LA Sx Exam #2: Esophagus, Rectum, Anus Flashcards
Path of the esophagus in the horse
Begins dorsal to the trachea and goes to the LEFT as it moves caudal
*Three regions = cervical, thoracic, and small abdominal portion
Important structures surrounding the esophagus that we should watch out for (3)
1) Common carotid artery
2) Vagosympathetic trunk
3) Recurrent laryngeal nerve (mainly the left)
Four histologic areas of the esophagus
1) OUTER = outer fibrous layer (no serosa in abdominal area)
2) Muscular layer in concentric overlapping spirals, striated proximally and smooth m near the cardia, relatively inelastic
3) Submucosa = tensile strength for closure
4) Mucosa = stratified squamous epithelium in longitudinal folds the “close” the lumen when relaxed, very elastic and mobile
DDx for ingesta coming out of the nose (2)
1) Choke
2) Ruptured stomach
What fun thing happens when you incise into the esophagus?
Mucosa/submucosa separate from the outer layer and adventitia
*Could accidentally force a nasogastric tube through the tissue w/ a ruptured esophagus
Describe the esophageal blood supply
- Arcuate
- Segmental
- Minimal collateral circulation = can’t really perform resection and anastamoses
Dx? Ptyalism, dysphagia, regurgitation of ingesta, head/neck extension, coughing, agitation, sweating, grinding teeth, attempts to swallow
Early choke - esophageal impaction or obstruction
Progression of choke signs from acute to chronic
Chronic = anorexia, dullness, depression, dehydration = metabolic abnormalities (loss of bicarb and Cl with regurg and drooling)
Causes of choke (7)
1) Feed or bedding = carrots, apples, ground grains (too finely ground, inadequate saliva), sugar beet pulp (powder = too dry), wood shavings
2) Gluttonous behavior
3) Eating before cooling down
4) Sedation, alpha-2 agonists like romifidine (most problematic, xylazine = least)
5) Dental abnormalities, not chewing properly
6) Pre-existing lesions like strictures
7) Rare = foreign body (selective eaters)
Diagnosis of choke (6)
- Clinical signs
- PE = palpate laryngeal/cervical region, thoracic auscultation (aspiration pneumonia), hydration status (PCV, TP, electrolyte conc), oral exam w/ speculum
- Nasogastric intubation = both dx and tx
+/- Endoscopy = not really helpful, only really evaluates the mucosa - Radiology = gas due to rupture? air pockets distal/proximal to obstruction? visualize obstruction?
- Contrast studies = negative w/ air (cuffed NG tube and sedation), positive w/ barium or aqueous contrast (no sedation), BOTH
- Pressure esophagram = cuffed NG tube and liquid barium/water soluble contrast, shows esophageal distensibility
Things to remember about nasogastric intubation
- Use the largest NG tube = easier to pass, occludes the esophagus, avoids twisting and displacement of the tube
- Can used cuffed NG or ET tubes
- Use SEDATION
- Keep the head DOWN
What do you do if you can’t relieve the esophageal obstruction?
*Depends on what you suspect the cause is = some food may soften and pass in 12 hours
- NSAID’s
+/- Antibiotics (worried about aspiration pneumonia)
- Remove all food
- Muzzle
- In a bare stall
- Only access to water
- Repeat attempts to relieve obstruction
- Can try esophageal lavage under general anesthesia
What should you do after having relieved the esophageal obstruction?
*Time w/ aftercare depends on duration and nature of obstruction
- Withhold field = likely to be flaccid and hypomotile
- Slowly introduce small quantities of soaked feed or lush grass (ideal)
- NSAID’s
- Antibiotics
- Expectorants if concerned about aspiration pneumonia
+/- Other dx if recurrent
Use of endoscope with esophageal choke
Allows you to evaluate the mucosa following an obstruction, start caudal and move rostral
How do differentiate between esophageal peristalsis and stricture on radiograph?
Wait and re-radiograph to see if it’s persistent
True or false? Carrot and apple piece chokes in the esophagus resolve spontaneously
True
True or false? Rough foreign bodies or food parts in the esophagus resolve spontaneously
False
Sequelae of excessive nasogastric tube use
Esophageal rupture
True or false? Pushing tight esophageal obstructions into the thorax may help in relieving the choke
FALSE - make them more difficult to remove
Sequelae of a prolonged tight esophageal obstruction
- Mucosal ulceration
- Stricture
- Necrosis
- Rupture
Preferred treatment method for rough esophageal impactions or impactions not responsive to conservative treatment?
Esophagotomy (less traumatic than repeated NG manipulations)
Standing or under GA (majority = GA under dorsal recumbency)
True or false? Esophagotomy sites are commonly infected upon closure
True, often place a suction drain to mitigate any infection
What does not having a serosal layer cause?
Decreased rapid healing ability
What may you have to do if the esophagus is compromised?
