Caecal disease in equids

AJ DART ab , DR HODGSON c and JR SNYDER a

Veterinary Medical Teaching Hospital, University of California, Davis CA 95616 USA
Present address: Rural Veterinary Centre, The University of Sydney, PMB 4 Werombi Road, Camden, New South Wales 2570 Rural Veterinary Centre, The University of Sydney, PMB 4 Werombi Road, Camden, New South Wales 2570

Design Retrospective study of 96 cases.

Procedure The breed, age, and gender of the study population were compared with the corresponding hospital population for the same period. The means (± SD) for clinical and laboratory findings were recorded for each caecal disorder. Treatment was categorised as medical or surgical, and outcome was recorded.

Results Caecal diseases included impaction (40% of total cases), rupture associated with concurrent unrelated disease (13%), rupture with parturition (9%), rupture with no associated disease (5%), infarction (11%), torsion (9%), abscess or adhesion (7%), tumour (3%), and miscellaneous conditions (3%). The breed or gender of affected horses did not differ from the hospital population, although horses > 15 years were more frequently represented (P < 0.05). This age group was specifically more predisposed to caecal impaction (P < 0.05), as were Arabian, Morgan, and Appaloosa breeds (P < 0.05). In horses with caecal impaction transrectal examination was the most useful diagnostic procedure; 90% of affected horses treated medically were discharged while horses treated by typhlotomy alone, or typhlotomy and blind end ileocolostomy, had survival rates to discharge of 71% and 86%, respectively. Horses with caecal rupture associated with concurrent un-related disease showed no signs of impending rupture; all were receiving phenylbutazone, all were euthanased, and 50% had caecal ulceration at necropsy. Of horses with caecal rupture with parturition 56% had prior dystocia; in two-thirds the site of rupture was the ileocaecal junction and all were euthanased. Horses with caecal rupture with no associated disease died or were euthanased; rupture was idiopathic. Horses with caecal infarction usually had signs of abdominal pain and abdominal fluid changes consistent with peritonitis; transrectal examination was nonspecific, and typhlectomy was successful in seven of eight horses. Horses with caecal torsion had signs of severe, acute abdominal pain and typhlectomy was successful in three of five horses. Diagnosis of caecal adhesion or abscess was assisted by transrectal palpation in two of seven horses and surgical treatment was successful in two of five horses. A caecal tumour was diagnosed in three horses aged 20 years or older that presented with chronic weight loss. Other caecal diseases were uncommon.

Conclusion Caecal disease is uncommon in equids but some specific features of the history and physical findings can alert the veterinarian to the possibility of caecal involvement in horses with gastrointestinal dysfunction. Medical or surgical therapy can be effective in horses where caecal rupture has not occurred.

Aust Vet J 1997;75:55552-557
Key words: Caecum, horse, colic, surgery, gastrointestinal, impaction, rupture, infarction, torsion, abscess, tumour, parturition.

A comprehensive epidemiological study reported that 3.7% of horses presented to surgical referral centres with signs of acute abdominal pain had primary caecal disease. 1 Reported caecal disorders include: impaction; 1-6 rupture; 1 , 6 , 7-13 tympany; 1 ileocaecal, 14-16 caecocaecal, 6 and caecocolic intussusception; 6 , 17 , 18 infarction; 6 torsion; 6 , 19 congenital disorders; 6 , 19 , 20 tumours, adhesions secondary to abscesses or surgery, and caecal-cutaneous fistulas. 6 , 21 Apart from several large retrospective studies of caecal impaction in horses, information on caecal disease is derived largely from case reports or small case studies of specific conditions. Consequently the aetiology, pathogenesis, diagnosis, and treatment options for different forms of caecal disease are not well established.

We reviewed the case records of 96 equids with caecal disease with respect to age, gender, breed of horse, prevalence of specific conditions, and, where applicable, clinical and laboratory findings, treatment and outcome. We aimed to determine whether there are breed, age, or gender predilections for caecal disease in the horse, to report on the history, clinical and laboratory findings in specific caecal disorders, and to assess the prognosis for specific disorders with various treatments.

Materials and methods

We reviewed the clinical records of all horses presented to the Veterinary Medical Teaching Hospital, University of California, Davis, with primary caecal disease between 1980 and 1990.

