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Approach to Feline Chronic EnteropathyAndrew Kent BVSc DipECVIM-CA MRCVSChronic enteropathy is defined as the presence of clinical signs of gastrointestinal disease (diarrhoea, vomiting, weight loss and change of appetite) for longer than 3 weeks. This is a common presentation, in both cats and dogs, and a logical approach to investigations is essential to facilitate accurate diagnosis and treatment. Feline chronic enteropathy is particularly challenging due to the lack of evidence to guide therapy and the unclear aetiology. In dogs, chronic enteropathy is subdivided based on response to treatment and a similar approach is likely reasonable in cats:Food-responsive enteropathy (FRE)Antibiotic-responsive enteropathy (ARE) or small intestinal dysbiosisImmunosuppressant-responsive enteropathy (IRE) An important further category in this species would be alimentary lymphoma (typically small cell). Whilst this can present in a very similar way to an inflammatory enteropathy it has prognostic significance. The percentage of cats that fall into each category is unknown but, based on recent testing techniques, it is possible that up to 50% of cats with chronic gastrointestinal signs may have lymphoma.Aetiology of Chronic EnteropathyThe triggers for inflammation of the gastrointestinal tract and consequent chronic enteropathy remain poorly defined, especially in cats. The breakdown of immunologic tolerance to luminal antigens (including bacterial and dietary components) is likely critical and may result from disruption of the mucosal barrier, immune dysregulation, or disturbance of the intestinal microbiota. Genetic factors are also likely to play a significant part however investigation into this aspect in cats is lacking.The antigens derived from commensal bacteria are likely to be particularly important in cats based on the association observed between bacteria and inflammation in some studies.Cats commonly present with a unique syndrome, known as ‘triaditis’, and characterised by inflammatory gastrointestinal, pancreatic and hepatic disease. The link between these organs is unclear but hypotheses include anatomical predisposition and translocation of bacteria.Diagnosis of Chronic EnteropathyA standardised diagnostic approach to chronic enteropathy has been described in dogs, and applies equally to cats. This provides a logical method to investigating cases:Exclusion of extra-gastrointestinal diseaseCharacterisation of the nature and severity of disease Selection of treatment based on this severity assessmentThis approach can be further broken down into an adaptable diagnostic algorithm as follows:Clinical history and examinationLarge intestinal localization (dyschezia, tenesmus, increased frequency of defecation, small volume of faeces, mucous, blood).Small intestinal localization (large volume diarrhoea, weight loss, vomiting).Melaena (suggesting upper GI bleeding/ulceration).Atypical signs suggestive of other system involvement (e.g. PUPD)Detection of endoparasites and enteric pathogens or a therapeutic trial with a broad spectrum anthelminticClinicopathological Testing.Detection of non-GI diseaseHaematologyBiochemistryUrinalysisThyroid testingfPLIDetection & characterisation of GI diseaseTLIFolate & CobalaminDiagnostic ImagingRadiographs – structural GI disease.Abdominal ultrasound – obstruction, intussusception, focal masses, thickening, intestinal layering, hyperechoic striations. Also, evaluation of organs intimately associated with the GI tract (pancreas, liver, biliary tract).Clinical staging based on disease activity indexSeveral validated scoring systems are available including the Feline Chronic Enteropathy Activity Index (FCEAI).Therapeutic trials with diet +/- antibiotics.For cases with a high FCEAI or that have failed to respond to appropriate diet trials (exclusion diet fed for 3 weeks) and antibiotic therapy (see below), acquisition of histologic samples may be pursued. Endoscopic gastrointestinal biopsy:May be preferred if there is significant hypoalbuminaemia (wound healing)Samples obtainable from stomach, duodenum, ileum and colonSurgical gastrointestinal biopsyBiopsy samples are assessed for the severity of inflammation and any structural changes as well as the presence of malignancy (e.g. gastrointestinal lymphoma).In cats the use of clonality testing (for example PARR) may significantly increase the sensitivity for detecting alimentary lymphoma.Treatment of Chronic EnteropathyExclusion diet trial Commercial hydrolysed diet (consider choice of protein source)Commercial novel protein diet Home-cooked novel protein diet (ideally formulated by a nutritionist unless only fed for a short period of time)Antibiotic therapy (trial)Questionable antibiotic stewardship May offer effective treatment for their clinical signsMetronidazole (10mg/kg PO every 12 hours) Tylosin (10-40mg/kg PO every 12 hours) Immunosuppression Glucocorticoids, usually prednisolone (1-2mg/kg/day) considered first-line treatment BUT: adverse effect profile including catabolic effects that can lead to further weight loss (especially muscle mass) in already cachexic patients. Additional immunosuppressant medications can facilitate a more rapid taperChlorambucil (at 2mg per cat every 48-72hours) Ciclosporin (at 5mg/kg every 12-24 hours)Cobalamin supplementation if hypocobalaminaemic Injectable therapy Oral supplementation may be effective in some cases.Short-term supportive treatments Antacids (omeprazole, ranitidine)Anti-emetics (maropitant, metoclopramide, ondansetron)Pro-kinetics? (efficacy difficult to document) Mucosal protectantsTreatment of alimentary lymphomaAlimentary lymphoma (small cell) is typically treated with a combination of prednisolone and chlorambucil and can still have a reasonable prognosis if treated in this way (18 to 24 months). ................
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