Mis à jour : 5 avr. 2020
Introduction Colic is a life-threatening disease that affects horses’ gut. It is currently the number one cause of death in the horse industry (Loving, 2009, McCurnin’s, 2010). In the United States, 4,2% of horses have colic each year, 1,4% needs to go into surgery and 11% of colic result in death of the animal (Loving, 2009). Colic are really rare in the wild equine and common in domesticated horses (NRC, 2015), the problem is probably related to nutrition and horse management. Colic occurs when there is a disturbance in the digestive tract, it is important to know what is colic, being able to recognize the clinical sign, know the risk factors, the treatment and the prevention tips. All those things will help a horse owner to do the right thing at the right time and may help them save the life of their beloved horse.
What is colic?
Colic is principally a word used to talk about any abdominal pain in horses (NRC 2015, McCurmin’s 2010). There is more than one type of colic and each one is caused by something specific to them. They all cause a lot of pain to the horse and need to be treated quickly as they can be life threatening. Let’s start by knowing the different types of colic:
Impaction colic: Impaction occurs when a material obstructs the colon, partially or entirely (Loving, 2009). The obstruction prevents proper function of the gut. It can stop entirely the passage of the bowel through the intestine, which means that everything that the horse eats is blocked by the impaction and cannot pass through. Impaction colic is responsible for 8 to 10% of all colic (Loving, 2009).
Form of known sources of impaction colic:
Sand colic: Sand colic is developed when a horse is fed directly on a sandy soil or when he directly eat sand (coliccrusade.com). Sand therefore accumulates in the intestine and can cause severe irritation to the intestinal mucosa (Loving, 2009). With time sand will continue to accumulate and cause impaction, gas accumulation and displacement of the colon. In the worst case it can cause intestine rupture and death. An estimation of around 30% of the colic case is due to sand colic (NRC, 2015).
Enteroliths: Enteroliths are stone-like mineral formations. It forms by mineral salt deposit around a foreign body in the intestine (Loving, 2009, coliccrusade.com). It can cause a lot of pain, obstruct partially or totally the intestine and can even result its rupture.
Gas colic: Gas colic is caused by an accumulation of gas in the gut (myhorseuniversity.com), this cause distention and pain. When intestinal motility slows down, fermentation continues and gas accumulation occurs (Loving, 2009). With the distention resulted from gas accumulation, intestines can be displaced.
Torsion/intussusceptions/displacement colic: Torsion is when a part of the gastrointestinal (GI) system get twisted, intussusceptions is when the intestine slip back into itself and displacement is when a portion of the GI system get displaced in an inappropriate position (Loving, 2009). All of those problems are extremely painful for the horse and will almost always need surgery to be corrected.
Spasmodic colic: Spasmodic colic is due to spasms of the intestine smooth muscles which cause discomfort and pain (Loving 2009, myhorseuniversity.com).
Parasitic colic: Parasitic colic is the result of an important parasite level in the horse GI tract. Small strongyles cause inflammation to the GI mucosa when they become encysted. Large strongyles migrate through blood vessels and interfere with GI blood circulation. Ascarids can cause obstruction through the intestine lumen (Loving, 2009). Other parasites can cause injury to the GI tract and can even perforate it, which can lead to septicemia and death.
Observation is really important as the first clinical sign can be really subtle. Each horse owner knows his horse and it is important to note and explore every change in horse’s behaviour as it can be the first sign of health issues. Less appetite or change in the frequency or consistency of feces (too dry, covered of mucus or too sloppy) may indicate colic (Loving, 2009).
Pain can be classified in three categories: mild, moderate and severe. These categories can help to assess the severity of the disease as it is directly correlated to abdominal pain level (McCurmin’s, 2010).
Mild pain is shown with a horse that will start to paw, look at his flank, frequently try to urinate, play with the water in is buckets, do flehmen and stretch himself (McCurmin’s, 2010, Loving, 2009).
