Colon Agenesis – Roosevelt
Roosevelt was born normally on an October spring night. He stood up and nursed from his mum normally. Curiously, he did not pass meconium at all, even after 2 Fleet enema and 2 retention enema. His attending veterinarian noted the complete absence of faecal material. He was referred to the Camden Equine Centre Neonatal ICU for further diagnostics of his “problem”.
At presentation to the CEC NICU, Roosevelt was attended to by equine medicine specialist Dr Liz Tee and medicine resident Dr Celine Lee. The colt appeared completely normal on physical examination, but a digital examination of the rectum revealed a complete absence of faecal material.
Dr Liz Tee requested the assistance of radiologist Dr Juan Podadera, as she suspected an unusual congential condition in this foal, namely the incomplete formation of the gastrointestinal tract, leading to an “obstruction” and the complete absence of faecal material. A contrast material was administered per rectum after heavy sedation of the colt. Serial abdominal radiographs were taken to see the passage of the contrast material. The contrast radiograph revealed that the “obstruction” was extremely cranial and likely located deep in the abdomen.
A decision was made to admit the foal into surgery. Prof Andrew Dart, Dr Sara Biasutti and Dr Felix Chia performed an exploratory laparotomy. During surgery, it was discovered that the foal lacked a major section of his large colon, and the remaining colon ended in a blind sac that did not communicate with his rectum. This explains why the foal never passed any feces. A side-to-side anastomosis (joining) of the blind end of the colon to the small colon was performed.
Roosevelt recovered well from general anaesthesia. 7 days later, he was discharged from the hospital, as he was recovering remarkably well, passing faeces normally with no signs of abdominal pain during hospitalisation.
Roosevelt is currently growing strong and fast, and the owner has reported no signs of abdominal discomfort.
Colon agenesis is a rare condition in foals. Foals are usually born normally, but the most important clincial sign would be the complete absence of fecal material at the rectum. Foals usually pass their meconium within the first hour of birth. More commonly, foals that do not pass meconium has a “meconium impaction”, and that can be resolved either medically with enema(s), or surgery for the more refractory cases. The major difference between the more common meconium impaction and agenesis of the gastrointestinal tract (incomplete formation of the gastrointestinal tract) is the complete absence of fecal material/fecal stained fluid after enema(s).
A majority of large stud farms will often adminster an enema immediately after birth to prevent meconium impaction. Failure to pass meconium after 1 or 2 enemas should alert owners to the possibility of a more severe impaction/obstruction and may require more aggressive veterinary intervention.
Foals with unresolved meconium impaction or gastrointestinal agenesis will eventually exhibit signs of abdominal pain as the gastrointestinal tract progressively distends with food and fecal material. If unattended this will lead to severe compromise of the gastrointestinal tract and eventual rupture, necessating euthanasia of the foal.