MANAGEMENT OF COLIC IN EQUINE: AN OVERVIEW

MANAGEMENT OF COLIC IN EQUINE: AN OVERVIEW

K.P. Singh^*1 and Praneeta Singh² 

Government Veterinary Hospital, Deoranian, Bareilly,

Department of Animal Husbandry, Uttar Pradesh, India

1: Veterinary Officer, Government Veterinary Hospital, Deoranian, Bareilly, Uttar Pradesh,   Email: drkpsvet@rediffmail.com

2: Assistant Professor, Department of Livestock Product Technology, C.V.A.Sc., GBPUAT, Pantnagar, U.S.Nagar, Uttrakhand, Email: vet_praneeta12@rediffmail.com

Abstract

Colic is defined as a complex symptom exhibited by the animal when there is any abdominal organ pain and it is the major cause of morbidity and mortality in equine. Its results are due to accumulation of gas, intestinal displacement, impacted food mass, parasites and also some risk factors (breed, age, management factors) that increase the occurrence of colic. There are many typical signs of colic in the equine like, rolling, flank watching, pawing, sweating, elevated body temperature, frequent rising and lying down, elevated heart rate and respiratory rate. Many possible diagnostic methods are used to examine colic in equines such as history, rectal palpation, physical examination, ultrasonography and abdominal auscultation. Treatment of equine colic can be achieved with decompression of the stomach and large intestine, analgesics, rehydration, impaction colic treatment, fluids support and surgery. Preventive methods of equine colic include preventing the ingestion of dirt or sand, regular feeding schedule, regular deworming, regular dental care and a regular diet that does not change substantially in content or proportion.

Keywords: Colic, Equine, Impacted Food Mass, Intestinal Displacement, Parasite, Treatment

Introduction

Equines are monogastric animals that have their distinct behaviour. They are found mainly in temperate, semi-arid or highland areas. Colic is defined as any gastrointestinal pain which is considered the major disease state in horses and donkeys causing severe abdominal pain. Colic is a frequent and important cause of death to these species of animals. Equine colic can be divided into 2 major categories: gastrointestinal and non-gastrointestinal (Smith, 2002). Gastrointestinal colic can be caused by different conditions, ranging from harmless spasmodic colic to a life-threatening strangulation obstruction (Van Der Linden et al., 2003). Simple obstruction of the small colon in horse cause colic and concludes with intramural obstruction by foreign material and abnormal accumulation of ingesta, meconium, fibrous material and enteroliths (Ruggles and Ross, 1991). The etiological agents of this clinical syndrome are several including diseases based on the system that classifies the cause of colic as obstructive, displacement, gas, parasite, and enteritis (Radostits et al., 2007) and also some risk factors (breed, age, managemental factors) that increase the prevalence of colic in equines. The clinical sign syndrome is a spasm of the digestive system and the major sign is the pain manifested by pawing, stamping, kicking, or rolling (Radostits et al., 2007) Factors associated with impactions include poor dentition, lack of access to water, coarse feed, acute cessation of routine exercise with confinement and treatment for the musculoskeletal disease (White and Lopes, 2003). Damage or dysfunction of the enteric nervous system may also cause alteration in motility leading to impaction. Intestinal adhesions, which are suspected to alter motility pattern at the pelvic flexure are also known to cause colon impactions (Schusser and White, 1997). The main aim of treating horses with colic include relieving pain, correcting the physiological imbalance, stimulating or maintaining intestinal transit and decreasing intestinal inflammation. Equines are more susceptible to colic than other species due to their unique anatomy of the digestive system. Out of 100 horses in the general population 4- 10 cases of colic are expected in one year (Hillyer et al., 2001; Traub et al., 2001). About 10-15% of the colic cases are repeat cases with some horses having 2-4 colic episodes in a year (Traub et al., 2001). Losses caused by equine colic are almost entirely to the death of these animals. The predominant reasons for death were stomach rupture, strangulating lesions or enteritis. An early diagnosis of colic is important (Dukti and White, 2009) and carried out based on case history, clinical signs and parameters, rectal palpation and ultrasonography (Ferraro, 2008). Treatment of equine colic is an art and science at the same time (Sanchez and Robertson, 2014) colic can be treated medically, surgically, or by both medical and surgical treatment according to the case, Medically, tympanic, spasmodic, displacement colic is relieved by surgically (Hillyer et al., 2008). The incidence of colic can be reduced by restricted access to simple carbohydrates including sugars from feeds with excessive molasses, providing clean feed and drinking water, preventing the ingestion of dirt or sand by using an elevated feeding surface, a regular feeding schedule, regular deworming, regular dental care, a regular diet that does not change substantially in content or proportion and provide adequate exercises are the most relevant means of preventive and control measures for equine colic(White, 2014). The present paper was designed to study the recent advances in the management of colic in equine.

