Cecal amputation within the right ventral colon for surgical treatment of nonreducible cecocolic intussusception in 8 horses

OBJECTIVES: To report a surgical technique for treatment of nonreducible cecocolic intussusception and outcome in 8 horses. STUDY DESIGN: Retrospective study. ANIMALS: Eight horses with nonreducible cecocolic intussusception treated by cecal amputation through a right ventral colotomy. METHODS: Data were obtained from medical records and telephone conversations by using a standardized questionnaire. The large colon was exteriorized and, if necessary, evacuated of its contents through a pelvic flexure enterotomy. A second colotomy was made on the ventral surface of the right ventral colon (RVC) centered over or immediately distal to the intussusceptum. In most horses, attempts to manually reduce the intussusception by pushing the cecum from within the RVC through the cecocolic orifice were unsuccessful. Invaginated cecum was then pulled into the RVC and amputated; the cecum was either ligated with umbilical tape or sutured proximal to the site of amputation. After amputation, the remainder of the invaginated cecum was reduced. After further resection to healthy tissue, the typhlectomy was closed with a double-inverting suture pattern. RESULTS: The median horse age was 2 years (range, 1 to 8 years). Duration of colic ranged from 6 hours to 6 months. Median surgical time was 180 minutes (range, 135 to 300 minutes). Median duration of antibiotic therapy was 7 days (range, 5 to 14 days). Median duration of hospitalization was 12 days (range, 6 to 21 days). All horses survived to hospital discharge. One horse died 3 months postoperatively; however, the remainder survived (median survival, 30 months; range, 6 to 96 months) and returned to or exceeded previous function. CLINICAL RELEVANCE: Despite some contamination during surgery, horses with nonreducible cecocolic intussusception that underwent this method of surgical treatment had a good prognosis.     

lleocolostomy A Technique for Surgical Management of Equine Cecal Impaction

Several surgical alternatives have been described for the management of cecal impaction in the horse, but none has met with consistently successful results. This study was done to evaluate a surgical bypass of the cecum by anastomosis of the ileum to the right ventral colon (ileocolostomy). A ventral midline celiotomy was performed on nine adult ponies (155-350 kg) and a mechanically stapled 10 cm side-to-side ileocolostomy was created. In five ponies a complete cecal bypass (CCB) was created by transecting the ileum distal to the anastomosis. In the other four, an incomplete cecal bypass (ICB) was created with no interruption of the ileum. Six horses with clinical cecal impaction also underwent cecal bypass procedures. Five had a CCB and one had an ICB. All the ponies maintained body weight, had no change in consistency of the feces and had no abdominal pain during the 6 month observation period. At necropsy, the lengths of the lateral cecal band, lateral free band of the colon, and the diameter of the anastomotic stoma were compared to measurements made at surgery. The lateral cecal band length decreased significantly more in the CCB ponies than in the ICB ponies (p = 0.008). The anastomotic stoma diameter was significantly larger in the ICB group than in the CCB group (p = 0.032). Five of the six clinical cases recovered and returned to their previous activity. CCB by an ileocolostomy resulted in removal of the cecum from the functional flow of ingesta without complication in the ponies, and was successful in five clinical cases of cecal impaction.     

Surgical diseases of the equine cecum

Cecal impaction and cecal perforation, the two most common equine cecal diseases, are thought to develop after slowing or interruption of a single progressive motility pattern, which begins in a pacemaker area near the apex, occurs once every 3 minutes, and propels ingesta from the cecum to the right ventral colon. Rectal examination in horses with cecal impaction is the most useful technique to grade the severity of the condition. Medical treatment is undertaken if the impaction is judged to be mild to moderate. Surgical correction of cecal impaction in severe cases requires a ventral midline celiotomy, and exploration reveals a large ingesta-filled cecum and relatively empty large colon. Currently, the techniques of typhlotomy with manual evacuation of ingesta, combined with a complete bypass of the cecum by use of a jejunocolostomy, is the preferred method of surgical management. The use of a cecocolic anastomosis remains a viable alternative surgical procedure. Cecal perforation (CP), a uniformly fatal disease of horses, most often develops when the subtle signs of cecal impaction are missed or are masked by the administration of nonsteroidal antiinflammatory agents. CP can occur in mares around the time of foaling and, in this form, is not associated with cecal outflow dysfunction. Surgical management of cecocecal or cecocolic intussusception is required and involves resection of the diseased portion of cecum, either with extra- or intraluminal techniques. Both the side-to-side and end-to-side jejunocecal anastomoses are useful and successful techniques for bypass of simple or strangulating lesions of the ileum.     

