Outcome of medical and surgical treatment of cecal impaction in horses: 114 cases (1994–2004)

Amy E. Plummer Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX 77843-4475.

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Peter C. Rakestraw Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX 77843-4475.

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Joanne Hardy Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX 77843-4475.

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Ryan M. Lee Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX 77843-4475.

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Abstract

Objective—To determine short- and long-term outcomes, including recurrence rates, for horses with cecal impaction treated medically or surgically.

Design—Retrospective case series.

Animals—114 horses.

Procedures—Medical records were reviewed for information on signalment, history, clinical findings, treatment (medical vs surgical), and short-term outcome. Information on longterm outcome was obtained through a mail survey and telephone interview with owners.

Results—54 horses were treated medically, 49 horses were treated surgically, and 11 horses were euthanized after initial examination without further treatment. Horses treated surgically were significantly more likely to have signs of moderate or severe pain than were horses treated medically. Forty-four of the 54 (81%) horses treated medically were discharged from the hospital. Twelve of the 49 horses treated surgically were euthanized at surgery because of cecal rupture. Thirty-five of the 37 (95%) horses that were allowed to recover from surgery were discharged from the hospital. In 34 horses treated surgically, typhlotomy without a bypass procedure was performed. Long-term (≥ 1 year) follow-up information was available for 19 horses treated medically and 28 horses treated surgically. Eighteen (95%) and 25 (89%) of the horses, respectively, were alive at least 1 year after treatment.

Conclusions and Clinical Relevance—Results suggested that medical and surgical treatment were both associated with favorable outcomes in horses with cecal impactions. In this population, typhlotomy alone without cecal bypass was associated with a low recurrence rate. The long-term prognosis for horses that were discharged from the hospital was good.

Abstract

Objective—To determine short- and long-term outcomes, including recurrence rates, for horses with cecal impaction treated medically or surgically.

Design—Retrospective case series.

Animals—114 horses.

Procedures—Medical records were reviewed for information on signalment, history, clinical findings, treatment (medical vs surgical), and short-term outcome. Information on longterm outcome was obtained through a mail survey and telephone interview with owners.

Results—54 horses were treated medically, 49 horses were treated surgically, and 11 horses were euthanized after initial examination without further treatment. Horses treated surgically were significantly more likely to have signs of moderate or severe pain than were horses treated medically. Forty-four of the 54 (81%) horses treated medically were discharged from the hospital. Twelve of the 49 horses treated surgically were euthanized at surgery because of cecal rupture. Thirty-five of the 37 (95%) horses that were allowed to recover from surgery were discharged from the hospital. In 34 horses treated surgically, typhlotomy without a bypass procedure was performed. Long-term (≥ 1 year) follow-up information was available for 19 horses treated medically and 28 horses treated surgically. Eighteen (95%) and 25 (89%) of the horses, respectively, were alive at least 1 year after treatment.

Conclusions and Clinical Relevance—Results suggested that medical and surgical treatment were both associated with favorable outcomes in horses with cecal impactions. In this population, typhlotomy alone without cecal bypass was associated with a low recurrence rate. The long-term prognosis for horses that were discharged from the hospital was good.

Cecal impaction is the most common pathologic condition of the cecum in horses, accounting for 40% to 50% of horses with cecal disease, 5% of horses with intestinal impaction, and 2% of horses referred for treatment of colic.1,2,3,4,5 Cecal rupture has been reported to occur in as high as 57% of horses with cecal impaction.4 The pathogenesis of cecal impaction is likely multifactorial, varying from one case to the next, and the underlying cause in any individual case is typically unknown. Anecdotally, cecal impaction has been associated with poor dentition, coarse roughage intake, decreased water consumption, administration of nonsteroidal anti-inflammatory drugs, and infestation with Anaplocephala perfoliata.2,3,4 Cecal impaction has also been identified in horses that have been hospitalized for diseases unrelated to the gastrointestinal tract, predominately musculoskeletal abnormalities.4 Most of these horses had recently undergone general anesthesia and were receiving nonsteroidal anti-inflammatory drugs as part of their treatment regimen. Cecal dysfunction secondary to abnormalities in cecal motility, as opposed to mechanical obstruction by firm ingesta, is thought to play a role in the development of cecal impaction in these horses.

Medical and surgical treatment of horses with cecal impaction have been described.3,4,6-8 Medical treatment includes administration of fluids, laxatives, and analgesics and withholding of food until rectal examination confirms resolution of the impaction. Surgical treatment includes typhlotomy with or without a cecal bypass procedure.3,4,7-10 Unfortunately, there is limited published information regarding the shortand longterm outcomes of horses treated medically or surgically for cecal impaction. Although some authors recommend that surgical treatment be reserved for horses refractory to medical treatment or with severe cecal distention, other authors recommend earlier surgical intervention.3,4,9,11 Additionally, in those horses in which surgery is performed, a decision must be made as to whether to perform a cecal bypass procedure to prevent recurrent cecal impaction secondary to motility dysfunction.5,9-11 The purpose of the study reported here was to determine shortand long-term outcomes, including recurrence rates, for horses with cecal impaction treated medically or surgically.

