Unit 4 - Equine Enteric Flashcards by Jessica Carson

What are the common infectious causes of diarrhea in neonate (<2 mo) foals?

Rotavirus
C. perfringens A
C. difficile
Salmonella enterica (any age)

All have acute presentation which is more common

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What are the less common infectious causes of diarrhea in the neonate (<2 mo) foal?

Coronavirus
Cryptosporidium

All acute presentation

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What are the infectious causes of diarrhea in older foals?

R. equi
Lawsonia intracellularis
Intestinal parasites

Chronic more common

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What are the non-infectious causes of diarrhea in foals?

Foal heat diarrhea (acute)
Nutritional diarrhea
Septicemic diarrhea (acute)
Gastric ulcers

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T/F: More than 50% of foals will experience at least 1 episode of diarrhea before weaning.

True

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What are the common infectious causes of diarrhea in adult horses?

Salmonella - acute & chronic
Neorickettsia risticii - acute
Clostridoides difficile - acute > chronic

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What are the less common infectious causes of diarrhea in adult horses?

Coronavirus - acute

Intestinal parasites

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What are the non-infectious causes of diarrhea in adult horses?

Inflammatory bowel disease
Toxicities
Grain overload
Systemic diseases - heart failure, liver failure
Sand enteropathy
Gastric ulcers
Lymphosarcoma
Microbiota abnormalities

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What is a key issue of foal diarrhea?

Failure of passive transfer

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What is the level of antibody per mL that is suggestive of normal complete passive transfer? Partial failure? Complete failure?

Normal, complete - >800 mg/dl
Partial failure - 400-800 mg/dl
Complete failure - <400mg/dl

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What is the gold standard for measuring passive transfer?

Radial immunodiffusion

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What assays are semi-quantitative for measuring passive transfer?

Lateral flow/ELISA-type immunoassays

Immunoturbidometric assays

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What does a Brix refractometer measure?

Total solids to estimate IgG

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What is the gold standard for measuring colostrum quality?

Radial immunodiffusion

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What factors can affect passive transfer?

Maiden mares or >16 years of age
Premature lactation
Sick mares
Dystocia
Poor mothering instinct
Death of mare
Twinning
Sick foals
Congenital defects in foals

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What factors affect foal diarrhea?

Transportation of the mare prior to foaling
Lack of sanitation
Too much pre-partum nutrition of the mare
Too little post-partum nutrition of the mare
Excessive oral medications to the foal

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What is the etiologic agent of Salmonellosis?

Salmonella enterica subspecies enterica

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Most salmonellosis infections are subclinical, however, what can lead to clinical disease?

Stressors such as concurrent infections, deworming, surgery, and transport

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How is Salmonella transmitted?

Fecal-oral or fomite transmission

Highly contagious

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T/F: Salmonellosis is zoonotic.

True

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T/F: Outbreaks of salmonellosis in equine facilities have led to shut down of entire facilities for months.

True

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What clinical signs are associated with acute salmonellosis?

Diarrhea, fever, anorexia, +/- colic, +/- tachycardia, +/- tachypnea

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What will you see on a CBC in a patient with salmonellosis?

Leukopenia characterized by neutropenia +/- left shift, hemoconcentration

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What will you see on chemistry in a patient with salmonellosis?

Hypoproteinemia, acidosis, and electrolyte derangements

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How do patients with chronic salmonellosis present?

They are asymptomatic carriers that have chronic diarrhea

What is the rule of thumb when diagnosing salmonellosis?

A horse with diarrhea and fever or neutropenia has salmonellosis until proven otherwise

How is salmonellosis diagnosed antemortem?

Fecal PCR or culture

What is the gold standard for ruling out current Salmonella infection?

Repeat fecal samples (3-5) collected 12-24 hours apart

At necropsy, what should be cultured to identify Salmonella?

Intestinal tract or lymph nodes

How do you treat salmonellosis?

Supportive care - IV fluids, NSAIDs, polymyxin B, antibiotics, laminitis prevention

How is salmonellosis prevented and controlled in equine hospitals?

Isolate and test all clinical suspects Routine screening of patient population Strict attention to hygiene and disinfection

How is salmonellosis prevented and controlled on the farm?

