Lymphocytic-Plasmacytic Enteritis as a Cause of Long-Lasting Weight Loss and Recurrent Colic in an Elderly Horse

Lymphocytic-Plasmacytic Enteritis (LPE) is an uncommon cause of chronic inflammatory bowel disease in horses. The proliferative inflammatory cell infiltrate results in diffuse mucosal inflammation and impaired nutrients absorption, leading to chronic weight loss, recurrent abdominal pain and hypoproteinemia. This article reports the case of a 25-year-old horse with LPE causing long-lasting severe cachexia and recurrent colic episodes. A positive response to diet changes and medical treatment with corticosteroids was observed during a short period of time. However, relapse of recurrent colic episodes refractory to medical treatment determined the euthanasia of the horse. Chronic Inflammatory Bowel Disease; EPE: Equine Proliferative Enteritis; LPE: Lymphocytic Plasmacytic Enteritis; MEED: Multisystemic Eosinophilic Epitheliotrophic Disease; OGTT: Oral Glucose Tolerance Test Lymphocytic-Plasmacytic Enteritis as a Cause of Long-Lasting Weight Loss and Recurrent Colic in an Elderly Horse. idiopathic and lymphocytic-plasmacytic


Introduction
Intestinal malabsorption implies impaired digestive and absorptive processes due to functional or structural disorders of the small intestinal tract and/or related organs, such as pancreas, liver and biliary tract. Primarily clinical signs observed in affected horses are chronic wasting and poor body condition. Other signs may include recurrent colic, diarrhoea, anorexia, lethargy, fever, edema and skin lesions [1]. Malabsorption can be diagnosed by performing an Oral Glucose Tolerance Test (OGTT). Horses with total malabsorption reveal an increase of blood glucose less than 15% over the resting level 120 minutes after administering 1g of glucose per kg bwt as a 20% solution by nasogastric intubation [2]. Chronic Inflammatory Bowel Diseases (CIBD) are the most common cause of malabsorption in adult horses. Other causes include extensive small intestinal resection, enteric infections (Mycobacterium tuberculosis, Aspergillus fumigatus, Lawsonia intracellularis), parasitic infections (cyathostominosis), intestinal lymphoma and intestinal fibrosis [3].
CIBD collectively refers to a group of proliferative or inflammatory intestinal diseases, classified according to the cellular infiltrate type. Other frequent pathological changes within the small intestinal mucosa include villous stunting, fusion and deformation [4]. Differentiation between different causes of CIBD relies upon histopathological examination. In horses, main proliferative diseases causing CIBD are granulomatous enteritis, idiopathic eosinophilic enterocolitis, multi systemic eosinophilic epitheliotropic disease (MEED) and lymphocytic-plasmacytic enterocolitis [5]. In this paper, we report a case of Lymphocytic-Plasmacytic Enteritis (LPE) in an elderly horse, presenting longlasting severe cachexia and recurrent colic episodes [6].

Case history
A 25 year-old crossbreed gelding was brought to the clinic for colic examination. Anamnesis included long-lasting weight loss and recurrent colic episodes responsive to medical therapy. The horse was properly vaccinated and dewormed. Current feeding plan included low quality hay and regular grain, both fed twice daily.
General clinical examination revealed a 1/9 body condition score, tachycardia and tachypnea (72 bpm and 32 rpm, respectively), normal rectal temperature and generalized hypomotility [7]. Blood The horse was kept in short grass pasture over the day, receiving small amounts of soaked hay multiple times a day. Bran mash was also provided twice daily. During the course of treatment and following three months the horse remained comfortable with appetite improvement, although no remarkable changes in body condition were observed. Colic episode relapses started to occur, becoming progressively less responsive to medical therapy.
Based on horse's clinical condition and for well-being reasons, euthanasia was performed with owner consentment. Postmortem examination was immediately performed. Thickened-wall jejunum was macroscopically identified in about 80% of its full length, followed by samples collection and preservation in 10% formol.
Histopathological analysis revealed the presence of chronic LPE, with severe villi and mucosa glands atrophy (Figures 1 & 2).   Treatment for equine CIBD is based on dietary adjustments and corticosteroid therapy with prednisolone or dexamethasone, with medical therapy being necessary for a period rarely less than 3 months. In the presented case, due to financial reasons medical treatment was performed only for two weeks, although a positive response was observed, with appetite improvement and absence of colic signs during the following 3 months. Although results from previous studies vary, LPE is associated with long-term poor prognosis. Degree of villous atrophy seems to be a determining factor on prognosis establishment. Chronic LPE is reported as an uncommon cause of malabsorption syndrome in horses. In this case report, we present the case of an elderly horse with malabsorption syndrome caused by a well-advanced LPE, with more than 5 years of weight loss and recurrent colic history. Medical therapy and dietary changes were tried under limited conditions, and despite we found a positive response in the following months, relapse of recurrent colic episodes refractory to medical treatment determined the euthanasia of the horse.

Declaration
The authors have declared no competing interests.