3. large animal med- equine colic workup

what is colic? how common is it?

colic=vague term for abdominal pain

incidence of 10% of horses per year (75% cases are mild/only require 1 dose of pain meds)

what are signs of colic/abdominal pain in horses?

-lying down for long periods

-decreased appetite

-restlessness

-quivering upper lip

-looking at sides

-repeated stretching

-kicking at belly

-crouching/trying to lay down

-sweating

-rolling

what history questions should be asked when working up a colicking hrose?

-clinical signs/level of pain/duration

-meds given and response

-recent management/diet changes

-last defecation

-drinking/appetite

-presence of abdominal distention

-previous colic episodes/colic sx

-breeding/pregnancy

-deworming

-current diet

what is included in the physical exam of a horse with colic?

-distance exam (posture, attitude, appetite)

-grade pain level

-BCS and weight

-basic general exam (TPR, digital pulses)

-perfusion/hydration status

-GI auscultation/percussion

what diagnostics are done for horses presenting with colic?

-nasogastric intubation

-rectal exam

-belly tap

-abdominal U/S and rads

-CBC/chem

-fecal float (parasites) and sedimentation (sand)

-oral exam

-gastroscopy

how much reflux is normal in horses?

<2L of net fluid in a full sized horse

how is net refluxed calculated when performing nasogastric intubation in horses?

reflux= total volume of fluid obtained - volume of fluid instilled

if you are giving oral fluids through the NG tube, what is the max amount you can give for a full sized horse?

give no more than 8-10L

what are complications of nasogastric intubation?

-epistaxis (if tube hits ethmoids)

-pharyngeal/esophageal trauma (esp if tube left in for several days)

-aspiration (accidental NT intubation)

what restraint is necessary when performing a rectal exam in horses?

physical restraint +/- chemical (sedation) restraint

how is rectal relaxation achieved for rectal exams?

buscopan IV (smooth muscle relaxant), local lidocaine

how are rectal exams performed to prevent complications?

-use lots of lube

-evacuate rectum of feces

-never force arm against peristalsis

what structures are normally palpated via rectal examination in horses?

-aorta and iliac arteries

-caudal pole of left kidney

-nephrosplenic ligament

-caudal border of spleen

-pelvic flexure

-small colon with fecal balls

-bladder

-female repro organs

-cecum (medial cecal band)

what are the limitations of rectal exams in horses?

-only caudal 1/4-1/3 of abdomen can be palpated in a full size horse

-unable to perform in small patients

what is the main complication of rectal exams?

rectal tears

-always inspect rectal sleeve after rectal exam

-inform owner of concern

-bare arm exam to determine location/depth

-refer

what are indications of performing an abdominocentesis?

-persistent colic (differentiate from surgical vs non-surgical)

-to diagnose peritonitis

-to diagnose GI rupture (recommend euthanasia)

-if neoplasia is a differential

what are clinical signs of peritonitis?

fever

mild/chronic colic

diarrhea

what should normal peritoneal fluid look like?

-clear to straw colored

-watery (equine fluid should not clot)

-cytology: neuts and mononuclear cells predominate in horses

what is the normal WBC/TP/lactate/glucose of normal peritoneal fluid in horses?

WBC: <5000 cells/uL

TP: <2.5g/dL

lactate and gluose similar to blood values

what is the color of abdominal fluid in horses with a strangulating lesion? what is the lactate, glucose, total protein? WBC/diff/morphology? 

1. color: serosanguinous

2. lactate: 2x that of blood

3. TP: 2.5-6g/dL

4. glucose: similar to serum

5. neutrophils predominate/may be degenerate, >5,000-50,000 WBC,

what is the color of abdominal fluid in horses with septic peritonitis? what is the lactate, glucose and total protein? WBC/diff/morphology? 

1. color: cloudy

2. lactate: elevated (bc bacteria produce lactate)

3. TP: elevated

4. glucose: lower, differences >50mg/dL (bc bacteria are consuming glucose)

5. neutrophils predominate/may be degenerate, elevated-100,000 WBC, intracellular bacteria

what is seen in septic abdomens with markedly septic inflammation?

cell destruction

what is the color of abdominal fluid in horses with a GI rupture? what is the lactate, glucose and total protein? WBC/diff/morphology? 

