Horse Colic

Horse colic Prepared by

Dr. Ghalib S. Ridha Visiting Assistant professor of Internal medicine & Infectious diseases. Dept. of Internal Medicine Faculty of Veterinary Medicine

Al-Fateh university Tripoli, LIBYA 1

• The term “colic’’ means only ’’pain in the abdomen’’. • Colic is potential horse killer. It occurs sporadically and may be mild or severe, acute or chronic. • Repeated bouts or recurrent colic are not uncommon. 2

• A tour of GIT to explain why there are so many forms of colic. • Horse has a fairly small stomach • Food passes from stomach into S.I. (22 m length), capacity 40-50 liters. • At junction of S.I with L.I, a large blind-ended cecum (1 m length), capacity of 25-30 liters.

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• Colic due to some intestinal problems appears to be age related as meconium impactions are restricted to neonatal foals whereas feed impactions occur more frequently in older horses. • Accurate history is essential in defining possible etiologies and pathophysiologies of medical colics. • A complete physical examination should be attempted in all cases of colic to determined the site and cause of gastrointestinal pain. • The examination should be performed without sedation in tractable horses. If sedation is necessary, it should be administered only after complete general examination because sedation will affect clinically important findings. 4

Manifestations of horse colic  Pain and anxiety which is manifested by straining, pawing, stretching and sweating. It is important to determine if the pain is continuous or intermittent, static or changing in intensity, responsive or unresponsive to medication.  Change of attitude e.g. mild colic due to colon impaction may cause slight to moderate depression and animal will often continue to eat, while colic due to strangulation obstructions produce severe depression and toxemia resulting in severe colic. 5

 The temperature readings are normal to slightly

elevated with medical colic. Subnormal temperature may accompany cases of terminal shock and toxemia. High temperatures are associated with infections or septic conditions. If the owner or other veterinarian have been use antipyretics e.g. dipyrone, phenylbutazone, flunixin meglumine, the temperature may be normal.  The respiratory rates usually increased in proportion to the amount of pain. Metabolic acidosis causes an increase in the rates.

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The pulse rates may reflect the nature of colic as a slight increase in the rate occurs in mild colic whereas an increase of rate up to 100 or more may indicate serious and severe colic. Pulse quality should also be evaluated. Strong full pulse rather than a weak thready pulse is reflective of a mild and medically responsive colic. Normal mucosal color is indicative of normal circulatory status and mild or early colics. Congested mucous membrane indicates fluid loss or shock. 7

Colic in the Vet school Tripoli 30042008.3gp

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Examination of digestive tract:

• Normal abdominal contour of horse with medical colics. Distension is not a feature of serious small intestine obstruction but is most commonly observed with large intestine problems that are usually surgical in nature. • Sharp molar teeth may predispose to impaction colic. • Abdominal auscultation showing normal to increased borborygmi usually indicate a good prognosis for medical management. Hypermotility indicates early intestinal distention or enteritis. 9

Examination of gastric fluid could be determined. Low pH fluid (4-5) indicates gastric source whereas higher pH (6-7) indicates that the fluid is from the small intestine. • Rectal examination may identify normal and subnormal palpable structures. • Abdominocentesis often is performed on midline using 18 gauge hypodermic needle or blunt cannula to penetrate the peritoneum to collect fluid for analysis. •

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• Abnormal peritoneal fluid:

- Flocculent fluid, no odor----Bacteria and toxin in early infarction. - Serosanguinous, no odor----RBCs, bacteria and toxin from necrotic intestine. - Sanguineous, malodor, feces---- Ruptured viscous, teared rectum. - Frank blood in abdomen ---- Usually blood vessel penetration. 11

• Physical findings differentiating mild (medical) colics from severe (surgical) colics. Mild colic Severe colic -Yawing - Rolling, thrashing, - Muscle tremors - Self traumatization. - Straining - Depression, dullness - Groaning - Labored breathing - Pawing ground - Distended abdomen - Looking at flank - Sweating - Getting up & down - Attempts at vomiting - Possible sweating. 12

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Spasmodic colic •

It is the most common type of colic in horses.

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Etiology: 1) High carbohydrates diet (grain based feed, lush pasture) are the most common cause. 2) During thunder storms, preparation for showing or racing and drinks of cold water when hot and sweating after work. 3) Mucosal penetration and migration of strongylus vulgaris larvae causing intestinal spasm or ileus due to change of ileal myoelectrical activity. 18

Pathogenesis • An increase in parasympathetic tone under the influence of the factors mentioned above cause the hypermotility of spasmodic colic in horses.

