TIERKLINIK HOCHMOOR

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08.09.2010

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"Impaction of the small intestine in the horse" von Huskamp, N.H., Vortrag anläßlich des Internationalen Seminars über Kolikerkrankungen beim Pferd (Veranstalter: SIVE, Società Italiana Veterinari per Equini, Bologna, 02.05.98.

mpactions of the small intestine in horses most commonly (82-85%) involve the ileum (Obstipatio ilei), sometimes the jejunum (Obstipatio jejuni) and rarely the duodenum (DOBBERSTEIN and DINTER 1941, HUSKAMP 1982, Graf v. HELLDORF 1989, SIEBKE 1995, GERHARDS 1997). Primary impactions - these take place in lack of pathologic changes of the gut - are distinguished from secondary impactions. These are found cranially to the narrowing of the intestinal lumen caused by circular stenosis, inflammation, ulcus of the mucosa, ischemic necrosis, thrombose, adhesion, abscess, neoplasma, hematoma, diverticle or an insufficient anastomosis. Most authors suggest surgical intervention, while some articles describe successful medical treatment in cases of ileal impaction.

Etiology

The exact causes of primary ileal impactions are unknown. However it is likely that factors like feeding practices, type and age of the horse population, parasite control programs and anatomy of the ileocecal region influence formation of impaction.

Endoparasites can cause intestinal obstruction directly by obstruction of the lumen (Ascarids) (EDWARDS 1995), or facilitate it by stimulating a local inflammation of the mucosa (Anoplocephala perfoliata) or by thickening of the ileocecal junction caused by larval migration into the ileal wall (Strongylus vulgaris) (WHITE 1981). These larvae decrease the myoelectric activity of the ileum (BERRY et al. 1986) and disturb the emptying of it. In generating a primary ileal impaction, bad quality of the food or unsuitable feedstuff like short cut lawn grass (KÖRBER 1971), wild oats (Agrostis spica venti) (KÖRBER 1989), Coastal Bermuda grass hay (WHITE 1990), rice spelt (ZEREGA 1994), sawdust (GERHARDS 1997) or silage/grain of maize (authors´ observation) play an important role, as careful crushing of fibrefood particles is imperative for their passage through the alimentary tract. Pathological processes in the mouth and any kind of dental problems can cause problems in mastication and consequently in crushing the food. Three-year-old horses have been seen over-represented, probably because of their second dentition.

Because of its thick muscular wall and its narrow lumen, the ileum anatomy can lead to formation of an impaction. The fact that smaller breeds like Ponies, Arabians, Quarter Horses or Haflingerhorses are more likely subject to an ileal impaction than Warmbloods reflects the importance of the ileal anatomy.

Pathophysiology and clinical signs

During or soon after eating, the impaction develops and the horse shows signs of mild, rarely severe, colic. In horses with ileal impaction little change in their general condition (refusal of food) occurs, and systemic effects are minimal in the first 6 h of the disease. The jejunum increases the peristalsis (hypermotility) in order to surmount the obstruction. Fluid and gas accumulate cranially to the impacted ileum, and the colon dehydrates due to the failure of fluid passage and water absorption. As the condition progresses, the small intestine and, around 12-14 h into disease, even the stomach distend. Due to the stomach distention, abdominal pain in this phase increases. Propulsive peristalsis is now absent. In cases with an intestinal impaction situated more cranially in the jejunum or in the duodenum, the distention of the stomach can be seen much earlier. In a lot of cases with small intestine obstruction, a reflex inhibition decreases stomach emptying causing accumulation of firm ingesta.

The first signs of circular disorder in ileal impaction are recognized after 8-12 h, mainly by an increase of PCV (>42%), TPP (>7,5 mg/dl) and pulse (about 60/min).

About 24 h after the onset of an ileal impaction, the stomach is extremely distended and in rare cases regurgitation from the nostrils or mostly gastric ruptur occurs. Horses with gastric dilation show severe colic and may assume a "dog-sitting" posture. Immediately after stomach rupture, pain disappears and signs of shock, acidosis and cold sweating can be observed.

DIAGNOSIS

Interpretation of severity of pain and clinical signs related to the duration of impaction is mandatory in colic diagnostics. In cases of small intestine impaction, it is almost always possible to reach a diagnosis. This, however, requires time and experience.

