Equine Enteric Diseases Flashcards
What is the most common cause of foal infectious diarrhea?
Rotavirus
what is the most common cause of foal non-infectious diarrhea?
Foal Heat Diarrhea
What are the top 3 common causes of infectious diarrhea in adult horses?
Salmonella enterica
Neorickettsia risticii
Clostridioides difficile
What are the top 3 common causes of non-infectious diarrhea in adult horses?
IBD
Toxicities (such as Cantharidin, and NSAIDS)
Grain Overload
What is the timeframe for maximum absorption of maternal antibodies?
The first 8 hours of life
What are the main methods of measuring passive transfer utilized in practice?
Semi-quantitative immunoassay
Lateral flow/ELISA-type immunoassays
Immunoturbidometric assay
What factors effect FPT
Maiden mares, premature lactation, sick mares, dystocia, poor mothering instinct. etc.
Factors affecting foal diarrhea
transportation of the mare prior to foaling, lack of sanitation especially in the foaling area and facilitates where the foals are housed for the first 10 days, pre-partum nutrition of the mare. Too much is bad, Post-partum nutrition of the mare: too little is bad, excessive oral medications to the foal
What salmonella is most common
Salmonella enterica ss enterica
serovar Typhimurium is the most common (non-host adapted)
How is salmonella transmitted between animals
Fecal-oral or fomite transmission - HIGHLY CONTAGIOUS
What are acute clinical signs associated with Salmonella
Diarrhea (watery, +/-blood, +/- foul odor, +/- mucous) , Fever, and neutropenia are the most common clinical signs.
What clinical signs are associated with Chronic cases of Salmonella
Asymptomatic carriers- many only have a transient fever and/or cow-pie feces following stressful event
Chronic diarrhea- rare cases may develop chronic unresponsive cow-pie feces, weight loss.
How is Salmonellosis diagnosed in horses?
A fecal PCR or culture is most common.
One negative fecal on a suspect case is NOT enough!
Repeat Fecal samples (3-5) collected 12-24 hours apart is the gold standard
What treatment methods are suggested for Salmonellosis cases
Supportive Care
IV Fluids: Crystalloids (correct dehydration and electrolyte losses, Colloids- replace protein loss
NSAIDS, polymyxin B for endotoxemia
Antibiotics- Typically only used in foals or adults suspected of Septicemia
Laminitis prevention
What control protocols are used on the farm for cases of Salmonella
Quarantine all horses returning from shows and other events
Sanitize feeding and cleaning equipment between animals
Vaccination
What are the label claims for the Salmonella vaccination that is approved in the US?
Aid in the prevention of endotoxin-mediated disease
NOT labeled for diarrhea
> 6months of age, 2 initial shots with yearly booster
Not included in core or risk-based vaccine recommendations
What is the cause of Potomac Horse Fever
Neorickettsia risticii
When is the highest incidence of disease of Potomac Horse Fever
late summer/early fall
How is Potomac Horse Fever Transmitted?
Ingestion of feed or water contaminated with aquatic insects especially mayflies and caddis flies
What does Potomac Horse Fever infect?
Circulating macrophages.
What are Clinical Signs associated with the acute onset of Potomac Horse Fever?
Fever, anorexia, depression, injected mucous membranes
Diarrhea 24-72 hours after clinical signs
Initial presentation is the same as salmonellosis
What are clinical signs associated with chronic Potomac Horse Fever
Laminitis (up to 30%)
Abortion
What are the cause of death associated with Potomac Horse Fever
endotoxemia, laminitis
What methods of diagnosis are associated with Potomac Horse Fever
seasonal timing and geography highly suggestive
Often initiate treatment prior to receiving test results
PCR (current ideal)- feces, whole blood, (ideally submit both)
What methods of treatment are utilized in Potomac Horse Fever
Supportive care: IV fluids, NSAIDS (for endotoxemia), laminitis prevention
Antibiotics: Oxytetracycline (7-10mg/kg IV, BID), Response to therapy within 1-3 days
How soon after intiation of treatment for Potomac Horse Fever should you see a response
1-3 days
What vaccination protocols are used against Potomac Horse Fever
Vaccination is routinely practiced in endemic areas. It is thought to lessen severity and incidence of disease, but vaccinated animals can still develop disease
What steps can you take to prevent/control Potomac Horse Fever?
Turn off outside lights to discourage insects from being attracted.
Clean buckets and feed areas frquently and keep feed covered
Maintain riparian barriers along bodies of water in hopes that it will encourage aquatic insects to stay home
How is Rotavirus transmitted?
fecal oral
At what age are foals affected by Rotavirus?
Most clinical infections in foals <2 months of age
What are clinical signs associated with Rotavirus
Diarhea- virus destroys small intestinal villi –> malabsorption –> osmotic diarrhea
enterotoxin –> chloride secretion –> secretory diarrhea
How is Rotavirus diagnosed?
