Equine GI (Foreman) Flashcards
colic
symptomatic of gastrointestinal pain
Horse prehensile organ?
lips
Pallidal Encephalomalacia
disease in the brain that causes a horse to be unable to use its lips and they starve
hypsodont
tooth with open roots that continue to grow throughout an animal’s life
What tooth in the horse erupts as adult?
molars
Do horses have a natural over or under bite?
overbite
How do horse teeth wear?
side to side; sharp outer uppers (labial) and sharp inner lowers (mandibular)
quidding
dropping feedstuff from mouth while in the midst of chewing d/t dental disease and/or missing teeth
How much saliva can a horse produce in 24 hours?
4.8 - 6.4 liters
When is the only time a horse should be salivating?
during mastication/chewing
atropine
parasympatholytic that blocks saliva production
pilocarpine
parasympathomimetic that stimulates saliva production
Is saliva sympathetically or parasympathetically mediated?
parasympathetic
Is saliva acidic or alkaline? What are the main components?
More alkaline d/t high levels of potassium and bicarbonate
What is unique about a horse’s trachea and esophagus?
They criss-cross, with the esophagus going dorsally over the larynx
4 Examples of Upper Airway Obstruction in Horses
- Left laryngeal hemiplegia (LLH)
- Dorsally-displaced soft palate (DDSP)
- Epiglottic entrapment
- Dynamic pharyngeal collapse
Label the layers.
Problems with esophageal surgery for obstructions?
strictures and scarring are very common leading to additional problems later on
Are horses obligate nose breathers?
yes
From which side is it easier to intubate the horse?
Left - you can see the esophagus on this side
Esophagram
put radioactive material into esophagus through the nasogastric tube and take a radiograph to see where the blockage is and how significant
Diverticulum
side pouch
Margo plicatus
line between the non-glandular and gllanddular portion of the equine stomach
Why can’t horses vomit?
very tight cardiac sphincter
Can horses rupture their stomach?
Yes, and they do
This is a histological section of the margo plicatus. Which is glandular and which is non-glandular?
yellow = non-glandular
orange = glandular
Epithelium in the Non-Glandular Stomach
simple stratified squamous, no secretory cells, no absorption - functions to store food
Epithelium in the Glandular Stomach
simple tall columnar, hydrophobic, high blood supply, lots of glands
What buffers stomach acid?
- Saliva w/ bicarbonate
- Grass/hay (fiber)
- COX-1 derived prostaglandins
- Cell membranes (physical barrier)
How do COX-1 derived PGs create a healthier gastric mucosa?
increases blood flow
Do prostaglandins inhibit or stimulate acid production?
inhibit
Bute and Banamine effects on PGs
inhibit prostaglandins, therefore increasing acid –> risk of ulcers
When we drop below what pH do we have a higher risk of ulcers?
pH less than 4.0
Do horses secrete stomach acid (HCl) all the time?
yes
How can we damage the gastric lining?
- damage to barriers
- stress
- Envrionmental/Management factors
- abnormal gastric acidity
- NSAIDs
Common Equine Anti-Ulcer Drugs
- H2 receptor agonists (ranitidine)
- Proton pump inhibitors (omeprazole)
- Prostaglandin analogs
- Mucosal physical patch (sucralfate)
- Antacids
Do horses have bile?
yes
Do horses have a gallbladder?
no
Where is bile secreted from in the horse?
liver
Where does the duodenal bile duct opening sit in the horse?
the papilla sits dorsally (so gravity helps it spill out)
Energy Sources for Horses (4)
- Hydrolyzable carbohydrates
- Non-hydrolyzable carbohydrates
- Fats and oils
- Protein
Examples of hydrolyzable carbohydrates (CHOs)
simple sugars and polysaccharides
Highest density of ICCs in horses is where (3)?
- Ileum
- Body of Cecum
- Pelvic Flexure
In what layer are ICCs in the small intestine?
myenteric plexus
In what layer are ICCs in the large intestine?
circular muscular layer
What can cause decreased GI motility?
impactions, enteritis, thrombus, grass sickness, post-operative ileus, strangulations, worms
Cranial Mesenteric Artery Thrombus
caused by Strongylus vulgaris (bloodworm) at attack the main blood supply to the large colon
Intussuception
intestine telescopes upron itself and cuts off the blood supply
Gastrocolic reflex
when something is put in the stomach, communicates with the colon to make space
Where are the most common places for impactions?
sharp turns and changes in diameter (diaphragmatic flexure, pelvic felxure)
Enterolith
magnesium ammonium phosphate surrounding a nivus
Nivus
foreign material in the digetive tract
Large Intestinal Volvulus (torsion)
horse has gas and rolls
Dextomidine/Xylazine effect on spleen
increases splenic size and volume
Phenylepinephrine/epinephrine effect on spleen
splenic contraction, therefore decrease in size and volume
What can you palpate through a horse’s rectum? (6)
- Left kidney
- pelvic flexure
- aorta and bifurcation
- cecum (top of)
- small intestine
- spleen