Criteria for Selection of Cases

Medical records of horses examined at Texas A&M University because of signs of acute abdominal pain between January 1994 and January 2004 were reviewed. Horses were selected for inclusion in the study if a diagnosis of cecal impaction had been made during examination per rectum, exploratory celiotomy, or postmortem examination. A tentative diagnosis of cecal impaction was made during examination per rectum if the cecum in a horse with signs of abdominal pain was easily palpated to contain a greater than normal amount of ingesta or fluid; the diagnosis was confirmed if rectal examination findings were repeatable (ie, similar findings were obtained during a minimum of 2 examinations per rectum) or if cecal impaction was subsequently diagnosed during surgery or postmortem examination. A diagnosis of cecal impaction was made during surgery if there was distention of the cecum with ingesta or fluid; a diagnosis of cecal impaction was made during postmortem examination if there was distention of the cecum with ingesta or fluid.

Procedures

Medical record review—Medical records of horses included in the study were reviewed. For horses treated for cecal impaction more than once, information was obtained only for the first occurrence of cecal impaction. Information obtained from the medical records included signalment; history, including duration of signs of abdominal pain prior to examination at the veterinary teaching hospital; treatments administered by the referring veterinarian; concurrent health problems and medications; recent management changes in exercise or diet; and information regarding previous episodes of colic, recent administration of nonsteroidal anti-inflammatory drugs, and recent anesthetic episodes.

Physical examination findings at the time of admission and prior to surgery, severity of signs of abdominal pain at admission and prior to surgery, rectal examination findings at admission and prior to surgery, and volume of nasogastric reflux were also recorded, along with results of hematologic and serum biochemical testing and results of examination of abdominal fluid. Signs of abdominal pain were classified as mild if they included flank watching, occasional pawing, stretching, and kicking at the abdomen. Signs of abdominal pain were classified as moderate if they included persistent pawing, lying down, and rolling. Signs of abdominal pain were classified as severe if they included repeated rolling and failure to respond to analgesics. Cecal impaction was defined as mild if there was distention of the cecum, but the cecum was not full and the cecal content was easily indentable during rectal examination. Cecal impaction was classified as severe if the cecum was fully distended and the cecal content was not indentable during rectal examination. A diagnosis of cecal rupture was made during examination per rectum if there was palpable crepitus and feedstuff or air could be palpated free within the abdomen.

Records of horses treated medically were reviewed for information regarding treatment and duration of treatment until cecal impaction resolved. For horses undergoing exploratory laparotomy, time from admission until surgery and surgical findings and procedures were recorded. For horses that died or were euthanized, postmortem examination reports were reviewed. The location of rupture was recorded if present. For all horses, duration of hospitalization, outcome, and complications were recorded. Short-term survival was defined as discharge from the hospital. Follow-up information was obtained from medical records, a survey mailed to owners, and telephone conversations with the owners. Information obtained included outcome, complications after treatment, whether there were any additional episodes of colic, and whether there were any changes in environment or diet after discharge from the hospital. Long-term survival was defined as survival for at least 12 months after discharge.

Medical treatment—Medical treatment included administration of lactated Ringer's solution (120 to 180 mL/kg/d [54 to 82 mL/lb/d], IV) and flunixin meglumine (1.1 mg/kg [0.5 mg/lb], IV, q 6 h). Xylazine hydrochloride (0.33 to 0.44 mg/kg [0.15 to 0.2 mg/lb], IV) was administered for its sedative and analgesic effects, and butorphanol tartrate (0.033 mg/kg [0.015 mg/lb], IV) was administered if additional sedation was needed. Mineral oil (2 to 4 L [0.5 to 1 gallon]), magnesium sulfate (110 g), or both were administered by means of a nasogastric tube. Additional treatments in selected cases included administration of penicillin G potassium (22,000 U/kg [10,000 U/lb], IV, q 6 h), penicillin G procaine (22,000 U/kg, IM, q 12 h), gentamicin (6.6 mg/kg [3 mg/lb], IV, q 24 h), polymyxin B (6,000 U/kg [2,700 U/lb], IV, q 12 h), pentoxyphylline (8.5 mg/kg [3.9 mg/ lb], PO, q 12 h), and plasma (1 L, IV).

Surgical treatment—Horses that underwent surgery received the same medications that horses treated medically received. In addition, all horses that underwent surgery were treated with penicillin g potassium or penicillin g procaine, gentamicin, and flunixin meglumine; administration continued for 1 to 7 days after surgery.

