Digestive System part 2

what is a simple obstruction

the lumen is blocked by a foreign body preventing movement of ingesta

what is the lumen

opening within the intestine through which ingesta travels

Why are simple obstructions worse in the small intestine?

because the small intestine is closer to stomach and since buildup is proximal to obstruction the fluid and gas can cause gastric rupture in stomach

How can endotoxemia occur

when there is damage to mucus cells affecting the mucosal barrier

Why is laminitis associated with endotoxemia

because of the widespread systemic inflammation and vascular damage triggered when bacterial toxins enter the bloodstream

What can Ileus be caused by

intestinal distention causing a increase in smooth muscle tone and pressure in intestinal wall

what does Polymyxin B do?

calms the inflammatory cells

Why can reperfusion injury cause shock

because once blood supply is back, the sequested endotoxins are released and they shower through body which can cause shock

What happens if things arent moving to the cecum because of simple obstruction or anything

there is dehydration and electrolyte imbalance because water is not getting absorbed

where does a simple obstruction typically occur

in the large Intestine

what are the 2 main sequellas from a simple obstruction

gas and SI secretions accumulate proximal to the site of the obstruction and damage from direct pressure on interior of intestinal wall

when does a simple obstruction result in rapid deterioration

when the obstruction is in the small Intestine

when does a simple obstruction result in a slower onset of deterioration

when the obstruction is in the small colon

what does the accumulation of fluids proximal to the obstruction in a small obstruction result in

decreased absorption of this fluid into systemic circulation and eventual hypovolemia

In a simple obstruction, what is the result of pressure from the obstruction on the wall of the intestine

compromise of delicate vasculature, pain, ileus, intestinal necrosis and eventual endotoxic shock

what is a strangulating obstruction

both a physical blockage of the lumen and occlusion of mesenteric blood supply

why is venous outflow obstructed before arterial blood flow in a strangulating obstruction

veins have thinner walls

with a strangulating obstruction, about how long does it take for wall necrosis to occur

about 4 hrs

what does intestinal necrosis lead to

loss of integrity of the intestinal wall leading to a leakage of bacterial endotoxins into the peritoneal cavity

what can the leakage of bacterial endotoxins into the peritoneal cavity lead to

absorption of these bacteria into systemic circulation leading to endotoxemia and eventual endotoxic shock

what causes intestinal necrosis in a strangulating obstruction

blood engorgement of walls of affected intestine -> collapse of delicate capillaries -> tissue hypoxia

what is ileus

lack of progressive intestinal motility

what are the two types of ileus

segmental (specific part) or generalized (whole abdomen)

what are the 4 causes of ileus

intestinal distention, endotoxemia, electrolyte imbalances, and some drugs

what is ischemia

death of intestinal wall

what drugs can cause ileus

xylazine, butorphanol, and other anesthetic agents

what are some signs of ileus

decreased intestinal sounds (borborygmi), lack of fecal output, bloating, nasogastric reflux, pain

how is ileus treated

frequent NG intubation and siphoning for decompression, pain control, and promotility drugs

what drugs are used to control pain for ileus

banamine and butorphanol

what drugs are used in ileus as promotility drugs

lidocain, erythromycin, acepromazine

which promotility drugs can cause excitement, restlessness, and sweating

metaclopramide

when does reperfusion injury occur

usually occurs intra- or post operatively

how does reperfusion injury happen

oxygen free radicals and TDPs are suddenly released when an intestinal strangulation is surgically reduced and circulation returns to the previously compromised intestine, causing further tissue injury

how is reperfusion injury prevented

earlier decision to go to surgery, neutralize endotoxins, and prevent synthesis and action of inflammatory mediators

what drug is used to neutralize endotoxins

polymyxin B

What normal intestinal function moves fluid into the small intestine, contributing to fluid buildup during strangulating obstruction?

secretion

what is meant by a "loss of fluid to a 3rd space"

fluid leaks into body spaces that normally contain very little fluid

if venous occlusion causes large volumes of blood to accumulate in the wall of the damaged intestine, what kind of shock will occur?

