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Colic in horses is defined as abdominal pain, but it is a clinical symptom rather than a diagnosis. The term colic can encompass all forms of gastrointestinal conditions which cause pain as well as other causes of abdominal pain not involving the gastrointestinal tract.
Colic: Causes and Symptoms Colic is defined as any abdominal pain although horse owners typically refer to colic as problems with the gastro-intestinal tract. The causes of colic are numerous, but generally they are related to the anatomy and the microflora of the horse’s gastrointestinal tract. Some more common causes of colic include:-
• High grain based diets/Low forage diets
• Moldy/Tainted feed
• Abrupt change in feed
• Parasite infestation
• Lack of water consumption leading to impaction colic
• Sand ingestion
• Long term use of NSAIDS
• Stress
• Dental problems
Impaction: a blockage formed by something the horse has ingested
NSAID: non-steroidal anti-inflammatory drug
Figure 1. Parasites, such as strongyles can be a common cause of colic.
It is important to practice a deworming routine to prevent parasites in equine. (Refer Image right)
Antibiotics may lead to colic because they alter the microbial population in the gut, which in turn affects starch digestion. Dental problems may cause colic if the horse is unable to chew its food sufficiently. Older horses fed coarse hay are at greater risk of impaction colic.
Signs of colic include:-
• Pawing
• Rolling
• Bloating
• Sweating
• Distress
• Uneasiness
• Loss of interest in food and water
• Peculiar postures (sitting, stretching)
• Absence of gut sounds
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Numerous clinical signs are associated with colic. The most common include pawing repeatedly with a front foot, looking back at the flank region, curling the upper lip and arching the neck, repeatedly raising a rear leg or kicking at the abdomen, lying down, rolling from side to side, sweating, stretching out as if to urinate, straining to defecate, distention of the abdomen, loss of appetite, depression, and decreased number of bowel movements. It is uncommon for a horse with colic to exhibit all of these signs. Although they are reliable indicators of abdominal pain, the particular signs do not indicate which portion of the GI tract is involved or whether surgery will be needed.
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A diagnosis can be made and appropriate treatment begun only after thoroughly examining the horse, considering the history of any previous problems or treatments, determining which part of the intestinal tract is involved, and identifying the cause of the particular episode of colic. In most instances, colic develops for one of four reasons:
1) The wall of the intestine is stretched excessively by either gas, fluid, or ingesta. This stimulates the stretch-sensitive nerve endings located within the intestinal wall, and pain impulses are transmitted to the brain.
2) Pain develops due to excessive tension on the mesentery, as might occur with an intestinal displacement.
3) Ischemia develops, most often as a result of incarceration or severe twisting of the intestine.
4) Inflammation develops and may involve either the entire intestinal wall (enteritis) or the covering of the intestine (peritonitis). Under such circumstances, proinflammatory mediators in the wall of the intestine decrease the threshold for painful stimuli.
The list of possible conditions that cause colic is long, and it is reasonable first to determine the most likely type of disease and begin appropriate treatments and then to make a more specific diagnosis, if possible. The general types of disease that cause colic include excessive gas in the intestinal lumen (flatulent colic), simple obstruction of the intestinal lumen, obstruction of both the intestinal lumen and the blood supply to the intestine (strangulating obstruction), interruption of the blood supply to the intestine alone (nonstrangulating infarction), inflammation of the intestine (enteritis), inflammation of the lining of the abdominal cavity (peritonitis), erosion of the intestinal lining (ulceration), and “unexplained colic.” In general, horses with strangulating obstructions and complete obstructions require emergency abdominal surgery, whereas horses with the other types of disease can be treated medically.
The history of the present colic episode and previous episodes, if any, must be considered to determine whether the horse has had repeated or similar problems or whether this episode is an isolated event. The duration of the present episode, the rate of deterioration of the horse’s cardiovascular status, the severity of pain, whether feces have been passed, and the response to any treatments are important pieces of information. It is also critical to determine the horse’s deworming history (schedule, treatment dates, drugs used), when the teeth were floated last, if any changes in feed or water supply or amount have occurred, whether or not the horse is a “cribber,” and whether the horse was at rest or exercising when the colic episode started.
The physical examination should include assessment of the cardiopulmonary and GI systems. The oral mucous membranes should be evaluated for color, moistness, and capillary refill time. The mucous membranes may become cyanotic or pale in horses with acute cardiovascular compromise and eventually hyperemic or muddy as peripheral vasodilation develops later in shock. The capillary refill time (normal ~1.5 sec) may be shortened early but usually becomes prolonged as vascular stasis (venous pooling) develops. The membranes become dry as the horse becomes dehydrated. The heart rate increases due to pain, hemoconcentration, and hypotension; therefore, higher heart rates have been associated with more severe intestinal problems (strangulating obstruction). However, it is important to note that not all conditions requiring surgery are accompanied by a high heart rate.
