Approach to GI disease and localization Flashcards
Obj: Given a patient scenario, be able to categorize GI disease (acute vs chronic, primary vs secondary)
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Obj: Based on patient signalment, history, physical exam, and chronicity, determine the degree of testing and treatment required:
- Recommend when empirical treatment is apprpriate
- Recommend when additional diagnostics are needed
- Recommend specific tests based on chronicity and disease severity
- Recommend inpatient vs outpatient therapy
Obj: Given description of a patient’s clinical signs differentiate:
- Vomiting vs regurgitation
- small vs large intestinal diarrhea
Obj: Given results of GI “function” test choose the correct anatomic disease localization
What are the different ways of classifying GI Disease?
- Anatomic
- Primary vs Secondary (non-GI)
- Temporal
- <2-3wks = Acute
- >3-4wks/ recurrent = Chronic
- Mechanistic (diarrhea)
- Osmotic, secretory, dysmotility, exudative, etc)
- Disease category
- Infectious, inflammatory, immune-mediated, etc
- Treatment response
- Food, nutrient, fiber or other microbiome-targeted, steroid, etc
What history is important when diagnosing GI disease?
- Signalment
- Normal diet & any changes
- Vax/deworm status
- Duration/Chronicity
- Frequency
- Description of event
- Foreign body / Toxin ingestion
- Travel History
What history is important when a patient presents w/ vomiting?
- Association w/ eating/drinking
- Time of last BM
- Concurrent diarrhea
What PE findings are common w/ GI disease
- Dehydration
- Fever
- Abdominal pain/distention
- BCS
- Signs of systemic disease
- oral ulcerations, icterus, etc
What characteristics are common with Oral disease?
- Ptyalism
- Difficult food prehension, bolus formation, chewing
What are the Characteristics of Pharyngeal/Cricopharyngeal Disease
- Impaired food passage through oropharynx
- Gagging
- Immediate reflux when swallowing
What are the Characteristics of Esophageal Disease?
- Regurgitation
- Repeated swallowing attempts
- Ptyalism
What are the Characteristics of Gastric Disease?
- Vomiting
- Food 8-10hrs post-pradially suggests delayed gastric emptying
- Nausea
- Ptyalism
- Dysrexia
- Belching
- Abdominal Distention/bloating
- Cranial Abdominal pain
- Weight loss ONLY if decreased intake (uncommon)
What are the characteristics of Intestinal Disease
- Dysrexia
- Nausea
- Vomiting
- Diarrhea
- Small Intestinal diarrhea
- Large Intestinal diarrhea
- Constipation
How is SI diarrhea different from LI diarrhea
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SI Diarrhea:
- Normal - slightly increased frequency
- Large volume
- Lack of urgency
- +/- Melena
- +/- Vomiting
- +/- Wt loss
- +/- Flatulence
- +/- Steatorrhea
-
LI Diarrhea:
- Moderate - Severely increased frequency
- Small volume
- Urgency
- Tenesmus
- +/- Hematochezia
- +/- Mucus
What are the characteristics of Rectal/Anal Disease?
- Can be challenging to distinguish from LI Disease
- Tenesmus
- Dyschezia
- Mucoid/hemorrhagic discharge
What are the goals for the Diagnostic approach to GI disease?
- Define a patient’s severity of disease
- Determine if there is a concern for an underlying surgical etiology
What is the approach to diagnosing Acute Vomiting/Diarrhea w/ mild clinical signs
- Abdominal radiographs - if NO diarrhea/BM, Hx of FB ingestion, non-productive retching, abdominal distention or pain
- Labwork changes concerning for a proximal duodenal or pyloric outflow obstruction:
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Hypochloremic metabolic alkalosis
- HCl lost from the stomach w/out concurrent HCO3- loss from the duodenum
- alkalosis worsened by renal compensation and resorption of HCO3- in place of Cl
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Hypochloremic metabolic alkalosis
- Unproductive retching underscores importance of hx-taking
- concern for gastric dilation and volvulus but can be confused w/ vomiting and nausea by owners
- Labwork changes concerning for a proximal duodenal or pyloric outflow obstruction:
- PCV/TS
- +/- Fecal float
- Symptomatic therapy: Hydrated, non-painful, no other systemic signs
What is the approach to diagnosing Acute Vomiting/Diarrhea w/ Moderate-severe clinical or systemic signs
- Rule-out non-GI disease: CBC, Biochemistry, UA
- +/- Parvo testing
- Fecal Float
- Abdominal radiographs +/- Ultrasound
- Select Cases:
- Hypoadrenocorticism in dogs
- baseline cortisol
- +/- ACTH stimulation test
- Hypoadrenocorticism in dogs
What is the approach to diagnosing Chronic Vomiting/Diarrhea
- Rule-out systemic (non-GI) disease
- CBC, Biochem, UA
- Hyperthyroidism in cats (tT4)
- Hypoadrenocorticism in dogs
- baseline cortisol +/- ACTH stimulation test
- Select cases:
- testing for pancreatitis or exocrine pancreatic insufficiency, portosystemic shunts (bile acids)
- Fecal Float + empirical deworming (Fenbendazole)
- Exclusion of additional enteropathogens, as warranted by patient signs and lab work
- Abdominal Radiographs/Ultrasound:
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Radiographs:
- non-specific w/ chronic GI disease in Dogs/Cats
- Decreased serosal detail
- general GI distention w/ fluid/gas ( if decreased motility)
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Ultrasound: Intestinal Wall changes
- Increased thickness
- Decreased layering
- Mucosal hyperechogenicity
- Allows for sampling of effusion, masses or enlarged ln, Ultrasound changes, (particularly in wall layering/thickness) are none specific - but can help prioritize differentials or plan how to obtain biopsies.
