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Medicine
4th stage
Lec 3
Dr. Ali Rabee
Diseases of the alimentary tract
Principles of alimentary tract dysfunction
The primary functions of the alimentary tract are the prehension,
digestion and absorption of food and water and the maintenance of
the internal environment by modification of the amount and nature of
the materials absorbed. The primary functions can be divided into four
major modes and, correspondingly, there are four major modes of
alimentary dysfunction. There may be abnormality of motility, secretion,
digestion or absorption.
1- Motility
Abnormalities of stomach and intestinal motility represent the most
common consequence of gastrointestinal tract disease. Disruption in
gastrointestinal tract motility can result in:
 Hypermotility or hypomotility.
 Distension of segments of the tract.
 Abdominal pain.
 Dehydration and shock.
2- Secretion
Diseases in which abnormalities of secretion occur are not generally
recognized in farm animals, in small animals, defects of gastric and
pancreatic secretion produce syndromes that are readily recognized, but
they depend upon clinical pathological examination for diagnosis.
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4th stage
Medicine
Lec 3
Dr. Ali Rabee
3- Digestion and absorption
The ability of the alimentary tract to digest food depends on:
 Its motor and secretory functions.
 In herbivores, on the activity of the microflora that inhabits the
forestomachs of ruminants or cecum and colon of Equidae. The
flora of the forestomachs of ruminants is capable of digesting
cellulose, of fermenting the end-products of other carbohydrates to
volatile fatty acids and converting nitrogenous substances to
ammonia and protein.
 Absorption of fluids and the dissolved end-products of digestion
may be adversely affected by increased motility or by disease of
the intestinal mucosa. In most instances, the two occur together
but, occasionally, as with some helminth infestations, lesions occur
in the intestinal wall without accompanying changes in motility.
Manifestations of alimentary tract dysfunction
1- Abnormalities of prehension, mastication and swallowing
Causes:
1. Paralysis of the muscles of the jaw or tongue.
2. Malapposition of incisor teeth due to:
A. 1-Inherited skeletal defect (inherited displaced molar teeth,
inherited
mandibular
prognathism,
osteopetrosis).
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inherited
congenital
Medicine
4th stage
Lec 3
Dr. Ali Rabee
B. 2- Rickets.
3- Absence of some incisor teeth
4- Pain in the mouth due to:
A. Stomatitis and glossitis.
B. Foreign body in mouth.
C. Decayed teeth, e.g. fluorosis
5- Congenital abnormalities of tongue and lips:
A. Inherited harelip.
B. Inherited smooth tongue of cattle.
Causes of dysphagia and inability to swallow
1. Foreign body, tumor or inflammatory swelling in pharynx or
esophagus.
2. Painful condition of pharynx or esophagus.
3. Esophageal dilatation, diverticulum and spasm.
2- Drooling of saliva and excessive salivation
Causes
Local cause of drooling:
1- Foreign body in mouth or pharynx.
2- Ulceration, deep erosion or vesicular eruption of the oral mucosa.
3- Inability to swallow (esophageal abnormality).
Systemic causes of excessive salivation
1- Poisonous trees.
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Medicine
4th stage
Lec 3
Dr. Ali Rabee
2- Poisonous plants.
3- Fungal toxins.
4- Iodism.
5- Watery mouth of lambs.
6- Sweating sickness.
7- Methiocarb poisoning.
3- Vomiting and regurgitation
Vomiting: is the forceful ejection of contents of the stomach and the
proximal small intestine through the mouth and is a complex motor
disturbance of the alimentary tract.
It occurs in two forms: projectile and true vomiting.
Projectile vomiting: This is not accompanied by retching movements
and large amounts of fluid material are ejected with little effort. It is
almost always as a result of overloading of the stomach or forestomach
with feed or fluid.
True vomiting: As it occurs in monogastric animals like the dog and cat,
true vomiting is accompanied by retching movements including
contraction of the abdominal wall and of the neck muscles and extension
of the head. The movements are commonly prolonged and repeated and
the vomitus is usually small in amount and of porridge-like or pasty
consistency.
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Medicine
4th stage
Lec 3
Dr. Ali Rabee
Regurgitation: Is the expulsion through the mouth or nasal cavities of
feed, saliva and other substances that have not yet reached the stomach.
Causes of vomiting and regurgitation include:
1- Terminal vomiting in horses with acute gastric dilatation.
2- Vomiting in cattle is really regurgitation of large quantities of
rumen contents through the mouth causes includes:
A. Third-stage milk fever (loss of tone in the cardia).
B. Arsenic poisoning.
C. Poisoning by plants.
D. Veterinary administration of large quantities of fluids into the
rumen (regurgitation occurs while the stomach tube is in place).
E. Use of a large-bore stomach tube.
3- Regurgitation - in all diseases causing dysphagia or paralysis of
swallowing.
4- Diarrhea, constipation and scant feces
Diarrhea: Is the increased frequency of defecation accompanied by
feces that contain an increased concentration of water and decrease in
dry matter content. The consistency of the feces varies from soft to
liquid.
