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)
describe rotavirus
background:
1. short incubation period: 48 hr
- damages and denudes to microvilli of the small intestine
-lack of lactase leads to maldigestion of lactose and an increased osmotic load
-osmotic diarrhea - primarily affects foals 5-35d, peak at 14-12d
clinical findings:
1. lethargy, fever, anorexia
2. diarrhea
3. +/- mild colic
diagnosis: fecal ELISA, PCR, or electron microscopy
prognosis:
-generally good
-vaccine available for dams
-meticulous biosecurity required: only phenolic disinfectants are effective
describe coronavirus in foals
similar to adults but very rare cause of diarrhea in foals
describe foal heat diarrhea
background:
1. name due to timing; often coincides with mare’s first foal heat
-typically 5-14d old (peak 7-10d)
- likely due to dietary changes and development of normal intestinal flora
-coprophagy of foal helps contribute
clinical findings:
1. variable diarrhea
2. NO systemic signs
diagnosis: presumptive
prognosis: excellent
describe lawsonia background and clinical findings (chronic)
background:
1. lawsonia intracellularis: obligate intracellular bacterium
- fecal oral or soil oral transmission
- small intestinal mucosal hyperplasia, crypt hyperplasia, and villi atrophy leading to malabsorption and protein-losing enteropathy
clinical findings:
1. primarily weaning age foals (4-8 months)
2. mild to mod waxing waning chronic diarrhea
3. weight loss and ill thrift
4. hypoproteinemia and ventral edeam
5. thickened small intestine walls on ultrasound
describe diagnosis and prognosis of lawsonia
diagnosis:
1. presumptive based on clin signs, AUS showing thickened intestines
2. fecal PCR
3. serum titer
prognosis: good with treatment (tetracyclines)
describe lactose intolerance
- infrequent on its own
- common during recovery from other etiologies such as rotavirus
- diagnosis is often presumptive but can include lactose absorption tests
describe nutritional diarrhea
- excessive, sudden consumption of milk or milk replacers
- use of milk replacer in general
- improper mixing of milk replacer and/or hygiene of milk replacer feeding equipment
