Colic - Myths, Reality and Management 

Colic is  the number one killer of horses, a catch-all label for a multitude of illnesses and one shared experience among horse owners that we’d prefer to not to experience. If this column raises more questions than answers, please discuss colic with your Veterinarian or e-mail me for additional reading and column references.

What is colic?

Simply put, colic is gut pain in horses.

What are the symptoms?

The symptoms can vary from horse to horse but can include any of the following:

Pawing, rolling, biting/kicking at the side, sweating, fever, change in gut sounds, off feed, irregular stools, not wanting to stand/move, “parking” out, irregular pulse, irregular respiration as well as other symptoms.

What causes colic?

The causes of colic vary. Some common causes include:

1. Parasites.
2. Changes in feed, poor quality feed, feed imbalances.
3. Lack of constant access to clean, fresh water.
4. Lack of regular exercise, turn-out.
5. Medical conditions.
6. Unknown/undiagnosed causes.

PARASITES

Heavy parasite loads interfere with normal digestion and healthy gut flora. Furthermore, they can scar and damage the intestine and other organs causing difficulty in maintaining homeostasis (balance). One study found that horses de-wormed more often had higher incidents of colic. This fact implies that management, not frequency of worming is the key to a successful parasite control program (see box). It also may mean that frequent worming is so disruptive to the normal gut flora that imbalances following worming may predispose a horse to colic. Check with your Veterinarian about the use of probiotics if you must use commercial wormers frequently versus improved management practices to control parasites.

FEED

When feed is changed abruptly the horse’s gut pH changes rapidly as well, causing production of gas. This gas causes pain, commonly called gas colic. In addition, not providing enough roughage (hay) and over feeding of concentrates (grain) creates imbalances in a system that is designed to sustain itself mainly on forage. Mold and toxins in feed can also cause a horse to colic. Contrary to rumor, quality pellets or certain grass hays do not consistently cause colic. Then are often blamed when changes are made too quickly, no other reason is apparent and/or poor and inconsistent management practices are truly to blame. Plan on at least 10 days to implement any feed changes, especially when switching hay types or sources.

WATER

Water should be clean, fresh, free of additives and available at all times. In cold weather, studies show that horses drink less if the water tank is not kept free of ice. The risk for colic is 5 times higher for horses that are not getting water as a “group” (ie getting water in a communal water tank or pond/stream versus an individual source like a stall bucket or waterer). Maybe the social aspects of drinking together encourage more water intake?

A common practice many horse owners use to stop rodents from drowning in the water tank is to float a piece of wood in the tank. DO NOT use treated lumber for this! It is “treated” with chemicals. Chemical so toxic that treated lumber is now banned from use on new public park picnic tables and eating areas.

EXERCISE

Horses are designed to graze and move. With small stomachs and long intestine they should eat small meals frequently as they move along. Stalls, feedlots, small pens and poor feeding schedules with large, single meals all contribute to the increased risk of colic. Show horses, conversely, are 2.3 times more likely to colic than horses not shown. This does not necessarily equate to the physical activity of showing, but could correlate to the stress of hauling, unfamiliar water and/or feed. Bottom line is that horses need to move and the worst place for most horses is standing in a stall or small pen. Horses belong outside as much as possible (even in winter) with free access to shelter that blocks the wind and rain and snow.

MEDICAL CONDITIONS

Medical conditions that may cause or lead to colic include enteroliths (stones), lymphosarcomas (growths), obstructions, impactions, colon displacement/torsion and previous episodes of colic. Gray horses are more prone to lymphosarcomas. Some conditions may only be treated successfully with surgery.

What horses are at greatest risk to colic?

