Equine Diarrhea Flashcards
What is diarrhea?
Passage of unformed feces with increased water content and increased frequency of defecation
What are the pathophysiological mechanisms associated with diarrhea in the horse?
Hypersecretion
Motility Alterations
Malabsorption
GIT inflammation
Osmosis
Pressure alterations
What is a rare process that can be associated with diarrhea in foals?
Sepsis - septicemia –> secondary foal diarrhea
What is the primary site of water absorption in the adult horse? What other functions does this site perform?
Large Intestine (Colon)
Microbial digestion of carbohydrate and protein/non-protein nitrogen
What is the difference between adult and foal large intestine?
Foal LI not as well developed due to all milk diet
Which part of the intestines can be responsible in adult horses vs. foals?
Adult horses - large intestine
Foals - Large or small intestine
What are the common causes of neonatal foal diarrhea (<1 month of age)
- Foal heat diarrhea
- Rotavirus, Salmonellosis, Clostridiosis
- Neonatal Septicemia
What is foal heat diarrhea?
Foals are not systemically ill
Diarrhea occurs in foals <6d days of age, during the time when mare enters her first heat cycle after foaling
Foals eat mare’s feces during this time, could be the cause of changing GI flora (rapid increase in bacteria which digests cellulose). –> diarrhea
Is rotavirus, salmonella, and clostridiosis contagious in foals?
Salmonella - very contagious (zoonotic)
Clostridiosis - not contagious
Rotavirus - contagious
What are some uncommon causes of neonatal foal diarrhea?
Necrotizing enterocolitis
Strongyloides westeri
Dietary intolerances
Cryptosporidium
What are the predisposing factors for foal septicemia?
Difficult birth
Failure to receive an adequate quality and quantity of colostral antibodies
Gestational age of the foal (prematurity)
Poor health and condition of the dam
Presence of new disease-causing agents in the environment against which the mare has no antibodies
Unsanitary environmental conditions
What are the early warning signs of a foal with neonatal septicemia?
The earliest sign may be that the foal is slightly depressed or does not act as lively as other foals. This progresses to a foal that will not eat and lies down frequently. The mare’s udder is often distended with milk, indicating that the foal is not nursing with normal frequency.
What is the treatment protocol for foals with neonatal septicemia?
Broad-spectrum antibiotics
Plasma transfusions (replace antibodies not received in colostrum)
IV fluids (counter the effects of bacterial toxins and infection)
+/- sugar solution (many septic foals hypoglycemic)
Nutritional support VERY important
How do you distinguish Clostridial vs. Salmonella diarrhea?
Clinically indistinguishable
Both causes severe abdominal pain (colic), diarrhea, etc.
Salmonella can be cultured/identified using PCR
For Clostridiosis you need to demonstrate bacterial toxins in feces (ELISA or toxin gene PCR) and culture anaerobically
What are the predisposing factors for Clostridial diarrhea?
ANTIMICROBIAL USE,food deprivation, stressors –> overgrowth of C. perfringens/C. difficile –> GI disease.
What are the common causes of weanling foal diarrhea (10-12 months)
Larval cyathostominosis
Proliferative enteropathy (Lawsonia)
What is larval cyathostominosis and how does it cause diarrhea? What is the treatment?
Emergence of encysted cyathostomin larvae from the large intestinal walls –> acute, generalized typhlocolitis (inflammation of cecum/colon) –> profuse, watery diarrhea +/- ventral edema
Treatment - Macrolytic Lactones (Moxidectin)
How do you diagnose larval cyathostominosis?
Cyathostomin LARVAE in feces (fecal egg counts often negative)
Serological tests which detects IgG Ab specific to larval cyathostomins
What kind of organism is Lawsonia? How does it cause diarrhea?
Lawsonia intracellularis - obligate intracellular organism
Causes diarrhea in foals (weanlings)
Lawsonia causes proliferation of infected enterocytes –> thickening of small intestinal epithelium –> fever, lethargy, peripheral edema, diarrhea, colic, weight loss.
How do you treat EPE/Lawsonia?
Antimicrobials and supportive therapy
What are some uncommon causes of diarrhea in weanling foals?
- Sand enteropathy (foals this age love to eat sand, abrasive → diarrhea)
- Salmonellosis, Clostridiosis
- Rhodococcus equi enterocolitis (bacteria that causes pulmonary abscesses, sometimes causes enterocolitis)
What are some common causes of adulte horse diarrhea (over 12-24 months of age)
- Larval cyathostomiasis
- Clostridiosis, Salmonellosis
- Carbohydrate overload/Dietary
- Sand Enteropathy
- Antimicrobial Associated Diarrhea (AAD)
- NSAID Induced ulcerative right dorsal colitis
- Inflammatory Bowel Disease
- Undiagnosed/Idiopathic
What are some uncommon causes that you should always consider when diagnosing an adult horse with diarrhea?
- Equine coronavirus
- GI neoplasia
- Potomac horse fever
- Peritonitis
- Plant toxicosis
- Blister beetle poisoning (eaten by horses)
What is Potomac Horse Fever caused by? Where is it most common? What are the symptoms? Prevention/Treatment? Is this contagious?
Bacterial disease caused Neorickettsia risticii
Horse eats aquatic insect/flatworm carrying bacteria
Symptoms (range from mild to severe) - fever, lethargy, poor appetite, diarrhea, mild colic, and laminitis (can infrequently cause abortion)
Common in US
Prevention - Vaccine
Treatment - IV abx/supportive care
Not contagious from horse to horse