Breed, gender, and age distributions of the study population were determined from the records and compared with corresponding distributions of the hospital population for the same period. Apart from those horses with caecal impaction, the few horses in each category of caecal disease were considered insufficient to provide a reliable reflection of breed, gender, and age distributions so were not analysed statistically. Risk analysis was performed with the 2 test for frequency data (using expected frequencies for the respective categories in the reference population). Exact probabilities were computed from the binomial distribution, and the Wald statistic was used for comparing differences in observed multinomial class probabilities with the corresponding difference in reference population on the basis of expected multinomial class probabilities. 22 Where recorded, the means (± SD) were calculated for each disorder, for duration of signs of pain prior to presentation, rectal temperature and heart rate, haematocrit, total plasma protein concentration, and total nucleated cell count in peripheral blood, and total protein concentration and total nucleated cell count in peritoneal fluid, collected at the time of presentation. Results of transrectal examination, if performed, were also recorded. Treatment was categorised as medical or surgical, and the surgical procedure was recorded. Outcome was categorised as dead on arrival, discharged from hospital, or euthanased. Any other relevant case data were also retrieved.

Results

Diseases of the caecum were categorised as impaction, rupture associated with concurrent unrelated disease, rupture with no associated disease, rupture with parturition, infarction, torsion, abscess or adhesion, tumour, and miscellaneous conditions (caecocolic intussusception, strangulation through a mesenteric rent or strangulation through an abdominal hernia). Eleven breed categories were examined during the period of the study: Quarterhorse, Thoroughbred, Arabian, Appaloosa, Morgan, paint, Standardbred, pony and American miniature horse, draft, mule, and warmblood.

The breed and gender of horses presented with caecal disease did not differ from the normal hospital population (P < 0.05). There was no gender predisposition for horses presented with caecal impaction, however, Arabian, Morgan, and Appaloosa horses were at greater risk (P < 0.05) of presenting with caecal impaction when compared with the hospital population.

The mean (± SD) age of horses presented with caecal disease was 11 ± 5.1 y. Horses between 2 and 4 y were less
likely to suffer from caecal disease while horses older than 15 y were overrepresented (P < 0.05) when compared with the hospital population. Horses older than 15 y were more likely to be presented with a caecal impaction when compared with the hospital population, while horses less than 1 y and between 5 and 7 y were found to be at lower risk (P < 0.05).

Lesions were confirmed during surgery or autopsy in 87 horses. In the other nine horses a definitive diagnosis was not made, but all had transrectal findings consistent with caecal impaction, 1 , 5 and responded to medical treatment. The prevalences of caecal disease identified in this study were: impaction 40%, rupture associated with concurrent unrelated disease 13%, infarction 11%, rupture with parturition 9%, torsion 9%, abscess 7%, rupture with no associated disease 5%, tumour 3%, and miscellaneous conditions 3%.

Values for rectal temperature, heart rate, PCV, total plasma protein concentration, WCC, and the NCC and total protein concentration in the peritoneal fluid for each disorder are shown in Table 1 .

Horses with a caecal impaction presented with recorded signs of abdominal pain for 4 ± 3.7 d (range 1 to 21). Thirty-seven of 38 horses with caecal impaction had transrectal examination performed and 33 (89%) had findings consistent with an impacted caecum. 1 , 5 Seven horses were euthanased, either because of financial constraints (five horses) or full thickness rectal tears induced during the investigation (two horses). Ten horses were treated medically (faecal softeners via nasogastric tube, intravenous fluid therapy, and NSAIDs). Nine horses (90%) treated medically were discharged from hospital and the other died during treatment after the caecum ruptured. Twenty-one horses were treated surgically. Typhlotomy and evacuation of the caecum was performed in 14 and typhlotomy combined with a blind end ileocolostomy was performed in seven. Sixteen of 21 horses (76%) treated surgically were discharged. Ten of 14 horses (71%) treated by typhlotomy alone were discharged, the remaining 4 were euthanased due to recurrence. Six of the seven horses (86%) undergoing typhlotomy and ileocolostomy were discharged; one developed acute undifferentiated diarrhoea and died.