Most studies show that horses between the ages of 2 and 10 years are at greatest risk to colic. Insurance studies claim that Arabian horses are the breed most likely to colic but no data was available to show the percent of Arabians insured versus other breeds. Another regional study stated that Thoroughbreds are at highest risk and Arabians are the lowest risk group. Most studies show that mares are more likely to colic, especially mares that have foaled. Yet another insurance study stated that show-use geldings were the highest risk group. Additional risk factors include:

-Previous abdominal surgery

-In training

-Previous episode(s) of colic

-Recent change in stabling

-Recent change in feed (especially hay)

-Changes in the weather (although likely due to a change in exercise or feeding schedule as a result of the weather, versus the weather itself)

What horses are least likely to colic?

-Horses used for lessons or kept as “pets”.

-Foals and yearlings up to 18 months.

-Horses watered in groups.

-Horses kept at home (cared for by owner) versus boarded.

What can horse owner’s do to minimize the risk of colic?

1. Make any feed changes as gradually as possible.
2. Feed in feeders (at ground level), not on the bare ground or in feeders unnaturally elevated.
3. Feed hay before grain since hay is digested quicker than grain (to help avoid impaction colic).
4. Feed many small meals (or free-coice) versus one or two large meals.
5. Keep your horses teeth in good condition.
6. Minimize stress and provide appropriate turn-out and exercise.
7. Buy top quality feeds
8. Provide a clean water source along with an appropriate trace mineral salt block.
9. Keep horses off pastures fertilized with synthetic fertilizer for at least two months.
10. Devise a parasite prevention program and management plan with your Veterinarian or equine professional

 
SUGGESTED PARASITE MANAGEMENT PROGRAM

(This is just an example of an effective parasite control program that may reduce the risk of colic in horses. Please consult a Veterinarian or Equine professional for a program suited to your specific needs) 

 

Case #1 An existing herd

Step 1) Take fecal samples to the Veterinary Clinic for analysis.

Step 2) Worm all horses at the same time with a product (or products) recommended for your specific infestation. Remember that different wormers are effective on different parasites and that special doses may be necessary for tape worm and encysted worms. Follow the directions on the product or consult your Veterinarian for dosage instructions.

Step 3) The following day, begin all horses on a Veterinarian recommends daily wormer for 30 days. Studies have shown that administering a one-time purge wormer (any of the typical tube wormers) results in the death of many emerged worms.

However, recent research suggests that their death may actually send a chemical signal to encysted parasites (parasites embedded in tissue) to now emerge, creating a brand new influx of parasites immediately after the worming. For this reason, a daily wormer can be given for at least 30 days following the worming in an attempt to disrupt the cycle and lower the total parasite load.

Step 4) During this 31 day process, pick up manure and remove it from horse areas (practical in small turnouts and pens). This helps prevent horses from eating feces that may contain shed eggs. It is also a good management practice to not keep manure in areas where horses are housed or worked as horses can routinely shed salmonella and tetanus in their feces. This can pose a threat to other horses and people as well. Also utilize feeders to avoid contamination. Water tanks make excellent hay feeders as they are easy to clean and allow the horse to stretch down to ground level to eat in an optimal position.

Step 5) Re-submit fecal samples for testing. Repeat the cycle with different products if recommended by your Veterinarian.

Step 6) Submit fecal samples at regular intervals (time frame depending on your specific environment) for analysis to determine worming needs.

Case #2 Introduction of a new horse

Step 1) Quarantine the horse away from other horses (no shared areas where fecal exposure to others can occur).

Step 2) Submit a fecal sample for analysis

Step 3) Worm the horse as suggested and implement the 30 days of daily wormer. Follow the management guidelines given above.

Step 4) Re-submit the fecal sample for analysis, introduce the horse to shared areas when parasite load is at an acceptable level. 

Still more notes: Studies of daily wormers have shown that they are very effective when animals are kept in dry lot conditions. They are far less effective when horses are on live pasture as the living grass is an integral part of the parasite life cycle. For this reason, be thorough when managing parasites in horses that are grazing. Furthermore, avoid allowing horses to graze in areas that are overgrazed or common horse areas (such as show grounds, fairgrounds etc…). Parasite loads on these areas can be so heavy that a horse can pick up enough eggs in fifteen minutes to cause colic