Causes of equine colic

The gastrointestinal tract is the most important source of colic (Robertson and Sanchez, 2010). Causes of colic can be kept into four groups: distension, simple obstruction, complete obstruction and enteritis (Ferraro, 2008).

1. Distension: Distension can happen either because of physical obstruction due to accumulation of ingesta or fluids in the gastrointestinal tract, causing physical colic or without physical obstruction (Ferraro, 2008) known by ileus characterized by moderate to severe continuous signs of colic.
2. Simple obstruction is a partial blockage of the ingesta pathway in the digestive system, by food, enteroliths, parasites, foreign body (Ferraro, 2008), or sand (Hart et al., 2012) resulting in disruption of food movement downwards. This obstruction makes the horse shows clinical signs of colic ranging from mild to moderate (Ferraro, 2008). The most common site of impaction is the large colon, either in horses (Mezerova et al., 2001) or donkeys (Cox et al., 2007) but when small intestinal impaction happens in donkeys it is always very fatal (fatality rate reaches100%).
3. Enterolith is a mineral stone, composed especially of magnesium and ammonium phosphate. These minerals accumulate around a nidus (metal, plastic, or gravel which makes tone inside the bowl), it is usually formed in a large colon, then it passes out with feces or retains obstructing according to its size, colic because of this retained stone is usually chronic intermittent.
4. Complete obstruction

` Complete obstruction, happens because of intestinal accidents such as torsion and introsusception, causing severe intolerable pain and shock due to intestinal infarction and bacterial toxins that pass into the bloodstream (Ferraro, 2008).

5. Enteritis

Enteritis is inflammation of intestinal mucosa, because of microbial infections such as Salmonella, Clostridia and (Ferraro, 2008), Rickettsia, and equine viral arthritis, or chemical poisons, enteritis causes colic of short-lived which is characterized by fever, depression, and diarrhea (Edward and White, 1999).

6. Parasites Ascarid (Round worms):Occasionally there can be an obstruction by large numbers of roundworms. This is most commonly seen in young horses as a result of a very heavy infestation of Parascaris equorum that can subsequently cause a blockage and rupture of the small intestine. Acute diarrhea can be caused by cyathostomes or “small Strongylus type” worms that are encysted as larvae in the bowel wall, particularly if large numbers emerge simultaneously. The disease most frequently occurs in the wintertime. Pathological changes of the bowel reveal a typical “pepper and salt” color of the large intestines.

Large strongylus: Large strongyle worms, most commonly Strongylus vulgaris are implicated in colic. (Reed and Sellon, 2010; White, 2014).

Some more common causes of colic include:

• High grain-based diets/Low forage diets
• Moldy/ Tainted feed
• The abrupt change in feed
• Parasite infestation
• Lack of water consumption leading to impaction colic
• Sand ingestion
• Long term use of NSAIDs
• Stress
• NSAID: the non-steroidal anti-inflammatory drug
• 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.

Clinical signs: Based on the degree of vascular compromise and the length of the intestine that is affected and includes acute and severe colic seen with other forms of strangulation, strangulating obstruction.

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
• A colic foal may not show typical signs of colic. Instead, they may lay on their back with their legs tucked. The foal owner or manager needs to be on alert for any abnormal foal behaviour.

Risk factors associated with equine colic: A risk factor is not important to be the causative agent of equine colic but it means that horse will be more susceptible to the colic when it exposes to this factor (Edward and White,1999).