For surgery, horses were sedated with xylazine (0.1 to 0.2 mg/kg [0.045 to 0.09 mg/lb], IV), and anesthesia was induced with ketamine hydrochloride (2.2 mg/kg [1 mg/lb], IV) and diazepam (0.11 mg/kg [0.05 mg/lb], IV). Anesthesia was maintained with sevoflurane or isoflurane administered in oxygen with a semiclosed circle system incorporating positive-pressure ventilation. A ventral midline celiotomy was performed, and the apex and as much of the body of the cecum as possible were exteriorized. Typhlotomy was performed adjacent to the apex between the lateral and ventral cecal bands, and water was pumped into the cecum through a sterile tube placed through an enterotomy incision to facilitate evacuation of cecal contents. External massage at the base of the cecum and over the cupula was used as necessary to break down impacted material. In horses in which cecal bypass was considered necessary, an ileocolonic anastomosis was performed with a surgical stapling device. In selected cases, pelvic flexure enterotomy was performed to allow evacuation of the large colon.

Statistical analysis—Continuous variables were examined graphically for assumptions of normal distribution, and a Bartlett test was used to test for equality of variances. Continuous data that were normally distributed are reported as mean ± SD; continuous data that were not normally distributed are reported as median and range. For continuous variables, the Student t test (normally distributed data) or Mann-Whitney U test (non-normally distributed data) was used to compare values between medical or surgical treatment and outcome. The χ2 test was used to test whether categorical variables were significantly associated with medical or surgical treatment and outcome. All analyses were performed with standard software.a Values of P < 0.05 were considered significant.

Results

Signalment—A total of 114 cases met the criteria for inclusion in the study. This represented 4.1% of the 2,809 horses examined during the study period because of signs of acute abdominal pain. There were 57 (50%) geldings, 41 (36%) females, and 16 (14%) stallions. Eight of the 41 (20%) females were pregnant at the time of admission; mean ± SD duration of pregnancy was 6.5 ± 3.5 months. Nine (22%) of the female horses had foaled within the last 90 days (median time since foaling, 30 days; range, 9 to 87 days).

Horses with cecal impaction ranged from 4 months to 30 years old (mean ± SD, 13.2 ± 5.7 years). Mean age of horses with cecal impaction was significantly (P < 0.001) greater than mean age of all horses examined at the hospital for any reason during the study period (9.4 ± 2.26 years). Fifty-seven (50%) of the horses with cecal impaction were between 10 and 17 years old. There were 78 (68.4%) Quarter Horses; 9 (7.9%) Thoroughbreds; 7 (6.1%) Arabians; 7 (6.1%) Paints; 5 (4.4%) mixed-breed horses; 2 (1.7%) draft breed horses; and 1 horse of each of the following breeds: Saddlebred, Peruvian Paso, Miniature Horse, Tennessee Walking Horse, donkey, and Dutch Warmblood. The breed distribution for horses with cecal impaction generally reflected the breed distribution of the hospital population during the study period.

History—Eighty-two of the 114 (72%) horses were admitted between July 1 and January 30. The proportion of horses admitted during the 6 hottest months of the year (April through September) was not significantly different from the proportion admitted during the remainder of the year. Median duration of colic prior to examination at the teaching hospital was 36 hours (range, 2 to 336 hours); 85 (75%) horses were examined within 72 hours of the onset of signs of colic.

Information on housing was available for 89 horses. Of these, 29 (33%) were housed in a stall with daily pasture turnout, 23 (26%) were housed on pasture at all times, 17 (19%) were housed in a stall at all times, 16 (18%) were housed in a stall with paddock turnout, and 4 (4%) were housed in a paddock at all times. Of the 84 horses for which information on type of hay fed was recorded, 65 (77%) received Bermuda coastal hay only, 5 (6%) received alfalfa hay only, 12 (14%) received alfalfa and Bermuda coastal hay, and 2 (2%) received timothy hay only. Of the 107 horses for which information on any recent changes in housing had been recorded, 30 (28%) reportedly had had changes in housing within the previous 30 days, and 19 (18%) had had changes in housing within the previous 7 days. Of the 53 horses for which information on deworming history had been recorded, 50 (94%) had been dewormed during the 4 months prior to admission. Twenty-one of 96 (22%) horses had been transported recently for reasons other than medical treatment of cecal impaction, with most of these (16 [76.1%]) having been transported within 8 days prior to examination at the veterinary teaching hospital.

Information regarding any previous episodes of colic was obtained for 76 horses, of which 33 (43%) had had previous episodes of colic. Owners of 4 of the horses with previous episodes of colic reported that their horses had had cecal impaction.

Twelve of the 114 (11%) horses were hospitalized and being treated for a condition unrelated to colic when cecal impaction was diagnosed (11 at the veterinary teaching hospital and 1 at the referring veterinarian's hospital). One of these 12 horses died and 1 was euthanized because of the severity of clinical signs before treatment was administered or a diagnosis of cecal impaction was made. Four were treated medically, and 2 of the 4 were eventually discharged. Six were treated surgically, and 4 of the 6 were eventually discharged. One horse was euthanized at the time of surgery because of cecal rupture, and 1 horse was euthanized 2 days after surgery because of neurologic abnormalities.

