Alimentary System - Intestine, Pt.2 Flashcards
What causes bovine viral diarrhea? How does it typically present?
Pestivirus
ulcerative colitis in young cattle up to 2 years old - tends to be mild/subclinical
What is the most severe form of bovine viral diarrhea? In what animals does this most commonly seen?
low morbidity, high mortality mucosal disease with raised necrosis on Peyer’s patches
animals persistently infected with the cytopathic strain or when persistent infection allows virus to develop mutations (6 months to 2 years old)
What causes malignant catarrhal fever? What animals are commonly infected? What unique strain is seen in America?
gamma herpesvirus (Rhadinovirus)
variety of ruminants, including bison and cervids
sheep-associated MCF (OHV-2) spread from subclinical sheep to bovids and deer
What is the characteristic lesion of malignant catarrhal fever?
more prominent ulceration
fibrino-necrotizing vasculitis with prominent lymphocytic perivascular infiltrates in several organs and tissues (systemic!)
What is a common cause of viral neonatal diarrhea in calves? What other 3 agents cause similar disease?
Coronavirus
- Rotavirus
- Cryptosporidium
- E. coli
Where in the intestine does Coronavirus infect?
replicated the apical cytoplasm of absorptive enterocytes at the tip of villi
corona = crown = top of villi
What disease does Coronavirus cause in piglets? What is seen microscopically? How is it commonly diangosed?
transmissible gastroenteritis (TGE) - high mortality
severe villous atrophy (blunting) and fusion
fecal tests, cultures, antibody stains
How does transmissible gastroenteritis in piglets look grossly?
- translucent small intestine
- thin wall of the intestine
(non-specific)
What 2 signs are associated with Rotavirus infection? What is commonly seen in piglets?
- diarrhea in young animals of any species
- damage to surface enterocytes resulting in villous atrophy (infect apical cells)
subclinical infection
What causes Parvovirus in dogs? Cats? What are the most characteristic signs of each?
DOGS - CPV2; necrotizing and hemorrhagic enteritis in the small intestine with granular serosal surface (fibrin)
CATS - feline panleukopenia virus; bone marrow lesions with decreased leukocyte counts
What cells are targeted by Parvovirus?
cells undergoing mitosis - enterocytes, blood cells
Panleukopenia, cat:
- Parvovirus
- segmental fibrino-hemorrhagic enteritis
- diffuse reddening or serosal surface with bloody contents of the intestine
What is the best definitive diagnostic used for Parvovirus infection? What are the 2 most reliable diagnostics?
crypt cells with intranuclear inclusion bodies (not always easily seen)
- dilatation of crypts filled with necrotic debris with surrounding cells trying to cover it up, causing loss of intestinal lining
- negative stained TEM
What necrotizing enteritis similarly seen in Parvovirus infection is also seen in older cats?
FeLV infection
What are the 2 types of FIP? In what cats is it most commonly seen? In aged cats is this most commonly seen?
- effusive/wet - distended abdomen or thorax filled with yellow, protein-rich peritoneal and pleural fluid
- non-effusive/wet - chronic, plaque, pyogranulomatous exudate on organs within body cavities
young cats between 6-12 months
What causes effusive FIP?
vasculitis - increased permeability allows for fluid leakage
Non-effusive FIP:
dry, pyogranulomatous exudate
What is the characteristic renal presentation of non-effusive FIP? What important differential diagnosis needs to be made?
multifocal, gray lesions following vasculature of the kidney
LYMPHOMA - more prominent lesions not necessarily following vasculature
What 4 virulence factors are seen in E. coli?
- promotion of colonization or adhesion
- metabolic dysfunction or death of enterocytes
- affect on local/systemic vasculature
- invasion and septicemia
What 4 syndromes are caused by different strains of E. coli?
