GI pathology 3 (Stomach/abomasum, Intestines​)

what is catarrhal inflam?

serous inflam on mucosal surface + serosal surfaces

What is the gross appearance of Acute catarrhal gastritis?

• increased reddening and thickening of entire surface / parts of mucosa

• increased mucus production (appears wet)

milder than acute haemorrhagic

what causes Acute catarrhal gastritis?

• poisons

• infectious diseases e.g. cat Helicobacter spp

• parasites

what is braxy?

• Acute haemorrhagic abomasitis in sheep and calves

• due to Clostridium septicum enterotoxin

• → severe oedema + emphysema in submucosa, haemorrhage, venous thrombosis

what causes Acute haemorrhagic gastritis?

• poisons

• infectious diseases (eg. Swine erysipelas, Braxy)

• use of non-steroidal anti-inflammatory drugs (NSAIDs)

what can cause Haemorrhagic gastritis?

• sometimes with infectious diseases

  • classical swine fever

  • anthrax

  • lepto

• with uraemia —> secondary to renal failure → haemorrhagic gastritis

what is this?

Cat, adult —> haemorrhagic gastritis

what causes Uraemic gastritis?

chronic renal failure

pathogenesis of Uraemic gastritis?

• due to endothelial degeneration + necrosis → thrombosis → infarction

• due to excretion of high concentration of ammonium (with saliva + gastric juice)

histo appearance of Uraemic gastritis?

coagulative necrosis, haemorrhage,neutrophil infiltration, mineralisation

what is this?

Uraemic gastritis (more common in dogs than cats)

mineralisation —> gritty texture

what causes (fibrino-) necrotising gastritis?

• mycotic infection

• associated with mucosal destruction

what is this?

• Calf, abomasum —> mycotic abomasitis

• fibrino-necrotising —> fibrin on mucosa

What are gastric ulcers seen with?

Erosive / ulcerative gastritis

cause of gastric ulcers in cattle?

• (mainly calves, dairy cows, yearling cattle)

• mainly in pylorus of abomasum

• associated with environment (transport stress, diet...)

cause of gastric ulcers in pigs?

• in squamous epithelium

• associated with hyperacidity, finely ground grain diet, stress

cause of gastric ulcers in horses?

• mainly in non-glandular portion (squamous epithelium)

• association with Gastrophilus larvae

cause of gastric ulcers in dogs and cats?

pylorus, proximal duodenum —> with mast cell tumours elsewhere in body (raised histamine)

what is this?

stomach mucosa

chief cells = more basophilic

parietal cells = large

what is this?

chronic moderate focal ulcerative gastritis (gastric ulcer)

black area = carida region (squamous portion) ulceration (red-black)

What is this?

Stomach, multifocal to coalescing erosive & ulcerative gastritis

outcome of gastric ulcers?

• haemorrhage due to vascular erosion

  • → massive haemorrhage

  • → remittent mild haemorrhage

  • → anaemia (regen)

• perforation → peritonitis

what is this?

Dog, stomach —> perforated ulcer

what parasites can be found in the stomach of horses?

Gastrophilus spp. larvae (larvae of bot flies)

(most common G.intestinalis, nasalis & haemorrhoidalis)

pathogenesis of Gastrophilus spp. larvae in horses?

• Ova are deposited on hair and hatch spontaneously or after licking, first-stage larvae penetrate oral mucosa, molt, emerge and migrate down the alimentary tract

• Attach to squamous mucosa (pars oesophagea)

how do Gastrophilus spp. larvae affect the stomach of horses?

• Attach to squamous mucosa (pars oesophagea)

• induce erosions (and chronic hyperplastic gastritis), but no apparent association betweenbot infestation and development of gastric ulcers

what parasites can be found in the abomasum of ruminants?

• small ruminants —> Haemonchus sp., Teladorsagia circumcincta

• cattle —> Ostertagia ostertagi

What does haemonchus & teladorsagia cause in the abomasum mucosa

Cobblestone

pathogenesis if parasites found in the abomasum?

• blood-sucking parasites → inflammation, erosions, ulcers, anaemia, cachexia, hypoproteinaemic oedema

primary neoplasms of the stomach (and abomasum)?

• Adenocarcinoma

• adenoma / benign adenomatous polyps

• Squamous cell carcinoma —> common in spp. w/ squamous portion of stomach

• Lymphoma

• Leiomyoma / leiomyosarcoma

• Carcinoids

secondary neoplasms of the stomach (and abomasum)?

• Lymphoma

• Mast cell tumour

• Metastatic tumours from pancreas and liver

What is this?

Adenocarcinoma —> thickened hole of stomach wall

ulcerated + perforated, focally extensive

what is this?

Horse stomach early stage SCC

what is this?

Dog, adult —> gastric leiomyomas

well demarcated from smooth nodules

what is Atresia?

