs induce temporary ileus.

Do not mistake the absence of borborygmus after sedation with detomidine or butorphanol with a more serious small intestinal obstructive lesions.

Alpha-2s: very effective visceral analgesia

SIDE EFFECTS: Relate to COX-1 inhibition e.g. renal papillary necrosis, right dorsal colitis, pancytopenia, glandular gastric ulcers

side effects

Bradycardia

hypotension

GI ileus

Sweating

Diuresis

Xylazine 1.1mg/kg

Detomidine 10-20mg/kg: more potent sedative and analgesic

Spasmolytics

hyoscine/buscopan

short-acting, smooth muscle relaxant

side effects: increases HR and BP alterations

Opioids

Excellent analgesia and mild sedation

side effects

respiratory depression

non-propulsive GI spasm

CV effects: increased BP, HR, CO

Excitement

Pruritus esp. morphine

Butorphanol

0.01-0.04mg/kg IV or 0.04-0.2mg/kg IM

Morphine

0.2-0.6mg/kg

Acts 1-3 hours

Can use morphine and butorphanol as CRI, beware of long term motility effects.

Fluid therapy

To restore circulating volume and improve CO

Correct electrolyte and acid base disturbance

IV therapy

Large gauge catheter, wide bore delivery

Maintenance = 60ml/kg/day

calculate ongoing losses

record and monitor (USG, CS, PCV, TP, Lactate)

Isotonic polytonic solution (most common) add 10-20m Eq Kcl/L

Hartmanns contains Ca -> binds anticoagulants

Hypertonic saline

rapid expansion of circulating volume

follow with 10L isotonic for every 1L hypertonic saline within 2.5 hours

Enteral fluids

Contraindicated

ileus

intestinal obstruction

severe mucosal inflammation

unable to stand

if a rapid, large volume required for resuscitation

Advantages

GIT mucosa acts as a natural selective barrier

Iatrogenic imbalance less likely

Absorption is increased in hypovolaemia

Haemodynamic effects at 30 mins

Indications

Restore electrolyte balance

prevent dehydration

increase hydration of contents

stimulate intestinal motility (gastrocolic reflex)

usually 4-5L q 2 hrs (stomach can hold up to 10-12L)

Magnesium sulphate for impactions (isotonic)

maintenance= 2.5ml/kg/hr

Complications: aspirations, NGT associated abdominal discomfort, GI rupture, electrolyte imbalance

Pro kinetic drugs

Lignocaine

Increases smooth muscle contractility, analgesia and anti-inflammatory.

beware of muscle fasciculations, ataxia, seizure

Motility stimulants

Metaclopramide

side effects: excitement, aggression

SI ileus (stomach and proximal duodenum)

5-HT and cholinergic

good for foals, not adults

Neostigmine

Ach inhibitor

induces disorganised segmental contractions, good for SI ileus

may cause pain via the spasmodic contractions

N-butylscopolammonium bromide: anticholinergic drug

treats intestinal spasm and facilitate anal sphincter relaxation for rectal palpation

initial treatment for simple impactions and spasmodic colic

Contraindications: ileus, high blood pressure and glaucoma

0.3mg/kg IV slowly

May have a longer duration of effect with less impact on heart rate when given intramuscularly.

Red blood cells leach into the peritoneal fluid from the ischemic intestine

Can indicate ischaemia or inflammation, such as peritonitis or enteritis

Changes in abdominal fluid are more sensitive for a small than a large intestinal lesion and peritoneal fluid can appear grossly normal in a horse with a large colon volvulus.

Blood lactate concentration is important, as in the absence of oxygen pyruvate (produced from glucose by glycolysis and subsequently used in the Krebs cycle to produce adenosine triphosphate) is converted to lactate.

Increase in blood lactate concentration is an early sensitive indicator of anaerobic metabolism and poor peripheral perfusion.

Blood lactate concentration should be less than 0.8mmol/L

Horses with a large colon volvulus and plasma lactate of more than 6mmol/L have a poor prognosis for survival

Higher lactate concentration in peritoneal fluid than in blood suggests the horse has ischemic or inflamed intestine

Impactions of large colon usually occur at the pelvic flexure or in the right dorsal colon

causes include a decrease in water intake and altered function of the pelvic flexure pacemakers

Treatment includes osmotic laxatives e.g. magnesium sulphate and over hydration with intravenous crystalloids to promote intraluminal secretions and rehydrate the impaction.

Oral balanced electrolyte solution is a good treatment for large colon impactions, as it hydrates the contents of the right dorsal colon without causing electrolyte imbalances.

Enteral fluids rehydrate the impaction and cause gastric distension, which elicits the gastrocolic reflex and triggers the contraction of the colon.

Check for gastric reflux before each administration of oral fluids, as the impaction can compress the duodenum and occlude gastric emptying.

Usually 4-6L of lukewarm water + NaCL + KCl

Rectal palpation confirms impaction has passed, feed may be gradually introduced with access to grass being the best initial offering.

Medical if blood supply not impeded

Right dorsal colon displacement

Lose doses of analgesics, including flunixin meglumine and xylazine.

IV fluids with calcium gluconate (25ml/l)

Lung horse at trot/canter for 10-15 minutes

Enteral fluids to break up the impaction in the right dorsal colon (frequently present with large colon displacement)

Decreasing colonic gas distension reduces the intraluminal pressure within the caecum and the colon, which should improve gastrointestinal motility.

Trocarisation can remove substantial volumes of gas (use lidocaine subcutaneous and into oblique muscles of right flank before insertion)

Gas distended large colon and tight mesenteric bands that are palpable on rectal examination, but normal colon wall thickness on USS.

spontaneous resolution/surgery

Nephrosplenic entrapment

Colon moves dorsally in the left abdominal quadrant and hooks over the nephrosplenic ligament.

Rectal palpation finding of colon passing over the nephrosplenic space and confirm with USS. The left kidney cannot be imaged.

Many also have gastric distension because the duodenum is compressed by the large colon, which prevents gastric emptying. Advisable to pass a stomach tube before further medical treatment.

Standard treatment: administration of phenylephrine an alpha1-receptor agonist, to induce splenic contraction (as the colon is entrapped and occludes venous drainage from the spleen).

Causes vasoconstriction, bradycardia and an increase in blood pressure so administer slowly and monitor heart rate and keep it greater than 20 beats/minute.

If considered too risky e.g. horse over 15 years old. Then conservative management consisting of withholding feed, giving enteral +/- IV fluid therapy and providing analgesics without phenylephrine administration reported to be successful in 80% of horses.

If referral is not an option: rolling technique. Xylazine and ketamine and drop to right side.