Twelve horses (five Thoroughbreds, five Quarterhorses, a paint horse, and an Appaloosa) from 2 mo to 23 y had caecal rupture associated with concurrent unrelated disease. Of these, five sustained caecal rupture during hospitalisation following surgery, and seven sustained caecal rupture while being treated outside the hospital. Rupture occurred 1 to 5 d after surgery with no prodromal signs. Of the horses being treated in the field, two had a history of chronic diarrhoea, three were being treated for laminitis, one had a history of weight loss, and one had foaled 10 d previously and was being treated medically for retained foetal membranes. Rupture occurred 2 to 42 d after the onset of treatment. All horses were receiving phenylbutazone at the time. The duration and dose of phenylbutazone varied. Rupture was diagnosed in two horses at surgery and ten at necropsy. Of those horses diagnosed at necropsy, eight were found dead and two were euthanased with signs of acute septic shock. Caecal ulcers were identified in six (50%). There was no common site of caecal rupture.

Ten horses (six Quarterhorses, two Arabians, one Thoroughbred, and one mule) ranging from 1 to 12 y had caecal infarction. Nine of the 10 had apparent mild abdominal pain for 12 h to 3 d while one horse showed severe acute abdominal discomfort. Transrectal findings were not diagnostic in seven horses, but in two horses and the mule a hard mass could be felt in the right caudal quadrant in the area normally occupied by the caecum. One horse and the mule were euthanased for financial reasons and eight horses underwent typhlectomy. Seven of the eight horses (88%) were discharged from the hospital, and one was euthanased because of severe laminitis.

Nine horses (three Thoroughbreds, three Quarterhorses, one Arabian, 1 warmblood, and 1 Standardbred), aged 4 to 21 y, presented with caecal rupture after parturition. Five (56%) had a history of dystocia. Signs of abdominal pain began soon after parturition. Transrectal examination did not aid diagnosis in any of these horses. Three of the nine had faecal material in the peritoneal fluid and were euthanased, and six were diagnosed and euthanased during exploratory laparotomy. The site of rupture in six (67%) mares was at the ileocaecal junction, but the sites of rupture in the other three varied.

Nine horses (four Quarterhorses, two Arabians, two Thoroughbreds, and one Morgan) aged 5 mo to 25 y were diagnosed with caecal torsion. All had a sudden onset of signs of severe abdominal pain 2 to 12 h prior to presentation. Transrectal examination did not aid in the diagnosis. Three were euthanased for financial reasons, one was euthanased because of a poor prognosis based on faecal material in the peritoneal fluid, and one died during anaesthetic induction. Five horses underwent laparotomy: two were euthanased based on a poor prognosis during surgery, and three had typhlectomy and were subsequently discharged.

Seven horses (five Thoroughbreds, one Arabian, and one pony) from 5 to 25 y had a caecal abscess or adhesions. All had a history of mild abdominal pain for 12 h to 7 d. In two horses adhesions could be felt between the body wall and the caecum on transrectal palpation. Two were euthanased for financial reasons. Five underwent a laparotomy: three horses were euthanased because the caecum was ruptured while adhesions were being broken manually; in the other two, adhesions were broken successfully, typhlectomy was performed, and they were subsequently discharged from hospital. A piece of wire caused the abscess in one case, in two there was a perforated ulcer, and no cause was identified in the other four.

Five horses (two Appaloosas, one Quarterhorse, one drafthorse, and one Thoroughbred) from 3 to 20 y presented with acute rupture of the caecum with no concurrent disease: four were presented with signs of acute endotoxic shock and one was found dead. Transrectal examination did not assist diagnosis in any of these. There was ingesta in the peritoneal fluid in three horses that had an abdominocentesis performed. The four horses were euthanased because of a poor prognosis. Necropsy showed the caecum in these horses had ruptured at various sites and no cause could be determined.

Three horses (two Arabians and one paint horse), 20 to 26 y, were found to have primary caecal tumours. All were presented for euthanasia because of chronic weight loss and no physical or transrectal examination was performed. Histological diagnoses were leiomyoma, hemangiosarcoma, and papillary adenoma.

In the miscellaneous category were a 5 y Arabian horse with a caecocolic intussusception, and two Quarterhorses, 1 and 9 y, with caecal strangulation through a congenital abdominal hernia and a mesenteric rent, respectively. The horse with the caecocolic intussusception presented for chronic weight loss and intermittent signs of mild abdominal pain. Transrectal examination did not assist diagnosis. The intussusception could not be reduced and jejunocaecal bypass was performed. The horse died 2 d following surgery. Both horses with infarcting strangulations presented with signs of acute abdominal pain of less than 12 h duration. Transrectal examination was not diagnostic in either horse. Both horses were discharged following surgical reduction of the entrapped caecum and typhlectomy.

Table 1. Clinical and laboratory findings for 96 equids with caecal disease (mean ± SD)

a One animal only sampled.