Seven of the 114 (6%) horses had undergone general anesthesia within 8 days of the onset of cecal impaction. Another horse was referred for treatment of colic after having undergone anesthesia for splint bone removal at another hospital.

Fifteen (13%) horses were receiving phenylbutazone at the time they developed cecal impaction; 6 of these horses were also hospitalized at the time. Thirteen of these horses were being treated for a musculoskeletal injury, 1 was being treated for a laceration, and 1 was being treated for a kick injury. Of these 15 horses, 1 died before a diagnosis of cecal impaction was made and 3 were euthanized prior to treatment because of cecal rupture.

Findings reported by the referring veterinarian—In 48 of the 114 horses, a rectal examination had been performed by the referring veterinarian, with cecal impaction diagnosed in 14 (29%), cecal distention diagnosed in 5 (10%), large colon impaction diagnosed in 4 (8%), other conditions identified in 21 (44%), and no abnormalities identified in 4 (8%). Of the 92 horses for which the referring veterinarian described the severity of pain, 33 (36%) were described as mildly painful, 47 (51%) were described as moderately painful, and 12 (13%) were described as severely painful. The most common analgesics administered prior to admission to the veterinary teaching hospital were flunixin meglumine, xylazine hydrochloride, detomidine hydrochloride, and butorphanol tartrate. Seventy of 91 (76%) horses treated by a referring veterinarian were administered 1 or more oral laxatives (ie, mineral oil, magnesium sulfate, or dioctyl sodium sulfosuccinate).

Physical examination findings—Heart rate was recorded at the time of admission to the veterinary teaching hospital in 112 horses; median heart rate was 46 beats/min (range, 28 to 130 beats/min). Capillary refill time was recorded in 102 horses; median time was 2 seconds (range, 1 to 4 seconds). Fifteen of the 113 (13%) horses for which information on abdominal contour was recorded were described as having gross abdominal distention. Median net nasogastric reflux volume was 0 L (range, 0 to 17 L). Severity of pain at the time of admission was recorded as mild in 56 of 107 (52%) horses, moderate in 13 (12%), and severe in 6 (6%); 20 (19%) horses did not have any apparent signs of pain. Twelve (11%) horses were described as having signs of depression at the time of admission.

A rectal examination was performed on 111 of the 114 (97%) horses at the time of admission or, for hospitalized horses, at the time colic developed. Cecal impaction was diagnosed during the first rectal examination in 94 of the 111 (85%) horses. The impaction was described as mild in 40 of the 94 (43%) horses and as severe in 52 (55%); 1 horse had evidence of cecal rupture in combination with cecal impaction, and severity of cecal impaction was not reported in the remaining horse. In the remaining 17 horses, cecal impaction was not identified during the initial rectal examination. Two were thought to have large colon impaction, and in 9, a diagnosis was not made. In 6 horses, a diagnosis of gastrointestinal tract rupture without any palpable abnormalities of the cecum was made. Rectal examination was not performed in 3 horses, including 2 adults with uncontrollable signs of pain and a foal with cecal rupture.

The only physical examination finding significantly associated with short-term survival (ie, survival to discharge) was heart rate. Horses that survived to discharge had a significantly (P < 0.001) lower mean heart rate (mean ± SD, 49 ± 17.7 beats/min) than did horses that did not survive to discharge (75 ± 25.9 beats/min). Mean heart rate for horses treated medically (51.3 ± 18.1 beats/min) was not significantly different from mean heart rate for horses treated surgically (46.7 ± 14.1 beats/min).

Clinical laboratory findings—Packed cell volume was recorded in 110 horses, with mean ± SD PCV being 40.0 ± 10.3%. Packed cell volume was the only clinical laboratory finding significantly associated with shortterm survival. Horses that survived to discharge had a significantly (P < 0.001) lower mean PCV (39 ± 8.9%) than did horses that did not survive to discharge (52 ± 15%). Mean PCV of horses treated medically (40.5 ± 9.5%) was not significantly different from mean PCV of horses treated surgically (39.2 ± 7.4%). Serum electrolyte (ie, sodium, chloride, potassium, and calcium), total protein, albumin, and fibrinogen concentrations and WBC counts were obtained in 80 horses; for all variables, mean and median values were within reference limits. Serum creatinine concentration was measured at the time of admission in 83 horses; mean concentration was 2.3 ± 0.7 mg/dL.

