GI neonatal pathology Flashcards
What is the GI water cycle?
- Secretions and intake ~9L/day
- SI is major absorptive site
- Significant absorption in colon (esp. horses)
What are the mechanisms for diarrhea?
- Malabsorption - osmotic diarrhea, usually SI
-
Hypersecretion - structurally intact mucosa
- occurs as a result of net efflux of fluid and electrolytes independent of permeability changes or absorptive capacity
- Exudation - increased capillary pressure or epithelial permeability (PLE, Lymphangiectasia is a good ex)
- Hypermotility
What are the common causes of diarrhea in pigs from most to least?
- Atrophic enteritis
- idiopathic
- E.coli (ETEC)
- Rotavirus
- C. diff
- C. perf type A
- TGE
- Coccidia
- C. diff type C
What are the common causes of diarrhea in calves?
- Rotavirus
- Cryptosporidium
- Coronavirus
- Corona/crypto mix
- Rota/corona mix
- Rota/crypto mix
What are the Bovine viral agents for neonatal diarrhea?
- Bovine Viral Enteritis
- multiplication in villous intestinal epithelial cells
- Fecal - oral transmission
-
Bovine Enteric CoV
- common
- often involves other agents (rota, crypto)
- Causes fibrinonecrotic colitis
-
Bovine Rotavirus
- Ubiquitous- mostly group A/B/C rotavirus
- mostly subclinical - severity is a function of exposure dose, age, immunity
- Co-infections common (corona, crypto)
What is the Dx approach for viral ovine neonatal diarrhea?
- Fixed SI/colon for histology and IHC
- Fresh/frozen for viral detection (PCR, panels)
What are the viral agents responsible for swine neonatal diarrhea?
-
Transmissible gastroenteritis Virus (TGE)
- Coronavirus historically common in suckling/nursery pigs
- mostly eradicated today by vaccination
- Cause of diarrhea, vomiting - any age
-
Porcine epidemic diarrhea Virus (PED)
- TGE-like coronavirus
- Emerged in US Spring 2013
- NOT detected by TGE molecular tests
-
Porcine delta coronavirus (PDCoV)
- Similar clinical signs, detected in wake of PED
- Probably less virulent
- Swine acute diarrhea syndrome (SADS)
- Swine rotavirus group A/B/C
-
Rotavirus:
- ubiquitous
- mostly subclinical
- severity depends on dose, age, immunity
How doe viral agents cause diarrhea in swine neonates?
- Fecal-oral transmission
- multiply in villous intestinal epithelial cells
- villous atrophy
How are viral agents of porcine neonatal diarrhea Dx?
- Fixed SI for histology and ICH
- Fresh/frozen tissue for viral detection (usually PCR)
Morphologic Dx? Pathogenesis?
- SI; villous atrophy/blunting and fusion (crypts are intact)
- Viral infection of villar tip epithelium
- necrosis of epithelium at tips
- villous atrophy
- healing by adjacent epithelium and cy crypt hyperplasia
- villous fusion
Morphologic Dx? Pathogenesis?
- SI: villous atrophy, blunting, and fusion
1. Enteric coronavirus (TGEV) infection of tip villar epithelium
How does Cryptosporidium parvum cause diarrhea
- Protozoa colonize villi
- usually 1-4 weeks of age
- Cause malabsoption and hypersecretion
- Co-infection with other agents is common
How would a Cryptosporidium infection be diagnosed?
- Fecal flotation/smear, Sucrose wet mount
- Fixed tissue for histopathology (distal SI)
- PCR
How does Coccidia affect swine neonates?
- affects pigs from 5-6 days to 2-3 weeks of age
- MDx - severe fibrinonecrotic enteritis
- infected Feces
- Rapid sporulation of C.suis in environment (12h) short prepatent period (5 days)
- ingested
- replicates in villous epithelium of SI
- necrosis of epithelium
- Villous atrophy, necrosis, erosion, ulceration, fibrin
- Malabsorptive (& effusive) diarrhea
How is a coccidial infection diagnosed ?>
- Mucosal scrapings/feces (fecal float)
- Fixed SI 9 (histo)