TREATING COLITIS IN THE FIELD. Rose D. Nolen-Walston, DVM, DACVIM (LAIM) Kennett Square, PA

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1 TREATING COLITIS IN THE FIELD. Rose D. Nolen-Walston, DVM, DACVIM (LAIM) Kennett Square, PA INTRODUCTION Colitis in horses is a scary disease on several levels. First, it results in huge fluid losses, sometimes up to 100 liters a day. These can be challenging to replace and keep up with. Second, regardless of etiology, a leaky colon wall frequently leads to endotoxemia, which wreaks havoc on the horse s physiology. Systemic Inflammatory Response Syndrome (SIRS) is a rapid result, leading to organ failure, especially of the horse s main shock organ, the foot. And thirdly, a few important differential diagnoses are either contagious or even zoonotic, leading to issues with biosecurity and barn management. WHAT CAUSES COLITIS? Potomac Horse Fever Summer/fall Big fever (~104 F) Laminitis EARLY Leukocytosis after a couple of days Blood and fecal PCR UCDavis or UKy Treat with oxytet *before* tests come back (feet fall off) Grain Overload Usually history of access to grain is present History Grain in reflux? C. difficile and perfringens Usually foals or after antimicrobial treatment Mild to very severe Foals: bloody diarrhea Fecal TOXIN ELISA Not culture! C. diff fecal PCR Salmonella Big fever, sometimes reflux too No appetite Usually leukopenic, sometimes leukocytosis Usually after GI surgery (#1 risk factor) Fecal PCR is best screening test 1. Pick the lab carefully 2. UPenn: very good Culture? Use to confirm

2 Coronavirus Big fever (~105 F) Sometimes mild colic, mild diarrhea Often profound neutopenia (<1000/ul) But doesn t look toxic! Multiple animals (sometimes) Fecal PCR UCDavis Cantharadin toxicosis ( Blister beetle ) Diarrhea, colic, hematuria Severe hypocalcemia Western alfalfa hay find the beetles Cantharidin levels in urine Larval cyathostomiasis Bad diarrhea Profound hypoproteinemia Fecal egg count NOT USEFUL 1. it s the larvae that cause disease, and they do not lay eggs 2. no correlation between number of adults and larvae 3. can only get a definitive diagnosis on necropsy or biopsy Thick colon on U/S (1cm!) Red larvae in manure, on sleeve Treat with moxidectin and steroids Small colon impaction What it looks like Masquerades as colitis: low volume diarrhea, colic (often bloated), fever Rectal: feels like an anaconda in the abdomen Colonic dysbiosis Any sort of colitis where the etiologic agent can t be found ~50% of cases Diagnosis of exclusion Common Clinical Signs on PE: THINK INFLAMMATORY! Fever Inappetence, dullness, depression Hyperemic mucous membranes Injected sclera Tachycardia Hypovolemia

3 How sick is the horse? Gums Have owner describe color: should be the color of the palm of their hand Usually is they say pale that s a good sign Heart rate Lactate <44 bpm: no hurry 48-60: evaluate soon > 60: evaluate ASAP, consider referral > 80: decompensating ***THE SCORECARD OF THE BODY!*** Lactate meter, handheld, costs $375, $2/strip, uses a drop of blood. Tells you if you are winning, or if you are losing. Normal: <2 mmol/l (usually <1!) 2-4: getting in some trouble 4-8: very bad things are happening 8-12: decompensating fast >12: may not make it to the hospital Hematology PCV Above 50%? Get worried Splitting! PCV goes up, TS goes down? Get really worried Total protein Don t usually run into problems unless < 4/g/dL Relative hypoproteinemia? Serum Chemistry Sodium Colitis cases: it s always 126 meq/l! (okay, not always, but oddly often) If it is <128, monitor If it is <125 meq/l, start treating If it is <118 meq/l, call a friendly internist! Potassium Don t let it get too low stay above 3 meq/l Bicarb? Stay on top of the sodium, it will fix itself Sometimes the best way to stay on top of the sodium is to give more, in the form of sodium bicarb. Ultrasonography Look for fluid in the colon (ventrally), wall thickness, sand shadows.

4 TREATING COLITIS IN THE FIELD Fluids Anti-endotoxics Anti-diarrheals Laminitis prophylaxis Definitive treatment Monitoring Fluids: IV Minimum effective amount: 20 L (5%) Can lose 5L/h Maximum bolus speed 5-7 L/h Hypertonic NaCl? Just as a bandaid Colloids? Not in the field Fluids: how much? 30 ml/kg boluses (15L per horse) until volume replete Warm extremities Better MM color Lower HR PEEING! ***lactate coming down*** Fluids: enteral Cheap and easy Okay, not easy NG tube Once a day (2x12L?) Taped in, funnel Bolus: up to 10 L every 30 minutes! Ileus: they will spit them back at you Realistically, 4-8L q 2-6 h Taped in, coil set, CRI Enteral feeding tube (thin) Can still eat! Use old fluid set (coil, 2 x 5Lbags with the corners cut off) 1-5L/h Fluids: electrolytes Isotonic: per liter, add 5.6 g of table salt 0.6 g of Lite Salt (50% NaCl, 50% KCl), 3.4 g of baking soda (NaHCO2) 1 ml (by volume) ~ 1g (use a syringe!) I usually use ½ strength or ¼ strength Isotonic is ~9ml powdered lytes per liter Half strength, 4-5 ml powder/liter Anti-endotoxic: Polymixin B Binds endotoxin in the blood 3,000-7,000 u/kg IV q 8-12h million units

5 3-6 vials/horse Dilute in saline, give slow Anti-endotoxic: Flunixin meglumine Inhibition of inflammatory mediators 0.25 mg/kg IV q 8h ml Toxin binder: Smectite Clay Binds Clostridial toxins in the lumen of the colon Go big or go home: 3lb loading dose 1 lb q6h, if you can! Intestinal Proctectants and Probiotics Bismuth subsalicylate Saccharomyces boulardii Probiotic Prospective clinical trial better than any of the other probiotics Fecal Transfaunation Very effective in humans with C diff No studies in horses Healthy horse, make a slurry from fresh manure, give 2-6 L Cryoprophylaxis Ice boots On 24 hours a day Jacks boots $65/pair Bagged ice *** If you wait until they are sore: too late!*** Definitive Treatment: Antibiotics PHF: oxytet if you even suspect it (summer time, geography) C diff/perf: metronidazole 15 mg/kg PO q 12 Double the dose if per rectum Salmonella No! (caveat) If neutrophils are <1000/ul, consider treating with broad spectrum parenteral antibiotics 1/3 of severe colitis cases are bacteremic; consider antibiotics if signs of severe sepsis Coronavirus No! Ignore the low neutrophils, you ll be fine Monitoring Creatinine Oxytet + Banamine + dehydration + endotoxin = kidney damage Measure creat every couple of days PCV/lactate Decrease or stop fluids if the horse can hold these steady Try to maintain lactate at <2 mmol/l

6 Total solids If dropping to 4, consider referral for colloids Do not decrease fluids to hold TS up! Perfusion is KING. Sodium Vital to monitor with foals, can get dangerously low dangerously fast Anything under 120 needs serious attention, very careful not to replace too fast (fatal neuro complications) Triglycerides Minis, ponies, donkeys will die of hepatic lipidosis if they are in a negative enrgy balance too long Measure triglycerides daily Supplement calories (feed!) or IV glucose (CRI hard in the field) if they get to mg/dl Add insulin if necessary (hard in the field, start at 0.1 u/kg SQ twice daily)