Clinical findings: • Most cases are mild, not fatal and solve on their own within few hours or with simple medical treatment. • Abdominal pain is intermittent with signs of rolling, pawing and kicking for few minutes then stand for few minutes until the next bout of pain occurs. • Intestinal sounds are often audible some distance and loud borborygmi are heard on auscultation. • A moderate increase in pulse rate (60/ minute) occur and patchy sweating may be seen. 19

Diagnosis: • Laboratory tests are not used in diagnosis. • D.D; • Enteritis & spasmodic coilc, both show abdominal pain and increased intestinal sounds but diarrhea is usually present in enteritis. • Acute intestinal obstruction may be confused with it but scant feces and presence of blood and mucus in rectum are typical of obstruction.

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• Obstructive urolithiasis, show similar posture adopted by a horse with spasmodic colic. Treatment: • Because of the transient nature of spasmodic colic, it may be not necessary to use specific spasmolytics. However, depomidine, xylazine or butorphanol are effective.

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Intestinal tympany in horses (flatulent colic) • Excessive gas accumulation in the intestinal tract. Etiology: • Gas builds up in the intestine, most commonly in large intestine and / or cecum. • In most cases it occur secondarily to obstruction of small intestine. 22

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Etiology

• Flatulent colic is either primary due to – Ingestion of large quantities of highly fermentable green feed – Administration of medicine such as atropine. – Horse that crib (wind suck) often cause colic and pain.

• Or it may be secondary due to • Stenosis caused by constricting fibrinous adhesion after castration. • Verminous aneurysm. 23

Pathogenesis: • It develops due to either excessive gas production Or gas retention in the intestine causing over distention and abdominal pain due to stretching the intestine. • In primary tympany, distention is relieved periodically due to evacuation of some gases but the course of tympany is longer. 24

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Pathogenesis

• In secondary tympany, the pathogenesis depends on primary causes. • Tympany may interfere with circulation or respiration which may contribute to death of affected horse.

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Clinical findings : • There is abdominal distention and in thin animal, distended loops may be visible through the abdominal wall. • Cecal tympany cause filling in right paralumber fossa, whereas large colon tympany cause bilateral abdominal gas distention. • Acute abdominal pain of affected horses characterized by rolling and pawing. 26

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Clinical findings

• Peristaltic intestinal sounds are reduced but tinkling and metallic sounds may be heard due to fluid rushing in the gasfilled intestinal loops. • On rectal palpation, gas filled loops fill the abdominal cavity. • In primary tympany, much intestinal gases (flatus) are passed out. 27

Diagnosis:

• A history of engorgement on highly fermentable green feed, with signs of feces and intestinal gases passed out may indicate a primary tympany. • In secondary tympany due to intestinal obstruction, rectal examination is difficult because of the gas-filled intestine beside it is usually cause death in much shorter time than other type of tympany. 28

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Diagnosis

• P.M. findings of primary cases reveals that the intestines are filled with gases and feces is pasty and loose, while in secondary tympany, the cause of obstruction is evident. • Laboratory tests are of no value in diagnosis.

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Treatment: • All cases should receive mineral oil (2-4 liters) containing antiferments such as turpentine oil, formalin or chloroform. • It may be necessary to administer a sedative if pain is acute. In secondary tympany correction of the obstruction cause relief. 30

Verminous mesenteric arteritis Synonym: Verminous aneurysm, thromboembolic colic.

Etiology: • Migration of strongylus vulgaris larvae into the wall of cranial mesenteric artery cause restriction of the blood supply or damage to the nerve supply to the intestines. Cases may occur in foals as young as 4-6

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Pathogenesis: • Complete vascular occlusion leads to infarction of sections of large intestine. In this disease the death rate is high in affected horses. • Recurrent colic of VMA is explained as being due to low-grade impairment of vascular and nerve supply to the intestine.

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VMA

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Pathogenesis

• Recurrent colic of low grade abdominal pain over a period of several months (chronic) also occur when secondary bacterial invasion of aneurysm, usually Strept. equi, Actinobacillus equuli or Salmonella typhimurium, causing gross enlargement and local peritonitis, development of adhesions and eventual constriction of the intestine. 35

Clinical findings: 1- Animals with infarction show severe abdominal pain for 3-4 days with complete cessation of defecation and absence of intestinal sounds due to stasis although - in early stage gut sounds are increased as it occurs in spasmodic colic.

