firocoxib for colic
Endotoxemia—the presence of endotoxins in the bloodstream—continues to be a significant and potentially deadly complication of colic and other gastrointestinal diseases in horses. But could something as simple as a change in anti-inflammatory drug selection help stave off endotoxemia and promote gut healing? Researchers have recently proven it’s possible, at least with small intestine strangulating obstructions.

Amanda Ziegler, DVM, PhD, a postdoctoral research fellow at the North Carolina State University College of Veterinary Medicine, in Raleigh, and colleagues conducted the research, and she presented their findings at the 2018 American Association of Equine Practitioners Convention, held Dec. 1-5 in San Francisco, California.

Non-steroidal anti-inflammatory drugs (NSAIDs) target the enzyme cyclooxygenase (COX), which is responsible for the body’s inflammatory responses. There are two COX “subtypes”: COX-2 is primarily associated with the development of inflammation and, so, can contribute to signs of endotoxemia, while COX-1 is associated with normal day-to-day inflammation-prevention or -attenuation processes such as protecting the gastric mucosa (lining) and promoting gut barrier function. This barrier is important, because it’s what can keep endotoxin—which is released after a proliferation and die-off of Gram-negative gut bacteria sparked by colic—from leaking into the bloodstream at levels that can overwhelm the immune system and be deadly.

While traditional NSAIDs, such as flunixin meglumine (Banamine, typically used to provide pain relief in colic cases), block both COX-1 and -2, (and, so, are referred to as nonselective), some newer ones—like firocoxib—are selective, designed to target COX-2-associated inflammation while sparing COX-1 enzymes that could help reduce the likelihood of endotoxemia development.

Further, studies have shown that, in equine small intestine strangulating obstruction models, barrier recovery (which needs to happen after the tissue injury) occurred faster with COX-2-selective NSAIDs versus nonselective NSAIDs, Ziegler said.

To investigate those findings in the live horse, Ziegler and her colleagues administered either flunixin meglumine or firocoxib to 56 horses admitted to three university equine hospitals for surgical treatment of small intestine strangulating obstructions. In addition to monitoring clinical signs, the researchers collected blood samples before surgery and at different time points after, evaluating those samples for endotoxemia biomarkers.

Ziegler said they found that:

  • Both NSAIDs controlled horses’ pain and heart rates (increased heart rates are indicative of pain) effectively; and
  • Horses treated with firocoxib had lower plasma sCD14 (an endotoxin biomarker) levels compared to their flunixin-meglumine-treated counterparts; and

Ultimately, Ziegler and colleagues concluded that firocoxib and flunixin meglumine provided similar levels of pain control, but firocoxib resulted in reduced evidence of endotoxemia at 48 hours post-surgery.

She said additional studies with larger numbers of horses could allow researchers to detect differences in short-term survival and complication risk.