Species: Compared to ruminants equines are more susceptible to colic.

Breed and age:  Arabian breed (Holdstock and Proudman, 2000), crossbred horses (Mehdi and Mohammad, 2006) and older horses are more susceptible to the colic (Rabuffo et al.,2009). Geriatric horses were found more susceptible to death due to colic unless there is surgical intervention (Southwood et al., 2010), aged horses have more opportunity to be subjected to the colic causative agents and its risk factors compared to younger ones.

Managemental factors Food and water: Equine nutrition has an important role in their health, although veterinarians are considered the basic sources of nutritional advice for equine owners (Murry and Robert, 2013).  Type of food (Concalves et al., 2002), sudden change of food (Archer and Proudman, 2006) and way of feeding are important risk factors for colic. When a horse is fed on the ground, or when it is being at a pasture with no grasses, or with short grasses, it will be more susceptible to sand colic (Husted et al., 2005), hay of poor quality is relatively indigestible. A decrease in water intake is considered a risk factor for equine colic (Scantle bury et al., 2011), in addition to over drinking of water, especially after heavy work (Hillyer et al., 2002).

 Control of internal parasite: An extensive usage of ivermectin and frequent usage of ivermectin increase the risk of colic due to tapeworm infection, but fortunately this problem can be overcome by administration of anticestodes (Holdstock and Proudman, 2000).

Teeth problems: Teeth problems are risk factors for colic in donkeys (Toit et al., 2008) and in horses (Scantlebury et al., 2011).

Exercise: Recent changes in stabling (Hillyer et al., 2002) and exercise schedule, reduce large intestine peristalsis, resulting in simple obstruction and distension of the colon. Exposure to cold (Mott et al., 2004, Scantlebury et al., 2011) fatigue, exhaustion, wet stormy weather, and overwork, paralyze the digestive system, making equine more susceptible to colic (Mott et al., 2004).

Types of Colic

Colic is related to many different maladies and includes the following:

Stomach distention: The small capacity of the horse’s stomach makes it susceptible to distension when large amounts of grain are ingested in a single meal. There is the potential for the stomach to rupture which is fatal.

Displacement colic: The small intestine is suspended in the abdominal cavity by the mesentery and is free-floating in the gut. This mobility can predispose the small intestine to become twisted. A twisted intestine requires immediate surgery to reposition the intestine and remove any portion of the intestine that is damaged due to restricted blood flow. In addition, both the small and large intestine can become displaced in the abdominal cavity causing both pain and restricted blood flow. Displacement colic can be caused by gas build-up in the gut that makes the intestines buoyant and subject to movement within the gut. Displacement colic needs immediate surgical treatment.

Impaction colic: The large intestine folds upon itself and has several changes of direction (flexures) and diameter changes. These flexures and diameter shifts can be sights for impactions, where a firm mass of feed or foreign material blocks the intestine (including the cecum). Impactions can be induced by coarse feedstuff, dehydration or accumulation of foreign material like sand.

Gas colic: All colics are associated with some gas build-up. Gas can accumulate in the stomach as well as the intestines. As gas builds up, the gut distends, causing abdominal pain. Excessive gas can be produced by bacteria in the gut after ingestion of large amounts of grain or moldy feeds. A nasogastric (stomach) tube inserted by a veterinarian is used to relieve the pressure of the gas and fluid accumulation in the stomach.

Spasmodic colic: It is defined as painful contractions of the smooth muscle in the intestines. Spasmodic colic has been compared to indigestion in people and is usually easily treated by a veterinarian. Over excitement can trigger spasmodic colic.

Enteritis: Inflammation of the intestine possibly due to bacteria, grain overload or tainted feed. Horses with enteritis may also have diarrhea. Enteritis is often hard to diagnose and may present itslf similar to displacement or impaction colics.

Diagnosis of equine colic:

An early diagnosis of colic is important for a favourable prognosis and a decrease in fatality rate (Dukti and White, 2009).