An important aspect of the physical examination is the response to passing a nasogastric tube. Because horses can neither regurgitate nor vomit, adynamic ileus, obstructions involving the small intestine, or distention of the stomach with gas or fluid may result in gastric rupture. Passing a stomach tube may, therefore, save the horse’s life and assist in diagnosis of these conditions. If fluid reflux occurs, the volume and color of the fluid should be noted. In healthy horses, it is common to retrieve <1 L of fluid from the stomach.
The abdomen and thorax should be auscultated and the abdomen percussed. The abdomen should be auscultated over several areas (cecum on the right, small intestine high on the left, colon lower on both the right and left). Intestinal sounds associated with episodes of pain may indicate an intraluminal obstruction (eg, impaction, enterolith). Gas sounds may indicate ileus or distention of a viscus. Fluid sounds may indicate impending diarrhea associated with colitis. A complete lack of sounds is usually associated with adynamic ileus or ischemia. Percussion helps identify a grossly distended segment of intestine (cecum on right, colon on left) that may need to be trocarized. The respiratory rate may be increased due to fever, pain, acidosis, or an underlying respiratory problem. Diaphragmatic hernia is also a possible cause of colic.
The most definitive part of the examination is the rectal examination. The veterinarian should develop a consistent method of palpating for the following: aorta, cranial mesenteric artery, cecal base and ventral cecal band, bladder, peritoneal surface, inguinal rings in stallions and geldings or the ovaries and uterus in mares, pelvic flexure, spleen, and left kidney. The intestine should be palpated for size, consistency of contents (gas, fluid, or impacted ingesta), distention, edematous walls, and pain on palpation. In healthy horses, the small intestine cannot be palpated; with small-intestinal obstruction, strangulating obstruction, or enteritis, the distended duodenum can be palpated dorsal to the base of the cecum on the right side of the abdomen, and distended loops of jejunum can be identified in the middle of the abdomen.
A sample of peritoneal fluid (obtained via paracentesis performed aseptically on midline) often reflects the degree of intestinal damage. The color, cell count and differential, and total protein concentration should be evaluated. Normal peritoneal fluid is clear to yellow, contains <5,000 WBCs/μL (most of which are mononuclear cells), and <2.5 g of protein/dL.
The age of the horse is important, because a number of age-related conditions cause colic. The more common of these include the following: in foals—atresia coli, meconium retention, uroperitoneum, and gastroduodenal ulcers; in yearlings—ascarid impaction; in the young—small-intestinal intussusception, nonstrangulating infarction, and foreign body obstruction; in the middle-aged—cecal impaction, enteroliths, and large-colon volvulus; and in the aged—pedunculated lipoma and mesocolic rupture.
Ultrasonographic evaluation of the abdomen may help differentiate between diseases that can be treated medically and those that require surgery. The technique also can be applied transrectally to clarify findings noted on rectal palpation. In foals, echoes from the large colon and small intestine are commonly identified from the ventral abdominal wall, whereas only large-colon echoes are usually seen in adult horses. The large colon can be identified by its sacculated appearance. The duodenum can be identified in the tenth intercostal space and traced around the caudal aspect of the right kidney. The jejunum is rarely identified during transabdominal ultrasonographic examination of normal adult horses, whereas the thick-walled ileum can be identified by transrectal examination.
The most common abnormalities identified by ultrasonography include inguinal hernia, renosplenic entrapment of the large colon, sand colic, intussusception, enterocolitis, right dorsal colitis, and peritonitis. Stallions with inguinal hernia have incarcerated intestine on the affected side; it is possible to identify the intestine and to obtain information concerning the thickness of its wall as well as the presence or lack of peristalsis. In horses with renosplenic entrapment of the large colon, the tail of the spleen or the left kidney cannot be imaged, or the gas-filled large colon is present in the caudodorsal aspect of the abdomen in the region of the renosplenic space. Horses with sand colic have granular hyperechoic echoes originating from the affected portion of the colon. The characteristic finding in horses with intussusception is the “bull’s eye” appearance of the affected portion of the small intestine. Very often the intestine proximal to the intussusception is distended, and the strangulated portion is thickened. Horses with enterocolitis frequently have evidence of hyperperistalsis, thickened areas of the bowel wall, and fluid distention of the intestine. In contrast, horses with right dorsal colitis commonly have marked thickening of the wall of the right dorsal colon. In horses with peritonitis, the peritoneal fluid may be anechoic, or there may be evidence of flocculent material and fibrin between serosal surfaces of the viscera.
