Common GI Problems

• Hind-gut fermentation

  • Trillions of bacteria and yeasts reside in the large colon
  • Responsible for digestion of FIBRE
  • Primary source of nutrition in horses
• Cellulose/hemicellulose digestion

  Cellulose/hemicellulose --> Volatile fatty acids --> Glucose
• Large colon

  • Holds 70-80L of semi-liquid ingesta
  • Contains 10% of total body water content
• Hind-gut disturbance

  • Horses don't well with sudden change; because the hind gut doesn't do well with change; especially the bacteria within the hind-gut
  • Hind-gut function = dependent upon healthy microbiome and optimal conditions for fermentation
  • Disruption of fermentation process or alteration of microbiome leads to decrease in pH of colon, increased production of gas, dysfunction of the large colon, colic, diarrhoea, systemic illness
• Causes of hind-gut disturbance


  • Sudden changes in diet
  • Carbohydrate Overload
  • Bacterial infections (e.g. Salmonella)
  • Parasite infestation
  • Ingestion of toxins
• Oral cavity


  • Mastication - Premolar and Molar arcades provide large occlusal grinding surface to break down fibre into smaller particles suitable for fermentation by bacteria
  • Mastication mixes food with saliva to start enzymatic breakdown of starch
• Equine dentition

  • Hypsodont teeth
  • Erupt over most of a horse's life at a rate of 2-3 mm/year
  • Continually wear due to attrition associated with masticatory forces
  • Should wear evenly to maintain maximal occlusal grinding surface
  • Teeth surface at about 5 degree angle
• Dental care

  • Good dentition is essential for normal digestive function
  • If wear = uneven, teeth can develop enamel overgrowths or sharp enamel points
  • Dental care is imperative for old horses (>20-25 y/o)
• Dental disease is major cause of weight loss in old horses and a major cause of colic in all horses
• Dental disease symptoms


  • Inappetence
  • Drooling
  • Halitosis
  • Facial swellings
  • Sinus Disease
  • Nasal Discharge
  • Ocular Discharge
  • Difficulty Eating
  • Diarrhoea/Colitis
• Oesophageal obstruction (choke)


  • Physical obstruction of the oesophagus, usually with organic matter
  • Can occur at any level of the oesophagus
• Causes of oesophageal obstruction

  • Rapid ingestion of food
  • Dry, coarse feed stuffs
  • Poor mastication / Dental disease
  • Primary oesophageal abnormalities
• Common areas of oesophageal obstruction

  • Proximal oesophagus
  • Thoracic inlet
  • Heart base
  • Cardia
• Clinical signs of oesophageal obstruction

  • Profuse salivary/food-stained nasal discharge
  • Drooling
  • Repeated spasm of neck muscles
  • Coughing
  • Agitation
  • Possibly mild tachycardia
  • Palpable mass in left lateroventral aspect of neck
• Treatment of oesophageal obstruction

  1. Give time

  2. Sedation

  3. Massage oesophagus

  4. Pass nasogastric tube
• Feeding modifications for oesophageal obstruction

  • Dampen 'high risk' hard-feeds (sugar beet pulp, coarse chaff)
  • Feed smaller volumes more regularly
  • Do not feed immediately after exercise (or after sedation!)
  • Reduce excitement prior to feeding
  • Allow access to hay prior to feeding hard-feed
  • Place obstacles in the food bowl
  • Pre-chopped, fine roughage for horses with dental disease
• Equine stomach

  • Simple monogastric stomach
  • Very acidic pH of 4
  • Double mucosa [squamous and glandular mucosa] uncommon in other mammals
  • Anatomy of oesophageal sphincter (the cardia) prevents eructation under normal conditions
• Equine gastric ulceration syndrome (EGUS)

  • Squamous ulceration - due to direct contact with gastric acid, common along greater or lesser curvature dorsal to the margo plicatus
  • Glandular erosions - due to breakdown in mucosal defenses, inflammation - hyperaemia - erosion - ulceration
• Risk factors for equine gastric ulceration

