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 Impaction of the large intestine:Impaction of the large intestine causes commonly in horses moderate abdominal pain, constipation, general depression and anorexia.
Etiology:1-Debility is a predisposing cause and the diminished intestinal muscle tone is incapable to move
the ingesta.2- Feeding on low-grade indigestible roughage, particularly old hay or sorghum.3- Bad teeth (improper mastication).4- Over-fed , fat horses are more susceptible.5- Interference with the blood supply to the intestine as in Verminus mesenteric arthritis may
interfere with the muscle tone.6- Presence of fiber-walls & enterolith.
Clinical findings:1- Moderate abdominal pain is the typical sign in affected horses, and is continuous for 3- 4 days
and sometimes for 2 weeks, and in the latter case it is accompanied with caecal impaction. Fits
of pain occur at intervals of up to 1/2 hours.2- Anorexia & constipation. Feces are passed in small amounts, hard and covered with thick
sticky mucous.3- Intestinal sounds are reduced or absent and much decreased in intensity.4- Rectal palpation reveals the following:a) Impaction of the pelvic flexure of the large colon is the commonest site. Solid-loops of the
intestine could be palpated at the pelvic rim or to the right of the midline.b) Impaction of the caecum can be palpated in the right flank extending from high up and
passing downwards and anteriorly.c) Impaction of the small colon may be felt dorsally to the right of the midline.5- Pulse rate is moderately increased (50/min).6- Animal does not eat but may drink small quantities of water.7- When death occurs this may be due to rupture of the intestine or from exhaustion after a large course in debilitated horses.8- In foals retention of the meconium causes continuous straining with elevation of the tail and walking backwards. Hard fecal balls can be palpated with the finger in the rectum.
D. Diagnosis:1- Other causes of constipation as in peritonitis and dehydration should be considered. In peritonitis there may be toxemia as a complication.2- In other forms of pain as gastric dilatation, acute intestinal obstruction and spasmodic colic the pains are more severe, and have a much shorter course.3- Palpation of the cranial mesenteric artery must be done to differentiate the disease from
Verminus mesenteric arteritis.Treatment:1- Administration of 1/2 - 1 gallon of mineral oil with 15-30 gram chloral hydrate in 1 - 1.5 liters of water by nasal tube. Repeat the treatment if the impaction is not relieved in 12 hrs. In this case you can inject s/c, in addition parasympathetic stimulant. Do not use parasympathetic stimulant without prior administration of mineral oil otherwise rupture of the intestine occurs. Linseed oil can be also used.2- Detergents combined with mineral oil could also be used.3- Violent purgatives as anthracene purgatives are also used ,but be careful about the dose to
avoid super purgation.4- Enema with soft soap and warm water may be used but have doubtful effect.5- Retention of the meconium in foals could be treated with the injection of mineral oil (90 ml)
or glycerin (30 ml) into the rectum by the use of a rubber tube. The enemas are repeated until
soft feces appear and the animal is comfortable. Oral doses of 120-250 ml of mineral oil are
also indicated; small doses of parasympathetic stimulants could also be injected (1/8 or 1/16 of
the adult dose).6- Pain is relieved with parentral administration of an ataractic drugs.