The most important diagnostic procedure is rectal examination. The most helpful parameters in differentiating obstruction from strangulation or incarceration are TPP and peritoneal fluid parameters. Diagnosis in the early stage (1st-8th h)

The ileal impaction can be felt on deep rectal exploration as a smooth, forearm-thick impacted part of the gut medial to the cecum (HUSKAMP and KOPF 1995). It can be identified by palpating the ileocecal fold. Very huge horses and a short arm of the veterinarian are limiting factors in reaching the ileum directly. The colon ascendens is filled with dehydrated ingesta. In cases of a caudal duodenal impaction or of a cranial jejunum impaction, an extremly distended duodenum is palpated. An impacted jejunum is freely mobile and can be discerned by its similar circumference. PCV (<40%), TPP (<7,0g/dl) and pulse (40-60/min) are quite normal. Only in the case of duodenal or cranial jejunum impaction, does gastric reflux occur in this stage. This early dilatation of the stomach causes severe colic in horses with a cranial intestinal obstruction.

In cases of jejunum or ileal impaction, spasmoanalgesics (Novalgin® , Buscopan comp. ®) produce good pain relief, this allowing to distinguish these cases from intestinal strangulation. On auscultation, increased sounds from the small intestine (hyperperistalsis) can be heard, but in cases of ileal impaction no squirt of fluid in the ileocecal region, are .

Diagnosis in the middle stage (9th.-16th. h)

In the case of jejunum or ileal impaction, distended loops of small intestine can be palpated rectally. The colon ascendens is more and more dehydrated, and the rectum is empty.

PCV (>45%), TPP (>8g/dl) and pulse (>60/min) are increased. After 12 h, 1-5 litres of nasogastric reflux is present. After 18 h, more than 15 litres of fluid can be seen in horses with ileal impaction. If the site of impaction is situated closer to the stomach, gastric distention occurs earlier in the of disease. At this time, pain is periodically more intense. Peritoneal fluid is clear, light yellow in color and contains protein, leukocytes, but no erythrocytes. On auscultation, propulsive sounds are now absent, only some fluid and gas interfacing sounds of bubbling can be heard. TPP over 8.0 g/dl indicates an impaction.

Diagnosis in the final stage (after 17th h)

Rectally, only very distended loops of small intestine and perhaps an extremely dehydrated colon ascendens are palpable in the caudal part of the abdomen. Pulse rate, respiratory rate, PCV (>50%) and TPP (>8,5%) are strongly increased and signs of shock (cyanosis of the mucosa, increased capillary refill time) are evident. Peritoneal fluid is increased in volume and slightly turbid in colour with a few erythrocytes. Colic is more severe but nasogastric decompression still gives some relief to the horse. Analgesics are not effective any longer in this stage of the disease. A high TPP (>8,5 g/dl) indicates an impaction in contrast with intestinal strangulation where protein levels decrease.

Differential diagnosis

Small intestine impaction must be differentiated from intestinal obstruction due to strangulation or incarceration. In the latter conditions, the course of the colic is more rapid and severe, analgesics are almost ineffective. Marked systemic effects develop within hours, TPP does not go up to 8 g/dl or higher.

Peritoneal fluid shows colour changes (erythrocytes) after only 4-6 h.

To differentiate impaction from gastro-duodeno-jejunitis (proximal enteritis) is more difficult, the signes of colic being mild in both cases. In cases of enteritis, horses show depression and gastric reflux containing blood. On rectal examination, distention is palpated in the duodenum and the degree of distention in the small intestine is decreased.

Treatment

Medical treatment (WIRTH 1956, JAKSCH 1982, HANSON et al. 1996, Gerhards 1997) and surgical treatment (EDWARDS 1981, HUSKAMP et al. 1982, ALLEN 1987, ALLEN 1990, GERHARDS 1990, DORAN et al. 1992, HAY 1996) have been described.

In practice, medical treatment shoud be attempted only in the early stage of disease. If diagnosis of small intestine impaction is certain, and provided the possibilities to monitor the horse closely and to reevaluate the clinical status are continually given, conservative therapy can be induced. If the impaction remains or increases in size or firmness for more than 3-5 h, the horse requires surgical intervention. Every delay will reduce the chance of survival.

Medical treatment consists of the application of spasmoanalgesics (Novalgin® and/or Buscopan comp.® , 2-3 times every 30 min), and fluids given intravenously (3l/h). The horse shoud not have access to feed and water. Intubation with the nasogastric tube has to be done every 3 hours. Mineral oil will reach the impaction only in the initial 3 h of the disease.

In a referral center medical treatment can be extended up to 10 h of disease. If the diagnosis is certain, the pulse rate will be less than 60/min, PCV (<45%) and TPP (<8,5) decrease due to infusion. Furthermore, intestinal loops are not extremely distended, peritoneal fluid contains no erythrocytes, pain is controllable with Novalgin®, and there is no or only little reflux.

Most impactions of the small intestine require surgery, even although in approximately 20% of the cases an early and consistent (strictly) medical treatment can heal the patient. Impactions in the ileum can be very firm and up to 1-2 m long. In these cases medical treatment seems to be unsuccessful.