Discussion

The results of this study indicate that there is no breed or gender predisposition for horses with caecal disease. These results are consistent with previous studies on acute abdominal crises in the horse. 23-25 However, horses with caecal disease are older than the general population of horses presenting with other conditions causing an acute abdominal crisis. 23 , 25

Caecal impaction

Our findings support previous reports indicating that impaction is the most common form of caecal disease, with older horses being most susceptible. 1 , 2 , 6 In contrast to a recent report where no breed disposition was identified, 5 we found that Arabians, Appaloosas and Morgans appeared predisposed to caecal impaction.

Some investigators have indicated that transrectal palpation findings of a taut ventral band and firm ingesta filling the caecum is diagnostic for caecal impaction. 1-5 These were found in 89% of our horses with caecal impaction examined transrectally, indicating this is a relatively sensitive diagnostic procedure for caecal impaction.

The results of this study confirm reports that most horses with caecal impaction demonstrate signs of mild abdominal pain associated with slow deterioration in physical and laboratory values. 1-6 Traditionally, caecal impaction has been considered a disorder of older horses, associated with poor dentition, feeding coarse roughage, general debilitation or some combination of these. 1 , 3 , 5 More recently, a disorder in caecal motility resulting in a functional outflow obstruction has been implicated. 1 , 4-6 While parasites, dietary changes, concurrent disease processes, anaesthetic agents and NSAIDs have been implicated, the pathogenesis is not clear. 5 , 6 Consequently, many treatment regimens have been suggested, including medical therapy, 1 , 5 , 6 typhlotomy alone, 1 , 2 , 6 , 26 and various bypass techniques involving typhlotomy followed by a caecocolic anastomosis, 1 , 6 , 27 ileocolostomy, 1 , 6 , 28 or jejunocolostomy. 1 , 6 , 29 Reported success rates vary. 5 , 26-29 Where there is abnormal caecal motility, medical management or typhlotomy alone is unlikely to be successful, 1 , 6 and bypass techniques may be preferable. White 1 suggested that caecal impaction secondary to inspissated feed could be recognised on transrectal palpation as a large, firm, dehydrated, food mass within a tightly stretched caecum, while outflow dysfunction was reflected by a large ingesta filled caecum of relative fluid consistency. However previous reports indicate differentation of these two entities in a clinical setting is often impossible, making the appropriate treatment choice difficult. 1-6 , 12 In this study ten horses were treated medically and 21 were treated surgically. The 90% discharge rate after medical therapy compares favourably with a recent study. 5 Surgery was successful in 76% of cases (typhlotomy alone 71%, typhlotomy and ileocolostomy 86%). Our results confirm the suggestion that where caecal impaction is not associated with a caecal motility disorder, medical therapy or typhlotomy is often successful. 5 If caecal impaction is associated with a functional outflow obstruction, these treatments will be unsuccessful, or the impaction will recur, and bypass techniques should produce superior results. Because it is not possible to differentiate between the two conditions, we agree with others that if early institution of medical therapy is not effective or caecal distention is severe, caecal bypass should be the preferred option. 1 , 4-6

Caecal rupture associated with concurrent unrelated disease and caecal rupture with no associated disease

Horses with caecal rupture associated with concurrent unrelated disease tended to be younger than those with caecal impaction. The findings in these patients were consistent with acute endotoxic shock or Gram negative sepsis. All horses in this group were being treated with phenylbutazone, and 50% had caecal ulcers at necropsy. Previous reports have identified a relationship between NSAIDs and caecal perforation. 5 , 6 , 12 These reports suggested that NSAIDs are more likely to play a role in masking the signs of mild gastrointestinal pain rather than having a primary ulcerogenic effect on the caecum. 5 , 6 , 12 While this might be so, the relatively high prevalence of caecal ulceration in the present study might suggest that NSAIDs contribute to caecal rupture by exacerbating existing intestinal ulceration associated with the concurrent disease, or, when the course of therapy is longer, may contribute to primary ulcer development. The varied site of perforation is consistent with previous reports. 6 , 12 General anaesthesia and tapeworm infestation have been implicated in the pathophysiology of this disease, 6 , 12 but only 42% of horses with caecal perforation in our study had undergone general anaesthesia and no tapeworms were identified at necropsy. The cause of caecal perforation in five horses presented with acute caecal rupture associated with no definable concurrent disease was unknown.

