Exam 1 - Approach to Diarrhea Flashcards
what is the definition of acute diarrhea?
duration of < 2-3 weeks - often self-limiting, usually requires little diagnostic evaluation, & focus is placed on symptomatic treatment
what are some common causes of acute diarrhea?
diet change, dietary indiscretion, poor quality diet, toxins, parasites, bacteria, & acute hemorrhagic diarrhea
what are some parasites commonly involved in causing diarrhea especially in younger animals?
giardia & toxocara - do at least 1 fecal exam
if you don’t see anything, treat with fenbendazole anyway
what is the main viral cause of diarrhea in young dogs?
parvo
T/F: bacterial causes of diarrhea are poorly understood because many bacteria are found in the feces of healthy dogs as well as those with diarrhea
true
what is acute hemorrhagic diarrhea syndrome likely caused by?
clostridium perfringens netF toxin
when are antimicrobials not indicated in a patient with acute hemorrhagic diarrhea syndrome?
not indicated for cases without signs of fever or sepsis
what animals are typically affected by acute hemorrhagic diarrhea syndrome? what is commonly seen on labwork?
typically small to medium breeds
dramatically increased PCV - hemoconcentration
what are some less common systemic causes of diarrhea?
acute liver disease, pancreatitis, acute kidney injury such as lepto, & addisons
what are some less common toxic causes of diarrhea?
chemicals & plants (sago palm)
what are some less common drug related causes of diarrhea?
antibiotics, NSAIDS, steroids, chemo, copper chelators, & dogoxin
what are some less common intestinal obstruction causes of diarrhea?
foreign body & intussussception
what is the difference in quantity in when comparing small bowel diarrhea to large bowel diarrhea?
small bowel - large volumes of watery diarrhea
large bowel - normal to mildly increased
what is the difference in frequency in when comparing small bowel diarrhea to large bowel diarrhea?
small bowel - normal to mildly increased
large bowel - markedly increased
what is the difference in tenesmus/urgency in when comparing small bowel diarrhea to large bowel diarrhea?
small bowel - absent
large bowel - usually present
what is the difference in the presence of mucus when comparing small bowel diarrhea to large bowel diarrhea?
small bowel - usually absent
large bowel - frequently present
what is the difference in presence of blood when comparing small bowel diarrhea to large bowel diarrhea?
small bowel - melena
large bowel - fresh blood
what is the difference in presence of weight loss when comparing small bowel diarrhea to large bowel diarrhea?
small bowel - may be present
large bowel - uncommon
what are some warning signs of potentially life-threatening diseases in patients with diarrhea?
shock, moderate/severe dehydration, abdominal pain, depression, frequent vomiting, abdominal masses, dilated bowel loop, ascites, & signs of systemic illness (lymphadenopathy, coughing, pyrexia, ocular/nasal discharge, icterus, hepatomegaly, & oliguria)
what is typically included in a diagnostic workup of a patient with diarrhea?
fecal, infectious disease testing (case by case - ex: parvo), CBC/chem/urinalysis (if systemically unwell)
+/- : baseline cortisol, abd rads/US
T/F: fecal cytology is helpful for detecting enteropathogens
false - not helpful, rectal scraping may be useful for fungal/algal organisms
what are some possible indications for pursuing a enteropathogen PCR panel?
diarrhea that isn’t self limiting, animal with signs of sepsis, when multiple animals are affected, immunocompromised animal, & pets eating raw diets
why are antibiotics not needed in most cases of diarrhea?
most cases are usually self-limiting - can be potentially detrimental
can consider in febrile patients or those with signs of sepsis
why is metronidazole often used for diarrhea?
activity against anaerobes
what is typically included in symptomatic treatment for a patient with diarrhea?
isolate the patient & practice good hygiene
fluid therapy - treat electrolyte abnormalities & hypoglycemia
diet - feed small meals as soon as possible & easily digestible diet
broad spectrum anthelmintics
probiotics - may speed resolution of acute diarrhea, choose a good product with good quality control
what is a contraindication for using loperamide for a patient with diarrhea?
dog with the ABCB1 mutation - toxic
why is fiber useful for patients with diarrhea?
binds water & improves stool quality
in young dogs/cats <2 years old, what are the most common causes of chronic diarrhea?
infectious disease & dietary problems
in older dogs/cats, what are the most common causes of chronic diarrhea?
neoplasia, IBD, & hyperthyroidism in cats
what disease predisposition do norweigian lundehunds have?
PLE & lymphangiectasia
what disease predisposition do german shepherds have?
EPI, IBD, & dysbiosis
what disease predisposition do soft coated wheaton terriers have?
PLE/PLN
what disease predisposition do boxers have?
granulomatis colitis
what disease predisposition do yorkies have?
lymphangiectasia
what history questions are important when working up a case for chronic diarrhea?
description of diarrhea, dietary history, lethargy, weight loss, & hyporexia
what should you pay attention to on physical exam when working up a case for chronic diarrhea?