Colopexy of the Left Large Colon to the Right Large Colon in the Horse

Three colopexy techniques were examined in 11 normal horses to determine which would prevent recurrence of targe colon displacement and volvulus. The medial free band of the left ventral colon was sutured to the medial free band of the right ventral colon (technique A). The free band of the left dorsal colon was sutured to the free band of the right dorsal colon (technique B). In technique C, both the ventral and dorsal colon were sutured as in techniques A and B, and the pelvic flexure was sutured to the mesocolon between the right dorsal and right ventral colon. Absorbable (surgical gut) and nonabsorbable (polypropylene) suture material were compared.
One horse from each group was euthanized 2 weeks and 6 months after surgery. The position of the colon and the integrity of the colopexy were examined. At necropsy, attempts were made to produce displacement and volvulus of the colon. In the remaining horses, exploratory celiotomy 1 year after surgery was used to examine the integrity of the colopexy.
Although all horses initially lost weight after surgery, all but one began gaining weight 2 to 4 weeks later and had attained their preoperative weight by 6 months. The horse that continued to lose weight was euthanized 2 months after surgery. Numerous small colon, omental, and large colon adhesions were found at necropsy.
For all colopexy techniques, the colopexy adhesion remained short and intact at polypropylene suture sites. At surgical gut sites, the adhesion had lengthened by 6 months and was absent at 1 year. At necropsy, all colopexies prevented manual displacement of the large colon and volvulus of the colon at the sternal and diaphragmatic flexures. The colopexies did not prevent manual creation of volvulus at the base of the colon. Technique A was the easiest to perform.     

Colopexy of the equine large colon: comparison of two techniques

A study was designed to evaluate 2 colopexy techniques (A and B) in 8 clinically normal horses to determine which technique would prevent recurrence of large-colon displacement and/or volvulus. For technique A, 35 cm of the lateral free band of the left ventral colon was sutured to the abdominal wall, 6 cm to the left of ventral midline. For technique B, the medial free band of the left ventral colon was sutured to the medial free band of the right ventral colon, and 8 cm of the lateral free band of the left ventral colon was sutured to the abdominal wall, 6 cm to the left of ventral midline. One horse from each group was euthanatized at 6 months, and another at 12 months after surgery. The position of the large colon, the integrity of the colopexy, and other adhesions within the abdominal cavity were evaluated. At necropsy, attempts were made to manually create displacement and volvulus of the large colon. The remaining horses in each group were anesthetized 6 months or 12 months after surgery, and the integrity of the colopexy was evaluated. After a 60-day recovery period, these horses were exercised for 2 months. Although each horse initially lost weight, the weight of all but 2 was acceptable at the conclusion of the study. Two horses that had technique-B colopexies had progressive weight loss serious enough to warrant euthanasia. Both colopexy techniques prevented manual creation of large-colon displacement and large-colon volvulus centered at the sternal and diaphragmatic flexures. Technique-A colopexy also prevented manual creation of volvulus of the large colon centered at its base.(ABSTRACT TRUNCATED AT 250 WORDS)     

Use of cecal bypass via side-to-side ileocolic anastomosis without ileal transection for treatment of cecocolic intussusception in three horses

CASE DESCRIPTION: 3 horses were evaluated for signs of colic; cecocolic intussusception was detected. CLINICAL FINDINGS: Abnormalities detected included diminished intestinal sounds, inflammatory leukogram, dehydration, unremarkable fi ndings via rectal palpation, and ultrasonographic evidence of large intestine intussusception. Laparotomy revealed cecocolic intussusception. TREATMENT AND OUTCOME: Cecal bypass via side-to-side ileocolic anastomosis without ileal transection was performed in each horse by use of an intraluminal anastomosis stapler device. Postoperative complications were minimal, and all horses recovered rapidly and were clinically normal at > 12 months after surgery. CLINICAL RELEVANCE: Cecal bypass via side-to-side ileocolic anastomosis without ileal transection seemed to offer 2 potential advantages over traditional surgical techniques for treating this condition. The risk of abdominal contamination was far less than with techniques in which the colotomy is needed to enable resection of the cecum or techniques in which the ileum is transected. Also, it was technically simpler to perform because there was no need to transect the ileum, oversew the ileal stump, perform cecal resection, or close the mesenteric space created by relocating the jejunal stump to the right ventral colon.     