- ENTEROTOXIGENIC colibacillosis - secretory diarrhea caused by enterotoxins in neonatal pigs, calves, and lambs
- septicemic colibacillosis caused by EIEC - penetration of E. coli into enterocytes leading to septicemia, sudden death, or subacute/chronic disease in neonatal calves, pigs, and foals (enteritis not common)
- post-weaning colibacillosis - secretory diarrhea with mild to no lesions in 2 month old pigs
- EPEC (attaching/effacing) - direct damage to mucosa leading to villous atrophy caused by attachment in pigs and dogs
What causes edema disease? How?
ETEC - produces Shiga toxin (enterotoxin, verotoxin) that causes endothelial cell injury in arterioles resulting in fluid loss and edema
(O138, O139, O141)
What 2 gross lesions are commonly seen in edema disease? What animal is this most commonly seen?
(ETEC)
- eyelid edema
- mesenteric edema in the spiral colon
pigs a few weeks after weaning
What is a unique presentation of edema disease in swine?
focal bilaterally symmetric encephalomalacia (cerebrospinal angiopathy) - pig survives and shows neurological signs if the Shiga toxin reaches blood vessels in the brain
What causes Clostridial enterotoxemia? What animals are most affected? How does it typically present?
Clostridium perfringens type A to E (D most common)
best nourished animals - high carbohydrates and proteins in diet can cause unbalance with the microflora of the gut
bloody diarrhea with necro-hemorrhagic enteritis
What type of toxin does Clostridium perfringens type D produce? What does this cause?
angiotoxin (epsilon toxin)
intestinal lesions and focal symmetrical encephalomalacia (FSE) in sheep that survive acute stages
What Clostridium perfringens group typically causes disease in poultry? What is seen grossly? Microscopically?
type A
hemorrhage in small intestine
attachment of bacteria to mucosal surface of the intestine seen with H&E and silver stains and loss of villi detail
What causes Tyzzer’s disease? What lesions are associated with it?
Clostridium piliforme
multifocal lesions on the liver, heart, and intestine (port of entry) with crisscrossed bacilli resembling Chinese characters or pickup sticks
What is Colitis X? What is thought to be the cause?
typhlocolitis in horses
dysbacteriosis from antibiotic therapy or dietary changes that leads to the proliferation of toxigenic clostridia, especially Clostridium perfringens type A and Clostridium difficile*
Salmonellosis, horse:
- colon
- edematous and thick mucosa
- multifocal to coalescing hemorrhage
Salmonellosis, horse:
- fibrino-necrotizing enterocolitis
- more acute ulceration and hemorrhage
What is a common secondary infection seen in Salmonellosis in horses?
embolic mycotic pneumonia
- secondary infection from ingesta
Embolic mycotic pneumonia, horse:
- sequel of Salmonellosis
- multifocal to coalescing
- surrounded by rings of hemorrhage
What are 2 common manifestations of chronic Salmonellosis in pigs?
- button ulcers
- rectal strictures due to vasculitis of the cranial hemorrhagic artery leading to fecal retention, megacolon, and abdominal distention
(Salmonella typhimurium)
How does proliferative enteritis grossly appear? In what animals is it most common?
ileal and jejunal mucosa proliferation, giving it a cerebriform appearance (garden hose)
pigs - Porcine Proliferative Enteropathy (Lawsonia intracellularis)
Necrotic enteritis, pig:
Lawsonia intracellularis —> most common in the ileus, resulting in mucosal thickening
In what animals is proliferative hemorrhagic enteropathy most common?
young sows
- Lawsonia intracellularis
- thick, hyperplastic mucosa
- lumen filled with blood due to sloughing of mucosa
- profuse hemorrhagic diarrhea
How can Lawsonia intracellularis infection be diagosed microscopically?
mucosal hyperplasia with surface or crypt enterocytes containing 1000s of bacteria in their apical surface stained by Warthin-Starry silver stain
- proliferative ileitis (Porcine Proliferative Enteropathy)
What causes swine dysentery? What is the characteristic sign? What aged pigs are most affected?
Brachyspira hyodysenteriae (spirochetal colitis)
large bowel diarrhea with mucus and blood in feces (muco-hemorrhagic)
8-14 weeks old
How can swine dysentery be differentiated from Salmonellosis?