Insert an esophagostomy tube
Dx? Skin wound draining saliva, cellulitis, emphysema (left to right), edema in brisket and forelimbs, fever, restless, dull, depressed
Esophageal rupture
*Clinical signs vary based on whether the skin is open or closed
Causes of esophageal rupture (6)
- TRAUMA
- Long standing obstruction
- Foreign body perforation
- Excessive force
- Extension of infection from perivascular infection
- Prolonged nasogastric intubation in animals with ileus = necrosis
Sequelae to esophageal rupture (2)
1) Horner’s syndrome = damaged vagosympathetic trunk
2) Roarer = damaged recurrent laryngeal
3) Spread of infection along fascial planes = septic mediastinitis, pleuritis, aspiration pneumonia, laminitis, death
4) Carotid rupture
Treatment of esophageal rupture
- Drainage of SQ
- Debridement of tissue and primary closure
*Not ID’ed early enough = drain and close by second intention - Systemic antibiotics
- NSAID’s
- Tetanus prophylaxis
- Fluid therapy
- Extraoral feeding by placing a distal tube
+/- Tracheostomy - Head support
Do you need to close the esophagostomy site when you remove the tube?
No - will close down on its own
Common cause, treatment, sequelae of mucosal esophageal ulceration
- Cause = longstanding esophageal impaction
- Tx: NSAID’s, antibiotics, soft food for 60 days
- Sequelae = epithelialize and resolve or stricture
Dx? Recurrent episodes of choke, inability to pass a normal NG tube
Esophageal stricture
How long does it take for esophageal strictures to occur? Tx?
- Occur 15-30 days after insult
- Diameter increases from 30-60 days, greatest change at 45 days (leave them along until then)
- Tx: soft feed elevated from ground (food acts as a bougienage to dilate)
Common sequelae to esophagostomies? Tx?
> Traction diverticulum = dx as a wide necked opening on barium swallow study
- Tx: nothing, usually don’t have complications, just monitor
Pulsation diverticulum and tx
> Defect in musculature that causes a flask-shaped out pouching
+ Swelling in the neck that gets larger over time
*Risk of obstruction or rupture
- Tx = surgically repair
Which do we need to surgically repair - traction or pulsation diverticuli?
Pulsation = risk obstructing or rupturing
What is the distal continuation of the small colon?
Rectum (from pelvic inlet to anus)
What muscle prevents anal prolapse during defecation?
Levator ani muscle
True or false - animals have two anal sphincters
True - internal and external
Most common cause of equine rectal tears
> IATROGENIC secondary to rectal palpation
- Other = breeding accident, parturition/dystocia, impactions, rectal thrombosis, idiopathic (fairly common)
Grade I rectal tear
Mucosa and submucosa only
Grade II rectal tear
Muscular layers only
Grade IIIa rectal tear
All layers (mucosa, submucosa, muscular) except serosa
Grade IIIb rectal tear
All layers (mucosa, submucosa, muscular, serosal) except mesorectum and retroperitoneal tissues
Grade IV rectal tear
Full thickness tear extending into the peritoneal tear
Clinical signs of a rectal tear
+ Sudden release of pressure on rectal palpation
+ Direct palpation of organs on rectal palpation
+ Blood on sleeve during rectal palpation
+ Colic, progressing to depression
+ Hemorrhagic feces
+ Tenesmus
+ Signs of peritonitis
+ Signs of endotoxemia (hyperemic to purple MM, toxic line dorsal to incisors, tachypnea and tachycardia, sweating)
+ Prolapse of intestines out the anus
Drugs we use to sedate the horse to examine for rectal tears
- Epidural of lidocaine
- Xylazine +/- butorphanol
- Buscopan = anti-spasmodic
- Lidocaine directly into rectum (diluted in tap water)
Diagnosis of rectal tears
- Sedation and epidural
- Bare arm or surgeon glove rectal exam = go SLOWLY and lubricate
+/- Tube speculum or endoscope (rectal folds can obscure) - CBC and abdominocentesis = indicative of peritonitis (esp. if grade III or IV)
First things you should do, as a practitioner, for grade III or IV rectal tears
1) Inform the owner = inherent risk of rectal palpation
2) Apply appropriate tx = epidural, evacuate and pack the rectum with cotton material 10 cm orad to defect, close anus w/ purse string
* Administer banamine, broad spectrum antibiotics, +/- fluid tx for shock
3) Refer ASAP
Treatment of grade I and II rectal tears
- Antibiotics, Ex: TMS
- Soft feed, Ex: grass, moistened pellets, bran mash, NO hay
- Laxatives, Ex: MgSO4 or mineral oil, 4 L every 4 hours to soften feces, decrease bulk
- May take 4-6 weeks to fully heal
Surgical treatments for rectal tears (3)
1) Direct suture repair = may want to wait a few days for grade 3 for edema and friable tissues to “heal”
2) Temporary rectal lining bypass = dorsal recumbency and GA, sutured oral to the tear, falls out in 10 days
3) Loop or end colostomy bypass = suture colon to body wall
Why is the loop or end colostomy not a favorable option? (2)
1) Prone to complications
2) Requires a second surgery to reverse the process
Complications of rectal tears
1) Peritonitis
2) Endotoxemia
3) Laminitis
4) Abscessation
5) Formation of adhesions
6) Stricture at tear site
7) Diverticulum at tear site
Prognosis of rectal tears
- Good for grade I and II
- 70% for grade III
- Poor for grade IV
- Direct suturing = 75% survival
What is the most important thing to remember about rectal tears?
