Equine Colic and the Equine GI Tract
The answers to your questions about Equine Colic and the Equine GI Tract by Vicky Johnson, DVM from Cleveland Equine Clinic, LLC
Colic (abdominal pain) causes, signs, diagnosis, do you call the vet, how do you prevent colic, how to manage colic, what to feed for colic, preventative maintenance, medical colic, surgical colic and treating colic.
An important note on the word "colic"
In the veterinary world - ‘colic’ is the most generalized term we use. It just means ‘abdominal pain’ and sometimes, it is a symptom, not a diagnosis.
Horses can appear colicky from a variety of conditions:
1. Diarrhea
2. Pneumonia
3. Choke
4 . Laminitis
5. Tying up/muscle pain
6. Ulcers
7. Orthopedic pain
8. Urinary tract pain
9. Foot abscess
10. Eye pain
11. Reproductive tract pain
12. True GI tract dysfunction -- Impaction, strangulation, refluxing/enteritis, ileus, dehydration, twist, thrombus… the list goes on
When your horse is colicky…
1) Remove all food (hay and grain) - access to water is usually ok -ask your care team
2) Walking - movement stimulates the GI tract
3) Time to call - when signs are severe or persist past 15-20 mins - even if to just start the conversation
4) Medications - ask your vet prior to administering medications
a) Decrease likelihood of potential side effects
b) Interactions with other medications
5) Share pertinent medical history (known conditions or medications)
6) Move the horse (if possible) to a safe place
7) Safety for horse and humans
The basic colic exam
- In Doc Johnson’s world - any horse that warrants a farm call, no matter how serious, should receive a physical exam, rectal exam and the passing of a nasogastric tube
- The physical exam can help us rule out other common causes of colic, and assess the severity of the situation at hand
- A rectal exam can help us determine if a more insidious form of colic is underlying, or give us additional differentials
- A nasogastric tube is both diagnostic (does the horse have contents backing up into his stomach) and therapeutic (administer fluids and electrolytes)
Additional Diagnostics
Bloodwork, Abdominocentesis (Ab Tap) and Abdominal Ultrasound
CLINICAL EXAM
FARM EXAM
For most colics, the GI tract is to blame, and understanding it in detail allows us to make better decisions about the care of our horses.
Let's get to the fun part!
Equine GI Tract Anatomy
1. Mouth
2. Esophagus
3. Stomach
4. Small Intestine
5. Cecum
6. Large Colon
7. Small Colon
8. Rectum
The mouth, esophagus and stomach
- The mouth
- Oral pain
- Tooth or sinus infection
- Food preparation
- The esophagus
- Choke
- The stomach
- Gastric ulcers
- Gastric impaction
The small intestine
- The stomach empties into the small intestine, which is approximately 70 feet long and has a volume capacity of 15 gal
- Horses do not have a gallbladder, so the pancreas and liver are constantly dropping digestive enzymes into the small intestine
- The small intestine is anchored to the body wall by the mesentery, which makes up the connective tissue that gives the SI bloodflow and tethers it into location
- Problems of the small intestine:
- Strangulation (lipoma, itself)
- Twist
- Mesentery dysfunction
- Parasites
- Enteritis
The cecum
- The small intestine empties into a sack shaped like a thumb, called the cecum (appendix)
- The cecum is 3-4 feet long and holds ~10 gallons
- Connected to other GI parts via ligaments
- This is the start of fermentation and large volume storage
- The cecum empties into the large colon
- Pathologies:
- Twist
- Impaction
- Blockage
The large colon
- The large colon is made up of 4 parts that make up 2 “U” shaped loops that sit on top of one another
- The entire large colon is ~12 feet long and can hold ~20 gallons
- The large colon is approximately 8-10” in diameter, except in the turns from bottom to top, which can be cause for problems
- In charge of fermentation, digestion and water/nutrient absorption
- Pathologies:
- Twist
- Impaction
- Infarction/clot => death of part or entire colon
- Displacement
- Colitis
- Enteroliths, fecoliths
The small colon and rectum
- The large colon narrows into the small colon where the last of water is removed
- Formed into fecal balls and passed into the last 8-12” of the rectum
- Pathologies:
- Small colon impactions
- Strangulation
- Infarction
- Twist
- Rectal tears
- Rectal fistulas
So now you know the parts…Why is understanding anatomy so important?
