MSU Extension 4-H Science Blast in the Class

Educational Elements

Key Concept:

Awareness of impaction colic and evaluation of horses’ risk

Overview:

The Healthy as a Horse: Investigating Impaction Colic lesson plan is designed to teach participants about impaction colic and the horse management principles used to prevent it. The lesson can be taught with or without the accompanying video. In both lesson methods, participants evaluate a pasture and develop a list of things that may decrease or increase the risk of impaction colic.

Age Level:

Ages 13 to 18

Life Skills:

Critical thinking, problem solving

Success Indicators:

After participation in this activity, participants will be able to: 

• Define the term “colic” as well as identify three general types of colic in horses. 
• Explain horse management principles that can be used to prevent impaction colic. 
• Evaluate pastures to determine the risk of impaction colic in horses that graze there.

Materials & Methods

Preparation Time: 

• Video Lesson: 10–15 minutes 
• On-farm lesson (no video): 30 minutes

Lesson Time:

30–45 minutes

Space: 

Video lesson: Enough seating for all participants, a place for the facilitator to stand and write comments from participants, room for projection equipment and screen or wall. 

On-farm lesson (no video): A pasture with grazing horses, enough seating for all participants, a place for the facilitator to stand and write comments from participants.

Materials:

Video lesson:

• Healthy as a Horse: Investigating Impaction Colic video: https://youtu.be/ZiMZyzxxvaM
• Flipcharts, dry erase board or blackboard, or easel pads and easel
• Writing utensil for facilitator (based on paper or board selection)
• Note-taking materials for each group recorder (paper and pens, cell phones with note app, or other means of taking notes) On-farm lesson (no video):
• Access to a pasture with horses grazing, or recently having grazed
• Flipcharts, dry erase board or blackboard, or easel pads and easel
• Writing utensil for facilitator (based on paper or board selection)
• Note-taking materials for each group recorder (paper and pens, cell phones with note app, or other means of taking notes)

Vocabulary: 

• Cecum – A space or pouch at the beginning of the large intestine. 
• Colic – Serious abdominal pain. 
• Depressed – A depressed horse may lack interest in its surroundings, feed, people, and other horses. It may appear withdrawn and may stand with its head in a lower position than normal. 
• Digesta – Partially digested feed in the digestive tract. 
• Euthanasia – Humane death; putting to death or allowing to die painlessly. 
• Gas colic – Colic caused by excessive production of gas in any portion of the horse’s intestinal tract. 
• Herbivore – An animal that eats only plants. 
• Impaction – Blockage or obstruction. 
• Impaction colic – Pain caused by obstructions in the bowel, typically in areas where the large intestine changes in direction or diameter. 
• Nonruminant – A simplestomached animal. 
• Prognosis – A forecast of the likely outcome of a disease or situation. 
• Spasmodic colic – Painful contractions of the smooth muscle in the intestines.

Background Information:

What is colic in horses?

Colic in horses may be defined as serious abdominal pain caused by a variety of things. The degree of pain can range from mild to serious, depending on its cause. In some cases, colic may be fatal. In fact, colic is the number one killer of horses.

Common types of colic

Three common types of colic include gas colic, spasmodic colic, and impaction colic. While this lesson will focus on impaction colic, we will start with a definition of gas and spasmodic colic.

Gas colic is caused by excessive production of gas in any portion of the horse’s intestinal tract. Since sudden changes in feed may contribute to gas colic, owners must make sure that horses have constant access to good quality hay and clean water. Changes in feed should be gradual. If treated promptly, the chance of recovery from gas colic is usually very good.

Spasmodic colic is defined as painful contractions of the smooth muscle in the intestines. This type of colic typically responds well to treatment by a veterinarian. It may be caused by overexcitement or stress. Spasmodic colic is similar to indigestion in humans.

Impaction colic is caused by obstructions in the bowel, typically in areas where the large intestine changes in direction or diameter. These obstructions may be caused by dry, firm masses of feed, or foreign material such as dirt or sand. Impaction colic can be very serious, or even fatal, and often requires treatment by a veterinarian.

Signs of colic

A horse that is experiencing abdominal pain or colic may stretch its body, paw, roll frequently, look at its flank or belly, start to sweat, or seem depressed. Typically, a horse experiencing colic will demonstrate some, but not necessarily all, of these signs. Occasionally, a horse with colic will lie down and stay quiet, but not roll. If this is the case, you need not force the horse to walk, as tradition often dictates, although movement may help move the impaction along the tract. However, if the horse does start rolling violently, walk it until veterinary help arrives.

What contributes to impaction colic?

Horses are nonruminant herbivores. This means they eat fibrous feeds such as grass and hay, but they do not have large rumens to extensively digest the fiber like cattle and sheep do. As a result, the horse has a complex digestive tract, which includes a relatively small stomach, a small and large intestine that are both very long, and a “cecum” (a space or pouch at the beginning of the large intestine) that contains fiber-digesting microbes. Since the digestive tract is so long, it makes many turns to fit into the abdominal cavity of the horse, and it also changes in diameter periodically. These turns and diameter changes provide locations where dried feed and foreign substances may get caught, blocking the flow of “digesta” (partially digested feed) through the tract and causing an impaction, or blockage. If the impaction is not released, gas is produced, which enlarges the tract, producing pain, or colic. In severe cases, the tract may rupture, ultimately requiring the euthanasia of the horse to prevent further suffering.

Mature horses must consume at least 10 gallons of clean, fresh water daily – more in hot weather or when the horse is working. Water will help prevent the horse from dehydrating and keep feed moist, decreasing the risk of impaction colic. Make sure you always have salt blocks available. Top-dress loose salt on grain to encourage horses reluctant to drink.

Providing horses with good quality feed in a sufficient quantity will help prevent impaction colic as well. Mature horses will consume 1.0–2.0% of their body weight in feed daily, the majority of which should come in the form of hay or pasture. Hay or pasture should not contain many weeds or overly mature plants with tough woody stems as these also can cause impaction colic.

When horses overgraze pasture or are allowed to graze on sandy soil, they often consume dirt and sand that can block the cecum and colon, which can also cause impaction colic. Horses should never graze on sandy soil nor graze pastures to a grass height of less than 3 to 5 inches.