1. Case history:The case history of a colicky horse is the time when the horse shows signs of colic. This can be estimated from the owner, by asking him, what is the first time he noticed that his horse was attacked by the colic and the last time he saw his horse well. Then he/she should be asked about the factors that preceded colic, especially those that are considered as risk factors for colic, such as stabling, food, usage of anthelmintics for treatment and prevention of internal parasites. The treatment with drugs that are known as causes of colic such as prolonged usage of non-steroidal anti-inflammatory agents (Edward and White,2001).
2. Clinical signs:Evaluation of pained animals depends on the observable clinical signs and their interpretation. So, identification of the animal, source of the pain and its duration are important data (Robertson and Sanchez, 2010). Clinical signs are also important for the identification and differentiation of medical treatable colic cases than surgical needed others (Suttonet al., 2009). Clinical parameters include evaluation of the cardiovascular system, such as heart rate, mucous membrane colour (Sutton et al., 2009) capillary refill time (Thoefner et al., 2001; Sutton et al., 2009) are negatively affected by fatal endotoxemia (Skyes et al., 2005). So, they play an important role in evaluating the outcome of the case. In addition to that degree of pain and deviation of temperature from 38oC are also important factors for the prognosis of colic cases (Thoefner et al., 2001). It was noticed that in old horses after exercise their temperature can reach 40 ^oC faster with increasing heart rate and more sweat loss than young horses (Mckeever et al., 2010). Distension of the abdomen is rarely noticed in colic horses. However, symmetrical distension of the abdomen refers to the accumulation of gas in the small colon and distension of the right flank is an indicator of gas accumulation in the caecum

Colic increases capillary refill time and pulse rate (Alsaad and Nori, 2010) and they are of great value in the assessment of the prognosis of colic horses (Southwood et al., 2010).  For a favourable prognosis, the pulse rate should be less than 80/minute, but when it reaches 100 pulse/minute than this is considered a bad prognosis (Bryan et al., 2009).

3. Examination of mucous membranesis important for the assessment of hydration, cardiovascular status, degree of shock and endotoxemia.  Pale, dry and clammy mucosa is an indicator of coma.   The congested dark red to purple colour with long capillary refill time are indicators of severe dehydration and shock. Respiratory rate is of less importance in estimating the prognosis of the colic horse. But it is to be increased in colic horses (Scantebury et al.,2011) due to either pain or acidosis (Bryan et al., 2009). Although body temperature is usually in the normal range in colic horses. However, sometimes it decreases as in shocking cases (Hillyer et al., 2008), or increases (Hart et al., 2012) as in acute (Alsaad and Nori, 2010) and sand colic (Hart et al., 2012).
4. Nasogastric intubationis important for the diagnosis of colic and relief of gastric distension, which will rupture the stomach, if not treated, because of the inability of equines to vomit (Ferraro, 2008). Normal stomach contents are thick, mucoid, acidic and of large quantities of fetid gas and fluids (Hillyeret al., 2008). But they become watery, bile-stained and alkaline as duodenum contents get into the stomach (Ferraro, 2008).
5. Rectal Examination is an important step in the diagnosis of colic. By rectal examination, the clinician can examine the reachable organs (Hillyer et al., 2008).   Impaction of pelvic flexure accurately diagnosable by rectal palpation. Intestinal ileus is characterized by palpable loops of distended small intestine with normal wall thickness (Hillyer et al.,2008). The distended small intestine appears in an accordion-like shape which can be located vertically or horizontally (Edward and White, 2001). Impaction of feces in the large intestine gives a palpable long column like-shape, which indicates impaction colic (Bryan et al., 2009). Stretching of the mesentery is detected when there are heavy contents in the intestine pulling it down, or when the small intestine is twisted or telescoped into itself.  If the rectum is empty from feces, this refers to either partial or complete obstruction. They are distinguishable by the administration of oil. The drenched oil will pass out through rectum in partial obstruction but not in complete obstruction (Bryan et al., 2009). Despite the importance of rectal palpation, it is difficult to be carried out in small-sized horses and in the horse with severe abdominal pain (Mezerova et al., 2001).   The rectal palpation findings are not dependable alone in final decision making. They should be interpreted with the results of other steps of examination (Bryan et al., 2009).
6. Ultrasonography: It is used for the examination of unreachable organs by rectal examination (Ferraro, 2008). Percutaneous ultrasonography is used in confirming gastric rupture, which is characterized by the increased volume of peritoneal fluids (Hillyer et al.,2008). Abdominal ultrasonography also can be used for the definitive diagnosis of small and large intestine diseases such as obstruction and strangulation (Beccanti et al.,2011).
7. Abdominal auscultation:  Auscultation to the abdomen by stethoscope is carried out parallel to the edge of the last rib on both sides (Edward and White, 2001) but one should pay attention so as not to confuse gas sound which is produced by microbes, with sounds of intestinal movement. There are two sounds that can be heard in normal equine short mixing sounds 2-4 times/minute and long propulsive sounds which can be heard one/2- 4minute. The last one increase directly after eating. In colic cases this sound would decrease or even be absent if the case was severe (Scantlebury et al.,2011) or may not be affected during the colic period (Hartet al., 2012).
8. Fecal examination:In areas, where sand colic is known to be common, feces can be examined for the presence of sand, often by mixing it in water and allowing the sand to settle out over 20 minutes (King and Marcia, 2014). However, sand is sometimes present in a normal horse’s feces, so the quantity of sand present must be assessed. Testing the feces for parasite load may also help diagnose colic secondary to parasitic infection. (Erica and Larson, 2014).

