Alimentary System - Intestine Flashcards
What is the most common congenital segmental anomaly of the intestine of domestic animals?
atresia coli - intestine undergoes stenosis (incomplete occlusion of lumen) or atresia (complete occlusion/obliteration of lumen)
colon can form a blind sac and no longer meet the rectum
What are 2 possible causes of atresia coli? What is the most common clinical sign?
- ischemia of a segment of the gut during fetal development
- autosomal recessive trait in Holstein calves
distended abdomen
What is atresia ani? Which gender tends to survive longer? Why?
imperforate anus - no anal orifice
females - tend to develop a recto-vaginal fistula allowing them to defecate from their vagina
What is the most common finding in atresia ani?
megacolon and enlarged cecum impacted with ingesta
(enlargement always occurs cranial to anomaly)
What is lethal white syndrome? In what animal does it occur?
congenital colonic aganglionosis (autosomal recessive) - no development of PSNS in the colon
American Paint horse - white spotting = carriers; affected foals = all or mostly white
What is seen microscopically in congenital colonic aganglionosis (lethal white syndrome)? What does this result in?
absence of myenteric and submucosal parasympathetic ganglia in the wall of the ileum, cecum, and colone leading to intestinal immotility and colic/impaction
(poorly developed colon and rectum covered in the green, mucin-like primary feces, meconium)
What are enteroliths?
concretions in the intestines composed of lamellae of magnesium ammonium phosphate (struvite) around a nucleus like a foreign body (nail, wire) that are unable to be digested and commonly result in obstructions
What roundworm commonly causes impaction in the intestines of horses?
Parascaris equorum
What is rectal stricture? What animals commonly develop this? What is thought to be the etiology?
decreased lumen size of the rectum due to penetrating wounds causing scar formation and fibrosis, making it less flexible
PIGS - chronic salmonellosis (Salmonella typhimurium) causing vasculitis of the cranial hemorrhoidal artery
What is a hernia? What are the 2 types? What is an example of each?
protrusion of an organ or part of an organ/tissue through an abnormal opening
- INTERNAL: displacement of the intestine through a normal or abnormal foramen within the abdominal cavity - incarceration of loops of the intestine through the epiploic foramen or tear in the mesentery
- EXTERNAL: displacement of the intestine, omentum, and other viscera (hernia contents) outside of the abdominal cavity within a pouch formed by peritoneum and skin (hernial sac), which protrudes through the hernial ring, an opening through the abdominal wall - inguinal, umbilical, diaphragmatic
What is eventration?
displaced abdominal contents in a hernia are not covered by parietal peritoneum or skin
Eventration of cecum, mare:
strangulated bare cecum not covered by skin or peritoneum
Cecum eventration, mare:
hemorrhagic —> compressed —> venous infarction
What organs are most likely to undergo diaphragmatic herniation?
liver and loops of the small intestine
(external —> thorax)
What makes scrotal (inguinal) herniation of the intestine more common?
ingesta and gas from bacteria in the intestine —> incarceration, venous infarction —> complicates castrations
Umbilical hernia, pig:
intestine gets stuck and strangulates (can come and go)
- hernial sac
Umbilical hernia, pig:
strangulated loop of small intestine with venous infarction (dark red, swollen, friable)
- intestines = hernial contents
- hernial ring
What part of the equine colon is more susceptible to torsion? Why? How can it be confirmed that it happened antemortem?
left colon - not fixed in place by mesentery
dark red discoloration + dilated veins = venous infarction
Colonic torsion, horse:
What is intestinal volvulus? What are 2 common signs?
torsion of the intestine along the mesenteric axis
- abdominal pain (colic)
- septic shock
Where is the small intestine most likely to undergo internal herniation?
through epiploic foramen of the omentum
- venous infarction!
What is a common cause of intestinal strangulation in horses?
pedunculated mesenteric lipomas naturally form with age and can become necrotic and undergo dystrophic calcification, making them heavier are more likely to twist around the intestines —> necrosis and venous infarction
Pedunculated lipoma, horse:
What is intussusception? What are the 2 parts?
piece of the intestine “telescopes” into another piece of the intestine
- INTUSSUSCEPTUM - piece of the intestine that goes within the other piece, dragging mesentery and vessels within, too (venous infarction
- INTUSSUSCIPIENS - part that receives the other piece of intestine
Intestinal intussusception, foal:
wrinkled intestine + mesentery tearing
What are 2 possible etiologies for intestinal intussusception in foals?
- coccidiosis
- inflammatory disease causing increased peristalsis