BCS, abdominal palpation, peripheral lymph node palpation, & rectal exam
what are some extra-gastrointestinal causes of chronic small bowel diarrhea in cats?
hyperthyroidism, hepatobiliary disease, pancreatitis, EPI, hypercalcemia, & renal disease
what are some extra-gastrointestinal causes of chronic small bowel diarrhea in dogs?
hepatobiliary disease, pancreatitis, EPI, hypercalcemia, renal disease, & addisons
what are some infectious causes of chronic small bowel diarrhea in cats?
helminths, protozoa, viral, bacterial, & fungal
what are some infectious causes of chronic small bowel diarrhea in dogs?
helminths, protozoa, bacterial, & fungal
what are some dietary responsive causes of chronic small bowel diarrhea in cats?
allergy/intolerance & dysbiosis
what are some dietary responsive causes of chronic small bowel diarrhea in dogs?
allergy/intolerance
what are some inflammatory causes of chronic small bowel diarrhea in cats?
IBD
what are some inflammatory causes of chronic small bowel diarrhea in dogss?
IBD
what are some neoplastic causes of chronic small bowel diarrhea in cats?
lymphoma, mast cell tumor, & carcinoma
what are some neoplastic causes of chronic small bowel diarrhea in dogs?
carcinoma & lymphoma
why perform a chemistry panel on a patient with chronic diarrhea?
evaluate for consequences of gi disease - hypoalbuminemia
evaluate for systemic disease that can cause GI signs - liver disease or hypercalcemia
why perform a urinalysis on a patient with chronic diarrhea?
polyuria may suggest a metabolic cause of GI signs - hypercalcemia/hyperthyroidism
look for urate crystals or bilirubinuria - suggest hepatic disease
why should you run a CBC for a patient with chronic diarrhea?
signs of inflammation/neoplasia
sick patient should have a stress leukogram - absence of one is consistent with addison’s disease
what are examples of endocrine diseases that can cause chronic diarrhea?
addison’s in dogs & hyperthyroidism in cats
why do both a direct smear & zinc sulfate floatation with centrifuge for patients with chronic diarrhea?
direct - detect protozoal trophozoites
zinc - detect helminths/other parasites, can pool 3 days of feces to increase sensitivity
how does giardia affect dogs & cats differently?
dogs - large bowel diarrhea
cats - small bowel diarrhea
what diagnostic test has better sensitivity for giardia than microscopic examination?
antigen testing
what diagnostic test is used by most labs to diagnose cryptosporidium?
immunofluorescence assays
T/F: most crypto infections in dogs & cats are sub-clinical
true - may cause chronic diarrhea in immunocompromised patients
why is it difficult to establish clostridium perfringens as a cause of chronic diarrhea?
enterotoxin producing strains have been found in healthy dogs - the enterotoxins are what cause diarrhea
________ _______ is an important cause of large bowel diarrhea in cats
tritrichomonas foetus
what is the most sensitive test for trich?
fecal PCR
how is histoplasmosis diagnosed?
cytology & EIA for antigen in serum or blood
how is heterobilharzia diagnosed?
fecal PCR is best - can also do fecal sedimentation
what is this?
tritrichomonas foetus
what are the arrows pointing to?
giardia cysts
what is this?
heterobilharzia americana egg
when are survey rads a better test for a patient with chronic diarrhea?
patients with vomiting as well as diarrhea
if this animal presented with diarrhea and you saw this on rads, what are you suspicious of?
canine schistosomiasis
what is the most useful imaging modality for dogs with diarrhea?
abdominal ultrasound - best in dogs with weight loss or a palpable abdominal mass
what is a TLI test?
tests for pancreatic disease - serum cTLI concentration is decreased in dogs/cats with EPI
very sensitive/specific test for this condition
what is the most accurate lab test for pancreatitis?
cPL/fPL
what is your interpretation of a high serum folate & low/normal serum cobalamin?
possible dysbiosis
what is your interpretation of a low serum folate & normal serum cobalamin?
proximal small intestinal disease
what is your interpretation of a normal serum folate & low serum cobalamin?
distal small intestinal disease, EPI, or dysbiosis
what is your interpretation of a low serum folate & low serum cobalamin?
small intestinal disease or EPI
what is your interpretation of a normal serum folate & serum cobalamin?
small intestinal disease is not ruled out
what diagnostic test evaluates intestinal absorption?
serum folate - should be absorbed proximal small intestinal (plentiful in all dog foods)
serum cobalamin - should be absorbed in distal small intestinal (plentiful in diet - should find r protein, protects from acid, binds to instrinsic factor)
what animals should be supplemented with cobalamin?
serum concentrations are <400ng/L
how could issues with cobalamin absorption cause issues?
could be lacking intrinsic factor produced from the exocrine pancreas or you could be missing the receptors in the distal small intestine
how should you supplement cobalamin?
cyanocobalamin - SQ once weekly for 6 weeks & then once monthly
can be used as an appetite stimulant
how do you give therapeutic trials diagnostic value?
performed in a logical manner with ideally only one intervention at a time
what are the 3 ways you can go with chronic enteropathies?