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Clinical findings

2- Rectal examination may reveal distended loops and stretched mesentery. It is often possible to palpate the artery as a fixed, firm swelling in midline, level with caudal pole of left kidney and it is usually pulsate. 3- Rupture of intestine may cause peritonitis, gangrene of the intestine causes toxemia. These cases always terminate fatally.

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Clinical findings

4- Uncommon syndrome may occur, such as: a) Development of massive hemorrhage within the mesentery. b) Occurrence of extensive occlusion leading to rapid death (12-24 Hours) probably due to endotoxic shock. 38

• Blood-stained feces may be passed due to extensive hemorrhage leakage into the intestinal lumen. Diagnosis: A- Clinically, there is abdominal pain and shock with pallor. Commonly the disease is not suspected until recurrent attacks of acute colic.

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Diagnosis

B- Paracentesis show blood-stained fluid in peritoneal cavity with high leukocytic count and shift to left. C- Radiological examination has been used to determine the presence of verminous aneurysm in ponies.

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Diagnosis

D- P.M. findings; • Partial or complete occlusion of the arteries • Presence of larvae in the arterial walls or free in the lumen. • In severe cases, large patches of gangrene are present in the intestinal wall. . 41

D.D: The signs produced by this disease are similar to those of mesenteric abscess and very similar to those of terminal ileal hypertrophy Treatment: • Ivermectin (0.2 mg/kg. b.w) is recommended but it does nothing to infracted intestine. • Surgical intervention is of little help.

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Impaction of large intestine of the horse • Impaction is a term used when the intestine become blocked by a firm mass of food. It occurs mostly at one of flexures. • Etiology: 1) Feeding on low grade indigestible roughage over long intervals. – Defective teeth may contribute in the occurrence of impaction due to improper mastication of the roughage. 43

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Etiology

2) Dietary causes are:

a) Over eating immediately after surgery, impaction may occur in horse as result manifesting itself next days. b) Feeding horses on high fiber diets such as maize plants or ingestion of large amounts of indigestible seeds may cause outbreaks of impaction colic. c) Change of diet; horses offered hard feed after being on soft grass or pasture is also likely to develop 44 impaction colic.

3- Other causes;

a- Breeding susceptibility. b- General debility is a predisposing cause because of decreased intestinal muscle tone. c- Interference of local blood supply to the intestine. d- Enteroliths and fiber balls may also cause obstruction of large intestine result in recurrent attacks of colic. e- Foreign bodies especially pieces of rope may cause impaction of small colon. f- Retention of meconium in foals is a common occurrence of impaction. g- Rectal paralysis in mare near parturition leads to constipation. 45

Pathogenesis: • Overloading of the colon and cecum occur primarily due to dietary errors or secondarily because of poor intestinal motility cause prolongation of intestinal sojourn of fecal materials with subsequent impairment of fecal mass movement by peristalsis leading to chronic constipation.

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Clinical findings: • 1- There is anorexia and the horse drinks small quantities of water. The feces are scanty, hard covered with thick sticky mucus. • 2- The temperature and respiratory rates are normal but pulse rate increased moderately (50/ minute).

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Clinical findings

• 3- Moderate abdominal pain is the typical signs in affected horses, manifested by stretching out and lying down. The bouts of pain occur at intervals of up to 30 minutes and often continue for 3-4 days. In cases associated with enteroliths, with signs of complete absence of feces, or cecal impaction, the abdominal pain is prolonged up to 2 weeks. 48

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Clinical findings

4- On rectal examination, the commonest sit of impaction are: • Large colon as the distended loops of pelvic flexure often extend to the pelvic brim or even to the right of midline. • Impacted small colon felt dorsally to right of the midline. Enteroliths and similar foreign bodies are usually located in small colon which may be palpable per rectum. • Impacted cecum can be palpated in the 49 right flank.

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Clinical findings

5- Drugs used in anesthesia may seriously reduce

gut motility predisposing to dilatation and rupture of colon or cecum. 6- The signs of retention of meconium in foals are: • Continuous straining and tail flagging • Humping of the back • Restlessness, lying down for much of time • Hard fecal balls can be palpated with the finger in the rectum.