  • High carbohydrate - Low forage Diet
  • Intermittent feeding / periods of fasting
  • Water restriction
  • Stress
  • Intense exercise
  • Decrease prostaglandin synthesis (stress, NSAID administration)
• Clinical signs of equine gastric ulceration

  • Poor performance
  • Altered or variable appetite
  • Weight loss or poor weight gain
  • Changes in behaviour
  • Coat changes – ill thrift
  • "Girthing" pain
  • Recurrent colic
• Treatment of equine gastric ulceration

  • Omeprazole once daily for 28 days --> 70-80% healing rate
  • Follow-up gastroscopy is important to assess response and plan further therapy
• Management of equine gastric ulceration

  • Ensure continual grazing behaviour - Avoid prolonged fasting
  • Provide regular access to pasture
  • Feed smaller volumes more regularly
  • Provide good quality forage - Lucerne (legume roughage) high in Ca++ natural buffering effect
  • Avoid diets high in starch / soluble carbohydrates
  • Minimise stress
  • Tailor exercise regimen – reduce periods of high intensity exercise
• Equine colic

  Clinical syndrome associated with abdominal pain, predominantly associated with GIT, may involve a number of body systems
• USA General population - 4.2 colic episodes /100 horse years, 11% fatality rate
• UK Thoroughbred population - 7.19 colic episodes/100 horse years, 6.2% fatality rate
• Outcomes of equine colic

  • Spontaneous recovery – 28.7%
  • Medical recovery – 63.1%
  • Surgical recovery – 2.0%
• Causes of equine colic

  • Smooth muscle spasm
  • Inflammation - Colitis / Ulceration
  • Distension - Impaction, Gas accumulation
  • Obstruction - Impaction
  • Tension on the mesentery - Displacement
  • Tissue congestion/necrosis - Torsion/volvulus, Strangulation
• Other signs of abdominal pain

  • Liver disease / hepatomegaly
  • Urinary disease
  • Peritonitis
  • Intra-abdominal abscess
  • Intra-abdominal neoplasia
  • Reproductive disorders
• Assessing severity of equine colic - onset and duration

  • When did signs of colic first start?
  • When was the horse last seen 'normal'?
  • Were there any earlier mild signs (reduction in appetite)?
  • Acute (sudden) or chronic (insidious) onset?
• Assessing severity of equine colic - nature of signs

  • What signs are being displayed?
  • Are they constant, persistent, intermittent?
• Assessing severity of equine colic - progression

  Are signs progressing (mild to severe)? How quickly?
• Equine colic signs by severity

  • Mild signs – restless, pawing, flank watching
  • Moderate signs – lying down flat out, groaning
  • Very fractious, violent rolling
  • Dull, unresponsive
• Assessing severity of equine colic - pain

  • Pain will only cause a mild-moderate increase in heart rate (40-60bpm)
  • Marked-severe tachycardia (>60bpm) is a sign of cardiovascular compromise
• Assessing severity of equine colic - hydration

  Moisture content of oral MM is an assessment of hydration status - moist = normal; tacky or dry is dehydration
• Assessing severity of equine colic - gut sounds

  Auscultation of GIT has some degree of specificity but low degree of sensitivity - hypermotility = increased smooth muscle activity, local hypomotility = localised stasis of GIT, general absence = GIT ileus
• 'Spasmodic' colic

  Very common, associated with spasm of smooth muscle in small or large intestines, increased motility of gut
• All Colics can present with "spasmodic" periods of pain
• Risk factors for equine colic

  • Increased stress
  • Change in diet
  • Restriction in movement
  • Pain
• Large colon impactions


  Accumulation of ingesta in the left ventral colon at level of pelvic flexure, interferes with passage of ingesta and reduces GIT function and motility
• Treating large colon impactions

  1. Enteric fluids - Bolus(es) of isotonic fluids, 5-8L can be given every 2hrs

  2. Purgatives - Liquid Paraffin, Magnesium Sulphate (Epsom Salts)