equine GI diseases notes

what is a simple intestinal obstruction

a blocage of the intestinal lumen, usually in the large intestine

what happens to gas and small intestinal secretions proximal to an obstruction

they accumulate before the blockage

how does simple obstruction affect fluid absorption

Fluid absorption decreases, potentially causeing hypovolemia and acid-base imbalance

why can small intestinal obstruction cause rapid deterioration

fluid and secretions accumulate quickly, causeing worsening fluid loss and pressure

how does small colon obstruction generally progress

it usually progresses more slowly than small intestinal obstruction

what can increased pressure from obstruction do to the intestinal wall

causes wall and vascular damage, edema, distension, and possible necrosis

what is ileus

a lack of progrssive intestional motility; it may be segmental or generalized

what can cause ileus

distension followed by atony, ischemia, endotoxins or inflammation, endotoxemia, electrolyte imbalance, and certain drugs

which drugs may contribite to ileus

Xylazine, bitorphanol, and anesthetics

what are common signs of ileus

decreased borborygmi, nasogastraic refux, decreased feces, bloating, and pain

what is a common supportive step for ileus

nasogastric decompression

what other supportive treatments for ileus

pain control and prokinetic drugs

what are some of the prokinetic drugs

bethanechol, acepromazine, yohimbine, erythromycin, metoclooramide, cisapride, and lidocanine

what is the usual resolution timeframe for ileus with support

often 2-6 days

what may happen if severe ileus is untreated

severe endotocemia and possibly gastric rupture

what is strangulation obstruction

an obstruction combined with occlusion of the mesenteric blood supply

what happens to venous outflow in strangulating obstruction

venous outflow is obstructed while arterial inflow may continue, causing engorgement

how can strangulation lead to intestinal ischemia

engorgement and pressure can collapse capillaries and occlude arterioles, reducing or stopping blood flow

how quickly can wall necrosis occure with strangulating obstruction

withing about 4 hours

what serious systemic complication can follow intestinal wall damage

endotoxemia and shock

what is endotoxin

a nonprotein component of the outer cell wall of gram negative bacteria

give an example of a gram-negative beacterium

E. Coli

what equine conditions are associated with endotoxemia

laminitis, interstinal disease, and retained placenta

what two normal barriers help protect an horse from endotoxin

mucosal mucis and liver detocification

how do small intestinal endotoxins reach the liver

through the portal vein

what intestinal injuries can allow endotoxin to ender the body

ischemia, obstruction, parasitic vasculitis, and thrombosis

what are major effects of endotoxemia

fever, poor organ perfustion, endothelial injury, ischemia, thrombocytopenia, hypercoagulation/DIC, and altered liver metabolism

what are the main goals of endotocemia treatment

prevent or correct shock, controle the cause, and restore blood volume

what are treatments for endotocemia

fluids, low-dose flunixin, polymyxin B, broad-spectrum antibiotics, immunoglobulins, and anti endotoxin antiserum

what is reperfusion injury

additional tissue damage that can occur when blood flow os restored after correction of strangulation

what substances may be released during reperfustion injury

sequestered endotocins, tissure degradation products, protaglandins, TNF, interleukins, and oxygen free radicals

what are some prevention measures for reperfustion injury

Early surgery, polymyxin B, and low dose flunixin

what is the peritoneum

a membrane that becomes a double layer at the mesentery and lines or covers abdominal structures

what does the parietal peritoneum line

the body wall and diaphragm

what does the visceral peritoneum cover

the abdomonal organs

what functions does the peritoneum provide

supports organs and carries blood vessles, lympthaticsm nerves

where are the kidney located relative to the peritoneum

mostly retroperitoneal

what happens to the perotoneum during inflammation

permeability increases, fluid and protein increasesm and phagocytes enter

how does the peritoneum help abdominal organs

it provides a gliding surface and helps remove waste through diffusion and phagocytosis

how can perotonitis be classified by origin

primary (rare) or secondary (common, such as form bowel leakage or external trauma)