Every minute that a horse is colicking feels like hours. It doesn’t matter if it is the second or 52nd time you’ve been through it, the ordeal never gets easier. One way veterinarians are attempting to facilitate and expedite the “diagnostic process” is via FLASH—a streamlined, targeted abdominal ultrasound examination of “high-yield” areas of the abdomen.

“Initially developed by Valeria Busoni, PhD, Dipl. ECVDI, and colleagues for abdominal examination of horses with colic, FLASH involves an abbreviated examination of the abdomen focusing on key locations to potentially identify the location of the problem and, most importantly, to try to determine whether or not emergency colic surgery is necessary,” said Louise Southwood, BVSc, PhD, Dipl. ACVS, ACVECC, associate professor in the Department of Clinical Studies at the University of Pennsylvania School of Veterinary Medicine’s New Bolton Center in Kennett Square.

Short for “fast localized abdominal sonography of horses,” veterinarians can use FLASH to examine seven key locations of the abdomen to potentially diagnose a variety of colics:

  • The underside of the abdomen along the midline (“ventral abdominal window”);
  • The left side of the abdomen in the stomach region (“gastric window”);
  • The left side of the abdomen to visualize the spleen and kidney (“nephrosplenic window”);
  • Both the left and right middle-thirds of the abdomen;
  • The right side of the abdomen to visualize the duodenum (“duodenal window”)—the first section of the small intestine; and
  • The cranioventral thorax (to check for a diaphragmatic hernia, an uncommon condition).

“The FLASH procedure, as originally reported, focuses on those seven areas because they are mostly likely to lead to the identification of an abnormality and provide information regarding the need for emergency colic surgery,” said Southwood.

Since its introduction in 2011, FLASH is being used with increasing frequency in horses presenting to referral hospitals on an emergency basis for signs of colic.

“When a horse presents with colic on an emergency basis, we need an answer quickly so that treatment is not delayed,” Southwood stressed, making FLASH—which can take a little as 10 to 15 minutes to complete—a useful tool.

“It may take slightly longer depending on modifications, the need to re-examine a particular area, and the experience of the examiner,” Southwood explained. In their original study, Busoni and colleagues reported that “the positive and negative predictive values of requirement for surgery of dilated turgid small intestinal loops using FLASH were 88.89% and 81.48%, respectively.” These rates indicate that the test is very accurate with few false positive and negative results.

Nonetheless, Southwood cautioned that these numbers might not necessarily apply to every practice and that FLASH’s accuracy can vary depending on the type of intestinal lesion and other factors.

“As with any diagnostic tool, the results must be interpreted in light of the other clinical findings,” she advised.

While the procedure’s success rates appear promising, FLASH isn’t for every scenario. Southwood encouraged clinicians to stop and ask, “Is there anything that I will find on FLASH that will change how I will treat the horse?” before proceeding. Often, she said, the answer is “no,” meaning the practitioner can save valuable time simply beginning treatment. For instance, she said, a horse that is severely or persistently painful probably won’t need a FLASH assessment because surgical treatment is clearly indicated and should not be delayed.

“Obtaining a good history from the owner or caregiver and performing a thorough physical examination are still the cornerstones of examining any horse with colic,” she explained. “It is also important to keep in mind that, at least on an emergency basis for horses presenting with colic, we are mainly trying to ascertain if surgery is indicated or if it is safe to pursue medical treatment. We do not always need a definitive diagnosis of the actual cause of colic because we will find that out at surgery.”

In Southwood’s experience, she’s found FLASH most useful in the moderately painful young horse that has a suspected nephrosplenic entrapment (his colon is entrapped over the spleen) that cannot be diagnosed based on examination per rectum. In such horses, veterinarians can manage the entrapment medically and avoid having to do surgery if they can confirm the diagnosis using FLASH.

Another case in which FLASH could be beneficial is in the geriatric horse with a suspected strangulating lipoma (a fatty tumor on a stalk that wraps around a piece of small intestine, cutting off the blood supply).

“If the horse is not particularly painful and I cannot palpate distended small intestine per rectum, then identification of distended small intestine sonographically and/or an increase in the volume of peritoneal fluid can prompt further diagnostics and early surgical intervention,” she said.

Southwood also noted that, in some cases, FLASH performed in a field setting can be useful.

“In general, anything that causes even a slight delay in referral of a painful or critically ill horse with colic should be avoided,” she said. “That said, some geriatric horses with a strangulating lipoma are not particularly painful and are temporarily responsive to treatment with a non-steroidal anti-inflammatory drug. Performing FLASH on the initial examination in the field may lead to early identification of distended small intestine and early referral.”

In summary, Southwood believes that there is an indication for using FLASH in the field. Its usefulness, however, will depend on the examiner’s ability to correctly interpret the findings.

“Our overall goal when managing horses with colic is for horses with colic to have an excellent chance for survival and live a long, colic-free life while keeping the expense at a minimum for the horse owner,” Southwood concluded. “FLASH is one of many diagnostic tests that may be useful for helping us achieve this goal.”