Blood Test Could Predict Intestinal Obstructions

quick response is crucial when a horse suffers a bout of colic, and a prompt diagnosis increases a horse's chance for survival. A team of German researchers recently determined that the blood level of a specific enzyme could indicate a strangulated intestine at presentation, allowing quicker initiation of potentially life-saving treatment without having to wait for exploratory surgery to take place.

"Colic due to acute intestinal obstruction can be a life-threatening situation and is the most common reason that horses are referred to an animal hospital," explained Gerald Fritz Schusser, DrVetMed, Dipl. ECEIM, a veterinarian in the Department of Large Animal Medicine at the University of Leipzig, Germany. "Unfortunately, determining the exact cause of the obstruction and (prognosis for) survival in these horses remains difficult without taking the horse to surgery."

Researchers believe the cause of death for most horses with strangulating obstructions (commonly twisted intestines) stems from the body's absorption of bacterial toxins released from dying or dead intestines (which occur when the blood supply to a region of the twisted intestine is cut off). Once these toxins are absorbed into the bloodstream, they "activate" specific cells in the immune system that injure the liver and threaten the horse's life.

"The enzyme alcohol dehydrogenase (ADH) is produced in specific regions of the liver and plays a key role in detoxification," noted Schusser. "Studies in rats recently showed that ADH could be used as a marker for intestinal ischemia (death)."

To evaluate whether ADH could help predict if horses had strangulating obstructions, Schusser and colleagues measured ADH levels in 33 healthy horses, 36 horses with confirmed nonstrangulating obstructions (e.g., impactions, displacements), 22 horses with confirmed small intestinal strangulations, and 19 horses with confirmed colon torsion.

Explore the power of the human-horse connection as you travel the emotional journey that veterinarians at Rood and Riddle Equine Hospital and owners embark on when a beloved horse becomes ill in Equine ER

Key findings of the study were:

• The median ADH activity was 10.5 U/L (enzyme units per liter of blood) in healthy horses;
• ADH levels were significantly higher in all three of groups of colicky horses than the control horses;
• Horses with an ADH activity >20 U/L were likely to have a strangulating obstruction; and
• Horses with an ADH activity <80 U/L were more likely to survive than horses with ADH activities >80 U/L.

"ADH appears to be useful in differentiating intestinal strangulations from other causes of colic, which is important for guiding treatment and determining outcome," concluded Schusser.

The study, "Clinical evaluation of serum alcohol dehydrogenase activity in horses with acute intestinal obstruction" was published in the June 2011 edition of the Journal of Veterinary Emergency and Critical Care. The abstract is available on PubMed.