Canine protein-losing enteropathies

There are a variety of disorders that can cause dogs to lose protein through their gastrointestinal tract. Overall, they are classified as “protein-losing enteropathies”, but there are a bewildering number of potential causes; Rance Sellon offers an overview of the condition, including a review of the signs, the diagnostic options and the potential treatments for the most common diseases.

Introduction

Protein-losing enteropathy (PLE) reflects a collection of gastrointestinal (GI) diseases characterized by enteric loss of proteins, principally albumin, but also globulins in some cases. Enteric protein loss in dogs can occur through any segment of the GI tract, but oral cavity and esophageal diseases are rare causes of PLE. Disease of the stomach and colon can occasionally cause PLE, but chronic dis-eases of the small intestine are the most common reasons. This article will provide an overview of the clinical features, diagnostic and treatment considerations for the most common etiologies of canine small intestinal PLE (Table 1) but more detailed information for many of the individual causes of PLE can be found elsewhere (1).

Signalment and clinical features

Any dog can develop a PLE, but several breeds, including yorkshire Terriers, Rottweilers, Wheaten Terriers, Norwegian Lundehunds, and German Shepherds are predisposed. Canine PLE may develop at any age, and the clinical signs can be variable, although weight loss (which may be seen with a normal or decreased appetite), vomiting and/or diarrhea are commonly noted. Some dogs develop hematemesis or melena if proximal GI tract bleeding occurs. In patients exhibiting diarrhea, features usually, but not always, localize diarrhea to the small intestine. However, not all patients with a PLE exhibit vomiting and/or diarrhea, so the absence of these signs should not lessen the suspicion of a PLE if other clinical aspects are consistent. Some owners will report abdominal distension (from ascites) or peripheral edema, or changes in respiratory rate or character (from pleural effusion) as the primary clinical sign. Occasional patients with a PLE are diagnosed after hypoalbuminemia is found incidentally on a serum biochemical profile and other causes of hypoalbuminemia have been excluded. Uncommonly, seizures secondary to hypocalcemia may be seen ( 2 ).

Physical examination abnormalities in dogs with PLE are also variable. Poor body condition could be expected in animals that have experienced weight loss. Peripheral edema, abdominal distension, and a palpable fluid wave are possible in patients with severe hypoalbuminemia. In some cases, there may be thickened loops of bowel or intestinal masses, so a careful and thorough abdominal palpation is a critical component of the physical examination, especially when abdominal effusion is absent. A rectal examination may reveal enlarged sublumbar lymph nodes in dogs with GI lymphoma or other infiltrative GI disease. Melena, which can also be detected by a rectal examination, can be a feature of some dogs with bleeding upper GI tract lesions. [...]