In foals (3-9 months), a special form of small intestine impaction is caused by the accumulation of ascarids. If this is suspected and worms are alive, conservative treatment (infusion, anthelmintic therapy, Prostigmin) shoud be attempted first. If intestinal obstruction occurs one day after anthelmintic therapy of the foal, surgical intervention is immediately recommended.

The ventral laparotomy starts with a midline incision cranially to the umbilicus. This gives good access to the cecum; following the ileocecal fold into the abdomen, the ileum can be easily found. Ileal impaction varies in extent (from egg-size up to 150cm in length) and consistency (from soft to very firm). In most cases, the impaction is 20-70cm long and soft or dry. Neither extent nor consistency are related to the duration of disease.

The condition of the impaction determines the method of carring out manual reduction. In the majority of cases, it is easy to massage impacted material into the cecum. If the impaction is dry or firm, it is necessary to soften the material either by mixing it with prestenotic fluid or by injecting fluid (water, oil, saline solution) directly into the impaction. In cases with a very firm consistency, it is recommended to use a rigid catheter to "flush" away the impaction with water. This catheter is introduced through an antimesenteric, 2cm-long incision into the lumen of the caudal part of the jejunum, and then passed between the ileum wall and the impaction to the ileocecal orifice. On retracting the catheter in cranial direction, water coming out of its tip breaks down the impacted mass. The application of techniques to soften the intraluminal mass is recommendable to avoid excessive manipulation of the ileum or the jejunum in order to minimize serosal trauma, which could stimulate intra-abdominal adhesion formation. For preventing adhesions, lavage of the extraperitoneal gut with 10-30 liters of sterill fisiologic solution during the entire operation shoud be done. Most important in adhesion prevention is avoiding any kind of abdominal contamination. Only in very rare cases of primary ileal impaction, enterotomy of the small intestine is necessary. Intestinal resection or bypass procedures are necessary in cases of ileal or jejunum hypertrophy or stenosis. Reimpaction of the ileum in the post-operative phase has been seen in less than in 1% of cases (HUSKAMP 1998). To keep the rate of post-operative ileus to a minimum once the ileal impaction is removed, the contents of the entire proximal small intestine has to be evacuated into the cecum. Horses with more than 12 h of time from the onset of disease show an extreme gas and fluid distention in the jejunum. These patients are at high risk for post-operative ileus and should be treated post-operatively with Neostigmin for 1-2 days. In these cases, if postoperative ileus is diagnosed, a relaparotomy performed within 24 h has been shown to be the most successful treatment (SCHLAG 1997).

Results of a retrospective study on 288 cases with ileal impaction

healed cases of total number: 81.6% of all patients
healed cases of completely operated horses: 86.4% o.a.p.
all horses with surgical treatment in the first 8 h of disease recovered, provided they had not been treated with saline laxatives
surgical treatment completed in 275 cases
age of the horses: 6 months to 25 years
3-year-old horses: 15,9% o.a.p.
duration of colic before hospitalisation: 3-96 h
7-12 h duration of colic before hospitalisation: 40,3% o.a.p.
heart rate at time of first examination in the clinic: 36-130 beats/min
heart rate at time of first examination in the clinic of 40-76 beats/min: 73% o.a.p.
PCV at hospitalisation: 28-71%
TPP at hospitalisation: 4.3-10.9 g/dl
gastric reflux at hospitalisation: 48.6% o.a.p.= >2 litres, 2% o.a.p.= >20 litres
over-represented in the material: 3-year-old horses, Arabians, Ponies, Haflingerhorses
under-represented in the material: Thoroughbreds and Standardbreds
43.7% o.a.p. were seen in the summer period (May-August)
size of the impaction varied from 4-200cm in length, (63% o.a.p. = 10-50cm)
enterotomy was done in few cases (11/275); bypass surgery has not been carried out
most common post-operative complications leading to death or euthanasia were shock (15/44=34 %), peritonitis/adhesions (13/44=29.5 %), enteritis (6/44=13,6%) and post-operative ileus (3/44=6,8%). 15 % of all operated patiens showed post-operative ileus, only 6.1% of horses with a duration of the disease of up to 12 hours suffered this complication.

