Strangulating obstruction caused by intestinal herniation through the proximal aspect of the cecocolic fold in 9 horses.

OBJECTIVE: To report the clinical and surgical findings and outcome for horses with strangulating obstruction caused by herniation through the proximal aspect of the cecocolic fold. STUDY DESIGN: Retrospective study. ANIMALS: Nine horses. METHODS: Medical records were reviewed for clinical signs, surgical findings and technique, and outcome. Cadaver ponies and necropsy specimens were also used to study the regional anatomy of the cecocolic fold. RESULTS: The ileum and distal jejunum were strangulated in 8 horses, whereas in 1 horse the small intestine and the left ascending colons were incarcerated in a rent in the cecocolic fold. Two horses were euthanatized at surgery, 6 horses had a small intestinal resection (mean length, 3 m; range, 1.5-6.4 m) and an end-to-side jejunocecostomy, and the entrapment was reduced without resection in the horse that had small intestine and ascending colon incarceration; cecocolic fold defects were not closed. One horse was euthanatized 36 hours after surgery because of endotoxemia. Six horses were discharged; 4 were available for long-term follow-up, of which 2 were euthanatized, and 2 were euthanatized 12 and 18 months after surgery because of colic signs. Variations in thickness of the cecocolic fold were observed in specimens obtained from necropsy of other horses and ponies. CONCLUSIONS: Reasons for this defect are unknown, although observed anatomic differences in cecocolic fold thickness may contribute to the development of defects. CLINICAL RELEVANCE: Reduction of the entrapped bowel is easiest when traction is placed on the bowel at a 90 degrees to the base of the cecum. Intestinal incarceration through rents within the proximal part of the cecocolic fold should be considered as a differential diagnosis for strangulating obstruction in horses.

Transection of the pelvic flexure to reduce incarceration of the large colon through the epiploic foramen in a horse.

A 7-year-old Thoroughbred mare underwent exploratory celiotomy for diagnosis and treatment of colic. An irreducible herniation of the large colon through the epiploic foramen was found. To reduce the hernia, the pelvic flexure was transected and the ends of the large colon were closed. The intercolonic mesentery was divided, and unaffected left ventral colon was moved into the epiploic foramen, providing sufficient space so that affected left dorsal colon could be reduced. The affected left ventral colon was then reduced and the diseased portion of both colons was resected. The colons were resected. The colons were rejoined with an end-to-end anastomosis.

Struvite urethral calculus in a three-month-old thoroughbred colt.

A 3-month-old Thoroughbred colt was presented with signs of colic. Findings from physical examination, abdominal paracentesis, abdominal radiographs and clinical pathology revealed uroperitoneum secondary to a calculus obstructing the urethra and causing subsequent urinary bladder rupture. Analysis of the calculus demonstrated a tissue center with outer concretions composed primarily of struvite.

Ectopic ureter managed by unilateral nephrectomy in two female horses.

Unilateral ureteral ectopia was diagnosed in three-year-old and 10-month-old fillies exhibiting urinary incontinence since birth. In one case reimplantation of the ureter onto the bladder was planned but considered to be impractical intra-operatively. Unilateral nephrectomy was performed successfully in both cases which alleviated the urinary incontinence. Both horses had normal urinary function postoperatively and became healthy, serviceable animals.

Bypass surgery for the treatment of small intestinal ileus in the horse. A report of three cases.

The medical management of three horses with simple and strangulating small intestinal obstructions was unsuccessful and was therefore supported by surgical bypasses. Jejunocecostomies were used to treat horses with postoperative paralytic ileus that was unresponsive to medical management. These horses had abdominal pain, gastric distention, heart rate elevations greater than 60/minute, and small intestinal distention on rectal palpation. Two horses experienced weight loss which responded to bypass removal. The bypass effectively decreased the need for intravenous fluid administration and repeated nasogastric intubation.

Electromyographic, myomechanical, and intraluminal pressure changes associated with acute extraluminal obstruction of the jejunum in conscious ponies.

Bipolar electrodes, strain gauge force transducers, intraluminal pressure recording catheters, and extraluminal intestinal obstructors were surgically implanted in 4 ponies to record myoelectrical and mechanical activity of the distal portion of the jejunum and ileum. After determining normal intestinal activity and pressures, the distal portion of the jejunum was obstructed with an extraluminal obstructor. Myoelectrical and mechanical activity recorded from jejunal segments proximal to the obstruction increased significantly (P less than 0.01), whereas activity distal to the obstruction remained unchanged. Intraluminal pressure increases were recorded during periods of intestinal spasm. Obstruction pressures remained unchanged from preobstruction pressures.

Neostigmine methylsulfate delays gastric emptying of particulate markers in horses.

Eight horses were allotted to 2 groups, each of 4 horses. All horses were given 100 plastic markers intragastrically via a nasogastric tube. One group of animals (control group) was not given medication after marker administration. The other group (test group) was given neostigmine methylsulfate (0.022 mg/kg of body weight) in the subcutaneous tissue at the time of marker administration and 30, 60, and 90 minutes later. All horses were killed 135 minutes after marker administration to locate the beads in the gastrointestinal tract. Gastric emptying of the markers was significantly delayed (P less than 0.05) in horses given neostigmine methylsulfate.

Effects of multiple intramuscular injections and doses of dexamethasone on plasma cortisol concentrations and adrenal responses to ACTH in horses.

Adrenocortical function was assessed in horses given multiple IM doses of dexamethasone to determine the duration of adrenocortical suppression and insufficiency caused by 2 commonly used dosages of dexamethasone (0.044 and 0.088 mg/kg of body weight). Dexamethasone was administered at 5-day intervals for a total of 6 injections. Daily blood samples were collected. The plasma was frozen and later assayed for cortisol. An ACTH response test was determined 2 days before the first injection of dexamethasone and again 8 days after the last dexamethasone injection. Maximum suppression of plasma cortisol was observed in horses given both dosages of dexamethasone (0.044 and 0.088 mg/kg). Plasma cortisol concentrations returned to base-line values in all horses by 4 days after dexamethasone injection. Normal ACTH responses observed after 6 dexamethasone injections given at 5-day intervals indicated that measurable adrenal atrophy did not develop under the conditions of this study.