Quarantine all horses returning from shows and other events Sanitize feeding and cleaning equipment between animals Vaccination

What is the label claim for the Salmonella vaccination?

Aid in prevention of endotoxin-mediated disease

What is the etiologic agent of Potomac Horse Fever?

Neorickettsia risticii

When is the highest incidence of PHF?

In late summer and early fall

What intermediate hosts are associated with PHF?

Trematodes, freshwater snails, and aquatic insects

How is PHF transmitted?

Ingestion of feed or water contaminated with aquatic insects especially mayflies and caddis flies

What does Neorickettsia risticii infect?

Circulating macrophages

What clinical signs are associated with acute cases of PHF?

Fever, anorexia, depression, ileus, injected mucous membranes, +/- colic Diarrhea 24-72hrs after clinical signs

What abnormalities will be on CBC in a patient with PHF?

Leukopenia, neutropenia +/- left shift, hemoconcentration

What abnormalities will be on chemistry in a patient with PHF?

Hypoproteinemia, acidosis, electrolyte derangements

What clinical signs are associated with chronic PHF?

Laminitis and abortion

T/F: PHF is not fatal.

False - it can be due to endotoxemia and laminitis

How is PHF diagnosed?

Seasonal timing and geography is highly suggestive Often initiate treatment prior to receiving test results PCR Paired serology

What is the preferred method of PHF diagnosis?

PCR with feces and/or whole blood

What increase in titers is indicative of PHF?

4-fold increase

How is PHF treated?

Supportive care - IV fluids, NSAIDs, laminitis | Antibiotics - oxytetracycline (response in 1-3 days)

How is PHF prevented and controlled?

Vaccination | Insect control

T/F: Vaccinated individuals against PHF can still develop disease.

True - the vaccine is just thought to lessen the severity of disease

What is the administration protocol for the PHF vaccine?

Initial 2 dose series - 3-4 weeks apart | Booster yearly or every 3-4 months prior to high risk period

What is the etiologic agent of Rotavirus?

Rotavirus A

T/F: Tramission of Rotavirus can cross species.

True

T/F: Almost all horses are exposed to Rotavirus in early life.

True

When do most clinical infections of Rotavirus occur?

In foals that are < 2 months

How is Rotavirus transmitted?

Fecal-oral

Rotavirus is a ____ dependent disease.

Dose

What clinical signs are associated with rotavirus infection?

Diarrhea

What types of diarrhea can Rotavirus cause?

Osmotic or secretory diarrhea

How does Rotavirus cause osmotic diarrhea?

The virus destroys small intestinal villi resulting in malabsorption and thus osmotic diarrhea

How does Rotavirus cause secretory diarrhea?

The enterotoxin causes chloride secretion which in turn results in secretory diarrhea

How is Rotavirus diagnosed?

PCR, ELISA, and Latex agglutination

How is Rotavirus treated?

Supportive care - IV fluids, NSAIDs, +/- broad spectrum abx

How is Rotavirus prevented and controlled?

General sanitation and biosecurity principles | Vaccination

What is the administration protocol for the Rotavirus vaccination?

Immunize mares 3x late in each gestation (8, 9, 10 months)

What is the etiologic agent of Coronavirus?

Equine coronavirus (ECoV) - beta coronavirus

Coronavirus has been recently identified as a primary causative agent of _____ diarrhea.

Adult

There is a high seroprevalence of Coronavirus in _____ breeds.

Draft

How is Coronavirus transmitted?

Fecal-oral transmission, fomites

What clinical signs are associated with coronavirus?

Acute necrotizing enteritis (small > large intestines) | Acute onset - fever, anorexia, lethargy, soft formed to diarrhea to scant feces to colic, +/- encephalopathy

What CBC abnormalities are associated with a coronavirus infection?

Leukopenia and neutropenia

How is coronavirus diagnosed?

PCR on feces - best time is 3-4 days after onset of clinical signs

How is coronavirus treated?

Supportive care only - fluids, electrolytes, NSAIDs

T/F: Vaccination for coronavirus provides life-long protection.

False - there is no vaccine

How is coronavirus prevented and controlled?

General sanitation and biosecurity principles | Known positive animals should be isolated for 3 weeks

What is the etiologic agent of clostridial enteritis?