Peritoneal fluid was evaluated in 51 horses. Median total protein concentration was 1.4 g/dL (range, 0.1 to 5.5 g/dL). On the basis of results of cytologic examination, peritoneal fluid was identified as a transudate in 27 (53%) horses, a modified transudate in 2 (4%), a nonseptic exudate in 1 (2%), and a septic exudate in 18 (35%); in the remaining 4 (8%) horses, fluid that was obtained was considered to most likely be a result of enterocentesis. Results of abdominocentesis were compared between horses treated medically and horses treated surgically, after horses with cecal rupture were removed. There was no significant difference in total protein concentration of the peritoneal fluid between horses treated medically (median, 1.4 g/dL; range, 0.1 to 4.1 g/dL) and horses treated surgically (median, 1.0 g/dL; range, 0.2 to 4.3 g/dL). There was also no significant difference in nucleated cell count of the peritoneal fluid between horses treated medically (median, 8.6 × 103 cells/μL; range, 1.4 to 15.2 × 103 cells/μL) and horses treated surgically (median, 8.7 × 103 cells/μL; range, 1.6 to 22.5 × 103 cells/μL).

Treatment—One hundred three of the 114 (90%) horses with cecal impaction were treated, of which 54 (52%) were treated medically and 49 (48%) were treated surgically. The remaining 11 (10%) horses were euthanized without treatment beyond initial emergency treatment. In 6 of these 11 horses, cecal rupture was diagnosed by means of rectal examination, and in all 6, the diagnosis was confirmed at necropsy. Two of the 11 horses that were euthanized without treatment were in the late stages of gestation and were euthanized because results of peritoneal fluid analysis were consistent with rupture. On rectal examination in these mares, the cecum was not palpable because of the size of the gravid uterus. In both mares, cecal impaction and rupture were found at necropsy. One horse was euthanized because of uncontrollable pain after the owner declined exploratory laparotomy; cecal impaction was diagnosed at necropsy. The remaining 2 horses died or were euthanized secondary to endotoxic shock before cecal impaction was diagnosed. One was a foal that had undergone internal fixation to treat a tibial fracture 7 days earlier; cecal impaction and rupture were identified at necropsy. The other had undergone surgery 5 days earlier to remove implants from previous metacarpal fracture repair and was euthanized because of endotoxic shock and diarrhea; cecal impaction and rupture were identified at necropsy.

Medical treatment—For the 54 horses that were treated medically, median duration of signs of colic prior to examination at the veterinary teaching hospital was 42 hours (range, 4 to 336 hours). Forty-three of the 54 (80%) had mild signs of pain at the time of admission, 10 (18%) had moderate signs of pain, and 1 (2%) had severe signs of pain. On rectal examination, cecal impaction was identified as mild in 33 (61%) and as severe in 19 (35%). In the remaining 2 (4%) horses, cecal impaction was not identified during rectal examination but was diagnosed at necropsy.

Forty-four of the 54 (81%) horses treated medically were discharged from the hospital, 9 (17%) were euthanized, and 1 (2%) died. Five horses were euthanized after a diagnosis of cecal rupture was made on the basis of rectal examination findings (3 horses) or results of abdominocentesis (2 horses). Cecal rupture was confirmed at necropsy in 4 of these horses; a necropsy was not performed in the remaining horse. Four horses were euthanized because of a lack of response to treatment and deterioration of physical examination parameters. In all 4, cecal impaction was confirmed at necropsy; 1 also had cecal rupture. One horse died while being treated, and cecal impaction and rupture were confirmed at necropsy. Surgical treatment was recommended before cecal rupture was diagnosed in 5 of the horses that did not survive but was declined by the owners because of financial constraints.

For horses in which medical treatment was successful, median duration of treatment (ie, time from admission to resolution of signs of abdominal pain) was 2.0 days (range, 2 to 4 days). Median duration of hospitalization was 11.0 days (range, 0.25 to 16 days).

Surgical treatment—For the 49 horses that were treated surgically, median duration of signs of colic prior to examination at the veterinary teaching hospital was 36 hours (range, 2 to 336 hours). Median time from admission to surgery was 3 hours (range, 0 to 120 hours), with 37 (76%) horses undergoing surgery within 10 hours after admission. The decision to perform surgery was made on the basis of severity of pain at the time of admission, persistence of pain or an increase in the severity of pain while hospitalized, severity of cecal distention on rectal examination, or failure to respond to medical treatment (ie, no change or an increase in the degree of distention of the cecum on rectal examination).

Severity of pain at the time of admission was reported to be mild in 21 (43%) horses, moderate in 22 (45%), and severe in 5 (10%); 1 horse did not have any signs of pain at admission. Severity of pain was reported to be a factor in the decision to perform surgery in 34 of the 49 (69%) horses. Ten of these 34 (29%) horses reportedly had moderate signs of pain, 12 (35%) reportedly had severe signs of pain, and 12 (35%) reportedly had an increase in the severity of pain following admission or uncontrollable pain. In 15 horses, severity of pain immediately prior to surgery was not recorded in the medical record. There was a significant (P = 0.001) difference in the proportion of horses with moderate or severe pain between horses treated surgically (27/49 [55%]) and horses treated medically (11/54 [20%]).