Treatment of equine colic

Colic can be treated medically, surgically, or by both medical and surgical treatment as per the case (Hillyer et al., 2008). Mild colic can relieve even without or with minimal medical care (Bryan et al.,2009). Medical treatable cases are more favourable in prognosis than surgical ones (Sutton et al., 2009). So, it is important to differentiate between them, because delays in the identification of complicated cases increase the probability of death (Bryan et al., 2009).

1. Decompression of stomach and large intestine:Nasogastric intubation is applicable for decompression of the stomach distended by gas or fluids. Intubation should be repeated until no gastric reflux is seen (Hillyer et al., 2008). The caecum is the most common place for gas accumulation. Caecum is punctured from outside in the right flank for removal of the gas.
2. Analgesics:Analgesics make the colic animals relax and prevent it from injuring themselves (White, 2006). The most used pain killers during the colic period are non-steroidal anti-inflammatory agents (Hart et al.,2012). Non-steroidal anti-inflammatory agents which include flunixin meglumine, ketoprofen, phenylbutazone (Robertson and Sanchez, 2010) and meloxicam (Mezerova et al., 2001) are the drugs used for relieving pain (Sanchez and Robertson, 2014) of either surgical or non-surgical cases (White,2006) and for management of endotoxemia associated with equine colic (Blikslager and Marshall, 2011). Non-steroidal drugs have different effects when they are used as pain killers. This may be either due to their mode of action (White, 2006) or to their distribution. Non-steroidal anti-inflammatory agents distribute at different levels in the different tissues. Phenylbutazone is concentrated in muscles more than in viscera. So, it is more useful in reliving somatic pain. Non-steroidal anti-inflammatory agents inhibit cyclo-oxygenase 1and cyclo-oxygenase 2 at different levels and these enzymes are distributed in different concentrations in the different tissues (White, 2006). Ketamine and/or butorphanol are being used for controlling severe pain; drugs such as gabapentin which control neuropathic pain are used for controlling pain like that of laminitis (Sanchez and Robertson,2014).

Flunixin meglumine is spasmolytic and analgesic drug (Huskamp and Scheidemann, 2000). It is the strongest available non-steroidal analgesic (Robertson and Sanchez, 2010) single dose of 1.1 mg/kg of flunixin meglumine given intravenous, intramuscular, or per os can treat many cases of colic completely (Robertson and Sanchez, 2010) Flunixin meglumine also is characterized by the relatively long duration of action, (Bartom and Moore, 2003 and White, 2006) and it keeps blood flow to the obstructed and strangulated organs (White, 2006), without interfering with the healing of damaged intestinal mucosa (Morton et al., 2011). Flunixin meglumine was found to influence the recovery of small intestine mucosa injury because of ischemia (Marshall et al., 2011) due to inhibition of cyclo-oxygenase enzymes (Marshall et al., 2011). The disadvantages of non-steroidal anti-inflammatory agents especially phenylbutazone include, gastrointestinal ulcers and renal damage (White, 2006).