Congenital absence, or pathological closure, of an opening, passage or cavity

where does Intestinal atresia occur?

ileum and colon, mostly in calves

what animals can get SCC in the stomach?

• horses

• rats

as these have squamous epitheliums in part of the stomach

appearance of Intestinal atresia?

complete lack of some part or: blind ends, but muscular + connective tissue layers present

what is anal + rectal atresia? what animals is it most often seen in?

• failure in development of anal opening

• most frequent in piglets

• anus + rectum are closed

what species can megacolon occur in?

• dog

• cat

• horse

• pig

causes of megacolon?

• Aplasia of neurons in large intestinal myenteric ganglia → lack of peristalsis —> so fills up w/ faeces → distension of colon

• Idiopathic megacolon

  • Unknown cause

  • Most common in old cats → requires enema

  • Recurrent + progressives episodes

  • Intractable constipation

  • Most common form of the disease

what is Herniation?

protrusion of an organ / tissue through an opening in its surrounding walls, especially in the abdominal region

what is Volvulus?

a torsion, or twisting, of the intestine, causing intestinal obstruction

main types of Herniation?

• (can be congenital or acquired)

• Diaphragmatic

• Epiploic entrapment

• inguinal

what is a Diaphragmatic hernia?

• displacement of omentum, stomach, small intestine, spleen, liver into thoracic cavity.

• Compression → pulmonary atelectasis → resp failure

what is Epiploic entrapment? Which species does it effect?

• horses

• herniation of small intestine into the Epiploic foramen

Describe this SI herniation

• Herniated through small area

• Closes venous return (arterial blood still pumping) → necrotic + devitalosed → ischamia (endotoxins in bloodstream)

what is this?

• diaphragmatic hernia

• intestines in thoracic cavity

  • often occurs after a RTA

Describe this herniation

Pericardial sac has intestines inside, no liver left

congen abnormality, died 24hrs after spay

what is this?

Pig, left inguinal hernia (of the intestines)

what is Intussusception?

“telescoping” of one segment of intestine into another w/ hyperactive bowel movement (e.g. enteritis)

where does Intussusception usually occur in dogs and horses?

• dog —> mainly small intestine (parvovirus infection,distemper)

• horse —> mainly ileum into caecum (mainly due to tapeworm infestation)

what is this?

intussusception

• fibrin between layers

• reddened —> devitalised tissue → endotoxic shock

why does congestion occur with intussusception?

venous drain blocked but arteries still functioning

what is a Volvulus?

twist at root of mesenteric attachment of intestines

where does a Volvulus occur in horses?

common in fat geldings

• jejunum, ileum (-180°)

• pedunculated lipoma around intestine

• segmental intestines

• haemorrhage

• distended mesenteric vessels

how to tell if an intestinal volvulus has happened before (i.e the cause) or after death?

find a portion of mesenteric vessels being haemorrhagic —> cause of death

what is this?

• Horse —> volvulus of pedunculated lipoma around right colon

• causes a weight and can wrap around the intestines

  • not a problem unless they wrap around

consequences of intestinal misalignment?

what can cause obstruction of intestinal lumen?

• ingesta

  • horse —> LI impaction, coprostasis

• FBs

  • enteroliths

• parasites —> ascarids

  • needs a very high burden to cause obstruction

• bezoars (impacted hair/fur)

• neoplasms

• haematoma

• abscesses

what is this?

Large intestine —> Enteroliths

What is this?

Pig, duodenum —> Ascaris suum (rare)

why are linear FBs problematic? (e.g string)

• gets caught along the GIT e.g stomach or tongue but the end still moved through the GIT

• intestines tries to push the sting through the GIT

• causes intestines to ruffle up

• pressure on the string can also have a cheese wire effect

how can a stenosis occur in the intestines?

(narrowing)

• Due to compression / strangulation: pedunculated lipoma

• Fibrosis after ulceration or surgery

example of functional intestine paralysis in horses?

• Grass sickness (primary dysautonomia)

• frequent in UK, mainly younger horses kept on pasture

What time of year is grass sickness most common?

Spring + autumn

How does chronic grass sickness present?

Loss of body condition

histo signs of Functional paralysis (e.g. grass sickness)?

necrosis + loss of neurons in sympathetic ganglia (coeliac) of intestines

gross signs of Functional paralysis (e.g. grass sickness)?

stomach + small intestine filled with watery food contents, densely packed and dry large intestine

what is wrong with this horse?

• Chronic grass sickness (primary dysautonomia)

• functional paralysis of intestines

What is the possible aetiology of functional paralysis (e.g. grass sickness)?

Clostridium botulinum toxins? Abnormal neuromuscular junction to neurotoxic phospholipase A₂

what is this?

grass sickness histo:

• coeliac ganglion

• black = Normal neurons

• green = Chromatolysis (neurons)

• blue = Shrunken + eosinophilic