hypovolemic shock

what is the body's initial response to loss of fluid volume

peripheral vasoconstriction and tachycardia

what are some early signs of hypovolemic shock

dehydration, tachycardia, weak pulses, cold extremities

what is an endotoxin

The non-protein structural component of the outer cell wall of G- negative bacteria

what are the 2 ways that a normal, healthy horse prevents endotoxins from entering systemic circulation

mucous made by the mucosal cells and detoxification by the liver

what changes in the intestine can lead to endotoxin absorption

inflammation, obstruction, and damaged intestinal wall

how does inflammation lead to increased endotoxin absorption

increased vascular permeability increases toxin absorption into portal blood (overwhelming livers ability to detoxify)

how does an obstruction lead to increased endotoxin absorption

because of bacterial death and release of increased amounts of endotoxin (overwhelming livers ability to detoxify)

what are the clinical signs associated with endotoxemia

fever, laminitis, colic, clotting disorders, death

what are the three main goals of therapy for endotoxemia

prevent or correct shock, control or eliminate cause, restore circulating blood volume

how is endotoxemia treated

IV fluids, NSAIDS, polymyxin B, broad spectrum atb, immunoglobulins

what is peritonitis

inflammation of all or part of peritoneum and peritoneal cavity

How does the peritoneal membrane help nourish cells within the abdominal cavity?

It allows nutrients to pass through the membrane to help nourish cells.

How does the peritoneal membrane help abdominal organs move smoothly?

It maintains a slippery, lubricated surface that allows abdominal organs (viscera) to glide past one another without excessive friction.

How does the peritoneal membrane help remove waste products?

It allows waste products to be removed from the peritoneal cavity.

What does retroperitoneal mean?

outside the peritoneal cavity

true or false - the kidneys are not suspended by mesentery and are mostly retroperitoneal, i.e. they are situated outside the peritoneal cavity

TRUE

what are the 4 ways peritonitis is described

origin (primary/secondary), presence of bacteria (septic/ non-septic), distribution (diffuse/ localized), and onset (peracute/ acute/ chronic)

what causes secondary peritonitis

contamination by bacteria from any source (penetrating wound, intestinal leakage)

true or false- septic peritonitis includes the presence of bacteria

true

what does peracute mean

extremely rapid onset

what are the 4 stages of peritonitis

contamination stage, acute diffuse peritonitis stage, acute adhesions stage, chronic abscessing stage

what are the signs of peritonitis

abdominal pain, fever, increased HR and RR, HYPOmotility (decreased motility) or ileus, gastric reflux, endotoxic shock, bowel rupture (initial immediate relief)

how is peritonitis diagnosed

peritoneal tap with evaluation of cells, color, protein, wbc

how is peritonitis treated

atb based on C and S, banamine, drainage through ventral site, surgical lavage, DMSO IV

what are possible sequellas from peritonitis

adhesions (fibrinous or fibrous)

what is a fibrinous adhesion

something that may form and later resolve during normal healing process or they can turn into fibrous adhesions

what is a fibrous adhesion

PERMANENT adhesion

how are adhesions prevented

decrease the inflammatory response (minimize trauma during therapies), supress the inflammatory response (medications perioperatively)

Which part of the horse's gastrointestinal system has the highest likelihood of impaction?

large intestine

What is the primary role of the cecum in the equine digestive system?

Microbial fermentation and water absorption

In a healthy horse, what structure keeps gut bacteria and endotoxins out of the bloodstream?

mucosal barrier

What is a primary symptom of endotoxemia in horses?

fever and shock

Which of the following treatments is most commonly used to promote motility in cases of ileus?

lidocaine

The ________ is responsible for breaking down cellulose through microbial fermentation and reabsorbing water.

cecum

A horse's stomach holds approximately __________ liters and is positioned to the ________of the midline.

8-15, left

When a simple obstruction occurs, the ____________ of the intestine is blocked, which prevents the movement of ingesta

lumen

What is the gold standard for evaluation of the stomach

gastroscopy

what do the lower left and lower right quadrants corresppond to

the large colon

what does the upper right quadrant correspond to?

the cecal base

What can be heard in upper left quadrant

sounds from small intestine or stomach

To relieve distension and prevent gastric rupture, a _____________tube can be used in horses experiencing colic.

gastro