Clinical gastroenterology: Presentation is everything (Proceedings)

Hypoalbuminemia

Although the combination of hypoalbuminemia and hypoglobulinemia is "textbook" for a protein-losing enteropathy (PLE) – assuming the dog is not bleeding out in front of you or has presented with 3rd degree burns over most of its body – it should be noted that a normal, or even elevated globulin level should never be the only reason to take PLE off a list of differentials that was generated by a history and physical examination. It should also be noted that PLE is not really a diagnosis at all, but simply a description of the consequences of the severity or chronicity of the actual underlying problem. The diagnostic work-up can begin by adjusting the above list of PLE differentials based on the breed and age of the dog, with IBD being more common in older animals, lymphosarcoma being less particular, and lymphangiectasia preferring certain breeds. Parvovirus and intussusception often occur together in young dogs, as does heavy GI parasitism, while histoplasmosis has a geographical distribution.

Hypoalbuminemia and protein-losing enteropathy differentials

Once hypoalbuminemia is noted on the biochemical profile and globulins are assessed the clinician needs to confirm that there is no significant loss of protein in the urine (urine protein:creatinine ratio) and the liver is cable of producing adequate protein (other biochemical indicators of liver function followed by a bile acids test if necessary). Other common laboratory abnormalities consistent with PLE include lymphopenia, hypocholesterolemia, hypomagnesemia, and hypocalcemia. It would be unusual for an animal with a PLE not to present with diarrhea, and a thorough fecal examination is an essential part of that diagnostic work-up. In addition, feces can be submitted (Texas A&M GI Laboratory) for measurement of fecal a1-protease inhibitor enzyme quantification, a molecule that is of similar size to albumen but is not degraded in it's journey through the GI tract, and hence, and indirect marker of albumen loss and a relatively sensitive (more sensitive than serum albumen?) marker of protein-loss through the GI tract.

The most direct route to a diagnosis in cases of PLE is histopathology. The advantages and pitfalls of the various techniques available (endoscopy, laparoscopy, and exploratory surgery) is beyond the scope of these notes. It is common for lesions suggestive of lymphangiectasia AND inflammatory bowel disease to be present within the same biopsy sample – the bursting of lacteals and release of their contents is likely to set up an inflammatory response, and the crowding of the interstitial space with cells of the immune system is likely to impede normal lymphatic flow. This makes the site (duodenum versus ileum), depth (mucosal versus full-thickness), and quality of the biopsy of significant importance in final interpretation. The potential diagnostic yield provided by abdominal ultrasound prior to any of the above-listed techniques is also beyond the scope of this discussion, as the literature continues to debate the significance and sensitivity of certain ultrasonographic abnormalities, such as a loss of normal intestinal wall architecture, intra-mural "speckles", or enlarged mesenteric lymph nodes..

Sig: 1.5 yo FS Yorkshire Terrier

CC: "Big belly"

Ascites, peripheral limb edema, and dyspnea secondary to pleural effusion suggest an albumen concentration < 1.5 g/dL.

Lymphangiectasia

Breed predisposition: Yorkshire and Soft-Coated Wheaten terriers

NOTE: If endoscopy is planned and lymphangiectasia is a primary differential, administration of corn oil one hour prior to the biopsy procedure may increase the likelihood of documenting dilated lacteals (Drs. Willard and Zoran, Texas A&M).

Treatment options for lymphangiectasia

Inflammatory bowel disease, alimentary lymphosarcoma

Exception to "The Rule"

Histiocytic ulcerative colitis