- several diet trials - food responsive enteropathy
- biopsy then immunosuppressant trial - immunosuppressant responsive enteropathy (IBD)
- tylosin trial - antibiotic responsive enteropathy
what are the 3 general causes of adverse food reactions?
- food allergy - hypersensitivity
- food intolerance - metabolic, pharmacological, & idiosyncratic
- intoxication - bacterial, fungal, or other
what are the 4 general options for diet trials?
- intestinal diet
- hydrolyzed antigen - smaller proteins, so easier to digest
- novel protein - need a good dietary history
- fiber supplemented
T/F: about 50% of dogs & cats respond to diet changes
true - tend to be younger, have large bowel diarrhea, & less severely affected
how long should a diet trial last?
expect to see a response within 3 weeks
if there is an improvement - continue for 12 weeks
at this time, may be possible to switch back to original diet
TEST QUESTION*
what is the drug commonly started with in animals with immunosuppressant responsive enteropathy?
prednisone/prednisolone - 2mg/kg PO every day
in dogs - add on cyclosporine
in cats - add on chlorambucil
T/F: we don’t know why some dogs with chronic enteropathy respond to antibiotics
true - tend to be younger, large breed dogs (especially GSD)
tend to have a short lived response
what antibiotic is commonly used for antibiotic responsive enteropathy? how long should you treat for?
tylosin - 20mg/kg PO every 12 hours - sometimes metronidazole at 10mg/kg PO every 12 hours
expect to see a response within 3 weeks - treat for 6-8 weeks
what are the advantages & disadvantages of pursuing an intestinal biopsy in cases of chronic enteropathy?
allows a histomorphicological diagnosis but doesn’t always tell us the etiology & aggrement between different pathologists is not great
what are the advantages & disadvantages of doing a surgical intestinal biopsy?
advantages - whole gi tract can be assessed, fuller thickness biopsies can be collected
disadvantages - invasive & less biopsies collected
what are the advantages & disadvantages of doing a endoscopic intestinal biopsy?
advantages - less invasive, multiple biopsies collected
disadvantages - smaller/more superficial biopsies & can’t sample the jejunum
what is stage I of the diagnostic approach to a patient with diarrhea?
rule out parasites - fecal float, direct smear, giardia antigen testing, & give fenbendazole
diet trial with highly digestible diet
what is stage IIa of the diagnostic approach to a patient with diarrhea?
rule out metabolic disease - CBC/chem, urinalysis, baseline cortisol, ACTH stim, thyroid testing in cats
what is stage IIb of the diagnostic approach to a patient with diarrhea?
non-invasive tests for gi disease - serum cPLI/fTLI, serum folate/cobalamin, +/- abdominal rads/ultrasound
what is stage III of the diagnostic approach to a patient with diarrhea?
therapeutic trials - parenteral cyanocobalamin if needed, diet trials, antibiotic trials in dogs (tylosin or metro), +/- probiotics, prebiotics, or synbiotics
what is stage IV of the diagnostic approach to a patient with diarrhea?
abdominal ultrasound +/- rads & intestinal biopsy (endoscopy for upper/lower gi tract or surgical - may be better in cats because you can also sample the liver)
what is stage V of the diagnostic approach to a patient with diarrhea?
further treatment based on histomorphological diagnosis
inflammation - steroids/other immunosuppressive drugs, further diet trials, therapy for infectious agents, & chemo or surgery for neoplasia
what are some factors that require earlier intestinal biopsies?
PLE, severe weight loss/hyporexia, other systemic illness (lymphadenopathy or pyrexia), melena/hematemesis, & masses seen on imaging
if your client won’t allow a biopsy, what do you need to rule out?
metabolic disease, infectious disease, dietary responsive disease, or presence of a mass
only 2 remaining possibilities are lymphoma & IBD - perform a treatment trial with prednisolone
what 2 tests are used to differentiate gi small cell lymphoma & lymphoplasmacytic enteritis in cats?
immunophenotyping - determines if lymphoid cells are of b-cell or t-cell origin
PARR - used to determine if the cells are clonal, polyclonal, or pseudoclonal
if you have an older cat that presents with weight loss with or without diarrhea & with or without increased appetite, what 3 differentials are you considering?
- IBD
- alimentary lymphoma
- hyperthyroidism
what are the 3 most common causes of chronic small intestinal disease?
parasites, diet, & bacteria
T/F: the most common causes of chronic small intestinal disease cannot be diagnosed with biopsy
true
does histoplasmosis cause small or large bowel diarrhea in dogs?
large bowel!!!
