L21: Diagnostic Approach To Chronic Diarrhea (Gallagher) Flashcards
Organizing the differential list
- systemic vs. GI dz
- based on signalment, hx, and PE
- if small bowel, can be maldigestion (EPI) or malabsorption (non-PLE or PLE)
Major causes of MALABSORPTIVE small bowel dz in DOGS
- dietary responsive (allergy or intolerance)
- parasites (Giardia, nematode)
- Abx responsive diarrhea
- IBD
- neoplasia (LSA, Carcinoma, Leiomyosarcoma)
- Fungal (Pythium, Histoplasma)
Major causes of MALABSORPTIVE small bowel dz in CATS
- dietary responsive (allergy or intolerance)
- parasites (Giardia)
- IBD
- neoplasia (LSA, small cell or lymphoblastic)
Specific things to assess on PE:
- General attitude
- body condition/muscle score
- abdominal effusion
- PLN
- thickened GIT/lymphadenopathy
- rectal exam (look for perianal fistula, thickening of colon, etc.)
*dogs with PLE may have weight loss more in muscle than fat
Major causes of PLE in DOGS
- intestinal lymphangiectasia
- lymphoma
- severe IBD
- fungal (pythium, histoplasma)
- GI hemorrhage (ulceration/erosion, neoplasia, parasites)
- massive hookworm/whipworm infection
Major causes of PLE in CATS
- GI lymphoma
- severe IBD
- GI hemorrhage (neoplasia, ulceration)
Major causes of Large Bowel Dz in DOGS
- dietary responsive (allergy or intolerance)
- fiber-responsive colitis
- irritable bowel syndrome (functional)
- parasites (whips, Giardia)
- bacterial dz (Clostridium, histiocytic ulcerative colitis)
- Fungal (Pythium, histoplasma)
- IBD
- Neoplasia (carcinoma, lymphoma)
Major causes of Large bowel dz in CATS
- dietary responsive (allergy or intolerance)
- fiber-responsive colitis
- IBD
- tritrichomonas
Giardia vs. Tritrichomonas appearance on saline smear
Giardia: “falling leaf” pattern, only see 2-3 per slide
Tritrichomonas: independently motile, see many per slide, most common in cats
Types of fecal exams
Flotation
Direct saline smear (for Tritrich. And Giardia)
Fecal cytology - look for spirochetes (campylobacter), Clostridium
Rectal cytology
Giardia ELISA
InPouch TF culture (for Tritrichomonas; largely replaced by PCR)
Major causes of PLE in DOGS
- intestinal lymphangiectasia
- lymphoma
- severe IBD
- fungal (pythium, histoplasma)
- GI hemorrhage (ulceration/erosion, neoplasia, parasites)
- massive hookworm/whipworm infection
Major causes of PLE in CATS
- GI lymphoma
- severe IBD
- GI hemorrhage (neoplasia, ulceration)
Major causes of Large Bowel Dz in DOGS
- dietary responsive (allergy or intolerance)
- fiber-responsive colitis
- irritable bowel syndrome (functional)
- parasites (whips, Giardia)
- bacterial dz (Clostridium, histiocytic ulcerative colitis)
- Fungal (Pythium, histoplasma)
- IBD
- Neoplasia (carcinoma, lymphoma)
Major causes of Large bowel dz in CATS
- dietary responsive (allergy or intolerance)
- fiber-responsive colitis
- IBD
- tritrichomonas
Giardia vs. Tritrichomonas appearance on saline smear
Giardia: “falling leaf” pattern, only see 2-3 per slide
Tritrichomonas: independently motile, see many per slide, most common in cats
Types of fecal exams
Flotation
Direct saline smear (for Tritrich. And Giardia)
Fecal cytology - look for spirochetes (campylobacter), Clostridium
Rectal cytology
Giardia ELISA
InPouch TF culture (for Tritrichomonas; largely replaced by PCR)
IDEXX RealPCR diarrhea panel tests for:
- Clostridium perfringens
- Salmonella spp.
- Cryptosporidium spp.
- Giardia spp.
- Toxoplasma gondii
- Canine Enteric Coronavirus
- Felive Coronavirus (FeCoV)
- Canine parvovirus
- Feline panleuk
- Canine Distemper
*caution: very sensitive and can have false positives
Soft-coated wheaton terriers can get PLE and PLN at the same time
:)
Lymphangiectasia –> lymphopenia
Chronic GI dz/inflammation–> thrombocytosis
:)
If you determine patient has PLE with albumin
Do intestinal biopsy
If patient has NON-PLE, what should you do next?
Serum Trypsin-like immunoreactivity (TLI) test to differentiate between small bowel dz and EPI
(Esp. Do TLI test if dog has rapid appetite, losing weight, has large voluminous diarrhea)
Normal pancreatic exocrine enzyme lvl (on TLI test)
5-45
Cobalamin/Folate Dx test
- previously used for dx of SIBO
- low concs. Of Cobalamin assoc. with chronic enteropathy, GI dz in cats
- often won’t get resolution of CS w/o supplementing Cobalamin
Diagnostic imaging
Rads:
- plain films rarely used but can ID chronic FB/focal obstruction
- contrast films can ID masses not palpable, chronic partial obstructions
US: rarely provides definitive dx
Biopsy for diarrhea patients
- usually last dx test
- exclude other causes first, unless p has low albumin or severe CS
-use endoscopy to get biopsies; can only go down to proximal duodenum or up to ileum
Other dx tests for diarrhea patients
- Ex lap: can get to jejunum
- laparoscopy: minimally invasive, can get full thickness GI biopsy and biopsy other organs
ARD
Anabolic responsive diarrhea
