In the ongoing hunt to explain the relationship between cribbing and colic, researchers have discovered that cribbing causes increased intra-abdominal pressure.
Intra-abdominal pressure—which is any kind of pressure, from exterior or interior sources, in the horse’s abdominal cavity—appears to be elevated in horses that are cribbing, said Amelia S. Munsterman, DVM, MS, Dipl. ACVS, ACVECC, clinical lecturer at Auburn University College of Veterinary Medicine, in Alabama.
“Our research is one more piece of the puzzle in determining the relationship between cribbing and colic,” Munsterman said. “It is apparent that they are linked, but how this increase in intra-abdominal pressure may affect the outcome of a colic episode in the horse is still under investigation. What we do know now is that the pressure does increase due to cribbing.”
Munsterman and her fellow researchers compared the intra-abdominal pressure of eight horses that crib to eight horses that don’t. They took pressure readings every minute for a two-hour period. All the cribbing horses were encouraged to crib at one point during the study period in order to investigate cribbing's immediate effect on intra-abdominal pressure.
They found that intra-abdominal pressure was much higher in cribbing horses as soon as they started to crib, compared to horses that don’t crib, Munsterman said. That pressure continued to rise as the horse continued to crib, and it remained at a constant elevated level for at least a half an hour after the horse stopped cribbing. In fact, the cribbers' intra-abdominal pressure was increased even before a cribbing episode, compared to the non-cribbers, she said; however, that difference was not significant from a scientific point of view. Even so, it could suggest that the intra-abdominal pressure effects of cribbing could linger for hours after a cribbing episode, she said.
The longer the horse cribbed, the more the intra-abdominal pressure increased, Munsterman said. However, the number of separate cribbing episodes did not seem to affect the related pressure.
Intra-abdominal pressure is not to be confused with bloating, although bloating is one source of such pressure, added Munsterman.
Other sources of acute increases in intra-abdominal pressure—including colic or peritonitis (inflammation of the peritoneum, or membrane lining the abdomen)—can be painful for the horse, she said. However, researchers are still working to understand the long-term effects of elevated intra-abdominal pressure, she said.
“This increase in pressure, called intra-abdominal hypertension, is noted in humans and other species to reduce oxygenation and perfusion of the organs within the abdomen, and it can also alter blood flow to and from the heart, resulting in hypoxia and compromise of other organ systems, including the brain,” Munsterman said. “We are still in the early stage of identifying the negative side effects of increased intra-abdominal pressure in the horse, but we are currently investigating these side effects in our clinical trial here at Auburn.”
The study, "Evaluation of Intra-Abdominal Pressure in Horses That Crib," will appear in an upcoming issue of Veterinary Surgery.
Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.