Equine Diarrhea Differential Diagnoses Flashcards
give background on salmonella (7) (acute D)
- 2500+ servotypes
- no enteric, host adapted serotype in horses
- S. typhimurium most common
- risk factors:
-young, old, and sick
-stress, hospitalization
-antibiotic use
-warmer months
-nosocomial disease - fecal-oral transmission!
- invasive: live and replicate intracellularly
- causes intestinal inflammation, hypersecretion, and malabsorption
describe clinical findings of salmonella (4)
- wide spectrum of disease possible
-asymptomatic carriers to severe, acute, necrotizing colitis - lethargy, fever, anorexia
- diarrhea: variable
- +/- colic, endotoxemia/SIRS
describe salmonella diagnosis (3)
- fecal culture or PCR
-repeated or pooled samples: 5x culture, 3x PCR
-shed intermittently! so need multiple samples - intestinal or lymph node culture post morten
- blood culture from foals
-enteric infection can translocate to bloodstream if infection severe enough
describe salmonella client education points (4)
- prognosis is variable
-treatment more supportive care (more later) - shedding period is weeks to months
-can shed in manure even after recover!! - ZOONOTIC, REPORTABLE in GA
- no equine vaccine available
give background on C. perfringens and C. difficile (4) (acute D)
- gram positive anaerobes, ubiquitous in environment
- C. perfringens = normal flora; C. difficile = transient flora
- produce many exotoxins and enterotoxins
-particularly during periods of stress, diet change, or antibiotic therapy - rabbits and rodents can develop the same issues (normal flora + stress = overgrowth and issues, per Dr. Divers)
describe clinical findings, diagnosis, and client education of C. perfringens and C. difficile
clinical findings:
- similar to those observed for more acute, severe salmonella cases
- diarrhea more likely to be bloody
diagnosis:
1. must demonstrate toxin ID via fecal ELISA or PCR
treatment note: add metronidazole to these cases!
client education:
1. prognosis is variable to poor (more worrisome than salmonella usually)
2. no equine vaccine
give background on potomac horse fever (3)
- neorickettsia risticii
-obligate intracellular pathogens of enterocytes and leukocytes - indirect oral transmission
-live in aquatic insects/snail that holds the flukes that hold the organism; accidentally ingested by horses - reside primarily within the colon epithelium and macrophages, leading to inflammation and necrosis
describe clinical findings of potomac horse fever (3)
- can be subclinical or may appear similar to salmonella
- biphasic fever may occur prior to onset of diarrhea
- laminitis is a commonly reported complication
-some horses will present with laminitis prior to presenting with diarrhea
describe diagnosis and client education of potomac horse fever (acute D)
diagnosis:
1. paired serum titers: acute and day 7
- blood or FECAL PCR (most common is fecal PCR)
treatment note: oxytetracycline!
client education
1. prognosis is variable (with laminitis = worse prognosis)
2. vaccines available for horses in endemic areas; reduce clinical signs
-one area of North Georgia does give some cases!!
give background on equine coronavirus (3)
- betacoronavirus
- fecal-oral transmission
- incubation period:
-clinical signs about 48-72 hours after exposure
-fecal shedding about 3-4 days after exposure
describe clinical findings, diagnosis, and client education of equine coronavirus (acute D)
clinical findings:
1. lethargy
2. fever
3. anorexia
4. diarrhea in <20% of cases
diagnosis: fecal PCR
client education: prognosis is good
describe antibiotic-induced colitis (acute D)
background:
1. disrupts normal intestinal flora and their fermentation products
- possible with ANY antibiotic!