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Diagnosis:

• Laboratory tests are not of value except for fecal examination of nematodes eggs. Paracentesis, hematology and clinical pathology are normal. • In necropsy findings, the large intestine is full of firm, dry fecal materials and rupture may have occurred. Enteroliths are located in the junction between dorsal colon and small colon. 51

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Diagnosis

• Palpation of cranial mesenteric artery is necessary to diagnose verminous mesenteric arteritis. • Tympany of large intestine in foals is much more serious than impaction beside abdominal distention and acute abdominal pain is the cardinal signs of tympany.

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Differential diagnosis:

• Peritonitis and dehydration may show similarity to impaction colic in respect of constipation. • Rectal palpation, absence of systemic signs and intestinal sounds may be used to differentiated impaction from other forms of colic • Acute gastric dilatation, acute intestinal obstruction and spasmodic colic are more severe

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Treatment: • Most cases of impactions respond to treatment, recurrence of impaction may occur due to failure to correct the cause and death occurs due to rupture or exhaustion. • Cecal impaction is difficult and may be fatal and idiopathic rupture or perforation of impacted cecum may occur causing death. 54

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Treatment

• Analgesics may be administered and IV fluid therapy should be provided. • 3-5 liters of mineral oil via nasogastric tube may be administered to soften the fecal mass which usually takes 12-24 hours. 55

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Treatment

• An effective fecal softening agent, dioctyl sodium sulpho-succinate (DOSS) has been used extensively for treatment of impaction of large intestine in horses in a dose of 7.5-30 g / adult horse orally with maximum dose of 200 mg / kg. b.w. Doss commonly used in the first day of treatment followed by administration of mineral oil on the second day. The 2 medicines should not be mixed nor given simultaneously. 56

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: Treatment

• If medical therapy is not effective by 72 hours after 2 treatment at 48 hours intervals with mineral oil, surgical correction is necessary. • If surgical therapy is not practical, a parasympathetic stimulant such as neostigmine (10-12 mg. IM) may be used but rupture of the gut is possible sequel and increased pain is expected. 57

• Treatment of retention of meconium in foals: • Using mild soap and water, rectal enemas are repeated until soft feces appear. • Injection of mineral oil, glycerin or DOSS (coloxyl) into the rectum may be required. • Oral doses of coloxyl or mineral oil (100-200 g) are also advisable. Affected foals should be treated regularly at 4 hours intervals until recovery. • Surgical removal is indicated when foal not sucked for more than 2 hours and its life is endangered or when amount of meconium is large and the rectum has been damaged. 58

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Sand colic

The syndrome is a combination of chronic impaction and enteritis. Etiology: • Grazing on sandy pasture or feeding horses on stored feed contaminated with sand or soil may cause sand colic. Clinical findings: • Signs vary in horses with sand impaction. Coarse sand frequently accumulates in the right colon, transverse colon and pelvic flexure, where fine sand may accumulate in the ventral colon. 60

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Recurrent attacks of colic vary from mild to severe combined with chronic diarrhea and loss of weight with case fatality rate of 30%.

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Recently, auscultation of abdominal sounds has been reported as being useful to reveals gritty sounds.

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Rock-hard large intestine impacted with sand may be palpated but in most cases there is only an increasing density of contents in distended cecum and colon. 61

Diagnosis: • Case history of sandy feed and characteristic clinical signs which may be similar to the signs resulting from impaction caused by certain feed but sand may also cause diarrhea. • Sand impaction can be diagnosed by rectal examination and palpation of a firm sand in the colon.

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• Examination of the feces for detection of

sands is performed by mixing feces with water in a bucket, then pouring off the water & looking for sand sediment. • On surgery, it has been found that; – There is a series of obstructions between iliocecal valve and the rectum. – Concurrent displacement or torsion of the colon occur in 50% of cases that comes to surgery.

• Radiologically deposit of sand in the gut could be visualized 63

Radiograph showing sand collected in pony's intestine.

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Treatment:

• The laxative of choice for sand impaction is administration of psyllium which is more effective than mineral oils in penetration and breaking down the fecal masses and recommended for treatment of chronic cases in a dose of 250-500 g. orally in 10 liters of warm water. • When mixed with water, psyllium forms a gelatinous mass that carries ingesta along the GI tract. Although usually given through a nasogastric tube, it also may be used as preventive by sandy environment or that persistently develop impactions may be given psyllium powder 0.5-2 cups / day in their feed. 65

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