PCR usually part of a diagnostic panel
ELISA is rapid and convenient
What treatment methods are utilized in Rotavirus cases
Suppportive Care: IV fluids,
NSAIDS for endotoxemia (caution in hypovolemic foals)
+/- broad spectrum antibiotics for suspect septicemia
How should Rotavirus be prevented/controlled:
Tends to be a problem on larger farms- movement of mares into different facilities can result in exposure of foals to new variants
General sanitation and biosecurity principles- Phenolic disinfectants are best
Vaccination-risk based recommendation
How are vacciantions used against Rotavirus infections
Risk based
Immunize mares 3x late in EACH gestation: 8,9,and 10 months -> Colostrum
Lessens the severity, foals may develop mild rotaviral diarrhea after the antibody levels decrease (60 days)
What is the etiology of Coronavirus?
Equine Coronavirus- beta coronavirus
Close relative of bovine coronavirus
How is Coronavirus transmitted?
Fecal oral transmission, fomites
Shed in feces for up to 21 days
What has recently been identified as the primary causative agent of adult diarrhea in horses?
Coronavirus
What time of year are Coronaviral infections most common
more common in the cooler months
What clinical signs are associated with Coronavirus?
Acute necrotizing enteritis (small>large intestines)
Acute onset: Fever, anorexia, lethargy, Range of enteric signs (soft formed to diarrhea to scant feces to colic)
May present with encephalopathy, often associated with hyperammonemia (<10% of cases)
Leukopenia, neutropenia
How is Coronavirus diagnosed?
PCR on feces- viral shedding peaks 3-4 days after development of lcinical signs. May test negative if sample is taken at initiation of disease.
Treatment associated with Coronavirus
High morbidity but lwo mortality
Supportive care only: Fluids & electrolytes, NSAIDS
Prevention and Control methods associated with Coronavirus
No vaccine available
General sanitation and biosecurity principles
Quarantine all horses
Known positive animals should be isolated for 3 weeks.
Clostridial infections associated in equine
Clostridium perfringens Type A and C in foals
Clostridioides difficile in foals and adults
What is the epidemiology of Clostridial infections?
Abnormal colonization of GI tract/overgrowth. Spores can become persistent in the environment. Fecal/oral transmission, fomites
clostridial enteritis associated with C. perfringens
Hemorrhagic diarrhea with sepsis (Type C worse than A)
Colic, dehydration, shock- may precede onset of diarrhea (sudden death in foals)
can progress to necrotizing colitis and typhlitis
Clostridial enteritis associated with C.difficile
Diarrhea with sepsis (less likely to contain blood)
Often history of antibiotics or hospitalization
You find mucosal and submucosal hemorrhage, necrotizing enteritis, hemorrhage and tan/orange pseudomembrane in a foal. What is your top differential?
C. difficile
An adult horse has a colon with watery contents, necrosis and thickening of the mucosal folds due to edema fluid. What is your top differential?
C. difficile
What is the top diagnostic method for Clostridial enteritis?
PCR- best test for toxin genes
Culture and genotyping of isolates becoming more common
What method of treatment is associated with Clostridial enteritis?
Aggressive supportive care (IV fluids and electrolytes, Biosponge [binds toxins])
Antibiotics: Metronidazole
What methods of prevention can be taken for Clostridial enteritis in horses
General sanitation and biosecurity, particularly in the foaling stalls. Sanitize feeding and cleaning equipment between animals.
what is the causative agent in “Proliferative Enteropathy”
Lawsonia intracellularis
How is Lawsonia intracellularis transmitted?
fecal-oral
Where in the GI tract does an infection of Lawsonia intracellularis most commonly occur
infection of the crypt epithelial cells in the ileum
What age animals are most affected by Proliferative enteropathy
Foals 3-4 months to 7-9 months of age are most commonly affected
Clinical signs associated with Proliferative enteropathy
“Poor doer”- rough hair coat, pot bellied appearance, concurrent infections
Erosion and ulceration of intestine may lead to perforation and death
Chemistry: hypoproteinemia, increased CK
How is Proliferative enteropathy diagnosed?
PCR on feces- quantitative but poor sensitivity due to intermittent shedding
Serology- (IMPA)- highly specific for exposure, but may not correlate to clinical disease, negative early
How is Proliferative enteropathy treated?
Early treatment is essential!
antibiotics: Macrolides +/- rifampin, tetracyclines, or chloramphenicol administered for 2-3 weeks
often take weeks to months to return to normal protein level and weight gain
NOT reported to spontaneously resolve without treatment
How is Proliferative enteropathy prevented in equine?
Extra-label use of live oral avirulent swine vaccines given transrectally has been shown to be safe and to decrease clinical disease and shedding
How is colibacillosis associated with enteric disease in equine
Usually not considered a primary pathogen in foal enteric diseases
Potentially combines with Rotavirus to cause a more serious disease
Joint infections, omphalophlebitis, and septicemia- may account for 25% of neonatal mortality