Caecal infarction

Caecal infarction has been reported to occur more commonly in horses less than 1 y old. Signs at presentation vary from mild abdominal pain and diarrhoea, to severe abdominal pain with acute cardiovascular collapse. 6 Affected horses in the present study ranged from 1 to 12 y old. All but one was presented with signs of mild abdominal pain increasing in severity over 1 to 24 h. Only one had diarrhoea. Peritoneal fluid analyses revealed severe inflammation consistent with intestinal ischaemia. Transrectal findings indicated a firm mass in the area of the caecum in 30% of cases. In all cases, the persistent signs of abdominal pain and the peritoneal fluid analysis were considered indicative of the need for surgery. Apart from one horse that developed laminitis, partial typhlectomy provided successful treatment, indicating the prognosis for affected horses may be good.

Caecal rupture with parturition

The cause of caecal rupture associated with parturition is unknown. 1 , 6 , 12 Previous reports suggested that death usually occurs within 24 h of parturition, although rupture occurred during gestation in one case. 7-9 , 11 , 12 All horses reported here showed signs of acute and persistent abdominal pain that began soon after foaling, suggesting that rupture was associated with events during parturition. Five of the nine horses (56%) received assistance at foaling. Rupture of the mesentry of the descending colon or jejunum during parturition in the horse is thought to result from vigorous reflex movements of the foetus during the first stage of labour, when it rotates from dorsal recumbency into a position for delivery. 30-32 Previous reports have indicated no consistent site of rupture, 7-9 , 11 , 12 but six of the nine mares in this study ruptured at the ileocaecal junction. The relatively fixed nature of the distal ileum as it joins the caecum might predispose this area to tearing if caecal mobility is reduced by the enlarged uterus. All mares presented with clinical and laboratory findings consistent with endotoxaemia or Gram negative sepsis. In the eight horses where abdominal fluid was obtained, three had evidence of faecal contamination, and five had changes consistent with peritonitis.

Caecal torsion

Caecal torsion is uncommon as a primary disease, 6 but has been reported secondary to hypoplasia of the caecocolic fold, 19 and in association with an absence of dorsal mesenteric attachments of the caecum. 20 While previous reports involved young Standardbreds, there was no apparent breed or age predisposition in our nine cases. All horses with caecal torsion presented with severe acute abdominal pain and in most cases transrectal palpation, haematology, and abdominal fluid analysis did not contribute to the diagnosis. Typhlotomy has been recommended where vascular compromise is severe, 1 and was successful in three of the five cases here. The degree of necrosis and abdominal contamination in the remaining two cases was associated with a poor prognosis and would suggest that early surgical intervention is warranted. Caecocolic fold hypoplasia or mesenteric defects were not reported in any horses in this study, but hypoplasia of the caecocolic fold may have gone unnoticed.

Caecal abscess or adhesion

Caecal abscesses with associated adhesions have not been reported previously in equids. In this study there appeared to be no age or breed predilection for this disorder. Apart from one horse with weight loss and pyrexia for 7 d before presentation, affected horses were presented following signs of mild abdominal pain for 1 to 3 d. Physical and haematological findings were not specific for an abdominal lesion in six of the seven horses. When peritoneal fluid was obtained, common findings consistent with peritonitis included increased total protein concentration and NCC. Transrectal examination assisted the diagnosis in two horses when adhesions could be felt. Surgical intervention was successful in horses where the adhesions could be broken down and the abscess and surrounding tissues resected without rupture of the caecum.

Miscellaneous conditions

Caecal tumours appear to be rare in the horse 33 , 34 and comprised only 3% of caecal diseases in the horses reported here. All three horses were old and presented for euthanasia for chronic weight loss without signs of abdominal pain. The prevalence of caecocolic intussusception in this study was low and consistent with previous reports. 1 , 4 , 6 Other conditions were sporadic. Caecal-cutaneous fistula has been reported following treatment of an abdominal hernia with a hernia clamp 21 suggesting that the caecum has the potential to become strangulated within a hernia.

Conclusion

Caecal disorders are an uncommon cause of gastrointestinal disease in the horse. This study would suggest that in some horses showing signs of gastrointestinal disease, specific features of the history and physical findings can alert the veterinarian to the possibility of caecal involvement. In horses where caecal rupture has not occurred medical or surgical therapy can be effective.

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(Accepted for publication 5 December 1996)

Information from the AUSTRALIAN VETERINARY JOURNAL - Vol 75 No 8 printed August 1997

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