Equine Med- Esophagus

wilsbach's version from 2016-02-18 20:58


Question Answer
******how much and which part of the eso is smooth versus striated mm?the proximal 2/3 is striated, and the last 1/3 is smooth (makes sense, blends into the mm that the rest of the GI is)
so the eso is part smooth mm and part skeletal mm-- how does this affect your drug choices when trying to medically treat a choke?(rostral 2/3 skele mm, caudal 1/3 smooth) OXYTOCIN will cause striated mm relaxation but smooth muscle contraction! BUSCOPAN will cause smooth mm relaxation (parasympatholytic)
**what is the most common CS of eso dz?Ptyalism(hypersalivation)
if the ptyalism is caused by intoxication, we call it..slobbers
Ptyalism can be ddx into what two major groups of problems?dysphagia vs oral cavity pain
CNs involved in mastication? V, VII, XII aka trigeminal, facial, and hypoglossal
CNs involved in swallowing?V, IX, X aka trigeminal, glossopharyngeal, vagus
dysphagia can be a cause of ptyalism-- what are the 3 phases eating which can be effected?(1) prehension (2) mastication (3) swallowing (pharyngeal or esophageal?)
almost always, oral cavity pain leading to ptyalism is due to...poor dentition (oral foreign body rare)
which LNs are near the guttural pouch, and how might ptyalism be related to this?retropharyngeal LNs near the guttural pouch. so if have strangles where these LNs swell, there can be salivation, so be aware of that
If you see this endoscopic pic,what are you looking at? (R and L) These are the pharyngeal openings of the guttural pouch
review of anatomy of guttural pouch (pic)
which CNs go through the gutteral pouch?IX, X, XII
What 3 other places MUST you rule out before you decide the problem is in the esopahgus?(1) oral cavity abnormalities (2) Guttural Pouch abnormalities (3) Cranial nerve abnormalities
whats the diff between primary and secondary choke?1*= usually too much roughage being swallowed at once, or insufficiently moistened beet pulp. 2*= some abnormality of the esophagus is what caused things to get stuck, not the things itself
what is a big risk factor which can cause choke?feeding too soon after sedation-- motility of eso isn't at full capacity (this is an example of 2* choke)
what are common clinical signs of choke?Frothy nasal discharge, Feed from nostrils, Ptyalism, Gagging / retching, Coughing
what are the most common sites for eso. obstruction?very cr eso, half way down eso, thoracic inlet, terminal eso (natural narrowing of lumen occurs in these places)
where do you want the head to be when you are trying to resolve choke? and why?LOWER THAN THE POINT OF THE SHOULDER!! This dec risk of aspiration pneumonia a bit, and also helps use gravity to get it out
So you want the horse's head lower than the point of their shoulder- how do you do this?SEDATION!! Use xylazine at about 0.5mg/kg IV (100mg/ml solution 1-2ml)
two benefits to using endoscopy to assess choke are...More information regarding nature of obstruction, Visualize the esophageal mucosa
you can use water to try to flush out the choke-- either with a siphon or a pump. What is the thing to think about with this debate?you cannot use too much pressure or you can cause perforation of eso. Siphon can never cause too much pressure, but a pump can.
Two drugs to relax eso?N-butylscopolammonium bromide (Buscopan®) IV, or Oxytocin IV. .....depends on if you are trying to relax skeletal mm (O) or smooth mm (B)
Choke is confirmed-- what do you do to fix it?(1) SEDATE SO HEAD LOWER THAN POINT OF SHOULDER (2) Pass NG tube until resistance is felt (3) Pump water in or use Siphon and gently apply pressure to the obstruction (4) Keep the head low to prevent aspiration of food material in trachea (5) repeat
If you tried lavage and the choke is still persistent, what should you do next?Place horse in stall- Nothing Per Os!! (put a muzzle on them), provide IV fluids and e-lytes, Sedatives / relax esophagus! Obstruction often resolves with time. Sometimes general anaesthesia needed.
what kinda broad spectrum abx would you want to consider using in prolonged choke?gentamycin, penicillin or TMS (if worried about anaerobes, can use metronidazole)
how long before it is considered prolonged choke? How would you manage them then?12-24hrs. Consider Broad spectrum antibiotics, Anti-inflammatory therapy (acidic material in eso + we keep running tubes through it= esophagitis), Sucralfate (inc healing), Refeeding considerations (wait to feed it a while per os, as damage--> change in motility--> re-choke)
3 common complications of choke are...(1) Aspiration pneumonia (2) Esophageal Stricture (linear or circumferential?) (3) Esophageal rupture (extra- or intrathoracic)
WHEN is re-feeding time? Why is this a critical time?24-48 hours! [need to wait at least a day before attempting to feed] They have a Inflamed esophagus and Motility may be abnormal, so re-obstruction is likely, making this a critical time. Dietary modifications are necessary (slurries, grass with high water content, etc. avoid dry roughage)
If diet changes isnt enough for a re-choking horse in the refeeding time, you might have to consider..ESOPHAGOTOMY--- create alternative passage so cr part has time to heal. it's difficult to do tho-- need very dilute slurry or everything gets obstructed. they support it, do quite well tho
Motility dysfunction of esophagus is a common complication. 2 problems that fall under this heading are?(1) megaeso. (2) Functional obstruction (Clinical signs similar as CHOKE)
what if the owner told you that they think the megaeso is from myasthenia gravis?silly owner, horses don't get myasthenia gravis
who can get congenital megaeso?fresians
what are the two kinds of megaeso?Acquired vs. Congenital (May occur following prolonged choke episode-- rule out possible underlying myopathy)