-most common offenders: macrolides in adult horses
clinical findings: similar to salmonella
diagnosis: no definitive (hx and r/o others)
client education:
1. prognosis is variable
2. use of pre and pro biotic products have NOT been shown to prevent
Dr. Divers note: rabbits and rodents also experience this
describe NSAID-induced colitis (acute D)
background:
1. inhibits cyclooxygenase and suppress production of intestinal prostaglandins needed for normal colon blood flow and health
-right dorsal colon most sensitive
- most common when excessive/overdoses occur, but can happen even at recommended doses
clinical findings:
1. similar to salmonella, although profuse watery diarrhea is not as common
2. protein loss is common
diagnosis:
-none definitive, but history and ultrasound revealing thickening of the right dorsal colon is supportive
client education: prognosis is variable
describe grain overload (acute D)
background:
-excessive grain ingestion or rapid dietary changes causes rapid carbohydrate fermentation and lactic acidosis, resulting in a change in normal intestinal flora
clinical findings:
1. colic
2. colitis
3. enteritis
4. endotoxemia/SIRS within hours to days
diagnosis: history
prognosis: variable
describe blister beetle toxicity (acute D)
background:
1. cantharadin is a mucosal irritant
-found inside blister beetles; get caught up in alfalfa hay; takes very few to cause severe disease
clinical findings:
1. oral ulcerations and hypersalivation
2. colic and (likely bloody) diarrhea
3. hematuria and stranguria
4. hypocalcemia!!! and hypomagnesemia
diagnosis:
1. GI and urinary signs with hypocalcemia in a horse receiving alfalfa
2. detect toxin in gastric reflux or urine
3. hard to find in hay
prognosis: guarded to poor
describe cyathostomes/small strongyles (chronic D)
background:
1. fecal oral transmissionL L3 larvae ingested, either mature or ENCYST in the large intestines
- extensive number of encysted larvae or sudden exit of encysted larvae lead to mucosal inflammation and injury
clinical findings:
1. failure to thrive
2. most often mild chronic waxing and waning diarrhea, but can appear as acute severe diarrhea too!
3. +/- larvae in the feces
4. hypoproteinemia
diagnosis:
1. larvae observed in feces; ova on fecal eggs count
-absence does NOT rule out!!
2. exclusion or response to treatment
prognosis:
1. variable but generally good with treatment if not resistant
2. regular FEC monitoring and strategic deworming is a good idea
describe sand enteropathy (chronic D) background and clinical findings
background:
1. accidental or purposeful ingestion
2. accumulates in the ventral colon, causing:
-mucosal irritation
-decreased water absorption
-decreased motility
-impaction/obstruction
clinical findings:
1. most: mild to moderate diarrhea, possible weight loss, failure to thrive
2. can also present acutely if impaction/obstruction occurs
3. occasionally sand rustling on ventral abdominal auscultation
describe sand enteropathy diagnosis and prognosis
diagnosis:
1. sand may be present in feces: visible alone or with sedimentation or not
2. abdominal radiographs are most definitive
prognosis/client education:
1. dependent on severity, generally good for medical management and/or cases that survive surgical removal
- tell client to eliminate/reduce exposure to sand
- use psyllium products intermittently and prophylactically
describe background and clinical findings of inflammatory bowel disease (chronic D)
background:
1. exact cause unknown
2. subcategories based on predominate cell infiltrating the intestinal wall
3. intestinal wall infiltration leads to nutrient malabsorption and hypoproteinemia
clinical findings:
1. weight loss despite good appetite
2. +/- hypoproteinemia and ventral edema
3. +/- diarrhea
4. +/- recurrent colic
5. rarely dermatopathy
Dr. Divers note: ferrets prone to malabsorption disease; most common subtype is eosinophilic
describe diagnosis and prognosis of inflammatory bowel disease
diagnosis:
1. clinical history of weight loss despite good appetite
2. abdominal ultrasound: small and/or large intestinal thickening
3. oral absorption tests support malabsorption
4. intestinal (rectal, endoscopic duodenal, or surgical) biopsy and histopath most definitive
prognosis: guarded to poor, particularly longterm unless there is a focal disease that can be resected
describe intestinal lymphoma
background:
-infiltration of the intestinal wall with neoplastic cells leading to malabsorption
clinical findings:
1. chronic weight loss and fever most common
2. diarrhea with more extensive disease
diagnosis:
-intestinal biopsy and histopathology
prognosis: palliative care possible but invariably fatal long term
describe acute diarrhea in foals
- foals can develop diarrhea as a result of EITHER small and/or large intestinal disease
- neonatal foals are more likely to develop true septicemia as a consequence of colitis/enterocolitis
-septicemia is also more likely to cause diarrhea in foals
describe salmonella in foals
- similar to adults but lean more towards severe end
- dam may be the source of infection
-subclinical mom shed = bad - age of onset is usually <14d old, but can occur any time
describe clostridium in foals
- similar to adults
- more likely to experience enteritis:
-gastric reflux, gas distension, colic, and/or sudden death in adults - age of onset usually 1-10 days of age (usually <5 d)
