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COLIC
Overview
Colic is a general term referring to abdominal pain in horses. There are numerous causes of colic in horses. Clinical signs are variable and depend on the cause of the colic and personality of the individual horse. Horses may exhibit no pain, mild pain, moderate pain, severe pain or depression. Generally, increases in heart rate reflect the severity of pain and disease. Normal resting adult equine heart rate is 28-40 beats/minute. Horses with mild obstructions may have heart rates of 50-60 beats/minute; whereas horses with strangulating (twisting) lesions may have heart rates in excess of 80-90 beats/minute. Horses exhibiting signs of colic should be examined by a veterinarian.
Clinical Signs
Clinical signs of colic in a horse may include any of the following:
- Depression (Figure 1)
- Inappetence
- Pawing
- Looking at the flank (Figure 2)
- Lying down more than usual (Figure 3)
- Curling the upper lip
- Playing in their water bucket
- Restlessness
- Kicking at the abdomen
- Rolling (Figure 4)
- Stretching out (Figure 5)
- Dog-sitting (Figure 6)
- Groaning
- Sweating
- Abdominal distention
- Cold extremities
- Minimal to no manure
- Diarrhea
- Foals may roll in their backs
- Foals may grind their teeth and salivate excessively
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Figure 1: Depression
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Figure 2: Looking at flank
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Figure 3: Lying down more than usual
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Figure 4: Rolling
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Figure 5: Stretching out
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Figure 6: Dog-sitting
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Causes
Colic is a general term that refers to any cause of abdominal pain in a horse. Abdominal pain can originate from either gastrointestinal system disease or disease in other body systems. The gastrointestinal system is the most common cause of colic. Other body systems that can cause signs of colic or that can cause signs that look like colic might include:
Reproductive System
- Uterine torsion (twisting of the uterus within the abdomen)
- Dystocia (difficulty delivering a foal)
- Retained placenta
- Granulosa cell tumor (a tumor of the ovary)
Urinary System
- Bladder or kidney stones
- Ruptured urinary bladder
Respiratory System
- Pneumonia
- Pleuritis (inflammation of the lining of the thoracic cavity)
Musculoskeletal System
- Laminitis (founder) *see the Laminitis topic on this website
- Tying up
Cardiovascular System
- Aortoiliac thrombosis (a blood clot in the iliac artery supplying blood to the intestines)
- Aortic rupture/acute hemorrhage
- Uterine artery rupture
- Myocardial infarction
- Pericarditis
Nervous System
- Tetanus
- Botulism
- Seizures
- Equine motor neuron disease
Gastrointestinal System
- Spasmodic colic
- Parasites
- Gastric ulcers
- Impactions
- Displacements
- Strangulation
- Perforation
- Infarction
- Tympany (gas colic)
- Intussusceptions
- Obstructions
- Hernias
- Enteroliths
- Intestinal atresia
- Rectal tears or prolapse
- Neoplasia (tumor)
- Abscesses
- Liver disease
- Adhesions
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Figure 7. Severe parasite infestation of a 4 month Belgian colt
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Figure 8. Gastric ulcers
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Figure 9. Strangulated, distended, devitalized small intestine
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Figure 10. Small intestine volvulus
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Figure 11. Small colon enterolith
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Figure 12. Severe sand impaction
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Figure 13. Strangulating lipoma of the small colon
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Figure 14. Adhesion of the small intestine
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Figure 15. Hernia
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Risk Factors
Age: Some causes of colic are more common in young horses; such as intussusception, bladder rupture and hernias. Strangulating lipomas and neoplasia are more common in older horses.
Breed: Arabian horses have been shown to be at increased risk for colic. Impactions of the small colon are more prevalent in miniature horses. Standardbreds are at an increased risk of scrotal or inguinal hernias. Broodmares that have recently foaled appear to be at increased risk for colonic volvulus (twist).
History of previous colic: Horses with a history of previous colic are also at increased risk of future colic.
Use: Race horses and show horses have a high incidence of gastric ulcers. Pleasure horses are at increased risk of developing gastric ulcers when confined with limited access to pasture, traveling, training and competing for short periods of time.
Management factors: Excessive amounts of grain in the diet and changes in forage are thought to contribute to an increased risk of colic. Nutritional counseling by your veterinarian is recommended to decrease the risk of colic. Continual access to fresh water is important in the prevention of colic. Changes in stabling and exercise level may cause an increased risk of colic.
Preventative medicine factors: Annual physical and dental exams with appropriate treatment by your veterinarian may decrease the risk of colic. Effective parasite control programs will decrease the risk of colic. Consult with your veterinarian about what program is best for your situation.
When to Seek Veterinary Advice
Normal temperature, pulse and respiration for an adult horse are 99–100.5F (37-38C), 28-40 beats/minute and 12-16 breaths/minute, respectively. If your horse is exhibiting any of the clinical signs of colic or has an abnormal temperature, pulse or respiratory rate, you should consult your veterinarian. Unless recommended by your veterinarian, avoid administering NSAIDS (nonsteroidal anti-inflammatory drugs), such as Banamine®, because they can both mask the clinical signs of colic and the severity of disease. Remove all hay and grain and hand walk the horse to prevent further injury from rolling until the veterinarian arrives.
Diagnostic Procedures
Your veterinarian may need to perform several diagnostic procedures to determine the cause of abdominal pain in a horse including, but not limited to, the following procedures:
History: An accurate history is important to determine if a horse’s pain is sudden, chronic or intermittent. A thorough discussion of management and preventative health practices may elucidate reasons for abdominal pain. Owners should be prepared to assess manure production and consistency and report all medications given to the horse.