1. color: green to brown

2. lactate: elevated

3. TP: elevated

4. glucose: lower than serum, difference >50 mg/dL

5. neutrophils predominate/degenerate/intracellular bacteria, elevated WBCs

how is enterocentesis (accidental gut puncture) differentiated from GI rupture with peritoneal fluid analysis?

with enterocentesis, will see:

-plant matter

-mixed extracellular bacteria and protozoa

-variable TP

-low nucleated cell count/white blood cell count (<1000); can increase tho in subsequent taps by 4 hours

are complications caused by abdominocentesis common?

no (0.47%)

what are possible complications of abdominocentesis?

-skin hemorrhage

-splenic penetration (P is fine, but complicates analysis)

-enterocentesis (puncture colon)

-cellulitis and SQ abscessation (animals with septic peritonitis)

-failure to succeed (cant get fluid/unsuccessful tap)

what are indications for abdominal ultrasound for colic workups?

-signs of colic for which diagnosis could not be made

-helpful in deciding if surgical intervention should be performed

-chronic and intermittent colic

-unexplained weight loss, decreased appetite and diarrhea

what are limitations of abdominal ultrasound for colic workups?

-blocked by gas (esp if colon is full of gas)

-maximum depth is 25-35cm with a 3.5mHz curvilinear probe

what lab work is performed for horses presenting with colic?

1.CBC

2. chemistry (kidney and liver dz, lyte abnormalities, decreased albumin [colitis])

3. blood gas (evidence of dehydration, lytes, lactate level)

what causes of colic can a CBC help diagnose?

1. helps with evidence of infection (peritonitis, abdominal abscess); neutrophilia

2. acute inflammation/endotoxemia (colitis, colon torsion); neutropenia

what parasites causing colic can be identified in fecal flotations?

-roundworms (ascarids- cause obstruction when dead)

-tapeworms

-small strongyles (encyst in colon)

-large strongyles

what can crude fecal sedimentation be helpful for?

to see if passing sand in stool — does not necessarily mean sand is a cause of colic

what are indications for performing gastroscopy for horses with colic?

-chronic, low grade colic

-suspicion of gastric ulcer or neoplasia

-to perform duodenal biopsy (concern for IBD)

how should horses be prepared for gastroscopy?

fast for 12-16 hours, remove water 1 hour prior

what are indications of taking abdominal radiographs?

-suspicion of enteroliths or sand

-chronic colic

-areas that enteroliths are common

what are GI causes of non-obstructive (distention/inflammation) colic?

-spasmodic/gas colic

-proximal enteritis

-IBD

-colitis

-sand

-peritonitis

-gastric ulcers

what are GI causes of simple obstructive colic?

-stomach impaction

-small intestinal impaction (ileum)

-ascarid impaction

-eosinophilic enteritis (mural bands)

-large colon impaction

-large colon displacement (right or left dorsal)

-enteroliths

-cecal impaction

-small colon impaction

what are GI causes of strangulating obstructive colic?

-strangulating lipoma of SI or small colon

-SI volvulus

-mesenteric rent

-epiploic foramen entrapment

-gastrosplenic entrapment

-intussusception

-large colon torsion

what are non-GI causes of colic?

1. neurologic: vestibular dz, rabies

2. cardiac dz leading to collapse

3. muscular dz causing tie-up

4. hepatic disease

5. pleuropneumonia

what are causes of chronic/intermittent colic?

-gastric ulcers (mild signs in adult horse)

-enteroliths

-sand colic

-IBD

-abdominal mass

-peritonitis

-intestinal adhesions

-parasitism

what are indications for colic surgery?

1. diagnosis of strangulation

2. intestinal obstruction that fails to respond to medical therapy

3. high level of pain/persistent pain (even when strangulating lesion is not obvious)

how are strangulating lesions diagnosed?

1. ultrasound findings: 2 populations of small intestine, small intestinal dilation, thickening of intestinal wall

2. abdominal fluid (serosanguinous, elevated abdominal lactate compared to peripheral)

3. rectal exam: small intestinal distention

4. suspicion of large colon volvulus

what are indications for referral?

-suspected surgical lesion on patient w/ surgical option

-need for intensive medical therapy (colitis, reflux, severe dehydration, recurrent pain)

-client expectations