Page 822 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Gastrointestinal system: 4.2 The lower gastrointestinal tr act 797

VetBooks.ir eosinophilic epitheliotropic disease (MEED) eosinophilic granulomas associated with vasculitis
and fibrinoid necrosis of intramural vessels, in con-
involves the intestinal tract and other organs.
Aetiology/pathophysiology trast to eosinophilic infiltrates that may be present
normally.
The aetiology is unknown. No breed or familial
predispositions have been reported for EE. Most Management
cases of MEED have been in young (<4 years of age) The long-term prognosis is guarded. Oral cor-
Standardbred horses. EE is characterised by eosino- ticosteroids (prednisolone, 1 mg/kg p/o q12 h for
philic infiltration of all layers of the intestine and 28 days, followed by gradual tapering) may be
fibrosis. MEED is characterised by infiltration of the effective. Intestinal obstruction by fibrous circum-
mucosa and submucosa of the intestine with eosino- ferential bands may cause recurrent colic. Some
phils, lymphocytes and macrophages, as well as inva- affected horses can be managed by feeding small
sion of other organs. Liver and pancreatic disease is meals of a pelleted complete ration, while resection
common. Basophilic enterocolitis is thought to be a of the affected area(s) may be required in others.
variant of MEED. Treatment of MEED is usually unrewarding,
although one horse treated repeatedly with paren-
Clinical presentation teral dexamethasone was reported to have survived
The most commonly reported presentation of EE is for at least 18 months. Administration of larvicidal
abdominal pain. Weight loss is uncommon and diar- anthelmintics has been suggested for both EE and
rhoea is rare. In horses with MEED, weight loss is MEED because nematode larvae have been pos-
almost invariably present and diarrhoea is common. tulated as having a role in the pathogenesis of the
Approximately two-thirds of horses with MEED diseases.
have skin lesions, consisting of exudative dermatitis
of the face, limbs and ventral abdomen. Lingual and Prognosis
buccal ulceration may be present. Ulcerative coroni- The prognosis for EE is reasonable. Horses that
tis and loss of chestnuts may also occur. respond to corticosteroid therapy often do not
experience a recurrence of disease. The presence of
Differential diagnosis fibrous circumferential bands worsens the progno-
A variety of differential diagnoses must be consid- sis; however, surgical intervention may be successful.
ered, depending on the clinical presentation. Causes In contrast, the prognosis for horses with MEED is
of colic, weight loss, hypoproteinaemia and skin very poor.
lesions may need to be evaluated.
CHRONIC AND RECURRENT COLIC
Diagnosis
Haematological abnormalities are uncommon Definition/overview
with EE. Carbohydrate absorption tests are typi- Chronic and recurrent colic are frustrating prob-
cally normal. Diagnosis is based on surgical biopsy lems that are often difficult to diagnose and manage.
and histological examination of affected intestine. Chronic colic has been defined as colic persisting for
Circumferential fibrous bands may be present in the 3 days or longer; however, this definition also encom-
intestinal wall, resulting in intestinal distension. passes cases of acute colic that are poorly responsive
Hypoproteinaemia, mainly from hypoalbu- to initial therapy. Recurrent colic is defined as mul-
minaemia, is common with MEED. WBC num- tiple, distinct episodes of colic.
bers are usually normal, but some horses may
have a marked eosinophilia. Biochemical changes Aetiology/pathophysiology
may be present depending on the involvement of The causes of chronic and recurrent colic are var-
other organ systems. Rectal mucosal biopsy can ied and often difficult to identify, even with aggres-
be diagnostic in many cases by identification of sive diagnostic testing. Some cases are extensions of