All the previous clinical signs can be performed by the horse at this stage, but horse can show more signs like an elevated heart rate (more than 40 beat per minute), anxiety, agitation, lie down and get up often and start to want to roll (McCurmin’s, 2010).
Previous clinical signs can also be observed in severe pain, but pawing will be constant, horse will try to kick himself on the abdomen, he will be really agitated, be sweaty, he will more violently try to lie down, almost throw himself on the ground and try to roll more vigorously (McCurmin’s, 2010, Loving, 2009). At this point, horse can be dangerous for himself and for the handler, caution is needed when horse is manipulated.
Sand colic: detection can be made with the help of a stethoscope under the horses’ abdomen. Sound will sound like the sea you ear in a seashell (Loving, 2009). There is a simple test that can be performed at home with a long disposable examination glove, simply put some fresh feces that didn’t touch the ground, add water and homogenize it. Let it rest for ten minutes and look if there is sand in the fingers.
Gas colic: distention can sometimes be seen at distance and it is possible to do a simple test to see if there is gas accumulation: by doing percussion to the horse abdomen while listening to the sounds that are produced with a stethoscope placed on the right paralumbar fossa (McCurmin’s, 2010). If a “ping” sound is eared, it is probably gas colic.
Always keep in mind that early treatment is really important in colic. Being able to recognize the early clinical sign of a horse in colic can make the difference between life and death. If any colic is suspected, it is really important to contact a veterinarian as quickly as possible.
For sand, enteroliths, torsion and parasitic colic, cause can be easy to find, as their name tells it. But for spasmodic, gas or impaction colic, causes are not always clearly identifiable (NRC, 2015), but there are some known risk factors.
Any change in feeding habits (changing hay types, change in routine of feeding, sudden change in concentrate quantity or types, etc.) can raise the risk of developing colic by 5 to 9,8 % (NRC, 2015). Other risk factors are: limited access to water, transportation, horse nervousness, too much or not enough exercise (Loving, 2009).
A major factor for impaction is the anatomy of the GI tract itself. The intestine narrows a lot in some of its section (Livesey). Ileal orifice, pelvic flexure and beginning of the transverse colon are those sections where the impactions are most likely to occur (Kainer and McCraken, 1998). There is also the fact that almost all the colon is loose in the body, there are two loops only that are attached. This is why it can become easily displaced or twisted (Livesey). Colon is also the major site for water absorption, the fecal balls are formed there, and if there is not sufficient water in the bowel, it will dry out and cause impaction.
A high concentrate and low fibre diet can raise the risk of a horse to develop colic (NRC, 2015). When the quantity of concentrates is too high, it cannot be all degraded in the small intestine and it goes to the hind gut. Starch, which is the carbohydrate of grain, is rapidly fermentable and will create lactate acidosis in the hindgut (NRC, 2015, Leglise, 2016). This can result in intestinal microflora imbalance and cause colic. According to NRC (2015), increase risk of colic of 4,8 to 6,3 percent occurs when 2,5 Kg/day to even more than 5Kg/day concentrates are given. If more energetic food is needed, oil can be added to a reasonable amount of concentrates. Oil can be a really good way to raise the caloric intake of a horse (Leglise, 2016, Cavanagh and Turnan, 2014) Fibre can help to retain water in the colon which can ensure that bowel will not dehydrate too much (Loving, 2009). High fibre died is really important for the health of the GI tract of the horse and when horses spend less time in the pasture or field, risk for colic increase by three times (NRC, 2015).
The antibiotic use can also raise the risk of colic, as antibiotics will not just affect the bacteria of the infection but can also affect the good bacteria of the GI tract of the horse. Again, this can result in an intestinal microflora imbalance, encouraging acid producing bacteria. This can lead to acidosis of the hindgut and result in colic (Cavanagh and Ternan, 2014).