Experimental Large Colon Resection at the Cecocolic Ligament in the Horse

Ten normal horses had approximately 95% of the length of the large colon resected with a side-to-side anastomosis between right ventral and right dorsal colon performed with surgical stapling equipment. Four horses died shortly after surgery of colitis (1 horse) or failure of the TA 90 transection staple line (3 horses). Another horse died 4 months after surgery from disseminated streptococcal infection but had recovered well from the colon resection. Five horses survived long term (18 months) with no clinical evidence of adverse effects of the resection. Surviving horses had weight loss and soft fecal consistency for 3 to 12 weeks after surgery but returned to preoperative values within 12 months. At a second surgery 1 year later (5 horses) or at necropsy 4 months later (1 horse), fibrous omental adhesions were present over the transection staple line in four horses and over the anastomotic staple line in two horses. Omental adhesions to the everted staple line were moderate but not associated with any clinical sequellae. An incisional hernia was present in one horse. The anastomotic stomata measured between 8 and 9 cm, which was 60% of the size of the original surgically created stomata. Failure of the transection staple line occurred in the first three of five horses in which the procedure was attempted due to improper configuration of the staples or crushing of the tissue between the staples. Experience corrected this complication.     

Colopexy in broodmares: 44 cases (1986-1990).

Colopexies were performed in 44 broodmares requiring abdominal surgery for large colon volvulus or right dorsal displacement of the large colon. Colopexies were performed by suturing the lateral bands of the left and right ventral colon to the ventral abdominal wall. Forty-seven percent of the mares in which a colopexy was performed had previous surgery for a large colon volvulus or right dorsal displacement of the large colon. Postoperative complications considered directly associated with the colopexy procedure were intermittent abdominal pain in 7, reoperation in 5, subcutaneous fistulous tracts in 1, and catastrophic rupture of the left ventral colon in 2 horses. Thirty-six horses survived greater than 6 months after colopexy, 34 of which had complete follow-up examinations. Twenty-seven mares have foaled at least once subsequent to the colopexy procedure, totalling 40 foals. Colopexy was considered a viable technique to prevent recurrence of large colon displacement or volvulus in selected predisposed populations.     

Short-Term Effects of Duodenocecostomy on Body Weight,Glucose Absorption,Serum Components,and Intestinal Histopathology in Four Normal Horses

The objective of this study was to evaluate duodenocecostomy in horses performed through a ventral midline laparotomy and report its influence on body weight, glucose absorption, serum components, and characteristics of jejunum, cecum, and large colon histology. Four horses were submitted to the duodenocecostomy technique through a ventral midline laparotomy with animals in dorsal recumbency under inhalation anesthesia, followed by abdominal exploration. A side-to-side anastomosis was performed between the duodenojejunal flexure and the base of the cecum with two simple continuous suture lines of the serosal and muscular layers. The size of the opening created was approximately 2 cm in diameter. The mucosa layer was not sutured. After 30 days, animals were submitted to a second laparotomy to check the patency of the duodenocaecal fistula. During both laparotomy procedures, excisional biopsies of different segments of the gastrointestinal tract were performed. Information on physical examination findings, results of hematologic and histopathologic evaluations, and oral glucose absorption test were recorded. The horses did not have significant weight loss from baseline, and absorption curve of glucose did not significantly vary from baseline. Only triglycerides had significant alterations. Histologic evaluation of jejunum, cecum, and large colon did not show alterations of intestinal structure and morphology. We concluded that the proposed technique, principally in relation to the fistula size and not suturing the mucosa layer, allowed partial or total occlusion of the fistulae without the necessity of a second surgery and avoided the permanent bypass of ingesta and weight loss.     

Obstruction of the cecocolic orifice by ileocecocolic intussusception following jejunocecostomy in a horse

A 4-year-old Thoroughbred stallion was referred for signs of mild to moderate colic, anorexia, and decreased water intake of 3 weeks' duration. Ultrasonographic examination revealed an intussusception, the most common of which would be a cecal inversion or ileocecal intussusception. Surgical exploration identified an ileocecocolic intussusception with extension of the intussusceptum into the right ventral colon; however, the cause of the intussusception could not be identified. The intussusception could not be surgically corrected, and the horse was euthanatized. A side-to-side jejunocecostomy that had been performed previously was identified at necropsy. The ileal stump had intussuscepted into the right ventral colon and become hypertrophied, causing partial obstruction of the cecocolic orifice and clinical signs of colic. In horses requiring an ileocecal or jejunocecal anastomosis, the ileal stump may be left to slough within the cecum as part of the treatment for an irreducible ileocecal intussusception or intentionally inverted into the cecum when the ileal stump is necrotic and cannot be exteriorized and resected. Efforts should be made to minimize the size of the ileal stump to reduce the liklihood of intussusception.     