On rectal examination at admission, 8 of the 49 horses that underwent surgery had cecal impactions classified as mild and 30 had cecal impactions classified as severe. Three horses had crepitation on rectal examination, 6 did not have palpable cecal impaction, and 2 did not undergo rectal examination because of uncontrollable pain. Rectal examination findings were reported to be a factor in the decision to perform surgery in 44 of the 49 (90%) horses. Twenty (41%) horses were taken to surgery without medical treatment on the basis of severity of cecal impaction during rectal examination, and 19 (39%) were taken to surgery after there was no improvement or an increase in the severity of cecal distention during repeated rectal examination. In 5 (10%) horses, cecal impaction and rupture were diagnosed on the basis of results of rectal examination at admission, but the owners requested exploratory laparotomy to confirm the diagnosis.

Cecal impaction and rupture were confirmed in 12 horses at the time of surgery, including the 5 horses in which cecal rupture had been diagnosed prior to surgery. Ten of these 12 horses had been taken to surgery immediately after the initial evaluation was completed. One horse had been treated medically with abdominal lavage, antimicrobials, and nonsteroidal anti-inflammatory drugs because of suspected septic peritonitis and endotoxemia for 19 hours prior to surgical exploration; neither cecal impaction nor cecal rupture had been diagnosed during rectal examination prior to surgery. The remaining horse was undergoing treatment for a corneal ulcer when signs of colic developed. Flunixin meglumine and mineral oil were administered, but 12 hours later, signs of colic were worse, and cecal impaction was diagnosed during rectal examination.

Thirty-seven of the 49 horses that underwent surgery were allowed to recover. In 34 of the 37 (92%), typhlotomy with cecal evacuation was performed to treat the cecal impaction; this included 1 horse in which typhlotomy was performed through a flank laparotomy because of financial constraints. In 2 of the 37 (5%) horses, an ileocolostomy was performed following typhlotomy and evacuation of the cecum. One of these horses had a history of multiple episodes of colic of unknown etiology; the other had undergone exploratory laparotomy 7 days previously for a cecal impaction. In the remaining horse, the cecal impaction was broken down by fluid injection and massage. In addition to the procedures performed for treatment of cecal impaction, small intestinal enterotomy was performed in 1 horse to decompress the small intestine and pelvic flexure enterotomy was performed in 3 horses to evacuate the contents of the large colon.

Thirty-five of 37 (95%) horses that were allowed to recover from surgery were discharged from the hospital. One horse was euthanized 6 days after surgery because of unremitting postoperative ileus. This horse had undergone ileocolostomy, and leakage at the anastomosis site and generalized peritonitis were found at necropsy. A second horse was euthanized because of signs of neurologic and renal disease followed by recumbency that developed within 24 hours after surgery. Ulcerative colitis was diagnosed at necropsy; the cause of the neurologic and renal abnormalities was not determined.

Median duration of hospitalization for the 37 horses that were recovered from surgery was 11 days (range, 0.2 to 16 days). Complications in the 37 horses allowed to recover from surgery included incisional drainage (n = 8 [22%]), postoperative ileus (7 [18.9%]), diarrhea (7 [19%]), laminitis (1 [3%]), septic peritonitis (1 [3%]), and neurologic and renal disease (1 [3%]).

Cecal rupture—Overall, 29 of the 114 (25.4%) horses had cecal rupture in combination with cecal impaction. A necropsy was performed in 22 of these horses, and the location of the rupture was recorded in 20. Ten horses had ruptures at the base of the cecum, 2 had ruptures at the apex of the cecum, and 7 had ruptures in the body of the cecum. One horse had a rupture at the base and in the body.

Long-term follow-up—Follow-up information was available on 47 horses discharged from the hospital, of which 43 (91%) were still alive at least 12 months later. Six of the 47 (13%) horses available for follow-up had a recurrence of cecal impaction. Three of the 6 horses with a recurrence of cecal impaction were reexamined at the hospital and recovered following medical treatment, 1 was treated successfully on the farm, 1 was euthanized because of the severity of colic, and 1 was treated surgically and found to have cecal rupture. An additional 6 horses (13%) reportedly had episodes of colic that were not diagnosed as cecal impaction.

Information was available on 19 of the 47 horses that were treated medically and discharged. Eighteen (95%) were alive 1 year after discharge. One horse died approximately 3 months after discharge as a result of colic of undiagnosed etiology.

Information was available for 28 of the 35 horses that were treated surgically and discharged. Twenty-five (89%) were alive 1 year after discharge. One horse was euthanized 2.5 months after discharge because of laminitis that had developed while hospitalized. One horse was euthanized 3.5 months after discharge because of complications with an abdominal abscess. One horse was euthanized 9.5 months after discharge because of recurrence of cecal impaction. Four (11%) horses were reported by their owners to have developed abdominal hernias. Two (6%) horses were reported by their owners to have had diarrhea after discharge from the hospital, which resolved in both horses. Long-term survival rate for surgically treated horses (25/28 [89%]) was not significantly different from rate for medically treated horses (18/19 [95%]).