Prognosis The prognosis for horses with jejunum or ileal impaction is not good if only medical treatment is possible, as no more than 10-20% of cases respond positively to medical treatment. If surgical intervention is not desired, medical treatment shoud be tried up for to 24 h from onset of disease.Horses which receive prompt surgical treatment (1-8 h) have an excellent prognosis (>90% of healing), provided they have had no preoperative treatment with saline solution. The survival rate decreases for horses with prolonged preoperative course of disease. Less than 50% of the patients with surgical treatment late in the course of the disease (>24 h) survived in one study (HUSKAMP 1998),

References

Allen D: Impaction of the Ileum. In: Current Therapy in Equine Medicine. ed. Robinson NE, Philadephia: W. B. Saunders 1987; 51-53
Allen D: Ileal Impaction. In: Current Practice of Equine Surgery. ed. White NA and Moore JN, Philadelphia: J. B. Lippincott Company 1990; 318-321
Berry CR, Merritt AM, Burrows CF, Campbell M, Drudge JH: Evaluation of the myoelectrical activity of the equine ileum infected with Strongylus vulgaris larvae. Am. J. Vet. Res. 47 (1), 1986; 27-30
Dobberstein J, Dinter W: Beiträge zur Sektionsstatistik der Kolik des Pferdes. 1941
Doran RE, Allen Jr. D, Orsini JA: Small Intestine. In: Equine surgery, ed.: Auer JA, Philadelphia: W. B. Saunders 1992; 360-378
Doran RE, Allen Jr. D, Orsini JA: Small Intestine. In: Equine surgery, ed.: Auer JA, Philadelphia: W. B. Saunders 1992; 360-378
Edwards GB: Obstruction of the ileum in the horse: A report of 27 clinical cases. Equine vet. J., 1981; 13 (3), 158-166
Edwards GB: Patologie del tenue. In: La colica nel cavallo, 1. congresso SIVE, Ferrara, Italien, 1995; 137-157
Gerhards H: Chirurgische Behandlung von Dünndarmerkrankungen beim Pferd. Vortrag während des Symposium "Kolik beim Pferd" anläßlich der 200-Jahr-Feier der Ludwig-Maximilians-Universität München, 1990
Gerhards H: pers. Mitteilung, 1997
Hanson RR, Schumacher J, Humburg J, Dunkerley SC: Medical treatment of horses with ileal impactions: 10 cases (1990-1994). JAVMA 1996; 208 (6), 898-900
Hay WP: Diagnosis and managment of ileal impaction. ACVS Vet. Symp. 3-6 Nov. 1996; 224-225
Helldorf, Graf von B:Ergebnisse der operativen Kolikbehandlung beim Pferd an der Klinik für Pferde der Tierärztlichen Hochschule Hannover von 1976 bis 1985. Vet. Med. Diss., Hannover, 1989
Huskamp B; The diagnosis and treatment of acute abdominal conditions in the horse; The various types and frequency as seen at the animal hospital in Hochmoor. Proc. Eq. Colic Res. Symp. 1, 1982;
Huskamp B, Daniels H, Kopf N: Magen- und Darmkrankheiten. In: Handbuch der Pferdekrankheiten für Wissenschaft und Praxis, Hrsg. Dietz O und Wiesner E, VEB
Gustav Fischer Verlag, Jena, 1982
Huskamp B, Kopf N: Die rektale Untersuchung beim Kolikpferd. Hrsg.: Huskamp B, wak Verlag, München 1995
Huskamp NH: Diagnostik und Therapie der Ileumobstipation beim Pferd. Eine retrospektive Studie an 288 Fällen. Vet. Med. Diss., München, 1998
Jaksch W: Krankheiten des Verdauungsapparates. In:Krankheiten des Pferdes, Hrsg.: Winzer HJ, Verlag Paul Parey, Berlin/Hamburg, 1982;
Körber HD: Windhalm (Agrostis spica venti) als eine Ursache der Kolik des Pferdes. Dtsch. Tierärztl. Wschr., 89 (7), 1989 , 285-288
Körber HD: Zur Kolikstatistik des Pferdes. Berl. u. Münch. tierärztl. Wschr. 4, 1971; 75-77
Schlag CS: Paralytischer Ileus beim Pferd nach Kolikoperationen- eine retrospektive Analyse. Vet. Med. Diss., Leipzig, 1997
Siebke AU: Statistische Erhebung über Kurz- und Langzeitergebnisse von 718 operativ behandelten Kolikpatienten. Vet. Med. Diss., Berlin, 1995
White NA: Intestinal infarction associated with mesenteric vascular thrombotic disease in the horse. JAVMA 178 (3), 1981; 259-262
White NA: Epidemiology and Etiology of colic. In: The Equine Acute Abdomen. ed.: White NA, Philadelphia: Lea & Febiger 1990; 49-64
WIRTH D: Über die Grundlagen der heutigen Diagnose und Therapie der Kolikerkrankungen des Pferdes. Schweizer Archiv für Tierheilkunde 98 (7), 1956, 267-287
Zerega U: pers. Mitteilung, 1994

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