Strangulated umbilical hernias in horses: 13 cases (1974-1985)

The medical records of 13 horses with strangulated umbilical hernias were reviewed. Typical history included increased swelling, warmth, and firmness of the hernial sac. Enterocutaneous fistulas had developed in 2 horses. Four horses had signs of abdominal pain. Surgery was performed on all horses, and the hernia was reduced by an open reduction technique. Incarcerated tissue included omentum (1 horse), jejunum (5), ileum (4), cecum (1), and ventral colon (2). All horses survived and were discharged from the hospital. Follow-up information on 9 horses (5 to 52 months after discharge) revealed no complications in 6 horses. Of the remaining 3 horses, one horse was euthanatized 5 months after discharge because of laminitis. One horse had persistent drainage from the skin incision requiring removal of nonabsorbable suture material 8 months after discharge. One foal required a second surgery because of signs of abdominal pain 17 days after the initial surgery. The foal was euthanatized during surgery because of severe peritonitis secondary to anastomotic leakage.     

Resection and Anastomosis of the Descending Colon in 43 Horses

Objectives: To determine (1) the short‐ (to hospital discharge) and long‐ (>6 months) term survival, (2) factors associated with short‐term survival, and (3) the perioperative course for horses with resection and anastomosis of the descending colon. Study Design: Multicentered case series. Animals: Horses (n=43) that had descending colon resection and anastomosis. Methods: Medical records (January 1995–June 2009) of 7 equine referral hospitals were reviewed for horses that had descending colon resection and anastomosis and were recovered from anesthesia. Retrieved data included history, results of clinical and clinicopathologic examinations, surgical findings, postsurgical treatment and complications, and short‐term survival (hospital discharge). Long‐term survival was defined as survival ≥6 months after hospital discharge. Results: Of 43 horses, 36 (84%) were discharged from the hospital. Twenty‐eight of 30 horses with follow‐up information survived ≥6 months. No significant associations between perioperative factors and short‐term survival were identified. Lesions included strangulating lipoma (n=27), postfoaling trauma (4), infarction (4), intraluminal obstruction (2), and other (6). Common postoperative complications included fever and diarrhea. During hospitalization 7 horses were euthanatized or died because of septic peritonitis (3), endotoxemia (3), and colic and ileus (1). Conclusions: Descending colon resection and anastomosis has a favorable prognosis for hospital discharge and survival ≥6 months. The most common cause of small colon incarceration was strangulating lipoma. Clinical Relevance: Complications include postoperative fever and diarrhea but the prognosis is good after small colon resection and anastomosis.     

Effects of fenoldopam on cecal blood flow and mechanical activity in horses

Lateral cecal arterial blood flow, carotid arterial pressure, heart rate, and mechanical activity in the duodenum, right ventral colon, cecal body, and cecal apex were measured in 6 conscious healthy horses for 60 minutes during and for 120 minutes after IV infusion of 0.9% NaCl solution (control) or fenoldopam. There were no significant changes in these measurements during or after infusion of 0.9% NaCl (saline) solution. Fenoldopam, a selective dopamine-1 receptor agonist, was administered in saline solution at dosages of 0.01, 0.05, and 0.1 micrograms/kg/min. Intravenous infusion of fenoldopam at 0.01 microgram/kg/min significantly increased heart rate, but did not change average carotid arterial pressure or lateral cecal arterial blood flow. Intravenous infusion of fenoldopam at both 0.05 and 0.1 microgram/kg/min significantly increased heart rate, significantly decreased average carotid arterial pressure, and significantly increased lateral cecal arterial blood flow. Intravenous infusion of fenoldopam at 0.01, 0.05, and 0.1 microgram/kg/min did not significantly change the mechanical activity measured by the area under the strain gauge deflection curve for the duodenum, right ventral colon, cecal body, or cecal apex. These results suggest that dopaminergic-1 receptors are present on the colonic vasculature of horses. There was no evidence, however, that dopaminergic-1 receptors exist on the visceral smooth muscle of the duodenum, right ventral colon, cecal body, or cecal apex of horses.     

