September Case of the Month - Intermittent Low Grade Colic

History: “Samson” Donovan, a 10-year-old Oldenberg gelding, presented on 8/24/12 for intermittent low-grade colic consisting mostly of parking out from discomfort, with no decline in condition or performance as a low-level dressage horse.  The owners report that he has also been gassy.  Physical examination and rectal exam were within normal limits and results of a sand flotation test are pending.  His colic episodes generally self-resolve or resolve with the aid of 5cc of Banamine.  He was recently started on the Succeed Digestive Conditioning Program and he is insured.

Labwork analysis:

1.      CBC/chemistry panel: Bloodwork was unremarkable, with insignificant changes in Cl and GGT.

2.      Fecal egg count: Fecal egg count was negative for parasites.

3.      Fecal occult blood: Fecal occult blood was negative for blood.

Diagnosis: Chronic colic, open.

Common causes of chronic intermittent colic include gastric ulceration, sand impaction, and enterolithiasis. 

Gastric ulcers are prevalent in horses, with statistics ranging from 58% of showhorses and 70% of Thoroughbred broodmares to 86% of racehorses.  Due to vague clinical signs and large variation in treatment dosage and duration using GastroGard, the gold standard method of diagnosis remains gastroscopy.  Alternative methods include the Succeed fecal blood test (limited in accuracy), urine sucrose, and blood sucrose.  The procedure for urine sucrose concentration for detecting gastric ulcers is documented in the paper: Evaluation of urine sucrose concentration for detection of gastric ulcers in horses.  O'Conner MS et al. Am J Vet Res. 2004 Jan;65(1):31-9.  In this study, horses were fed 1kg concentrate (Purina Horsechow 100) and intubated with 454g sucrose (10% solution in water).  Urine sucrose was collected 2h and 4h following the intubation.  Sucrose concentration is higher in horses with gastric ulceration, with a sensitivity of 83% and specificity of 90% using a cut-off of 0.7mg/ml.  The procedure for blood glucose can be found in the paper: Sucrose concentration in blood: a new method for assessment of gastric permeability in horses with gastric ulceration.  Hewetson M, Cohen ND, Love S, Buddington RK, Holmes W, Innocent GT, Roussel AJ.  J Vet Intern Med. 2006 Mar-Apr;20(2):388-94.  In this procedure, horses are withheld from feed for 20h, intubated with 250g sucrose, and serum sucrose was significantly elevated 45min later in horses with moderate to severe gastric ulceration. 

The definitive diagnosis for sand impaction and enterolithiasis is through abdominal radiography.   If the sand flotation that was performed by the owner is negative, the test can be improved by administering psyllium (Sand Clear instructions are 5oz daily for 7 days) and performing the sand flotation during and after the treatment.  Psyllium may also have some GI benefits of aiding in mucosal repair.

Recommendation:

1.      Diagnostics: I would recommend doing additional diagnostics, including gastroscopy.  If the gastroscopy is not possible, urine/blood sucrose or empirical treatment (take note GastroGard takes 3-5 days to take effect) can be used to indicate the presence of gastric ulcers.  If he is negative for ulcers, you may wish to consider referral for abdominal radiographs and/or a trial with psyllium and repeated fecal sand flotation.

2.      Treatment: For discomfort due to bloating, you may wish to consider administration of a proven prebiotic such as Saccharomyces boulardii (10 billion organisms PO BID).  All other treatments could be pursued based on the results of additional diagnostics.

Jean-Yin Tan, DVM, DACVIM (Large Animal Internal Medicine)