Learning about Horses - Digestive System

In my quest to make sure I am a good horse mama, I have made it my mission to learn as much as I can about horses. I learned all this stuff years and years ago when I was in my late teens/early 20's so these are refresher lessons.

So the two biggest problems that horses can encounter is digestive issues and hoof issues. So I started with digestive system. 

Here is what I am learning. 

Digestion in Horses

Mouth

• digestion starts
• 3 salivary glands
• 10 gallons of saliva
• mixes with feed
• moist, loosely formed balls, easy to swallow
• 2 ingredients
• bicarbonate
• buffers and protects against amino acids in stomach
• amylase
• assists carbohydrate digestion
• eating process on pasture
• horse graps grass using teeth, lips, tongue
• Floor Level Feeding
  
• make sure to use slow feeders for hay and grain

Esophagus

• 50-60 inches

• grass and hay few problems

• crunch items - carrots/apples can cause problems

• grain can also cause problems with “bolts” food

Stomach

• very small in relation to size of animal

• makes up only 10% of digestive capacity

• 8-16 quarts

• functions best when only ¾ full

• grazing is best - little bits of food all day

• food passes quickly

• in stomach food is mixed with pepsin 

• enzyme utilized in digestion of protein

• and hydrochloric acid

• helps break down solid particles

• 3 main regions

• saccus caecus

• located near the spot where the esophagus enters stomach

• where hydrochloric acid first mixes with food and slows fermentation process that began with the release of soluble sugars from the food in the horse’s mouth

• very little fermentation in stomach will cause the formation of gas, and horse has little capability to belch or otherwise dissipate accumulating gas

• funic 

• level of fermentation decrease even more

• pyloric

• where stomach joins the small intestine

• fermentation has almost ceased, but protein digestion increases

• stomach does not do well when empty

• acid attacks the unprotected squamous cells in the saccus caecus region

• can cause ulcers 

• strong acids in stomach 

• can be done in 15 min

Small Intestine

• partially digested food from the stomach passes into the small intestine 

• 28% of digestive system

• is tube that connects stomach with large intestines

• 70 feet long

• 3-4 inches in diameter when distended

• 12 gallon capacity

• serious digestive process takes place

• secretes enzymes to facilitate the process

• prime supplier is the pancreas

• provides enzymes that break down proteins, fats, starches, sugars

• pancreatic enzymes

• help digest the food while carbohydrates digest sugar and starches

• protease breaks down proteins into amino acids

• liver

• lipases and bile added to emulsify fats in water

• does NOT have a gallbladder

• once digestive process in the small intestine reaches a state of completion food is absorbed through the walls of the small intestine and is carried off by the bloodstream

• 30-60% of carbohydrate digestion and absorption, and almost all amino acid absorption o

• vitamins A, D, E, K are absorbed 

• some minerals

• calcium and some phosphorus

• 30-90 min to pass through small intestines

• faster - less time for enzymes to perform digestive tasks

• susceptible to colic FROM toxic materials

Large Intestine

• 5 basic parts

• cecum

• 4 feet long

• 1 foot diameter

• large colon

• 12 feet long

• 10 inches diameter

• small colon

• 10 feet long

• 4 inches diameter

• rectum

• anus

• contain active populations of bacteria and microbes that break down food through a fermentation process

• cecum

• 4 feet long x 1 foot diameter

• 8-10 gallons food & water

• undigested food from small intestines is broken down

• odd shaped organ 

• exit and entrance at the top

• food enters and leaves by the same route - can be a problem

• if heavy diet of dry food without adequate water impaction can occur in the lower end of the cecum and cause colic

• food stay for up to 7 hours allowing bacteria and microbes to handle their phase of the digestive process

• vitamins and fatty acids that result from the fermentation process are absorbed

• microbial populations specific for type of food the horse normally ingests

• VERY important - change a horse’s diet gradually give the microbes an opportunity to adjust

• could take several weeks

• large colon

• twisted gut

• consists of a right and left ventral and dorsal colon

• ventral colons have sacculated construction

• series of pouches

• designed to efficiently digest large quantities of fibrous materials

• pouches/sacs can become twisted

• filled with gas 

• SERIOUS case of colic

• small colon

• all nutrients have been digested

• mater not digestible by the horse

• reclaim moisture and return it to the body

• fecal balls formed

• passed through rectum and expelled out of anus

• digestion takes 36-72 hours