Discussion

The incidence of cecal impaction in the present study (4.1%) was higher than that previously reported for horses examined at a referral clinic because of abdominal pain.5 However, a high proportion of horses in this study were fed coastal hay, and coastal hay has been identified as a risk factor for ileal impaction.12 Thus, our findings may also suggest that feeding coastal hay may predispose horses to develop cecal impaction. Previous reports3,8 have suggested that horses > 15 years old have an increased risk of developing cecal impaction. Our findings support this observation, in that horses with cecal impaction were significantly older than horses examined for any other reason during the study period. Although in 1 report,8 Arabians, Appaloosas, and Morgan horses were identified as having an increased risk of cecal impaction, the distribution of breeds in the present study generally reflected the distribution in the general hospital population. Similar to other studies,1,3,4 no sex predilection was found in the present study.

It has been suggested that impaction of the large colon may be associated with freezing temperatures, with decreased water intake leading to dehydration.13,14 Freezing temperatures are rare in the region where the present study was performed, although high temperatures (> 32°C [90°F]) often occur and could also potentially cause dehydration. However, the frequency of cecal impactions was not increased during the 6 hottest months of the year. Decreased exercise has been reported to be a risk factor for colic in general and specifically for development of large colon impaction.14,15 Changes in housing were reported within the previous 30 days in 30 of 107 (28%) horses in the present study, with 19 of those having had changes in housing within the previous 7 days. Unfortunately, we were not able to determine whether these changes in housing reflected a decrease in the amount of exercise.

Tapeworm (A perfoliata) infestation has been reported to be associated with development of cecal impaction in horses.4,7,16,17 In a recent retrospective study7 of 10 horses with cecal impaction treated by typhlotomy, tapeworms were seen in several during surgery, supporting the possible association between tapeworm infestation and cecal impaction as well as recommendations for postoperative treatment with larvicidal anthelmintics to decrease the risk of recurrence. Of the 53 horses in the present study for which deworming history was available, 50 (94%) had been dewormed during the 4 months prior to examination. However, we were not able to determine the types of anthelmintic that had been used, and fecal examinations were not performed on any of the horses. On the other hand, tapeworm infestation was not confirmed at surgery or necropsy in any horse.

The only physical examination finding that was significantly different between medically and surgically treated horses in the present study was severity of pain at the time of initial examination, with surgically treated horses significantly more likely to have moderate or severe pain than medically treated horses. Severity of pain and an increase in the severity of pain were used to determine whether horses were treated medically or surgically. The only physical examination and clinicopathologic variables found to be significantly associated with whether a horse would survive were heart rate and PCV. Horses that survived had significantly lower heart rates and PCVs than did those that did not survive. These findings highlight the fact that predicting outcome can be difficult in horses with cecal impaction and that clinical judgment plays a large role in assessing these patients and formulating recommendations for owners as to treatment. Similarly, there were no significant differences in total protein concentration or WBC count for abdominal fluid from medically versus surgically treated horses, indicating that evaluation of abdominal fluid was seldom useful in assessing whether surgery is necessary. Abdominocentesis, however, may be useful in identifying cecal rupture.

The severity of pain in horses with cecal impactions is typically reported to be mild, and signs of pain can continue for several days.4,8,11,18 In addition, some horses with cecal impaction and rupture may not have any history of substantial abdominal pain. Alternatively, in some horses with cecal impaction, the condition may progress so rapidly as to preclude successful treatment, even if the horses are being monitored in a hospital environment at the onset.4,8,11,19 Four of 6 horses in the present study in which cecal rupture was diagnosed on admission were reported by the owners to have had only mild signs of abdominal pain, and 2 of 12 horses that were hospitalized when cecal impaction developed had cecal rupture before treatment could be initiated. These cases highlight the importance of early rectal examination of hospitalized horses at risk for cecal impaction.

In most cases, a diagnosis of cecal impaction can be made on the basis of results of rectal examination. It has been stated that the earliest abnormality felt during rectal examination is increased tension on the ventral cecal band,3 suggesting that the early stages of cecal impaction may be difficult to identify during rectal examination. Additionally, in some horses with cecal distention, it may be difficult to differentiate cecal from large colon distention. Because the cecum is attached dorsally to the body wall, it is not possible to pass a hand dorsally over a distended cecum, and this should aid in differentiating between the 2 conditions. Cecal impaction was diagnosed by the referring veterinarian in only 14 of 48 (29%) horses in the present study, whereas large colon impaction was diagnosed in 4 (8%). In contrast, cecal impaction was diagnosed at the time of the initial rectal examination at the veterinary teaching hospital in 94 of 111 (85%) horses. The higher percentage of horses with accurate diagnoses during initial examination at the veterinary teaching hospital may have been due to continued enlargement of the impaction or greater experience of the clinicians at the teaching hospital. Even with experience, some cases can be difficult to diagnose by rectal examination. Nevertheless, 2 horses in the present study were mistakenly thought to have large colon impaction on initial examination at the veterinary teaching hospital.