Correlation Between Peritonitis and Incisional Infections in Horses

Surgical site infection of abdominal incisions is an important complication after laparotomy with increased risk of incisional hernia formation in horses. This study aims to evaluate the healing process of abdominal incisions and correlate peritonitis with the occurrence of surgical site infection and incisional hernias. Nine horses underwent standardized laparotomy, intestinal exploration, and induced septic peritonitis. Standardized relaparotomy was performed two (n = 3), four (n = 3), and six (n = 3) months later to evaluate the abdominal cavity for adhesions and to collect the sutured ventral abdominal wall to evaluate and prepare it for histopathological and tensile strength study. All horses presented with endotoxemia, controllable peritonitis, heat and touch-sensitive ventral abdominal edema and surgical wound infection with presence of purulent discharge. Adhesion of the cecum or colon to the internal portion of the surgical wound was observed. Healing of the infected surgical wounds occurred by second intention and a space between the rectus abdominis muscles developed because of the presence of a scar, which was related to incisional hernia. In the histopathological evaluation, the collagen content increased, and the inflammation decreased over time. The tensile strength increased over time and was highest after 6 months. After the second surgical intervention, there was no infection of the surgical wound in any of the animals and healing by first intention occurred. Surgical site infection may be a symptom of peritonitis in horses recovering from abdominal surgery. Infected surgical wounds heal by second intention, which favors the spacing of rectus abdominis muscle and the formation of incisional hernia.     

The equine teniae coli: An electrophysiological study

Previous morphological studies of the equine teniae coli (intestinal bands) have shown them to be highly innervated. In this study, EMG electrodes were placed in the wall of the left ventral colon in order to determine whether intestinal bands serve as major conduits of myo-electrical activity. Specifically, electrodes were implanted in the lateral mesocolic band and the adjacent tenia-free bowel of 6 horses. In 3 of these horses, a 1 cm length of the intestinal band was excised to determine if a lesion of this size would ablate local waves of depolarization. Our results indicate that sequential EMG activity persisted despite this small, focal excision. The persistence of sequential EMG activity might reflect the importance of constantly regenerating stimuli to the intestinal motility of the horse. Whether making similar or somewhat larger lesions in all four teniae of the left ventral, colon would more definitively disrupt normal pelvic flexure peristalsis will require further research.     

A Modified Technique for Extensive Large Colon Resection and Anastomosis in Horses

Objective —To describe an alternative technique for large colon resection and anastomosis in horses.
Study Design —Retrospective study of clinical patients.
Animal Population —37 horses that had ventral midline celiotomies between July 1, 1990, and July 1, 1994.
Methods —Large colon resection and anastomosis was performed using a modification of previously described techniques. Modifications include mesocolon ligation with a stapling device and an end-to-end apposition of the right ventral and right dorsal colon.
Results —Twenty-one of the 37 horses were discharged from the hospital without complications. Two horses were euthanatized immediately after recovery from anesthesia because of hindlimb fracture. Fourteen horses were euthanatized in the initial postoperative period because of persistent endotoxemia and abdominal pain.
Conclusions —The described technique is a safe, reliable method for large colon resection and anastomosis in horses.
Clinical Relevance —The described technique is fairly simple to perform and requires less surgical time compared with other techniques.     

Initial evaluation of a technique for complete cecal bypass in the horse

OBJECTIVE: To describe a novel stapling technique for creation of a complete cecal bypass, without ileal transection in horses. STUDY DESIGN: Experimental study. ANIMALS: Four adult horses. METHODS: Through a ventral median celiotomy, jejunocolostomy was made with an intraluminal anastomosis device (ILA-100) and oversewn with a Cushing pattern to reinforce the staple line. Immediately distal to the anastomosis, 4 rows of staples were applied using a thoracoabdominal stapling device (TA-90) to occlude the lumen of the distal jejunum and proximal ileum. Necropsy exams were performed at least 60 days after surgery. RESULTS: No intraoperative complications occurred. Cecal bypass was functional in all horses at necropsy. The most oral staple line across the ileum partially failed in 1 horse; however cecal bypass was functional. CONCLUSIONS: Complete cecal bypass without ileal transection is a viable alternative to traditional methods of complete cecal bypass. Two sets of staple lines across the ileum are recommended. Longer term follow-up is warranted before clinical use of this technique. CLINICAL RELEVANCE: Cecal bypass without ileal transection is technically simple and effectively bypasses the cecum. It also should intuitively require less time and have a reduced risk of contamination compared with complete cecal bypass with ileal transection.     

