Exam 3: Management of Diarrhea in Horses

signs of equine colitis

• diarrhea with a change in fecal character

• lethargy

• fever

• colic

• anorexia/hyporexia

• clinical signs of endotoxemia 

• dehydration 

• abnormal GI auscultation 

course of disease in colitis in adult horses

• in typical cases, fever, depression, endotoxemia usually precede diarrhea by 2-5 days

• sometimes diarrhea never occurs

• in a few severe cases, severe acute shock and death occur before diarrhea 

diagnostics for all cases of acute diarrhea

• CBC

• chemistry

• venous blood gas

• blood lactate 

• abdominal ultrasound 

• fecal testing 

Diagnostics for select cases of acute diarrea 

• abdominocentesis if peritonitis is suspected 

• NG tube if abdominal pain is present 

• rectal palpation if horse is distended and painful 

chemistry panels for colitis 

• hyponatremia 

• hypochloremia 

• hypokalemia 

• hypocalcemia 

• metabolic acidosis 

• ± azotemia 

• ± hypoproteinemia 

• these signs may precede passage of diarrhea 

two paths of treatment for acute diarrhea

• symptomatic= same regardless of cause, and is supportive while the colon heals

• agent specific target if known

goals of general therapy

• replace fluid and electrolyte losses → MOST IMPORTANT

• reduce systemic inflammation

• reduce intestinal inflammation

• promote intestinal mucosal repair

• re-establish the normal intestinal microflora

IV crystalloids 

• Normosol-R, LRS, or Plasma-lyte 

• no additives 

• give an iniial bolus of fluids at 6-20ml/kg 

• give over 20-30 minutes 

• do NOT add calcium and potassium additives to initial bolus 

hypertonic saline

• hypovolemic shock

• 2-4mh/kg IV

• follow immediately with cystalloid therapy 10-1 ratio

additives to IV fluids

• calcium gluconate 1mEq/mL, 50/L if hypo, 25/L if normal

• potassium chloride 2mEq/mL, hypo 30-40, normal 10-20

oral electrolyte therapy 

• can be used in mildly dehydrated patients 

• requires voluntary intake by the patient 

• commercial power= 1oz/5gal 

• homemade= 2tsp NaCl, 2tsp lite salt, 2tbsp baking soda 

oral replacement fluid therapy

• can be administered indwelling NG tube up to 4-6L every 2 hrs

• can cause ileus, Nasopharyngeal treuma

NSAIDs for endotoxemia

• flunixin meglumine

• low dose= decreases endotoxin mediated production of thromboxane to improve cardiovascular status

• high dose= analgesic and improves appetite

• may slow healing of colon, high doses should only be used for a few days

colloid therapy for endotoxemia 

• not for treatment of hypoproteinemia beccaue its too expensive 

• low plasma doses 1-2L to counter the effects of endotoxemia- provide anibody to bind endotoxin and inflammation modulating proteins, improves clinical signs 

other options for reducing systemic inflammation

• pentoxifylline- phosphodiesterase inhibitor, decreases TNF production

• Polymyxin B- aminoglycoside, binds endotoxin lipid A, nephrotoxic

• Biosponge- silicate that attracts positively charged bacterial exotoxin/endotoxin , reduces systemic toxin absorption

• DMSO

• bismuth subsalicylate

we know not to use antibiotics with all antibiotics. When do you you them?

• Neorickettsia or Clostridium

• to treat infection in another organ such as pnemonia

• pt with prolonged neutropenia

• diarrhea in a neonatal foal

promote intestinal mucosal repair 

• sucralfate- disaccharide and mucosal protectant, useful for gastric ulcers but nlikely that sufficient concentrations of active drug reach the colonic mucosa 

• psylliym- scaffolding to increase stool consistency also increases VFA production to improve healing 

sand enteropathy

• impaction and chronic diarrhea from chronic GI mucosal irritaton

• psyllium may help with sand evacation but evidence is conflicting, used to prevent sand colic

treatment options for antibiotic induced diarrhea

• probiotics ±

• prebiotics

• fecal microbiota trans[lantation- risk of transmission of pathogens

treat clostridium spp 

• metrodidazole 

treat potomac horse fever

• oxytetracycline daily for 5 days

• trimethoprim sulfa and rifampin combination

treat cyathostomes

larvacidal dose of fenbendazole

treat NSAID associated colitis 

• Misprostol 

• side effects include diarrhea and abdominal discomfort, contraindicated in pregnant mare 

lamitis prevention

• frog support with molded plastics, memory foal, deep bedding

• ice boots and cryotherapy

skin barrier protection

• apply petrolium jelly or zinc oxide cream to perineum and hindlimbs

  • to prevent scalding and moist dermatitis from frequent diarrhea

diet changes for colitis 

• fresh grass 

• grass hay/alfalfa 

• avoid grain or offer very small amounts 

• high fiber pellet - grass hay, alfalfa, purina senior 

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diet changes with NSAID associated colitis

• complete pelleted feed only

• low residue diet

• no hay!

why avoid carbhydrate rich diets

leads to change in colonic microflora, increases lactic acid producing bacteria

complications of colitis 

• circulatory shock 

• thrombophlebitis 

• edema due to hypoproteinemia or endotoxemia 

• severe colon damage 

• laminitis 

colitis prognosis

• 75% survival

• some cases develop complications due to highly virulent infectious pathogen, immunity of the host, infectious dose