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Horses with colic may need either medical or surgical treatments. Almost all require some form of medical treatment, but only those with certain mechanical obstructions of the intestine need surgery. The type of medical treatment is determined by the cause of colic and the severity of the disease. In some instances, the horse may be treated medically first and the response evaluated; this is particularly appropriate if the horse is mildly painful and the cardiovascular system is functioning normally. Ultrasonography can be used to evaluate the effectiveness of nonsurgical treatment. If necessary, surgery can be used for diagnosis as well as treatment.
If evidence of intestinal obstruction with dry ingesta is found on rectal examination, a primary aim of treatment is to rehydrate and evacuate the intestinal contents. If the horse is severely painful and has clinical signs indicating loss of fluid from the bloodstream (high heart rate, prolonged capillary refill time, and discoloration of the mucous membranes), the initial aims of treatment are to relieve pain, restore tissue perfusion, and correct any abnormalities in the composition of the blood and body fluids
See Table & link below: General Concepts Regarding Fluid Needs in Dehydrated Horses
https://www.msdvetmanual.com/multimedia/table/v4721336
If damage to the intestinal wall (as a result of either severe inflammation or a displacement or strangulating obstruction) is suspected, steps should be taken to prevent or counteract the ill effects of bacterial endotoxins that cross the damaged intestinal wall and enter the bloodstream. Finally, if there is evidence the colic episode is caused by parasites, one aim of treatment is to eliminate the parasites.
Anything that can be done to manage the natural grazing diet of the horse will certainly be beneficial to support the normal digestive system and to prevent colic due to dietary complications. Horses are grazing herbivores, and their gastrointestinal tract is set up in a way that thrives on consistent access to high-fiber forages to function optimally. Horses on full pasture turnout have less incidences of colic than those stalled for most or all of the day.
Management recommendations for managing the diet of the Horse:
• Providing a free choice hay to stalled horses can reduce the risk of colic significantly.
• For horses that need additional calories from grain, feeding smaller, more frequent meals can allow the small intestine to properly digest the simple carbohydrate load and prevent hindgut acidosis which can prevent colic.
• Introduce new feeds gradually, including hay, to allow the beneficial bacteria in the hindgut to adapt to new feeds.
• Provide a daily wellness supplement with digestive care that contains omega-3 fatty acids to support normal healthy levels of intestinal inflammation and pre- and probiotics to maintain healthy hindgut bacteria and aid in normal digestion.
• It has also been stated that garlic supplementation assists in improving equine respiratory problems, acts as a natural fly repellent and maintains beneficial gut flora. Garlic for horses is a popular supplement as it is rich is selenium and sulfur.
Garlic has antiseptic, anti-inflammatory and antibiotic effects and consists of a compound called Allicin, which is released when garlic is chewed or crushed. Allicin is a natural defence mechanism for garlic cloves against pathogens in the soils. When fungi or other soil pathogens attack the cloves, allicin is released and the anti-bacterial, antiseptic and antibiotic action takes place. It has also been stated that garlic supplementation assists in improving equine respiratory problems, acts as a natural fly repellent and maintains beneficial gut flora.
Garlic for horses is a popular supplement as it is rich is selenium and sulfur. Sulphur is recognized as having blood-cleansing properties that are useful in treating and preventing equine disease. However, it is essential that over supplementation of garlic does not occur. If too much is provided in the equine diet, a toxic element known as N-propyl disulfide accumulates in the body. N-propyl disulfide alters an enzyme present within the blood cell, which in turn depletes the cell of phosphate dehydrogenase, a chemical responsible for protecting the cell against natural oxidative damage.
If an overdose of garlic is provided and more red blood cells are prematurely damaged, then the horse becomes anaemic.
The NRC (2009) reported that (more data is required), intake levels of 15mg/kg of body weight per day of dried garlic powder on a long-term basis were unlikely to result in a risk of adverse events such as anaemia, in horses under normal circumstances.
Mega Oil EQ from Catalyst LS consists of natural garlic oil well below this safe level to ensure your horse benefits from the antiseptic, anti-inflammatory and antibiotic properties without breaching the safety level.
Garlic for horses is extremely palatable ensuring that horses enjoy their feed. Mage Oil EQ provides Omega 3 and Omega 6 fatty acid which is a good energy source that does not excite horses as is seen with high grain diets.