EQUINE VETERINARY EDUCATION / AE / SEPTEMBER 2018


467


TABLE 1: Case signalment, preoperative clinical parameters and outcome of the five horses with focal eosinophilic colitis lesions of the small colon


Case number Age (years)


Gender Breed


Bodyweight (kg)


Stereotypical behaviour Duration of colic signs (h) Preoperative diarrhoea


Preoperative abdominal distention Temperature (°C) HR (beats/min) PCV (%) TP (g/l)


Lactate (mmol/l)


Resection length (cm) Survival days


Cause of death * Data not available.


intensely hyperaemic, with moderate diffuse eosinophil dominated cellular infiltrates and fibroblast activation (Fig 2d). There was no evidence of an aetiological agent on examination of these portions of small colon using standard (haematoxylin and eosin) stains.


Outcome Following an initial good recovery from surgery, Horse 1 deteriorated rapidly


11 days post-operatively and


Fig 1: Gross appearance of focal eosinophilic colitis lesions identified in the small colon at exploratory laparotomy, demonstrating the degree of serosal hyperaemia and petechation evident, together with focal areas of mural necrosis.


varying degrees of ulceration, intense hyperaemia and moderate multifocal haemorrhage, with moderate mixed cellular infiltrates of plasma cells, lymphocytes, macrophages and often mild but sometimes moderate infiltrates of eosinophils


(Fig 2a). Moderate infiltrates of neutrophils


accompanied ulcerated areas. The submucosa was markedly hyperaemic, with multifocal haemorrhage and severe diffuse oedema with lymphangiectasia and fibrin exudation. Severe multifocal to coalescing aggregates of primarily


perivascular macrophages and eosinophils


dominated on a background of diffuse cellular infiltration (Fig 2b). The muscularis was characterised by multifocal to coalescing aggregates of eosinophils and macrophages, sometimes with mild infiltrates of neutrophils. Additionally, there were multiple foci of homogenous eosinophilic debris, surrounded by macrophages and multinucleated giant cells with an outer rim of lymphocytes (eosinophilic granuloma). Occasionally these foci were associated with inflammatory tracts extending between muscle layers, coalescing with follicular lymphoid aggregates (Fig 2c). Serosal regions were


developed marked abdominal pain that was nonresponsive to analgesia. The owner did not want repeat laparotomy to be performed and the gelding was subjected to euthanasia on Day 12. Post-mortem examination revealed multiple adhesions between the small intestine and small colon anastomosis site resulting in a small intestinal obstruction. A small 3–4 mm defect was evident in the anastomosis once the adhesions had been dissected. Horses 2, 3 and 4 recovered uneventfully and were discharged at a mean of 10.33 days post-operatively (short- term survival of horses recovered from surgery was 75%). Horse 2 was subjected to euthanasia 184 days post- operatively due to recurrent colic episodes, but no post- mortem examination was performed. Horse 3 was still alive at the time of writing, with no further signs of colic observed. Horse 4 was subjected to euthanasia 257 days post-operatively following an acute injury and fracture associated with the cubital joint.


Discussion


This study is the first to describe the clinical and histopathological features of a series of focal eosinophilic lesions of the small colon. The lesions were visibly striking in appearance and should be considered as a rare, but possible cause of simple obstruction of the small colon, when there is no evidence of a primary intraluminal obstruction, which may necessitate intestinal resection. There are both similarities and differences between the clinical and histological features of focal eosinophilic lesions of the small colon, when compared with those previously described in both the large colon (Edwards et al. 2000) and small intestine (IFEE; Archer et al. 2006).


© 2016 EVJ Ltd


1 7


Gelding TBX 508 No *


No No


37.6 48 37 75 *


15 12


Colic-related 2 11


Gelding Cob 484 No 75


No Yes


37.9 88 30 62 *


30 184 Colic-related


3 7


Mare Pony 365


Crib biter *


No * *


68 35 62


1.4 60


>2000 N/A


4 18


Gelding WB 500 No *


No No


37.9 46 27 70


1.7


180 257


Fractured elbow 5 21


Gelding Cob 562 No 4


No Yes


38.2 60 40 78


2.5


N/A 0


Lesion inoperable


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