Cecal perforation in the horse

The case records of 23 horses with cecal perforation (CP) were reviewed. The horses averaged 4.5 years of age (6 weeks to 13 years) and included 9 intact males, 12 mares, and 2 geldings. Twelve of the horses were Standardbreds, 9 were Thoroughbreds, and 1 each, a Belgian and Morgan. The horses were allotted to 2 groups: group I-13 hospitalized horses in which CP occurred unexpectedly, and group II-10 horses with CP at the time of admission. The horses characteristically had been sick or affected with disease unrelated to the cecum. Sixteen horses had been given nonsteroidal anti-inflammatory drugs before the onset of CP. Twelve of the 13 hospitalized patients (group I) had vague, scarcely recognizable clinical signs of gastrointestinal disease before CP. The clinical signs and clinical laboratory changes that appeared in affected horses were identifiable with severe endotoxin shock, secondary to peritoneal contamination with ingesta and bacteria. All horses died. At necropsy of the horses, the cecum was large and firm and was filled with ingesta, and the colon was empty; however, in 1 postpartum mare, the cecum and colon contained the usual amount of ingesta and were normal in size. In all horses, a single perforation was present, which appeared at various sites. The most common was a transverse perforation along the ventral aspect of the cecal body. Gross and microscopic examinations uncovered no existing disease near the perforation site or in other areas of the cecal wall or cecocolic orifice.(ABSTRACT TRUNCATED AT 250 WORDS)     

Results of surgical treatment of colic in miniature breed horses: 11 cases

OBJECTIVE: To report on the outcome of surgical treatment of acute abdominal crises in miniature breed horses. DESIGN: Retrospective case series of miniature horses presented to the University Veterinary Centre, Camden with an acute abdominal crisis. METHODS: Hospital records of all miniature horses that underwent ventral midline laparotomy for acute abdominal crisis between 1997 and 2001 were reviewed. The signalment, history, clinical signs, results of ancillary diagnostic procedures, location and type of intestinal lesion, treatment and outcome were retrieved from each case record. Long-term survival was determined by telephone interview of owners. RESULTS: Eleven miniature horses including five females and six males underwent ventral midline laparotomies for acute abdominal crisis during the study period. Ages ranged between 1 month and 19 years. Surgical findings included faecalith obstruction (seven horses), enterolith (one horse), strangulating lipoma of the descending colon (one horse), jejunal infarction (one horse), and caecal infarction (one horse). Long-term survival rate (minimum 12 months post surgery) was 55%. Six of eight horses with simple intraluminal obstructions survived, while the three horses with gastrointestinal lesions associated with vascular compromise were euthanased either at surgery (caecal infarction), or postoperatively, due to complications (strangulating lipoma of the descending colon, jejunal infarction). Postoperative complications in this study included impaction of the descending colon (two horses), diarrhoea (two horses), peritonitis (one horse), hyperlipaemia (two horses), incisional infection (two horses) and abdominal adhesions (one horse). Hyperlipidaemia was present in five of seven horses in which serum triglycerides were measured at presentation. CONCLUSIONS: Simple intraluminal obstructions of the large intestine were frequently encountered during exploratory laparotomy in miniature horses presented for acute abdominal crises, and their surgical treatment was associated with a good prognosis. In contrast, this study suggested that abdominal pain associated with vascular compromise of gastrointestinal tissues in miniature horses was associated with a poorer prognosis, consistent with reports in other horse breeds. Possible contributing factors to faecalith formation, including poor quality roughage, dental disease, and inadequate water consumption, should be recognised and avoided in miniature horses. Serum triglyceride concentrations should be measured in miniature horses presented for acute abdominal pain. If elevated, nutritional supplementation should be provided.     

The teniae of the equine intestinal tract.

At several locations along the equine cecum and colon, the outer longitudinal portion of the tunica muscularis is gathered into discrete bands of smooth muscle and connective tissue called "teniae". In this study, the disposition of the teniae ceci and coli was traced along the equine intestinal tract. It was discovered that, in several instances, arrays of teniae converge toward the valves and sphincters which separate the various intestinal compartments. The teniae may also provide support for and directionality to, peristaltic contraction waves. The tissue proportions of the teniae vary in different locations. The tenia libera lateralis of the ventral colon is rich in elastic connective tissue, while that of the right dorsal colon is primarily composed of smooth muscle. This may reflect the different responsibilities of these two compartments. The teniae are innervated and their smooth muscle cells are joined by many gap junctions. The connective tissue constituents afford intestinal support while yielding to intestinal distension. The smooth muscle and neural elements may foster active tenial participation in peristalsis. This premise must be tested by electrophysiological experimentation. Further experimentation is also necessary to ascertain whether injury to the teniae might predispose a horse to colic.