While some authors have suggested that surgical intervention should be used only in horses with refractory cecal impaction and in horses with severe distention,3 others have advocated early surgical intervention.4 In the present study, 54 (52%) horses were treated medically and 49 (48%) were treated surgically. For horses that underwent surgery, median time from admission to surgery was only 3 hours, compared with a previous study3 in which mean time to surgery was 32 hours. Our results suggest that medical treatment of cecal impaction can be successful in some horses, but that early surgical intervention is critical for horses not responding to medical treatment. The potential for cecal rupture with medical treatment should be adequately addressed with the owner when discussing treatment options.

Surgical treatment of cecal impaction involves various methods for evacuation of cecal contents followed, in some instances, by a bypass procedure.4,9,10,20,21 In our experience, infusion of fluid into the cecum through a needle followed by massage of the cecal contents had limited value in the surgical treatment of cecal impaction, and a typhlotomy was performed in 36 of the 37 (97%) horses that were eventually allowed to recover from surgery. However, a bypass procedure was performed in only 2 of the 37 (5%) horses.

Performing a bypass procedure in horses with cecal impaction is controversial. These bypass procedures were originally developed in an effort to decrease the rate of recurrence,10,11,20,22 as it was thought that cecal impaction would recur in horses with cecal motility dysfunction if the cecum was not bypassed. The decision to perform a bypass procedure in 2 horses in the present study was made on the basis of a history of recurrent colic in one and a history of previous cecal impaction in the other. In both horses, ileocolostomy was performed. One horse was subsequently euthanized because of leakage and septic peritonitis; the other was discharged from the hospital but had numerous episodes of mild colic in the year following discharge.

Numerous reports3,4,8 describe cecal rupture as a common complication in horses with cecal impaction, and in the present study, 12 horses that underwent surgery were found to have cecal rupture during initial exploration of the abdomen. In addition, 7 horses had cecal rupture while being treated medically. Surgical correction was recommended before the diagnosis of cecal rupture was made in 5 of these horses but declined by the owners because of financial constraints. Overall, 29 of the 114 (25.4%) horses in the present study had cecal rupture at the time of initial examination or during treatment. This was lower than the prevalence in previous reports,3,4 in which 40% to 57% of cases had cecal rupture, and we believe that early surgical intervention reduced the number of cecal ruptures in the present study. As a matter of policy, we routinely discuss the risk of cecal rupture with owners of horses undergoing treatment for cecal impaction.

It has been stated that horses that develop cecal impaction while hospitalized have a poor prognosis, with cecal rupture occurring within 24 hours of diagnosis.3,4 Of the 12 horses in the present study that were hospitalized when cecal impaction developed, 2 died or were euthanized before treatment, 1 was euthanized at surgery because of cecal rupture, 4 were treated medically with 2 surviving, and 5 were treated surgically with 4 surviving. The higher success rate for horses in the present study, compared with horses in these previous studies,3,4 may have been due, in part, to a greater awareness of the risk of cecal impaction in hospitalized horses as well as a better understanding of the risk of cecal rupture, even without prior signs of moderate or severe abdominal pain. This knowledge may have contributed to more timely diagnosis and treatment of these cases.

Follow-up information was available on 47 horses in the present study that were discharged from the hospital, and long-term survival rate was 91%, with no difference in survival rate of medically versus surgically treated horses. Six (13%) horses had a recurrence of cecal impaction.

In the present study, typhlotomy without cecal bypass was associated with good long-term results. However, 2 points should be emphasized. First, the authors believe that most horses in this study had cecal impaction secondary to feed impaction, not cecal dysfunction, which contributed to the favorable response to surgical decompression without bypass. In geographic areas where horses are not typically fed coastal hay, the proportion of horses with cecal impaction secondary to cecal dysfunction is likely to be higher, and a higher proportion of horses would likely require cecal bypass.

Second, although our results with cecal decompression alone were good, several horses did have a recurrence of cecal impaction. In our hospital, if a horse with cecal impaction has a history of previous episodes of cecal impaction or of multiple episodes of colic, cecal bypass was recommended. We were not able to determine from medical records in the present study whether individual horses were classified as having cecal dysfunction or primary feed impaction. Nevertheless, we believe that this classification has merit and that horses with a gasor fluid-filled cecum are more likely to have cecal dysfunction and more likely to benefit from cecal bypass. We have recently performed a stapled bypass procedure without resection, as described,23 with good results.

a.

Epi-Info, version 3.3.2, CDC, Atlanta, Ga. Available at: www.cdc.gov/EpiInfo/. Accessed Feb 9, 2005.

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