17) diagnostic approach of diarrhea

Question 1

diarrhea - definition

Answer 1

▪ Primary clinical sign of intestinal disorders
▪ Increase in faecal fluidity
\+- defecation frequency
\+- volume of faeces
Pathophysiology: 4 major mechanisms
▪ Osmotic diarrhoea
▪ Secretory diarrhoea
▪ Exudative diarrhoea (increased permeability)
▪ Dysmotility (altered peristalsis)
Clinical approach
o Classification
• Temporal:
o Acute ↔ chronic > 3 weeks
• Etiologic
o Intestinal ↔ extraintestinal
• Anatomic / localization
o Small intestinal ↔ large intestinal
o Diffuse
• Clinical / severity
o Acute, self-limiting ↔ acute, life threatening

Question 2

extraintestinal causes

Answer 2

▪ Polysystemic infection: Canine distemper;
o Leptospirosis; FIP, FeLV, FIV
▪ Renal disease: uraemia
▪ Liver disease; PSS (portosystemic shunt)
▪ Pancreatic disease: EPI, pancreatitis
▪ Endocrine disease: hypoadrenocorticism, feline hyperthyroidism
▪ Miscellaneous
o Endotoxemias (peritonitis, pyometra)
o Cardiac disorders
o Toxins: chemicals, heavy metals; plants
o Drugs (NSAIDs, antibiotics; iatrogenic)

Question 3

SI- disorder

Answer 3

large stool volume, rarely mucus, melena formation, sometimes fat or undigested food, rare tenesmus, uncommon urgency, nimral frequency or slightly elevated
common vomitus, rare gas, common weight loss

Question 4

LI- disorder

Answer 4

small dense stool volume, common mucus, blood stripe fresh, abesent fat or undigested food, common tenesmus, common urgeny, higher frequency, rare vomitus, absence of gas, rare weight loss

Question 5

nationale in diarrhea

Answer 5

• Age
o Young: infectious diseases
o Older: neoplastic diseases, chronic enteropathies
• Breed
German Shepperd Chronic inflammatory disease
Retrivers Food allergy
Yorkshire terrier, Rottweiler Lymphangectasia
Cat Alimentary Lymphoma

Question 6

physical exam

Answer 6

• Primary clinical sign
▪ DIARRHEA; but NOT always present! (e.g. lymphagiectasia)
• Secondary clinical signs
▪ Vomiting
▪ Altered appetite: anorexia or polyphagia?
▪ Abdominal discomfort, pain
▪ Fever or hypothermia?
▪ Dehydration; hypovolemia, hypovolemic shock
▪ Weight loss

Question 7

history of diarrhea

Answer 7

• What are the symptoms?
• For how long has been ill?
• Exposure to parasites, toxins
• Contact with infected animals
• Diet
• Vaccination & deworming status
• Previous medications

Question 8

fecal analysis steps

Answer 8

1. Direct smear & cytology – even in mild diarrhea
   o Fresh sample/ unstained
   ▪ Protozoa
   ▪ Parasite ova
   o Special stains
   ▪ RBC, inflammatory cells
   ▪ Suspected malabsorption
   ▪ Bacteria ≠ cause!
   o Exfoliative cytology/ rectum
   ▪ Neoplasm
   ▪ Histoplasma
2. Fecal flotation – parasites
3. Bacterial culture
   o Campylobacter spp, Salmonella, Clostridium spp.
   o Only in case of relevant clinical signs, BECAUSE
   o Asymptomatic carrier stage is common
4. Fecal ag ELISA, PCR
   o Viruses: Parvo (ELISA), Corona (PCR)
   o Protozoa: Giardia (ELISA), Tritrichomonas (PCR)
   o Bacteria: Campylob., Clostr. perf., Cl. difficile (PCR)
   o Cl. enterotoxins (ELISA)
5. Inflammatory markers – severity, monitoring
   o Calprotectin, fecal S100A12, lactoferrin

Question 9

laboratory tests in diarrhea

Answer 9

• Extraintestinal causes – exclude
o CBC, biochemistry, urinalysis
o Ca: spec cPL, TLI, ACTH-test
o Fe: spec fPL, T4, FeLV, FIV
• Severity → therapeutic interventions
o PCV, TP, acid-base, ionogram, bloodG – homeostasis
o Ca: CRP – severity of inflammation
• SI function – malabsorption/ PLE? → albumin
• SI function + localization – GI SPECIFIC TESTS:
o Cobalamine + Folate test

Question 10

diarrhea dianostic imaging

Answer 10

o Plain radiography
o Radiodense foreign body (FB)
o Contrast radiography
o Radiolucent FB
• Linear FB
o Motility disorder
o Abdominal ultrasonography (US)
o Other types of ileus
▪ Subileus
▪ Intusussception
Structure, layers of intestines: loss of layering – infiltrative disorder?

Question 11

additional examinations

Answer 11

→ Endoscopic examination
o Gross examination of SI mucosa:
• Friability
• Granularity
• Erosion
• Lymphatic dilat.
• Mass
o Biopsy → Histopath
→ Diagnostic laparotomy
o Ileus; resection of mass lesion
o Full-thickness biopsy – tumour / lymphoma?
o Affected jejunum (endoscope CANNOT reach it)
o Other organs in abd. Cavity
→ Intestinal biopsy
o Histology – diagnostic; criteria:
o Sample: appropriate amount & quality
o Appropriate histologic interpretation
o Molecular technics
o FISH – pathogen pathogen in the wall of intestine
o Malignancy – lymphoma lymphoma vs IBD
▪ Immunohistochemistry
▪ Flow cytometry
▪ PCR / PARR – clonality testing