C. perfringens A and C in foals | C. difficile in foals and adults

How is clostridial enteritis transmitted?

Fecal/oral, fomites

What clinical signs are associated with C. perfringens clostridial enteritis?

Acute onset - hemorrhagic diarrhea with sepsis, colic, dehydration, shock Can progrss to necrotizing colitis and typhlitis

What clinical signs are associated with C. difficile clostridial enteritis?

Acute onset of diarrhea with sepsis

What history is often associated with C. difficile clostridial enteritis?

A history of antibiotics or hospitalization

How is clostridial enteritis diagnosed?

Demonstrate large numbers of gram positive rods in feces or from affected areas of the intestines PCR Culture and genotyping Commercial ELISA for C. difficile

How is clostridial enteritis treated?

Aggressive supportive care - IV fluids, electrolytes, biosponge, antitoxin (extralabel) Antibiotics - Metro and/or penicillin in foals with C. perfringens, metro in adults with C. diff

How is clostridial enteritis prevented and controlled?

Vaccination - extralabel General sanitation and biosecurity principles Hyperimmune plasma Probiotics

What is the etiologic agent of proliferative enteropathy?

Lawsonia intracellularis

T/F: Lawsonia intracellularis is an obligate intracellular pathogen.

True

How is L. intracellularis transmitted?

Fecal-oral

What cells does L. intracellularis infect?

Crypt epithelial cells in the ileum

What age group is most commonly affected by proliferative enteropathy ?

Foals 3-4 months to 7-9 months of age

What clinical signs are associated with proliferative enteropathy?

Ventral edema, diarrhea, weight loss (all due to protein losing enteropathy) Fever, lethargy, anroexia Poor doer - rough hair coat, pot bellied appearance, concurrent infections Acute necrotizing colitis

What lesion can lead to perforation and death associated with proliferative enteropathy?

Erosion and ulceration of intestine

What CBC abnormalities are consistent with a patient with proliferative enteropathy?

Anemia and leukocytosis

What chemistry abnormalities are consistent with a patient with proliferative enteropathy?

Hypoproteinemia, increased CK

How is proliferative enteropathy presumptively diagnosed?

Based on signalment, clinical signs, hypoproteinemia, and thickened small intestines and abdominal ultrasound

How is proliferative enteropathy confirmed?

PCR on feces | Serology (Immunoperoxidase monolayer assay

How is proliferative enteropathy diagnosed at necropsy?

IHC staining

How is proliferative enteropathy treated?

Early treatment is key! | Antibiotics and supportive care (colloids)

How is proliferative enteropathy prevented and controlled?

Extra-label vaccination | Monitoring - 1-2x monthly serum TP and serologic status testing

Colibacillosis is not usually considered a primary pathogen in foal _____ disease.

enteric

What does colibacillosis cause in neonates?

Joint infections, omphalophlebitis, and septicemia

What is the primary disease process that Rhodococcus equi causes?

Pyogranulomatous pneumonia

What non-respiratory disease can R. equi cause in horses and what age group?

May cause enteric disease in 2-6 mo foals

T/F: Extrapulmonary infections due to R. equi are associated with increased mortality.

True

How do you treat R. equi enteric infections?

The same as with respiratory infections - macrolide + rifampin

What is the etiologic agent of Actinobacillosis?

Actinobacillus equuli

Actinobacillosis is also known as what?

Sleepy foal disease

T/F: A. equuli is a common organism found in the intestinal tracts of many horses

True - mares may also carry it in their genital tracts

What are the clinical signs of actinobacillosis in neonates?

Early septicemia (1-4 days of age) - lethargy, anorexia, diarrhea, joint infections, abscesses in multiple organs, sudden death

What does actinobacillosis cause in adults?

Peritonitis, endometritis, endocarditis

How is actinobacillosis diagnosed?

Culture

What antemortem samples should be used for diagnosis of actinobacillosis?

Blood, joint

What post mortem samples should be used for diagnosis of actinobacillosis?

Kidney, lung, liver

How is actinobacillosis treated?

Antibiotics - gram negative septicemic coverage

How is actinobacillosis prevented and controlled?

Adequate passive transfer | Good sanitation at foaling