Going under together
When a mare develops colic late in her pregnancy, surgery could put her life, as well as the life of her foal, at risk.
It’s not unusual for a pregnant mare to lie down in her stall, but Kim Schmidt knew her mare Susie well enough to realize something was amiss. Susie was due to deliver her foal in less than a week’s time but Schmidt could tell that her mare’s behavior indicated something other than labor.
“I bred her, raised her and trained her myself,” says Schmidt, a dressage rider, trainer and judge based at her central Virginia facility, Grayson Farm. Under her registered name, O’Susannah, Susie had excelled at three-day eventing and dressage, and she had experience as a broodmare. “I’d helped her deliver two foals before, so I had a pretty good idea of what was normal for her, and this wasn’t it.”
Susie would lie down and stretch out flat, then get up only to lie down and stretch out again. “She wasn’t pacing or sweating or looking anxious like a mare would in labor,” says Schmidt. “But she wasn’t rolling or looking at her sides like a horse with full-blown colic will. She was just stretched out flat and looking uncomfortable. She also wasn’t picking through her hay like I’d expect her to be doing. It was subtle, but I knew something wasn’t right.”
Schmidt called Keswick Equine Clinic in Gordonsville, Virginia, and after discussing Susie’s signs with the on-call veterinarian, was instructed to give the mare a dose of Banamine0 and monitor her very closely. “I was told that if Banamine took away the signs, it was probably colic,” says Schmidt. A labor and delivery nurse herself, Schmidt was comfortable administering the drug, and afterward she kept an eye on her mare.
“The Banamine took the signs away completely,” says Schmidt. “She was up and eating and looking comfortable within 20 minutes.” After calling the clinic back with this update, Schmidt was advised to continue watching the mare and call again if the colic signs came back. They did, and soon Rebecca Kramer, DVM, from Keswick was on her way to the farm.
When Kramer arrived, she found Susie lying sternally in her stall. She gave the mare a full exam and found signs of mild discomfort, including an elevated heart rate of 56 beats per minute. Kramer needed to determine if the pain was coming from colic or dystocia, a difficult delivery. She performed a rectal exam on the mare and concluded that the foal was not positioned as if Susie were in labor. The foal filled the entire left half of the abdomen, and Kramer felt a large pocket of gas on the right side, which concerned her. Kramer used a nasogastric tube to check for reflux, the mix of accumulated feed, water and gastric juices that can indicate a horse’s stomach is not emptying. Finding no reflux, Kramer used the tube to deliver water, mineral oil and electrolytes to Susie, a combination that would keep her hydrated and encourage her gut to function normally. By the time Kramer left, Susie was happily eating hay. She left Schmidt with
instructions to watch the mare closely throughout the night and call if she showed signs of discomfort.
Susie continued to be intermittently uncomfortable, so when morning arrived so did Mark Foley, DVM, also from Keswick. He gave her another thorough exam and, based on her continued discomfort and lack of manure production, determined that she either had an impaction or displacement of her large colon. He made a call to Blue Ridge Equine Clinic in nearby Earlysville and arranged for a referral to the clinic for a more extensive workup and treatment.
“I loaded her up immediately and headed out,” says Schmidt.
An intestinal impasse
Susie received a full examination from Paul Stephens, DVM, ACVS, when she arrived at Blue Ridge late Friday afternoon. “At this point, we were increasingly concerned that rather than a simple impaction, we were dealing with something more complicated,” he says. “I told Kim we’d give it another 12 hours in case it was just an impaction that might move, but if things didn’t improve, surgery might be our only option.”
It was still unclear what was causing Susie’s colic, but her case and condition had already revealed several clues. An impaction of feed or hay in the intestines would likely have already been moved by the large amounts of fluid and oil she had been given. A twist in the colon (torsion) would be causing acute pain, but Susie still seemed only mildly uncomfortable. “Considering all of this, our number one differential diagnosis was a displacement of the colon of some type, where a change in position of the organ causes it to become blocked off,” says Stephens.
An ultrasound0 examination the following morning provided one last important clue to the specific type of displacement Susie had. “In a left dorsal displacement, the colon moves up between the spleen and body wall on the left side. There is a notch where the colon can drop down and become caught,” explains Stephens. “On an ultrasound in those cases, you’ll see only gas above the spleen, not the kidney like you should.” Susie’s ultrasound revealed both the spleen and kidney, suggesting her displacement was a right dorsal displacement, where the colon folds back on itself, like a kink in a garden hose.