- Brachyspira hyodysenteriae
- diarrhea confined to colon and is more bloody and mucoid
Rhodococcus equi infection, foal:
pyogranulomatous colitis
Involvement of what tissue is common in Rhodococcus equi infection?
regional lymph nodes
- pyogranulomatous colic lymphadenitis
- enlarged, prominent, and fused LN
- pale, tan, nodular
Pyogranulomatous colonic lymphadenitis, foal:
Rhodococcus equi
- enlarged, fused regional LN
What is a common sign of foals being infected with Rhodococcus equi?
pneumonia that does not respond to typical antibiotic therapy
- suppurative
- pyogranulomatous
- raised, pale, tan nodules
What causes Johne’s disease? What 3 signs are common? In what animals does it typically occur?
paratuberculosis - Mycobacterium avium spp. paratuberculosis
- diarrhea
- emaciation (prominent pelvic bones and ribs)
- hypoproteinemia
ruminants older than 19 months - infected as neonates with bacteria having long incubation periods
What 3 parts of the GI tract are affected by Johne’s disease? What is also commonly involved?
- ileum
- cecum
- proximal colon
ileocecal valve
(cerebriform hyperplasia)
Johne’s disease, bovine:
- jejunum
- granulomatous enteritis
How can Johne’s disease be microscopically identified?
epithelioid macrophages abundant in cytoplasm with acid-fast positive organisms within
What is characteristic of Johne’s disease in sheep and goats?
lymphangiectasia - thickened, firm, and dilated lymphatic vessels
Johne’s disease, goat, histology:
- granulomatous lymphagitis
- migration of inflammatory cells, likely epithelioid macrophages
In what 2 breeds of dogs is histiocytic ulcerative colitis most common?
- Boxers
- French Bulldogs
(granulomatous colitis)
How does histiocytic ulcerative colitis present in dogs? How does it appear grossly?
Boxers or French Bulldogs less than 2 years old with soft feces
multifocal ulceration in the colon
What is histiocytic ulcerative colitis in Boxers associated with? Similar findings are seen in what human disease?
selective intramucosal colonization by enteroinvasive E. coli in epithelioid macrophages
inflammatory bowel disease, particularly with Crohn’s disease
How are calves affected by Cryptosporidiosis? How is this diagnosed?
neonatal malabsorptive diarrhea caused by the protozoa covering the mucosa, interfering with nutrient absorption
finding of numerous protozoal organisms attached to the apical surface of enterocytes of fresh tissue
(common zoonosis of veterinary students in their clinical year)
Cryptosporidiosis, histology:
no inflammatory response —> just protozoans on apical surface
How do the lesions of coccidial enteritis vary in sheep/goats and dogs/cats/cattle?
S/G = proliferative and hyperplastic
D/C/C = hemorrhagic and necrotizing
Coccidial enteritis:
multifocal hyperplasia containing protozoa
From what animal is this coccidial enteritis likely found?
lumen filled with blood (hemorrhagic) —> calf*, dog, cat
(however, there is some proliferative lesions below also)
What are the 2 most common hookworms of dogs? What do they cause? How can they be passed from mother to offspring?
- Ancylostoma caninum
- Unicaria stenocephala
blood-sucking can cause anemia and hypoproteinemia in puppies
larvae can be found in the colostrum
What tapeworm is commonly found in the ileocecal valve of horses? How do horses typically present?
Anoplocephala perfoliata
doesn’t typically cause clinical sign, but if they cause impaction, colic and intussusception may result
What whipworm most commonly parasitizes domestic species? Where do they commonly infect? What do severe infections lead to?
Trichuris spp.
cecum* and colon
- bloody diarrhea
- weight loss
- dehydration
- anemia
What nematode commonly infects pigs? What is a common sequel to this infection?
Ascaris suum - small intestine
stage 3 larvae penetrate the intestine, allowing them to get into portal circulation and reach the liver to cause damage and focal fibrosis - AKA milk spotted liver
Lymphosarcoma, pig:
- tumor ruptured and caused fatal peritonitis
- mesenteric lymph nodes enlargement
- cancer cells infiltrating lymphatics