Physical Exam: Temperature, pulse and respiratory rate, capillary refill time and mucous membrane color are assessed. The facial and digital pulse are evaluated for rate and character, ie, absent, reduced, normal, increased, or bounding
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Figure 16. Palpation of the facial artery
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Figure 17. Palpation of the digital artery
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Mucous membranes are assessed for deviations from normal pink color and normal capillary refill, less than 2 seconds, which can indicate poor blood supply to the peripheral tissues and impending cardiovascular collapse.
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Figure 18. Assessing mucous membrane color
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Figure 19. Assessing capillary refill
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Figure 20. Normal capillary refill is less than 2 seconds.
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Figures 21 and 22. Abnormal dark pink to red mucous membranes. The horse needs to be evaluated by a veterinarian.
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Figure 23. Abnormally pale mucous membranes that could indicate shock.
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Lack of intestinal motility is correlated with severity of abdominal disease. Listening for intestinal sounds on both sides of the abdomen is another aspect of the physical exam. Abdominal distension is noted and percussed for pings (gas accumulation producing a high- pitched resonance).
Rectal Exam: A rectal exam can clearly indicate bowel thickness and distension, displacements, impactions, masses or hernias. Rectal exams should only be performed by a veterinarian. The horse may require sedation to ensure a meaningful exam and the safety of the veterinarian and horse.
Nasogastric Intubation: Horses are unable to regurgitate. It is necessary to pass a tube through the horse’s nostril into the stomach to relieve fluid and gas distension so that the stomach does not rupture. Horses with abnormal amounts of gastric reflux should be transported to a veterinary hospital with a nasogastric tube in place.
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Figure 24. Abnormal amount of fluid from the stomach of a horse.
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Abdominocentesis: Peritoneal fluid is a lubricant that bathes the surface of abdominal organs and reflects changes in the health of those organs, including the intestine. A small amount of fluid is collected from the abdomen and analyzed for the presence of protein, red blood cells, white blood cells, and bacteria.
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Figure 25. Abnormal peritoneal fluid in the left tube and normal peritoneal fluid in the right tube.
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Ultrasound: In foals and miniature horses where rectal exams cannot be performed, ultrasound may be used to evaluate excess peritoneal fluid, adhesions, masses, small intestinal distension, lack of intestinal motility, intussusceptions and left dorsal displacement of the large colon (nephrosplenic entrapment).
Radiography: X-rays have been used in special circumstances to document the presence of sand colic and enteroliths.
Gastroscopy: Utilized to diagnose gastric ulcers and stomach masses (tumors).
Laboratory tests: CBC and differential, packed cell volume and total protein, blood gas, electrolytes and serum chemistries.
Response to medical treatment: The majority of horses exhibiting mild signs of colic will respond favorably to medical therapy. The goals of medical therapy are to relieve pain, restore normal intestinal motility and normal fluid balance and treat endotoxemia. Horses with colic signs that increase in severity after appropriate medical therapy may require surgery.
Treatment
The goals of medical therapy are to relieve pain, restore normal intestinal motility and normal fluid balance and treat endotoxemia. Horses with colic signs that increase in severity after appropriate medical therapy may require surgical intervention.
When to Refer a Horse with Signs of Colic
The decision to refer a horse with signs of colic is made independently from the decision to perform surgery. Colicky horses, unresponsive to appropriate medical therapy, may require further evaluation and monitoring, intensive care and/or surgery. Horses exhibiting signs of severe unrelenting pain, abnormal rectal findings, large quantities of gastric reflux, lack of intestinal sounds, abnormal peritoneal fluid, progressive abdominal distension, lack of fecal production, recurrent episodes of colic or chronic colic that has persisted greater than 24 hours are candidates for referral to an equine hospital. Horses with abnormal amounts of gastric reflux should be transported to a veterinary hospital with a nasogastric tube in place.
Surgical Criteria
Surgery may be necessary to relieve obstructions, tympany (gas accumulation), sand, enteroliths, foreign bodies; remove devitalized intestine or reposition displaced intestine. There is no single criterion that determines the need for surgery in horse exhibiting signs of colic. It is often necessary to repeat the examination and assessment process of the horse over a period of time before concluding that surgery should be performed. Some of the more important indications for performing surgery include severe unrelenting pain, lack of response to appropriate medical therapy, persistently elevated heart rate, large quantities of gastric reflux, lack of intestinal sounds or fecal production, abnormal rectal findings, abnormal abdominal fluid and progressive abdominal distension. Find an ACVS Veterinary Surgeon.
Postoperative Care
The main goals of postoperative therapy are to return and maintain normal fluid balance, plasma proteins, electrolytes and intestinal motility; minimize pain; and, treat postoperative complications. Postoperative care plans may differ slightly due to the cause of the colic. Most horses will receive intensive care and monitoring immediately after surgery. As the horse recovers from surgery, feed and hand walking are gradually included in the postoperative plan. Often the horse will have sutures or staples that will need to be removed by your veterinarian 10 to 14 days after surgery. Horses with uncomplicated recoveries from surgery typically return to work after 2 to 3 months of stall, small paddock and pasture rest. You should consult your veterinarian before returning the horse to work.
Prognosis
The prognosis for horses with colic often depends on the cause of the colic; typically non- strangulating lesions have a better prognosis than strangulating lesions. Generally, surgical success rates have improved dramatically due to earlier referral to a surgical hospital and surgical intervention. Horses with prolonged, severely increased heart rates, capillary refill times, packed cell volume and blood lactate values, and decreased plasma protein tend to have the poorest prognosis. This emphasizes the importance of calling your veterinarian early.
—Elizabeth Boulton, DVM
Diplomate ACVS
Posted 9/30/2005
Updated 5/30/2008 by Dr. Boulton
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