By nasal tubing up to 10 liters (2.5 gallons) of water—which theoretically seeps into the impacted feces to soften them and facilitate movement through the intestines—veterinarians could unintentionally cause the horse more discomfort. That’s because if the stomach is also blocked, the large volume of water could cause painful stretching of the stomach walls. The extra bulk might also reduce abdominal space, causing pressure and leading to twisting (volvulus) of the colon, said Marco Gandini, DVM, PhD, of the University of Turin’s Department of Veterinary Sciences, in Grugliasco, Italy.

Providing these horses with smaller volumes of water more often in combination with intravenous fluids might be a better option, Gandini said.

“The frequent administration of small quantities of fluids can promote hydration of the fecal mass and resolution of impaction without distension of the viscera,” he said.

Four Cases of Horses Getting Worse After Standard Impaction Colic Treatment

Gandini and his colleagues examined four cases over a seven-year period of horses admitted to the Veterinary Teaching Hospital of Turin that had worsened after receiving large quantities of water through a nasal tube to relieve colon impaction. The two mares, one gelding, and one stallion were all 16 and 19 years old and weighed between 500 and 675 kilograms (1,100 and 1,485 pounds).

The horses originally had mild to moderate colic pain, and their primary veterinarian treated them with spasm-reducers, intravenous fluids, and 8 to 15 liters (2 to 3.75 gallons) of water pumped through a nasal tube into the stomach.

Instead of improving, though, they all got worse within a matter of minutes, with increasing heart rates and signs of discomfort that painkillers did not relieve. They had to be transferred to the Turin referral clinic, where they underwent surgery.

The surgeons found that all four horses not only had colon impactions but also stomach impactions, Gandini said. Additionally, they all had twisted intestines—one of the most painful and rapidly fatal causes of colic, he added—which had to be untwisted during surgery.

Tube Water Slowly for Impaction Colics, Especially With Gastric Impaction

Gastric impactions could trap the many liters of water meant to treat the horses’ colons, stretching out the stomach and causing extreme pain, said Gandini. The treatment might also create enough pressure inside the abdomen that the colon twists, sometimes making a full 360-degree turn.

Veterinarians should consider performing a transabdominal ultrasound before treating horses with large volumes of water to resolve colon impaction, to see if the stomach is impacted as well, he said.

Better yet, horses should receive smaller quantities of water more frequently instead of one large dose, Gandini explained. The horses in his case studies still had impaction colic after surgery, but they all improved when they received only 2 liters (half a gallon) of water through a nasal tube twice a day for three days.

Because the horses simultaneously received intravenous fluids, their bodies weren’t using the pumped-in water to hydrate themselves, he said. Rather, all the water worked toward softening the packed digestive matter that was causing the impaction.

A New Protocol for Addressing Impaction Colics?

The findings suggest veterinarians should consider modifying the way they deal with impaction colics, said Gandini. “Even in our clinic we used to administer large amounts of water (up to 10 liters in a 500-kilogram horse) via nasogastric tube to resolve large colon impactions, until we came across these cases,” he said. “Then we changed our protocols, going instead for frequent, low volume (water through a nasal tube) combined with intravenous fluid therapy.

“Based on our clinical experience, we believe that our approach can guarantee a rapid resolution of the problem, limiting the risks associated with common therapeutic protocols,” Gandini continued. “In particular, the use of frequent enteral (direct into the digestive system) fluid therapy with small quantities of water with the administration of parenteral (intravenous) isotonic fluids is useful in resolving colon impactions, even those that are quite severe.”

Although the researchers only saw four such cases in seven years, that doesn’t mean they’re uncommon, Gandini added. Their referral clinic only receives complex cases in horses whose owners have accepted the financial costs associated with colic surgery. Many more horses might experience such issues and then undergo euthanasia, for example. “This could be an underdiagnosed condition,” he said.

The paper, “Gastric and Large Colon Impactions Combined With Aggressive Enteral Fluid Therapy May Predispose to Large Colon Volvulus: 4 Cases,” was published in the Journal of Equine Veterinary Science’s July 2021 edition.