Impaction colic treatment: Impaction is treated either by laxatives or anthraquinone purgatives. The efficacy of anthraquinones is variable and may cause severe diarrhea. They lubricate the intestine and prevent toxins absorption the recommended dose is 5-10ml/kg. Mineral oil administration is contraindicated in horses with obstruction especially obstruction of the small intestine because they worsen the already distended stomach. So, they must not be given to horses with severe colic without accurate diagnosis (White and Edward, 2001).

Fluids therapy: Fluids are commonly given, either orally by nasogastric tube or by intravenous catheter, to restore proper hydration and electrolyte balance. In cases of strangulating obstruction or enteritis, the intestine will have decreased absorption and increased secretion of fluid into the intestinal lumen making oral fluids ineffective and possibly dangerous if they cause gastric distention and rupture. This process of secretion into the intestinal lumen leads to dehydration and these horses require large amounts of intravenous fluids to prevent hypotension and subsequent cardiovascular collapse. The intravenous fluid requirement of horses with simple obstruction is dependent on the location of the obstruction. Those that are obstructed further distally, such as at the pelvic flexure, can absorb more oral fluid than those obstructed in the small intestine, and therefore require less intravenous fluid support (Merck, 2014). Impactions are usually managed with fluids for 3–5 days before surgery is considered. Fluids are given based on results of the physical examination, such as mucous membrane quality, packed cell volume and electrolyte levels. Horses in circulatory shock, such as those suffering from endotoxemia, require very high rates of intravenous fluid administration. Oral fluids via nasogastric tube are often given in the case of impactions to help lubricate the obstruction obtained (Merck, 2014).

Surgical treatment: Most of the death due to colic happens after surgical treatment of colic (Ihler et al., 2004) due to post-operative complications. Most cases of death are noticed during the first ten days of postsurgical operation (Proudman et al., 2002). Surgical intervention should be done only when there is an accurate diagnosis of intestinal obstruction (Mezerova et al., 2001) and the real need for it. Severe abdominal pain and the mild one because of caecal hypertrophy (Scheidemann, 2000) and which do not respond to analgesics need surgical intervention long duration of the disease, high degree of general health alteration are good indicators of the need for surgical treatment, especially in right dorsal colon impaction cases (Mezerova et al., 2001).

Prevention

 The incidence of colic can be reduced by restricted access to simple carbohydrates (White, 2014) including sugars from feeds with excessive molasses, providing clean feed and drinking water and preventing the ingestion of dirt or sand by using an elevated feeding surface. A regular feeding schedule, regular deworming, regular dental care, a regular diet that does not change substantially in content or proportion and prevention of heatstroke.

Conclusion

Colic is the most common symptomatic illness in equines which leads to the middle to severe abdominal pain with high morbidity and mortality rate and also equines are more susceptible to colic than other species. Equine are hindgut fomenters and their cecal microbiome can easily be altered due to environmental and physiological changes. Distention, simple obstruction, complete obstruction, enteritis, and parasites are the major causes of equine colic. In addition to these, there are detrimental factors like species, breed, age and some management factors which can increase the risk of equine colic. Tympanic, impaction, displacement and spasmodic colic are the commonest types of equine colic. Hence, to increase the quality of life for equine, it is vital to understand the causes, signs, diagnostics, treatment, and prevention of colic. A regular deworming program should be practiced for effective parasite control. Avoid all causes and predisposing factors that contribute to the occurrence of equine colic. The owners should feed the animal on a regular schedule with an appropriate dry matter and concentrate ratio. The sudden change of feed should be avoided and gradual feeding should be implemented. Keep feed boxes and hay racks as well as the feedstuffs clean and free of mold and dust. Check teeth frequently for dental problems that may cause chewing issues. Keep feed off the ground to avoid sand ingestion.

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