“Displacements aren’t as bad as twists,” says Stephens, “because the blood supply in the intestines isn’t cut off. You won’t have the horrible pain and death of the organ, and there’s not as much urgency to correct the problem before more damage is done.”
Definitively diagnosing right dorsal displacements requires surgery, and if Susie hadn’t been in foal, she would have been headed to the operating room. But, says Stephens, “you never want to put a pregnant mare through surgery if you can avoid it, particularly one as far along as she was.” On the other hand, Susie had gone without food for nearly 48 hours, meaning her foal was also being deprived of nutrition. The multiple doses of medications could also be adversely affecting the foal, along with the generalized stress Susie’s body was under. It was a difficult judgment call, but one that had to be made.
“I told Kim we’d give it one more night to see any improvement,” say Stephens. More fluids and painkillers brought no changes, and early Sunday morning Susie was prepped and headed into surgery.
“I remember Dr. Stephens telling me that if it comes down to saving either the mare or the foal, he chooses the mare,” says Schmidt. “He wanted to know if I agreed with that. I told him I’d love to have both, but if he could only save one, to make it Susie.”
Table for two
Performing surgery on a heavily pregnant mare puts both the mare and foal at risk, says Stephens:
“There are a couple of areas of concern. First of all is anesthesia for the mare. When you place her on her back, the foal presses into her diaphragm, so it becomes very hard to keep her ventilated and breathing properly. There’s also concern about her blood pressure because the foal presses down on her caudal vena cava, which returns blood to the heart. If her blood pressure drops, so will the foal’s, but there’s no way to even monitor that. Then you have worries about recovery. When a mare is that size, she can have trouble getting back to her feet, and the risk of a traumatic injury, like fracturing a leg, increases.
These are just a few of the reasons we are loath to put a mare on the table that late in a pregnancy.”
If Susie were a woman, her physician might choose to deliver the baby via cesarean section before performing any other necessary surgery. That, however, isn’t an option in equine veterinary medicine. “Foals need every single day of gestation they can get,” says Stephens. “Cesareans are occasionally done in horses, but only after the mare has gone into labor on her own. Any earlier and the survival rate is not good at all. Delivering a foal even a week early by cesarean section would be extremely risky.” Furthermore, the additional time in surgery a cesarean section would require would also put Susie’s life at risk. “There’s additional stress, blood loss and a risk of contamination,” says Stephens.
The only option would be to surgically correct the colic and then close Susie up and let her deliver on her own.
As soon as the surgical team had opened Susie’s abdomen, it was clear to Stephens that a right dorsal displacement was the cause of her colic. “It was what we had anticipated and were prepared to fix, so that was somewhat reassuring,” he says.
The first step was to pull the mare’s colon up and out of her abdomen, then lay it out on a tray next to the surgical table. “In these cases the colon is extremely heavy and packed with backedup feed,” says Stephens. “It’s a delicate procedure because it’s easy to tear the intestines, creating a very bad situation.” With the colon pulled out and accessible, Stephens made a small incision and carefully massaged out the packed feedstuff, flushing the space with a large amount of water as he worked.
Once the colon was empty, Stephens could begin to de-rotate it back into its normal position. That process, however, was greatly complicated by the large fetus lying directly on top of the crucial area. “You have very, very limited space to work within, and you can’t see anything,” he says. “Essentially, I had my arms down in this deep, dark hole of her abdomen, working by feel alone. It was extremely technically challenging---one of the most difficult displacements I’ve had to correct.”
With that done, Stephens sutured the 10-inch incision, and Susie was put in a snug bellyband to help protect the incision site from trauma or contamination. A typical colic patient would wear the bellyband for only a few days, but Stephens advised Schmidt to leave it on Susie until she had delivered her foal because it could potentially provide additional support to the incision.
Performing surgery on a heavily pregnant mare puts both mother
and foal at risk.
SUPPORTIVE CARE: Intravenous fluids kept Susie hydrated as veterinarians worked to uncover the cause of her colic.
SONNY BOY: With surgery and a difficult birth behind them, Susie and Dino are happy and healthy.