How should protein-losing enteropathy in dogs be worked up and what are the treatment options?

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Canine protein-losing enteropathy (PLE) is a life-threatening syndrome with a pooled case fatality rate of 54.2%, making systematic workup and prompt, layered treatment essential. The most common underlying causes are chronic inflammatory enteropathy (CIE) and intestinal lymphangiectasia (IL), which frequently coexist — 76% of dogs with CIE and PLE have concurrent lacteal dilation on histopathology.6 ---  Diagnostic Workup The hallmark laboratory finding is hypoalbuminemia, but the full biochemical picture guides both diagnosis and prognosis. Additional abnormalities include hypoglobulinemia, hypocholesterolemia, lymphopenia, hypocalcemia, and hypomagnesemia.8 At presentation to a veterinary nutrition service, mean albumin was 2.40 ± 0.64 g/dL, mean globulin was 2.43 ± 0.71 g/dL, and mean cholesterol was 129 ± 63 mg/dL.1 Serum albumin below 2.0 g/dL, hypocobalaminemia, and hypovitaminosis D are established negative prognostic indicators.810 Vitamin D concentrations below the reference interval are common in PLE and are associated with worse outcome compared to dogs with normal vitamin D.13 Cobalamin, vitamin D (25-hydroxyvitamin D), and C-reactive protein should be measured at baseline. Hypocobalaminemia correlates with serum albumin concentration and carries negative prognostic significance.8 Elevated C-reactive protein and decreased 25-hydroxyvitamin D both have independent prognostic value.8 Serum symmetric dimethylarginine (SDMA) may be elevated in PLE dogs due to increased protein turnover rather than renal disease, which is relevant when interpreting renal biomarkers in this population.12 Hypercoagulability is a clinically important systemic complication documented in 45% of dogs with chronic enteropathy and was suspected as the cause of mortality in 10% of Yorkshire terriers with PLE — coagulation assessment is warranted in severely affected cases.11 Additional systemic complications to investigate include tryptophan deficiency and vitamin D3 deficiency.10 In