For the veterinarian:
- Diagnose the problem
- Choose appropriate treatments
- Give information on expected progression and response
- Timely and appropriate referral if needed
- Predict recurrence, guide prevention
For the owner:
- Understand cause, progression
- Make informed decisions regarding treatment
- Likelihood to respond on farm vs in hospital vs with surgery
- Understand limitations
- Prevention
All colics fall into 1 of 2 categories (medically)
Medica
- Cases that can resulve with only supportive care
- IV fluids, enteral (via the GI tract) fluids, nutrition, medication
(no one's favorite: medical colics that become surgical)
Surgical
- Cases that do not respond to supportive care alone
- Require surgery to fix underlying cause or the sequelae of disease
- All surgical cases still require medical management/supportive care
(Sometimes surgical colics are treated as medical colics due to factors out of our control)
MEDICAL COLIC EXAMPLES
Gas Colic
- The most common cause of colic
- Any part of the GI tract can become distended, pushing on other structures or pulling on its attachments in the abdomen
- Can range from just punky to down/rolling
- Typically resolve with minimal involvement (banamine or walking, etc)
- Once resolved, horses go completely back to normal and require no additional intervention
Dehydration/Ileus
- Water is most important molecule in the body
- Without it, many GI tract functions can not occur, including peristalsis, or forward movement of ingesta
- Ileus itself can be painful as food sits in the GI tract
- Can lead to impactions
- Treating with IV/oral fluids can help prevent further problems
- Occasionally, ileus can be severe and promotility meds are used
Enteritis
- Dysfunction of the small intestine leads to a build up of digestive juices in the stomach
- Can also be infectious causing ileus (lack of GI motility)
- Horses can’t vomit actively
- Causes stomach distension, GI pain, fever
- Horses must be ‘refluxed’ - using a tube to remove contents from the stomach
- Because nothing is moving through or being absorbed, and they are losing water in the form of ‘vomit’, they often require intense IV fluids, antibiotics for infectious cause and pain relief
- Can be tough to diagnose
Medical-ish Colic Impaction
- Most common in the large colon, specifically the pelvic flexure
- Feed material becomes slowed down, dehydrated, then consolidates into a large mass
- Severity, length of treatment all depend on size, location and firmness
- Some can be resolved on farm with tubings
- Others require hospitalization for IV fluids (hydrate from the ‘outside’) and/or sedation, as we run out of NSAID usage
- Very severe impactions, or horses with unrelenting pain may need surgery to physically remove impaction
- Small colon impactions respond less to medical management than large colon impactions
Medical-ish Colic Displacements
- Although the large colon is anchored to the body wall and other organs by robust ligaments, it sometimes goes on a road trip in the abdomen
- When it leaves its normal location, it often gets ‘stuck’ on neighbors
- Balloon in the fishtank analogy
- Medical vs surgical depends on pain level, duration, and other overall health parameters
- Medical management - maintain body health while waiting for colon to replace itself, occasionally using targeted treatments
- Surgical management – open the abdomen and manually replace the colon, especially needed if movement has caused injury to colon
- Easier seen than explained…
SURGICAL COLIC EXAMPLES
Strangulations and Twists
- Can occur to any part of the intestinal tract
- Strangulation: something cuts off the blood supply or tube of intestine, resulting in injury and if left strangled, death
- Strangulation can occur by masses (lipomas - fatty masses on stalks) or by other soft tissue structures in the abdomen
- Twists (volvulus) - the ‘ball’ of intestines twists on itself and causes a loss of blood flow to the GI tract, eventually (and sometimes quickly) causes death
- Once the intestine has lost blood flow, you must quickly correct the problem
- This is why if a strangulation or twist is suspected, swift decision making to go to surgery is critical
- If left, the intestine can die
- Once dead, it leaks bacteria and cellular debris into the abdomen and horse’s circulation, the horse will become septic and die
- Truly surgical lesions CANNOT be fixed with time and supportive care, as sepsis will supercede treatment
Considerations for Colic Surgery
- Finances - average colic surgery is going to start at $8,000+ for simple opening of the abdomen
- Price increases if parts of intestine need opened or removed
- Anytime we manipulate the intestines outside of their normal function, rate of complications increase
- Rehabilitation time and patient lifestyle
- Age - just a number?
- Prognosis based on lesion
- Systemic health
- Some conditions, when discovered are not treatable
- Some anatomy does not tolerate surgery well
THE GOOD NEWS
- According to recent studies:
- ~60-80% of horses undergoing colic surgery survived to discharge
- 96% of horses that went home, were alive at 1 yr post-op
- 63-72% of horses returned to previous level of work
- Survival to discharge was correlated to type of colic, incidence of complications and time spent in the ICU
PREVENTING AND MANAGING COLIC
Horses Hate Change
- Maintaining a stable environment
- Minimize changes to feed, hay, water access
- Change gradually to acclimate their GI tract
- Provide constant access to fresh, potable and appetizing water
- Feed quality hay and grain taking into account horse’s needs and overall health
- Supplements -
- Some supplements can provide stabilizing ingredients to help support hind gut health and digestion
- Pre- and pro-biotics can be beneficial for regulating digestion
- Poor understanding of true benefit or which strains are best indicated in horses
- Saccharomyces cerevisiae - most clinically indicated at this time
- Supplements for gastric support - Stress
- Good, basic management (dentistry, fecal egg counts)
** This blog is for informational purposes only. Please contact your veterinarian if your horse has any signs of colic.
TAKEAWAYS
1. When you identify colic, reach out to your vet ASAP - come up with timeline, treatment plan
2. If examined - ask questions, understand what is happening, make plan for what happens if the horse does not respond to initial treatment
3. Recognize that some colics will require additional care, have a plan if it happens to your horse
4. Timely identification and treatment saves intestine, and lives
5. Know your horse’s normals and find ways to encourage healthy eating and drinking habits
6. Control chronic diseases that may impact their overall health
7. Utilize products that support your horse’s overall health, and gut health as needed
** This blog is for informational learning purposes only. Please contact your veterinarian if your horse has any signs of colic.
