Diarrhea

Question 1

What are the infectious causes of diarrhea in horses?

Answer 1

Bacteria: salmonella, C. perfringens or difficile (acute)
Viral: Equine coronavirus (acute)
Parasites: Neorickettsia risticii, cyathostomes (chronic)

Question 2

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

Answer 2

Abx, NSAIDs, grain overload (ACUTE), sand (chronic)
Toxins: blister beetle (acute), ionophore, IBD (chronic)

Question 3

CS in a horse with acute salmonellosis

Answer 3

Abdominal pain, acute diarrhea, inappetence
Small colon impaction
Sepsis/ septic shock, laminitis

Question 4

CS in a horse with acute clostridial colitis

Answer 4

Peracute, acute or gradual diarrhea (hemorrhagic, dark/ foul smelling) *
Colic, fever, inappetence, septic shock, sudden death
Abdominal distention, scant feces, bowel necrosis then death

Question 5

Tx for a horse with clostridial colitis and acute salmonellosis

Answer 5

Metronidazole, di-tri- octahedral smectite, NSAIDs (polymixin B)
IV fluids with electrolytes
Plasma therapy, cryotherapy, colloid therapy

Question 6

Plasma therapy

Answer 6

Commercial hyperimmune plasma with Abs and proteins (albumin) that maintain circulation, minimize edema and minimize endotoxemia effects

Question 7

How would you differentiate between acute salmonellosis and acute clostridial colitis?

Answer 7

Salmonella: can dx with cx and PCR, could have a fever, small colon impaction, watery diarrhea, laminitis
Clostridium: hemorrhagic diarrhea, fever and sudden death

Question 8

CS of Potomac Horse Fever

Answer 8

High fever (107F), 7-14d before colitis signs develop
Mild to moderate colic and ↓ GI signs
Edema: limbs, prepuce and ventral body
Abortion (transplacental trans)

Question 9

What geographical areas is PHF found?

Answer 9

Swampy areas (summer dz)

Question 10

Tx for PHF

Answer 10

Oxytetracycline (IV) and supportive therapy

Question 11

DX PHF

Answer 11

PCR (sensitive and specific)
IFA (seroconversion, >30% false +)

Question 12

CS of equine enteric coronavirus

Answer 12

Anorexia, lethargy, fever
Leukopenia secondary to neutropenia or lymphopenia
Hypoalbuminemia and neuro abnormalities
Hyperammonemia (severe cases)

Question 13

Dx equine enteric coronavirus

Answer 13

PCR (chilled sample or frozen if testing delayed for more than 3-4 days)

Question 14

What horses are predisposed to clinical dz in larval cyathostomiasis

Answer 14

Young adults <6yrs

Question 15

CS of larval cyathostomiasis

Answer 15

Acute diarrhea → chr.
WL, colic and peripheral edema

Question 16

Dx of larval cyathostomiasis

Answer 16

HY
Fecal exm (float and EPG)
CBC/ chemistry

Question 17

Prognosis of larval cyathostomiasis if severe CS develop

Answer 17

???

Question 18

Tx of horse with larval cyathostomiasis

Answer 18

Anthelmintics (adult larvae)
Corticosteroids (dexmeth, pred)

Question 19

Which anthelminics are used for larval cyathostomiasis?

Answer 19

Fendendazole and avermectins
Repeated doses are needed to kill parasites as they emerge from arrested state leading to resistance

Question 20

How would you use fecal egg counts and egg reappearance times to strategize anthelmintics?

Answer 20

???

Question 21

Main site of GI damage with NSAIDs

Answer 21

Right dorsal colon

Question 22

Right dorsal colitis pathophysiology

Answer 22

NSAIDs inhibit COX enzyme → reduction in cytoprotective effects from PGE2 → hypoxic or ischemic damage to the mucosa → phenylbutazone is bound to roughage and released after fermentation in large colon → slow transit time and narrowing of lumen @ junction

Question 23

What factors contribute to right dorsal colitis?

Answer 23

Dehydration, enterotoxemia, inappropriate dosing or pre-existing lesions of the colon

Question 24

Clinical pathology of right dorsal colitis

Answer 24

Hypoproteinemia
Hypocalcemia
Azotemia (prerenal or acute renal damage)
Anemia (chr. cases, mild)

Question 25

CS of acute RDC

Answer 25

Profuse diarrhea, severe colic, dehydration, endotoxic shock and death

Question 26

CS of chr. RDC

Answer 26

Mild to moderate intermittent colic
Ventral edema, WL
Weeks to months

Question 27

RDC dx

Answer 27

US (colon wall thickened)
Scintigraphy

Question 28

RDC tx

Answer 28

Pain management: opioids, xylazine
NSAIDs (avoid if possible but ketoprofen, firocoxib)
Low bulk diet and avoid roughage
Metro, sucralfate and glutamine (healing and repair)

Question 29

Blister beetle toxicity (cantharidin)

Answer 29

Ingestion of dead beetles in alfalfa hay (males produce toxin)
4-6g of dead beetles is lethal
Vesicant and mucosal irritant

Question 30

CS of BBT

Answer 30

Shock and death (massive dose)
Sweat profusely, ↑ HR, resp. and temp
Bright red mm, prolonged CRT, massive fasciculations, hematuria

Question 31

Electrolyte abnormalities in BBT

Answer 31

Hypomagnesium, hypoproteinemia, elevated CK and mild azotemia

Question 32

CS of sand enteropathy

Answer 32

40lb to cause colic
Diarrhea:

Question 33

Dx sand enteropathy

Answer 33

Auscultation cd. to xyphoid cartilage: sand swirling in paper bag (20lb)

Question 34

How do you tx sand enteropathy and prevent recurrence?

Answer 34

Sx- sand impaction
Laxatives- mineral oil, Mg sulfate, pelled complete feed ration
Combo of psyllium and MgSO4 via nasogastric intubation (4d)
Prevent with mowl horse feeder, or pre-vent horse feeder