Alimentary System - Esophagus, Forestomachs, Stomach Flashcards
What causes congenital megaesophagus?
persistent right aortic arch (PRAA) - right aorta develops instead of the left one and forms a vascular ring with the ligamentum arteriosum that constricts the esophagus
How do animals with persistent right aortic arch typically die?
aspiration pneumonia
Congenital megaesophagus, puppy:
persistent right aortic arch (PRAA)
Where does esophageal dilatation occur in persistent right aortic arch?
cranial to the aorta - can be seen in radiographs
What are the 2 most common causes of acquired megaesophagus? How can it be differentiated from congenital megaesophagus from persistent right aortic arch?
- idiopathic
- manifestation of myasthenia gravis
whole esophagus will be dilatated, not just cranial to the aorta
What causes choke? Where does it most commonly occur? How does it present postmortem?
foreign bodies or food is swallowed and becomes stuck in the esophagus
dorsal to the larynx —> area cannot expand
focal compressive necrosis causing poor vascular supply and ischemia
What are 2 complications of choke?
- regurgitation
- bloat
What is reflux esophagitis? In what animals is it common?
damage to the esophagus due to leakage of acidic gastric contents, causing ulceration and thickened linear epithelium (heart burn)
pigs - more common to have gastric ulcers near the entrance to the stomach
What is a common cause ot erosive-ulcerative esophagitis?
BVD
What is the most common cause of parasitic esophagitis in dogs? How does it present?
Spirocerca lupi
chronic (granulomatous) inflammation in the distal esophagus with nodule formation and may occasionally lead to neoplastic transformation
What are the 2 most common neoplastic transformation in canine parasitic esophagitis?
- osteosarcoma
- fibrosarcoma
Esophageal osteosarcoma caused by Spirocerca lupi occupies space in the thorax. What can this lead to?
Marie’s disease - periosteal proliferation in distal limbs
What is ruminal tympany/bloat? What are the 2 types?
over-distention of the rumen and reticulum by gases produced during fermentation
- PRIMARY - new diets that promote the formation of stable foam (grain, alfalfa, clover)
- SECONDARY - physical or functional obstruction of the esophagus resulting in failure to eructate (vagus indigestion, esophageal papillomas, lymphosarcoma)
What are other names for ruminal tympany/bloat? How does it typically present?
frothy bloat (bubbles in ruminal content), free-gas bloat
assymetrically enlarged rumen causing distention of the paralumbar fossa
How can the cause of ruminal tympany be differentiated?
entire herd = primary due to diet in pasture
single individual = secondary due to physical or functional obstruction of the esophagus
Why is it important to know the time of death when investigating a case of ruminal tympany/bloat?
if bloat is thought to be the cause of death, the necropsy must occur close to the time of death, since all corpses will eventually bloat naturally after death due to the overgrowth of bacteria
Bloat, cow:
What is the most reliable postmortem indicator of antemortem bloat? What else can be used?
bloat line at the level of the thoracic inlet
ruminal pH —> acidic pH of <5.5 is indicative of primary bloat
What causes the discoloration after the bloat line?
bloat causes the diaphragm to push the heart and lungs cranially, causing cardiopulmonary failure and the push of venous blood to the head and neck
What are trichobezoars? Phytobezoars/phytotrichobezoars?
solid concretions of hairballs
hairballs composed mainly of plant material impregnated with some phosphate salts commonly found in the colon of horses
How do trichobezoars compare to enteroliths from the forestomach and abomasum?
not as heavy
What is traumatic reticulitis?
foreign body is swallowed and perforates the reticulum and may puncture lungs, diaphragm, and pericardium (tamponade)
What is hardware disease? What 2 things does it typically lead to?
traumatic reticuloperitonitis due to the ingestion of nails or wire (cattle have a hard time discriminating between hardware and grass)
- vagus indigestion
- ruminal atony
What is a common complication to hardware disease (traumatic reticuloperitonitis)?
chronic pericarditis and epicarditis
(pericardium is thick due to fibrosis)
What is the most common cause of chemical rumenitis? How does it present?
lactic acidosis from grain overload in cattle - grain decreases pH and damages the epithelium and keratinocytes)
green - normal
red = ulceration
What are 2 common complications with chemical rumenitis?
- bacteria and normal flora can reach portal circulation and lead to bacteremia, liver abscesses, and vena cava thrombosis
- opportunistic fungi can cause mycotic rumenitis
What are commonly indicative of old bouts of chemical rumenitis?
stellate ulcers —> focal scar formation from healed ulcers
Grain overload, heifer:
treatment = rumenectomy (take out rumen content and put in healthy content)
What is gastric dilation-volvulus? In what 2 animals is it most common?
torsion of the stomach along the long gastrosplenic ligament most common after eating/drinking
- large deep-chested dogs
- sows
What are 4 clinical signs of gastric dilatation-volvulus?
- progressive abdominal distention
- non-productive retching
- hypersalivation
- restlessness
Gastric dilatation-volvulus, dog:
venous infarction of stomach and spleen
- easy movement of stomach full of water and food after over-excitement
Gastric dilatation-volvulus, dog
intraluminal hemorrhage + venous infarction —> friable stomach wall
When does abomasal displacement most commonly occur? How do the 2 types compare?
post-parturient dairy cows and calves
- LEFT-SIDED: most common and with a better prognosis, typically leasing to a partial obstruction of abomasal flow
- RIGHT-SIDED: more problematic, 20% result in abomasal volvulus
What are 6 common clinical signs of abomasal displacement? How is it typically treated?