Lack of exercise or abrupt change in pasture or field turnout can increase the risk of colic, as slow exercise can contribute to the GI health. 53,7% of obstruction colic are caused by a recent change in turnout time (Loving, 2009). Confinements slow down the GI motility which can make the bowel pass too slowly through the colon. This can dehydrate the bowel as too much water is absorbed.
Selenium toxicity can also be a cause (Cavanagh and Ternan, 2014).
First thing to do is to contact a veterinarian.
Severity of pain, pulse, temperature, gastrointestinal motility, respiration, CRT (capillary refill time), mucous membrane colour and hydration are all parameters that can help your veterinarian to determine the treatment needed for the horse (McCurnin’s, 2010). Veterinarians can proceed to a rectal examination and an ultrasound; both examinations can be an excellent way to see if there is any displacement or abnormal thing with the intestine.
The priority of treatment when a horse is suspected of being in colic is to manage the pain properly (-Agonists are often used) (McCurmin’s, 2010). A horse in strong pain can be dangerous for himself and for people around, so it is important to first manage the pain. Stronger is the pain, less the horse will respond to sedation and pain killers.
Feed should be removed, then mineral oil can be given to the horse, if he is dehydrated it is really important to give him IV fluid as it can help to rehydrate his bowel and maybe help to solve impaction. A veterinarian can proceed to a nasogastric intubation, this way the excess of gas or reflux can get out of the stomach (which will be really relieving to the horse) and he can give more mineral oil to the horse with less difficulty and in bigger quantity.
Walking a horse can help with spasmodic and gas colic, but when pain gets too severe it can be counterproductive as it reduces energy reserves available for the horse. It is important not to force him to walk when he is in too much pain or if he gets tired and weak. If walking a horse doesn’t seem to make him more comfortable, it is probably better to stop doing it (Loving, 2009). On the other hand, if the horse is too agitated (but not dangerous) it can be helpful to walk him in an attempt to distract him (Loving, 2009).
When a horse is really infested of worms, it is important to establish a special deworming program with a veterinarian. If horses get treated drastically with a dewormer, parasites can cause obstruction as they massively die. So a progressive deworming program is needed.
Fortunately, colic episode that demands a surgical intervention represents a really small percentage of the population and most of them can be treated with medication and proper veterinary care (McCurmin’s, 2010).
A really important part of colic is caused by improper management of equine nutrition. Horses should be fed small meals all day long (as intestine motility is stimulated by the volume of food ingested (Loving, 2009)), have ad libitum access to clean fresh water, a block of salt and have a proper fibre intake, as fibres can increase the water content of the colon by 30% (Loving, 2009) which can help to reduce the risk of impaction. When the episode of colic is over, feeding management will be an important part of the “after”. Gradual feed reintroduction will be a critical part of the recovery and will need to be highly supervised (Leglise, 2016). Recovery time will depend on the severity of colic and the intervention needed, in consequence, food reintroduction will be made at different times, it is a case-by-case. After that, special care should be provided with nutrition management of the horse. Making sure that the horse feeding routine is as punctual as possible, that his diet is composed of a minimum of 60% forage (Loving, 2009) and not too much concentrate, that changes in feeds are kept to a minimum and that when it is really needed, it is made really gradually to be sure not to disturb GI health. Turnout the horse as long as possible is also a great way to help is GI motility, making sure that no abrupt change in turnout time is made.
Feed the minimal amount of concentrates. Large concentrate meal can lead to an exaggerated fermentation in the gut of the horse. This can cause an alteration in the fluid balance of the gut (NRC, 2015). This could lead to impaction colic. If horse needs more caloric intake, oil can be used.
Horses need to have a high fibre-based died, this help retain water in the colon and keep the bowel hydrated. High quality hay is really important and horses should be fed a minimum of 60% of his diet or a minimum of 1% (NRC, 2015) of his body weight in forage.
