Exam 3: Management of Disorders of the Esophagus and Stomach

anatomic areas that predispose to esophageal obstruction due to feed material

• thoracic inlet

• hiatal and LES

pathophysiology of esophageal obstruction or choke

• anatomy of esophagus= striated skeletal muscle proximal 2/3, smooth muscle distal 1/3 with tight caudal esophageal sphincter

first step in treating equine choke

• sedation with xylazine or detomidine

• Buscopan

  • pass NG tube

  • lavage esophagus

  • move ube back and forth without exerting too much pressure until the obstruction resolves and the tube can be passed to the stomach

  • oxytocin

function of buscopan in choke treatment 

• anticholinergic, competitive antagonist of muscarinic acetylcholine receptors, inhibits the action of AcH 

• relaxation of smooth muscle contractions, antispasmodic, decreasing abdominal cramps, reduces the frequency and intensity of muscle contractions, alleviating pain and discomfort 

• peripheral action only

oxytocin for choke 

• binds to receptors in smooth muscle cells 

• triggers calcium release from the sarcoplasmic reticulum 

• increased calcium causes muscles to contract 

potential complications of choke

• aspiration pneumonia (TTW)

• esophagitis, esophageal erosion/ulceration (endoscopy)

• esophageal stricture (endoscopy)

• esopageal rupture (gas formation under the skin, barium swallow, endo)

  • antibitotics

horse presents with being off feed, tachycardia, tachypnea, colic signs, phenylbutazone for lameness, and inability to eat or swallow. Immediate next steps

• sedate with xylazine or detomidine

• pass an HG tube to check for reflux

describe gastric acid secretion in horses 

• continuous and variable- acid secretion occurs without the presence of feed mterials 

• non-parietal secretions - bile acids and pancreatic juices are voluminous 

• gastric acidity is greater in fasted horses compared to fed horses 

risk factors or squamous ulcers

• thoroughbreds

• poor performance

• exercise intensity

• exercising 5-7x/week

• multiple handlers

• country music or talk radio in the barn

risk factors for glandular ulcers

• warmbloods

• performing bellow expectations

• increased number of days spent exercising

• lower performance level

• playing polo inversely associated

• breeding stallions actively breeding

• stress

treatment and management of gastric ulcers 

• eliminate or reduce dose of NSAIDs (phenylbutazone and flunixin meglumine) 

• ometrazole paste next line of defense 

• gastrogard proton pump inhibitor 

• histamine antagonists 

• Ranitidine HCl 

• Sucralfate 

• Misoprostol

proton pump inhibitor gastroggard for treating gastric ulcers

• substituted benzimidazole

• inhibits H-K ATPase parietal cell

• treatment and prevention of recurrence

• can maintain training program

• FDA approved

histamine receptor antagonists for gastric ulcers

• Zantac ranitidine HCl

• competitive inhibition of the interaction of histamine with parietal cell

• dose dependent inhibition of gastric acid secretion

  • available as generic and been shown to sugnificantly inhibit gastric acid secretion

sucralfate for gastric ulcers 

• cytoprotective 

• sucrose sulfate aluminum complex 

• binds to the ulcer bed creating a physical barrier 

• protects from stomach acid 

• prevents the degadation of mucus 

• promote bicarbonate production 

• acts like an acid buffer 

MOA of misoprostol

• synthetic prostaglandin

• stimulates prostaglandins E1 receptors on parietal cells in the stomach to reduce gastric acid secretion

• mucus and bicarbonate secretion are also increased aliong with thickening of the mucosal bilayer so the mucosa can generate new cells

• DO NOT USE IN PREGNANT MARES

antibiotics for gastric ulcers

• primarily used in humans with helicobacter pylori

• colonization of ulcer bed -bacteria rapidly colonize ulcer bed and decrease ulcer healing

• H. equorum has been recently isolated from stomach

  • TMS, metro, bismuth compounds

diet modifications for gastric ulcers

• limit periods of fasting

• increase roughage

• pasture turnout, free choice hay, alfalfa hay is a dietary antacid

• reduce grain and concentrates to decrease production of organic acids

recommendations for horses with gastric ulcers 

• provide good quality hay day and nght 

• feed alfalfa hay 

• limit high starch grain to <5lbs every 6hrs 

• gastrogard 

• relyne mixed with feed after gastrogard treatment 

• ulcergard for prevention is worthwhile 

• monitor horses behavior for signs of stress and recrrence 

gastric impaction

• infrequent cause of colic in horses

• dry feed material and decreased water intake

• may occur during winter when dry hay is fed and water intake is lower

• diagnosed at surgery in horses with colic

• endoscope

• treat with DSS

• lavage at surgery, resolve in 24-48hrs

duodenal ulcers/stricture

• part of EGUS and more common in foals with similar pathogenesis and clinical signs

• usually associated with bruxism, ptylism, and diarrhea

• delayed gastric emptying

• associated with esophageal ulcers

diagnosis of duodenal ulcers/strictures 

• clinical signs 

• duodenoscopy 

• rads 

• necropsy 

describe bethanechol

• synthetic parasympathomimetic not degraded by ACH

• induces intestinal smooth muscle contraction acting on the M2 and M3 of GI tract

• enhances gastric emptying in gastroduodenal ulcer disease and duodenal strictures

treatment of duodenal ulcers or structures

• omeprazole

• ranitidine

• surgery for gastrojejunostomy in foals

gastric neoplasia 

• SCC most common, also includes lymphosarcoma, adenosarcoma 

• arises from squamous mucosa and metastaizes to abdominal cavity and viscera and or extends up the esophagus 

• chronic weight loss, anemia, NG reflux, colic 

diagnosis and treatment of gastric neoplasia

• clinical signs

• endoscopy

• biopsy

• abdominal ultrasound

• necropsy

• no treatment, grave prognosis