- abdominal pain
- elevated heart rate
- anorexia
- dehydration
- depressed peristalsis with lack of feces
- abomasal typany
gastropexy
What are the most common causes of gastric ruptures in horses?
- intestinal obstruction (ileus) leads to adynamic and mechanical ileus —> inhibiton of bowel motility caused by peritonitis
- increased diet of fermentable carbs (grains) and excessive water causes swelling of gastric contents
Why are horses more likely to develop gastric ruptures?
horses are unable to vomit due to their strong cardiac sphincter, leaving no relief
(would need a nasogastric tube to move contents)
How can antemortem gastric rupture be differentiated from postmortem rupture?
ANTEMORTEM = tearing with blood/hemorrhage and congestion
POSTMORTEM = no blood
How can chronic diaphragmatic hernias lead to gastric rupture?
stomach can push through hernia and get stuck, allowing fluid accumulation, proliferation of bacteria, and rupture
Ingestion of what fruit has been associated with gastric impaction/rupture in horses?
persimmons (+ water = swelling, no vomiting for relief)
In what animals is gastric ulceration most commonly seen? What causes this? Where in the stomach is most affected?
PIGS —> finely ground rations that increase HCl content and wheat in the feed
esophageal portion covered with stratified squamous epithelium
Where are gastric ulcers most commonly found in horses?
cardiac portion, mostly near the margo plicatus
What is the pathogenesis of NSAID-caused gastric ulceration?
NSAIDs block COX, which decreases prostaglanding production (PGE2, PGI1), which usually play a protective role for the gastric epithelium
What is a common secondary effect of gastric ulcers?
reflux esophagitis
Most gastric ulcers in cats and dogs are idiopathic. What is a common exception? What is the pathogenesis?
cutaneous mast-cell tumors in dogs may lead to gastric ulcers
histamine from mast cells are released into the blood and binds to receptors of parietal cells of the stomach and increases HCl secretion
Perforated gastro-duodenal ulcer, dog:
dog = mast cell tumor
What are 4 gross findings with gastric ulceration? What is it commonly secondary to?
- thrombosis
- vasculitis
- hemorrhage of mucosa
- increased mucous secretion
endotoxemia or bacterial sepsis (E. coli, Salmonella)
What is uremic gastropathy most commonly secondary to?
renal failure - imbalanced calcium to phosphate ration resulting in mineralization + congestion and hemorrhage
Uremic gastritis, Shih-Tzu with familial renal disease:
mucosal and smooth muscle mineralization
What stain can be used to diagnose uremic gastritis?
Von-Kossa —> stains calcium
What is the most common cause of bacterial abomastitis in lambs? What is this called? What is it associated with?
Clostridium septicum
Braxy (bradsot)
winter - ingestion of frozen feed that injures abomasum and allows for proliferation and invasion of the bacteria
What is the most common gross finding of Braxy?
(Clostridium septicum —> Braxy, bradsot)
necro-hemorrhagic abomastitis with submucosal emphysema
What is the most common cause of mycotic gastritis? What 4 species are the most common causes?
long-term antibiotic therapy that destroys resident bacterial flora and promotes the growth of angio-invasive fungi (hemorrhage, necrosis)
- Aspergillus
- Absidia
- Rhizopus
- Mucor
Mycotic abomastitis, calf:
multifocal hemorrhage
Why is it important to use special stains for vasculitis/perivasculitis?
GMS stain can point out fungi not seen on H&E that seemed like intestinal cancer
Gasterophilus nasalis and intestinalis, horse:
fly develops as larvae in the nose and are ingested
Gasterophilus intestinalis, horse:
larvae firmly attached to stomach —> proliferative, erosive, and ulcerative gastritis
Gasterophilus intestinalis, horse:
erosive-ulcerative lesion
What causes a Moroccan leather appearance of the abomasal folds?
proliferative (hyperplastic) abomasitis due to Ostertagia spp. infection encysted into the mucosa
- cattle!
What does Draschia megastoma infection cause?
mucosal/submucosal brood pouch (granulomatous nodule) formation close to the margo plicatus
- usually incidental, but can look like lymphosarcoma
What is Haemonchus contortus?
trichostrongylid nematode that causes disease primarily in sheep and goats resulting in blood loss, anemia (pale MM), and hypoproteinemia causing edema of the neck (bottle jaw)
What gives the dark appearance of blood during parasitic abomastitis?
blood sucking parasite digests blood (melena)
What is another name for Haemonchus contortus?
barber’s pole worm —> blood-filled intestine
What is the most common gastric neoplasia in horses?
squamous cell carcinoma
Where does gastric squamous cell carcinomas of horses typically arise? What are some clinical signs?
ulcerative and proliferative (fibrotic) lesions arise from the cardiac portion of mucosa
- weight loss
- hypoproteinemia
- edema
- melena (lesion is bleeding)
What is a common sequel to gastric squamous cell carcinoma?
peritoneal carcinomatosis - metastasis of carcinomas in organs in the abdominal cavity to the abdominal wall and other organs due to spread from peritoneal fluid
Gastric lymphosarcoma, horse:
- nodular
- involvement of stomach folds near the margo plicatus
- multifocal gastric ulceration
Abomasal lymphosarcoma, cow:
- multicentric
- folds are nodular and thick
Abomasal multicentric lymphosarcoma, cow:
- ulceration of abomasal folds due to tumor suppressing blood vessels
- diffusely thickened