Any change into feed need to be really progressive, introduction of new feed should be extended into three weeks to give the time to the GI microflora to adapt to it (Cavanagh and Ternan, 2014). Keep food change to a minimum and try to keep the same hay source all year round.
A good deworming program is also important in the prevention of colic, as parasites can really be dangerous to horses. Ask your veterinarian to make a good deworming program for your horse.
Give horse ad libidum access to water, lack of water can dehydrate the bowel and cause impaction (Marteniuk and all. 2009). It is important to have clean, fresh and temperate water at all time. Snow is not enough to fulfill the water intake needs of horses and freezing cold water can discourage a horse to drink (Loving, 2009).
One should also gives his horse loose salt in their daily concentrates ration. Indeed, salt licks are not enough. Some horse doesn't lick them enough. So giving them salt in their daily ration is the best way to ensure that they ingest enough salt. Salt will helps to ensure that horse will drink enough in his day. Moreover, owner should always keep an eye in their horse to spot which ones are good drinker and which ones are not. Horse that do not drink enough should always be given salt or electrolytes. But salt benefit to all horses, we are never too careful. I personnaly encounter a horse that was deprived of fresh water in winter and lost his thirst reflex. If not given electrolytes every day, he would just not drink.
Horse is an animal of habits, feeding the same amount of food in a regular schedule is important. Avoid change in frequency and schedule of feeding as this can cause stress to horse and disturb his GI tract (coliccrusade.com, Loving, 2009).
Horses’ teeth are examined by a veterinarian each year to make sure any problem is identified and treated. Good mastication the first point of a healthy GI tract (Loving, 2009, coliccrusade.com).
Avoid feeding a horse directly on the ground, as the horse may eat some sand, dirt or foreign object which can lead to sand or impaction colic (Loving, 2009, myhorseuniversity.com).
Give horses occasion to exercise by giving them maximum turnout time possible (Loving, 2009).
Causes are not always easy to find with some types of colic, there is still unclear link between colic and some cause, but some nutritional management tips can reduce those risks. However, it is important to keep in mind that there is always a risk and knowing the first clinical sign and what to do in that case is also really important. A fast response to the first clinical sign can make the difference for the prognosis. However, prevention is always better, and adoption of a good nutrition management now can help to reduce the risk to deal with colic later.
McCurmin, D.M, Bassert D.M, Clinical Textbook for Veterinary Technicians, Seventh Edition, Saunders Elsivier, 2010
Committee on Nutrient Requirements of Horses, Nutrient Requirements of Horses, sixth revised edition, Board on Agricultural and Natural Resources, Division on Earth and Life Studies, National Research Council (NRC) of The National Academies, The National Academies Press, 2015
Loving, N.S, Nouveau Manuel Vétérinaire Pour Propriétaire de Chevaux, VF of All Horse Systems Go (2006), Translated by Dr, Morin,P, Édition Vigot, 2009
Cavanagh and Ternan, From The Horses’ Mouth Nutrition, Feeds and Feeding, First Edition, Matrice Multimedia, 2014
Kainer, R.A, McCracken, T.O, Horse Anatomy a Coloring Atlas, Second Edition, Alpine Publication 1998
Livesey, M, The structure, Function and Dysfunction of the Equine Digestive System, Clinical studies, Ontario Veterinary College, Equine Research Center.
Marteniuk, J and Carr, E, Horse Health Tips for Extreme Cold Weather, Michigan State University College of Veterinary Medicine, January 14 2009, Article # 13448
Leglise, A-S, DVM, Chirurgie: adapter la ration en période péri-opératoire, Dossier nutrition, Cheval Santé, Février-Mars 2016, #102
Colic Crusade, Crusade Againt Equine Colic, Presented by Succeed, Digestive Conditioning Programm, 2016
My Horse University, Equine Colic: Causes, Symptoms, Treatment and Prevention, adapted from the online equine nutrition course, Michigan State University, 2012