Prevention»_space;> treatment, use lube, go slow, sedate, use lidocaine/buscopan
Causes of rectal prolapse
- Diarrhea
- Dystocia
- Parasitism
- Colic
- Proctitis = inflammation of rectum
- Rectal tumors
- Foreign bodies
- Short tail amputations, affects musculature around the anus (really just in sheep)
Type I rectal prolapse
Rectal mucosa and submucosa protrude from the anus
*More common finding
Type II rectal prolapse
Complete prolapse of the full thickness rectal ampulla (retroperitoneal portion)
*More common finding
Type III rectal prolapse
Type II (complete and full thickness prolapse of retroperitoneal rectal portion) with small colon intussception into the rectum
Type IV rectal prolapse
Peritoneal rectum and variable amount of small colon intusscept through the anus
*Seen with dystocias
Clinical signs of rectal prolapse
+ Mucosal mass (type I, II, III) or tube (type IV) protruding from anus
+ Variable amounts of edema, bruising, cyanosis, necrosis
+ Colic and peritonitis (types III and IV) due to disruption of vasculature
Non-surgical treatment of rectal prolapse
- Epidural
- Reduction w/ application osmotic agent (glycerin, sugar, lidocaine, MgSO4)
- Purse string suture (umbilical tape), keep it tight and untie every 2-4 hours to empty rectum
- Laxatives
- Temporary starvation (12-24 hrs) to decrease rectal volume
- Soft feed
- Peritoneal fluid/laparoscopy to observe the viability of the mesocolon and colon
Surgical treatment of rectal prolapse (2)
1) Submucosal resection = circumferential incision mucosa to mucosa
2) Resection and anastamosis = full thickness incision
* Stylet or spinal needle across the anus to hold it in/out
Prognosis of rectal prolapse
- Type I and II = good
- Type III and IV = guarded to poor, dependent on the degree of vascular damage
Dx? Mass near rectum (lateral or dorsal), mild colic, depression, lethargy, inappetence, decreased fecal output, tenesmus, fever
Perirectal abscess
Etiologies of perirectal abscesses
- Idiopathic = most common
- Previous rectal tear
- Rectal puncture
- Rectal inflammation
- Gravitation of gluteal abscess post-injection
- Lymphadenopathy from Strep equi zoo or E. coli
Dx of perirectal abscess
- Rectal palpation = firm, submucosal mass
- Aspirate transcutaneously or transrectally
- Culture and sensitivity of aspirate
- U/S - may not differentiate between lymph node, abscess, or hematoma
Treatment of perirectal abscess
- Sedation and epidural (or local anesthesia)
- Establish drainage = lateral via percutaneous, dorsal via rectum, ventral via vagina or percutaneous
- Flush daily (up to 5-7 days)
- Laxatives
- NSAID’s
+/- Sx in younger horses with lymph node abscessation (antibiotics, NSAID’s laxatives, dietary modification)
Prognosis for perirectal abscesses
GOOD - as long as there’s not involvement of the abdominal cavity or organs
Dx? Neonate with tenesmus, signs of colic, progressive abdominal distension, no fecal passage, no meconium staining, straining of rectum SQ during straining, toxemic
Atresia ani
Is atresi ani or recti common in horses?
No - more common in pigs or cattle
What should you always check if you suspect atresia ani or recti?
For other congenital abnormalities
Ex: atresia coli, renal aplasia/hypoplasia/dyplasia, absence of a tail, musculoskeletal deformities, microophthalmia, rectovaginal fistula, other urogenital abnormalities
Dx of atresia ani or recti
- Signalment and clinical signs
- Digital rectal palpation
+/- Imaging = U/S or rads
Treatment of atresia ani with complete rectal pouch
- Incise persistent anal membrane and skin caudal to anal sphincter
- Suture rectal wall to skin
- Close any communication with the urogenital tract with inverting sutures
Treatment of atresia recti
- Blunt dissection cranially
- Pull rectal pouch caudally
- Suture rectum SQ
- Incise pouch and suture mucosa to skin
- Close any communication with the urogenital tract w/ inverting sutures
Prognosis with atresia ani and recti
- Ani or recti = favorable
- Normal anal sphincter may not be obtained
- Coli is present = prognosis is poor
Most common perineal tumors (2) Clinical signs?
1) SCC = necrotic, foul smelly, locally invasive, slow to met
2) Melanomas = solitary/multiple nodules (common in older > 15 yo grey horses)
- Other = polyps, leiomyosarcoma, adenocarcinoma
Dx and tx of perineal tumors
- Dx = histopath via biopsy
- Tx = surgical excision, cryosurgery, laser surgery, radiation tx, immunotherapy, bypass the rectum procedure