Common causes of diarrhea are
1- Enteritis.
2- Malabsorption, e.g. due to villous atrophy.
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Medicine
4th stage
Lec 3
Dr. Ali Rabee
3- Neurogenic diarrhea as in excitement.
4- Local structural lesions of the stomach or intestine, including:
 Ulcer of the abomasum or stomach.
 tumor, e.g. intestinal adenocarcinoma.
5- Indigestible diet, e.g. lactose intolerance in foals.
6- Carbohydrate engorgement in cattle.
7- Terminal stages of congestive heart failure (visceral edema).
8- Endotoxic mastitis in cattle (splanchnic congestion).
9- Chronic and acute undifferentiated diarrhea in horses.
10- Vagus indigestion.
Constipation: Is the decreased frequency of defecation accompanied
by feces that contain a decreased concentration of water.
Causes
1- When the motility of the intestine is reduced, the alimentary transit
time is prolonged and constipation or scant feces occurs, because
of the increased time afforded for fluid absorption, the feces are
dry, hard and of small bulk and are passed at infrequent intervals.
2- Constipation may also occur when defecation is painful, as in cattle
with acute traumatic reticuloperitonitis.
Scant feces: are small quantities of feces, which may be dry or soft occur
most commonly in cattle with abnormalities of the forestomach or
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Medicine
4th stage
Lec 3
Dr. Ali Rabee
abomasum resulting in the movement of only small quantities of ingesta
into the small and large intestines.
Causes
1- Diseases of the forestomach and abomasum.
2- Impaction of the large intestine in the horse.
3- Severe debility, as in old age.
4- Deficient dietary bulk, usually fiber.
5- Chronic dehydration.
6- Partial obstruction of large intestine.
7- Painful conditions of the anus.
8- Paralytic ileus.
9- Grass sickness in horses.
10- Chronic zinc poisoning in cattle.
11- Terminal stages of pregnancy in cows.
5- Ileus
Ileus: Is a state of functional obstruction of the intestines or failure of
peristalsis.
Causes
1- Acute peritonitis.
2- Excessive handling of viscera during surgery.
3- Prolonged and severe distension of the intestines as in intestinal
obstruction or enteritis.
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Medicine
4th stage
Lec 3
Dr. Ali Rabee
4- Ileus can also be caused by acid-base imbalance, dehydration,
electrolyte imbalances such as hypocalcemia and hypokalemia, and
toxemia.
6- Alimentary tract hemorrhage
Hemorrhage into the stomach or intestine is a common occurrence in
farm animals.
The main causes are:
1- Gastric or abomasal (rarely duodenal) ulcers.
2- Severe hemorrhagic enteritis.
3- Structural lesions of the intestinal wall.
4- Infestation with blood-sucking nematodes.
5- Local vascular engorgement or obstruction as in intussusception
and verminous thrombosis.
7-Abdominal pain
The pain associated with diseases of the abdominal viscera.
Causes
Horses
1- Acute pain: All causes of intestinal obstruction, gastric dilatation,
enteritis generally, colitis X, rarely salmonellosis
2- Subacute pain: Thromboembolic colic, impaction of the large
intestine, ileal hypertrophy.
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Medicine
4th stage
Lec 3
Dr. Ali Rabee
Cattle
1- Acute pain: Intestinal obstruction and poisoning.
2- Subacute pain: Traumatic reticuloperitonitis and peritonitis and
abomasal volvulus.
8- Tenesmus
Tenesmus or persistent straining: is common in many diseases of the
organs of the pelvic cavity; therefore it is not necessarily a diagnostic sign
of disease in the lower alimentary tract.
Causes
Cattle
1- Lower alimentary tract disease, e.g. colitis and proctitis caused by
coccidiosis.
2- Genital tract disease, e.g. severe vaginitis, retained placenta
3- 4-aminopyridine poisoning and Methiocarb poisoning.
4- Lower spinal cord lesions – spinal cord abscess, rabies.
5- Idiopathic.
Horses
Tenesmus does not usually occur except during parturition.
9- Shock and dehydration
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Medicine
4th stage
Lec 3
Dr. Ali Rabee
10- Abdominal distension
Distension of the abdomen is a common manifestation of disease of the
alimentary tract. Generally, abdominal distension associated with the
alimentary tract is caused by distension of viscera with gas or fluid.
Distension may be symmetrical, asymmetrical or more pronounced
dorsally or ventrally on one or both sides.
Causes
1- Intestinal tympany - due to excessive gas production caused by
abnormal fermentation in the large intestine.
2- Obstruction of the large intestine.
3- Retention of the meconium.
4- Ruminal tympany.
11- Abnormal nutrition
Failure of normal motor, secretory, digestive or absorptive functions
causes impairment of nutrient supply to body tissues, inanition or partial
starvation results and the animal fails to grow, loses body weight or
shows other signs of specific nutritional deficiencies.
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