WATCH: In this video, large animal internal medicine specialist Dr. Claudia Cruz Villagran gives an overview of a challenging disease in horses — equine colic. Video length: 26:27. 

Click the buttons below to view the above video in five sections: 

• Video 1 | Equine colic: diagnostic and treatment tools (5:00)
• Video 2 | What are the signs of colic? (3:17)
• Video 3 | Equine colic: types, diagnosis and prevention (7:46)
• Video 4 | Gas colic and impaction colic (9:24)
• Video 5 | Colic and the use of banamine (1:49)

• Link to all videos
• Video 1
• Video 2
• Video 3
• Video 4
• Video 5

Closely monitoring a horse and measuring its vital signs can help owners determine if something is wrong with their animal: an increased heart rate and an elevated temperature are both signs that the horse is in some type of distress.

But when in doubt, calling your veterinarian is recommended. With colic, the rule of thumb is that the sooner a veterinarian can assess the horse’s condition, the better.

• Contact VMC
• What to expect: colic
• 24-hour emergency services

Diagnosing colic

During a field service visit, the veterinarian must first determine whether colic is actually the problem. The first step is to perform a physical examination, which includes a rectal exam and the insertion of a nasogastric tube through the horse’s nose and into its stomach to remove excess fluid.

During the rectal examination, the veterinarian may feel a dry, hard mass of feed content — pointing to impaction colic. If the equipment is available, the field service clinician may also want to perform an ultrasound examination to check specific areas of the horse’s abdomen.

Once the physical exam is completed, the veterinarian will generally know what kind of colic the horse suffers from — and whether treatment in the field is sufficient or if the horse needs further treatment at a veterinary referral centre.

While it can be difficult to load a horse that is in pain and wants to roll, the veterinarian can give the patient a combination of sedatives and pain killing drugs that can help to stabilize the animal long enough for it to be transported by trailer.

Once the horse arrives at the referral centre, the clinical team usually conducts another physical examination that includes a rectal exam since the loading process and transport can be enough to change the horse’s condition.

Next, a veterinarian will perform a blood test to check electrolyte levels and how well the horse is perfused. Additionally, another ultrasound examination may help the veterinarian to further assess the horse’s gastrointestinal changes.

Treatment

Medical colic

Cases of medical colic can be treated in a variety of ways, but the main thing is to control the pain with analgesic (painkilling) drugs and anti-inflammatory medication.

The other key issue is to ensure that the horse doesn’t get dehydrated, which can occur very quickly in horses that colic. Rehydration in horses can be performed orally through a nasogastric tube (orally) that gives the horse fluids or water with electrolytes.

If the dehydration becomes worse, the horse may also be given fluids into the vein; in some cases, the clinicians can give the patient fluid orally and intravenously at the same time. Very mild dehydration doesn’t require this measure, but especially in cases of impaction colic, the doubling of fluids can help to resolve the colic issue more quickly. Typically, a veterinarian will keep the horse on fluids until it’s rehydrated or the colic is resolved.

Surgical colic

In cases of surgical colic, the veterinary team will conduct a procedure known as an exploratory laparotomy during which the horse is put under general anesthesia. The surgical specialist opens the patient’s abdomen and thoroughly assesses all structures found in the abdominal cavity to determine what’s causing the pain.

If possible, the surgeon will resolve the cause of colic — the type of surgical treatment depends on the type of colic. Once the incision is closed, the horse can then recover from the general anesthesia. The post-surgical treatments vary case by case, but usually, the initial diet consists of slowly feeding the horse small amounts of grass or hay and giving it access to water.

Colic is common in horses due to their unique anatomy and physiology, although certain breeds can be more inclined to experience different types of colic.

Mares (before and after foaling)

Mares in the last stage of gestation are especially vulnerable to colic. They can develop uterus torsion (when the uterus twists around itself and causes severe colic symptoms), and in these cases, it can be difficult to save both mare and foal.

The two-week period after giving birth can also be a risky time for a mare. After foaling, the mother’s gastrointestinal (GI) tract has to adapt to having more space and the different way that food travels through the GI tract, putting the mare at risk of displacement.

Certain times of year

Unfortunately, colic can strike at any time and has many risk factors. Each season, horses have access to different feed and hay types.

While changing seasons don’t usually affect horses that are stabled year round, horses that are kept on pasture are at a higher risk of developing season-related colic since abrupt changes in diet and the moisture level of the diet can increase the likelihood of a horse developing the condition.

Changes in diet will change fermentation in the horse’s large intestine. The population of organisms in the large intestine that are needed for proper digestion will mirror the food that is presented to them, but this adaptation takes time. That’s why gradual diet changes (over at least five to seven days) are always advisable for horses.

Spring

During the spring, horses make the transition from an all-hay winter diet to a spring diet that includes highly fermentable green grass. The richer grass diet can change the level of gas in the gut and cause gas colic.

Fall and winter months

Another tricky time is during the transition between the fall and winter months when the horse’s diet has less moisture and the source of water may freeze over, leaving the horse with little to no water.

Horses are also less inclined to drink water if it’s too cold, so horse owners should consider investing in a heated watering bowl or tank heater to keep the water at the ideal temperature of about 10 degrees Celsius (in the range of seven to 18 C).

While snow was once considered to be an adequate watering method, veterinarians don’t recommend it since horses are usually not able to eat enough snow to cover their requirements — leading to dehydration and eventually impaction colic.

Some horses that are acclimated to winter weather conditions can meet their water requirements from snow. However, there are health risks associated with snow consumption including the length of adjustment period as horses learn to ingest snow, the actual water content of the snow, and local water intake. Some wild horses can obtain their water needs from snow, but the risk of colic and reduced feed intake is significant for domestic horses.

Inactivity

During winter, inactivity can be a colic risk factor. Horses should be provided with regular turnout unless the weather is very bad. While turning out horses to snow-covered pastures can keep them moving, frozen pasture grass shouldn’t be used as their primary feed source.

Horses usually don’t like eating frozen grass, and they may not eat enough to meet their nutritional needs. Spreading their hay out across the snow-covered pasture can keep your horses moving, plus it ensures that they get enough to eat on a daily basis. When weather conditions are so bad that the horses are barely moving, ensuring adequate water intake by having the heated water source next to the feeding area will help to prevent impaction colic.

Make gradual changes in feed. Changes in diet will change fermentation in the horse’s large intestine. The population of organisms in the large intestine that are needed for proper digestion will mirror the food that is presented to them, but this adaptation takes time. That’s why gradual diet changes (over at least five to seven days) are always advisable for horses.

Have fresh water and a source of available throughout the year. Horses drink more when the water is warmed above freezing during cold weather. Regular salt intake will also stimulate horses to drink more. For an adult horse, normal salt intake should be about one to two ounces of salt per day. Waterers should be cleaned regularly, and clean, fresh water should always be available. Water heaters should be carefully inspected for worn wires or other damage, plus the water should be checked for electrical sensations or shocks.

Adequate shelter and feed. Ensure that your horses have adequate shelter and access to feed and water throughout the winter — especially during stormy weather. 

Regular veterinary care. Schedule regular health and teeth examinations, and maintain a regular deworming program.  

As part of the WCVM's EquineED Talks series for the horse community, large animal surgeon and PhD student Dr. Michelle Tucker gave the following presentation on equine colic.

Horse Health | WCVM

• Horse Health Lines
• WCVM Today
• Townsend Equine Health Research Fund (TEHRF)