- 30% of dogs/cats w/ idiopathic inflammatory Bowel Disease will have completely normal abdominal US findings
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Radiographs:
- Perform GI-specific diagnostics and treatment trials
Obj: Explain the utility and limitations of GI biopsies. Decide whether they should be recommended for a specific patient description and choose further testing or design a treatment plan based on results
What criteria warrant additional evaluation for GI issues?
- Dull/depressed patient mentation
- fever
- tachycardia/bradycardia
- abdominal pain
- melena
- hematemesis
- frequent or severe GI signs
- PE abnormalities
- Unresponsive to symptomatic treatment
What is a “Gastrointestinal Panel”?
- GI Function Testing
- Combination of tests that help to rule out (or diagnose) pancreatic disease as a cause for GI signs. help localize Gi disease, and can help define severity of disease
- Components:
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Cobalamin (Vit B12)
- Absorbed by receptors specifically located in the ileum
- Decreased blood concentrations are usually associated w/ small intestinal (ileal), malabsorptive disease
- TLI must be run when initially testing cobalamin levels in patients. The pancreas produces intrinsic factor, which is required for cobalamin-receptor binding.
- Low cobalamin + low TLI = decreased absorption
- due to exocrine pancreatic insufficiency (decreased intrinsic factor production_ and NOT small intestinal disease
- Low cobalamin + low TLI = decreased absorption
- Methylmalonic acid (MMA) is a more sensitive test for cellular/functional cobalamin deficiency
- Elevated MMA blood concentrations suggest cobalamin deficiency even if blood cobalamin concentrations are normal
- MMA is not available as a combined test on the “GI Panel” can be performed separately in dogs and cats
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Folate:
- absorbed in the proximal GI tract (duodenum)
- Decreased blood concentrations are associated with proximal SI malabsorptive disease
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Pancreatic Lipase immunoreactivity (pancreatic specific lipase; specPL)
- increased specPL is associated with pancreatitis
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Trypsin-like immunoreactivity (TLI)
- Decreased TLI is diagnostic for exocrine pancreatic insufficiency
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Cobalamin (Vit B12)
When should Biopsies be recommended for chronic GI disease?
- No single criterion
- Patients with more severe signs or multiple factors
- Clinical signs:
- Inappetence
- lethargy
- Progressive weight loss
- Treatment trial failure, PRIOR to steroids
- Biochemical or imagining findings
- Hypoalbuminemia
- Hypocobalaminemia
- GI abnormalities on ultrasound
- Clinical suspicion of infectious or neoplastic etiology
What are the Benefits/Risks of taking GI biopsies through surgery?
- Benefits:
- full-thickness biopsies
- Ability to biopsy all of small intestine or feel focal lesions
- ability to biopsy lymph nodes and other organs
- Risks:
- Decreased healing and dehiscence w/ diffuse, infiltrative disease or hypoalbuminemia
- Colonic biopsies usually NOT performed
- More invasive procedure and increased healing time compared to endoscopy
What are the benefits/risks of taking biopsies through endoscopy?
- Both upper (stomach and duodenum) and lower (ileum and colon) GI biopsies are recommended.
- may have different diagnosis in each portion
- Benefits:
- Able to visualize internal lesions
- Safter to obtain colonic biopsies and less risk in patients with diffuse, infiltrative disease or hypoalbuminemia
- Out-patient procedure
- Risks:
- Partial thickness, small biopsies may miss the diagnosis
- Inability to reach all parts of the GI tract or visualize focal lesions that are not intraluminal
- Histopathologic severity does NOT predict response to treatment for Idiopathic inflammatory enteropathies but more severe changes are prognostic
- Difficult to distinguish small cell lymphoma from severe inflammatory Bowel Disease
What are the possible Histopathologic findings in Idiopathic inflammatory Bowel Disease
- Lymphoplasmacystic inflammation **
- Concern for neoplasia?
- can perform PCR for antigen receptor rearrangement (PARR)
- help distinguish IBD from small cell lymphoma
- clonal results being consistent with small cell lymphoma
- help distinguish IBD from small cell lymphoma
- can perform PCR for antigen receptor rearrangement (PARR)
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Neutrophilic inflammation
- consider fluorescent in situ hybridization (FISH)
- consider testing for Campylobaceter in cats
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Eosinophilic inflammation
- repeat deworming
- consider diet trial
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Pyogranulomatous
- fungal or atypical bacteria search
- Histopathologic score is prognostic
- NONE of these patterns are specific for a certain diseae or treatment response.
What are the limitations of GI biopsies?
- Do not differentiate between treatment responses
- diet, microbiome-targeted, steroids
- Only 30% agreement between duodenal and ileal biopsies
- Histopathologic severity does not correlate with clinical sign severity
- Microscopic changes do not resolve with treatment