Clinical remission of granulomatous enteritis in a standardbred gelding following long-term dexamethasone administration.

The study involves a mature Standardbred horse diagnosed with granulomatous enteritis, a chronic inflammatory bowel disease, which successfully underwent remission after being treated with dexamethasone.

Background

• Granulomatous enteritis is a type of chronic inflammatory bowel disease that is common in mature horses. It often leads to weight loss, low protein in the blood (hypoproteinaemia), and build-up of fluid beneath the skin (subcutaneous oedema).
• The direct cause of this disease is still unidentified. It is, however, linked to infectious agents and immune responses.
• Previously, the prognosis for this disease has been severe as the treatments carried out didn’t result in restoration of normal intestinal absorption function.
• The paper narrates the case of a Standardbred horse with granulomatous enteritis, which underwent successful treatment by injecting dexamethasone.

Case Report

• A six-year-old Standardbred racehorse was brought into VMTH-Cornell University following signs of poor performance, weight loss, and intermittent fever over a two-month period.
• Prior treatments including the administration of antimicrobial (gentamicin sulphate, procaine penicillin) and anti-inflammatory (phenylbutazone, flunixin meglumine) agents. However, no clinical improvement was witnessed.

Discussion

• Granulomatous enteritis has been identified as a leading cause of weight loss, subcutaneous oedema, and intermittent fever in horses for nearly 20 years.
• The disease is known to have a possible familial tendency within the Standardbred horses, suggesting likely genetic predisposition.
• The exact cause of the disease remains unknown, but some infectious agents like Mycobacterium, Histoplasma, or Campylobacter species have been suggested. Other proposed possible causes include immune reactions to dietary, parasitic, or bacterial antigens.
• Previously, corticosteroids like prednisolone and dexamethasone have been used to treat the disease. However, their effectiveness has not been universally established.

Treatment

• In the present case, the horse was treated with dexamethasone sodium phosphate due to limited success with other treatment methods. The treatment protocol was modified and the dosage was gradually decreased over a period of 4.5 months.
• The horse showed notable clinical improvements and no undesirable side effects despite the likely risk of complications such as laminitis, adrenal insufficiency, and secondary bacterial infections.
• Throughout the treatment process, steady increases in the total protein levels in the horse’s serum and notable improvements in the xylose absorption tests were noted, indicating the restoration of intestinal function.
• Furthermore, after dexamethasone therapy had been ceased for five months, the horse continued to gain weight and the xylose absorption returned to normal.

Conclusion

• This case study implies that it may not be entirely hopeless for all cases of equine granulomatous enteritis, and dexamethasone treatment should be considered before resorting to the surgical removal of the affected bowel.
• However, as more cases are needed to confirm this therapeutic approach, the potential for the disease’s recurrence suggests that a careful prognosis must be maintained.