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1. Description of PLE/PLN

2. Description of Renal Dysplasia

3. Recommended screening for all SCWT

4. Treatment of SCWT affected with PLE/PLN

5. Prognosis of affected SCWT

1. Description of PLE/PLN

In 1990, Drs. Littman and Giger first described protein-losing enteropathy (PLE) and protein-losing nephropathy (PLN) in 19 closely related soft coated wheaten terriers (SCWT). Unfortunately, the diagnosis has since been established in a larger number of dogs. In fact, Dr. Littman has now accumulated data from 222 affected SCWT. Of these dogs, 34% had PLE, 38% had PLN and 27% had both PLE and PLN. The incidence of subclinical PLE or PLN in dogs said to have only PLN or PLE, respectively, has not been determined. Ages of affected dogs range from 6 months to 12 years, although most dogs are 4-6 years of age at the time of diagnosis. Females are diagnosed with the disease more commonly than are males (Female:Male = 1.5 to 1.7). Affected dogs may exhibit vomiting, diarrhea, weight loss, lethargy, decreased appetite, fluid accumulation (peripheral edema, abdominal effusion), and/or increased water intake and urination. Occasionally, affected dogs will form blood clots within the body (thromboembolic disease) or have high blood pressure (hypertension). As many as 23% of the dogs in Dr. Littman's study were reported to have skin problems; many of these dogs were diagnosed with allergic skin disease.

The most common clinicopathologic (bloodwork) abnormality in affected SCWT is a low blood protein (hypoproteinemia). Dogs with PLN usually have only low albumin (hypoalbuminemia). Dogs with PLE can have low albumin (hypoalbuminemia) and low globulin (hypoglobulinemia). Dogs with PLN are losing protein through the kidney and may have increased urine protein:creatinine ratios. Likewise, dogs with PLE are losing protein through the intestinal tract and often have increased fecal alpha¹-protease inhibitor (API) concentration. Finding a normal fecal API and/or a normal urine protein:creatinine ratio should not be interpreted as finding a normal SCWT. A more appropriate interpretation is that they are not losing substantial amounts of protein in the urine or feces at the time the samples are collected.

Dogs with PLE may also have low cholesterol (hypocholesterolemia), whereas dogs with PLN may have high cholesterol (hypercholesterolemia). Dogs with PLN may present in kidney failure and have increased serum creatinine and urea nitrogen (azotemia), increased phosphorous (hyperphosphatemia) and anemia. Dogs with PLE or PLN may have decreased peripheral blood lymphocyte counts (lymphopenia), and increased (eosinophilia) or decreased (eosinopenia) peripheral eosinophil counts.

Intestinal biopsy of dogs with PLE most commonly reveals lymphangiectasia, inflammatory bowel disease and/or lipogranulomatous lymphangitis. The inflammatory infiltrate can be lymphocytic-plasmacytic, eosinophilic or of mixed cellularity. Renal biopsy most commonly shows glomerulonephritis in SCWT with PLN. Glomerulonephritis may be further characterized as membranous or membranoproliferative. Glomerulosclerosis is a common finding in dogs with advanced disease. Immunofluorescent and electron micrographic studies of kidneys from affected dogs have been limited; however, findings are consistent with a secondary glomerular disease resulting from immune-complex induced damage to the glomeruli.

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2. Description of Renal Dysplasia

Renal dysplasia is another familial renal disease of SCWT that occurs when the kidneys fail to develop properly in utero. Renal dysplasia can be differentiated from PLN by the following:

• Renal dysplasia causes renal failure and death at an earlier age than does PLN.
• Most dogs with renal dysplasia die from renal failure before 2 years of age.
• Renal dysplasia is not generally associated with protein losing enteropathy as is PLN of SCWT.
• Dogs with renal dysplasia do not generally lose excessive protein in the urine.
• Dogs with renal dysplasia have small kidneys at a very early age.
• Ultrasound of the kidneys of dogs with renal dysplasia often reveals multiple cysts. This finding is not characteristic of PLN.
• A definitive diagnosis of renal dysplasia can be established through renal biopsy.

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3. Recommended screening for all SCWT

All SCWT should be monitored for PLE/PLN on a regular basis. We recommend evaluating urine protein:creatinine ratios, fecal alpha¹-protease inhibitor concentrations and serum globulin, albumin and creatinine concentrations yearly. PLN should be suspected when the urine protein:creatinine ratio is increased in a urine sample that has not been contaminated by blood or inflammatory debris. PLE should be suspected when the fecal alpha^l-protease inhibitor concentration is increased. However, a normal urine protein:creatinine ratio and/or a normal fecal alpha¹-protease inhibitor concentration does not exclude the possibility that the dog is affected with this syndrome. Preliminary evidence suggest that affected dogs have increased fecal apha1-protease inhibitor concentrations early in life (less than 2-3 years of age), but the magnitudes of increase decreases with advancing age. The need for evaluation of renal or intestinal biopsy specimens should be determined on a case by case basis.

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4. Treatment of SCWT affected with PLE/PLN

In dogs that have isolated PLN, an attempt should be made to identify and eliminate any underlying disease that could have caused PLN. Dogs with PLN should be fed a diet that is moderately reduced in protein. Angiotensin converting enzyme inhibitors (usually enalapril) are frequently used to decreased the degree of proteinuria. Dogs that have serum albumin of < 2.0 g/dl should be given a low-dose of aspirin to help prevent thromboembolic disease. Systemic hypertension must be controlled.

Dogs with PLE should be fed a hypoallergenic diet. Food hypersensitivity reactions do occur in SCWT with PLE/PLN and begin during the early stages of the disease. However, the exact role of food hypersensitivity reactions in the pathogenesis of this disorder is unknown. Most of the dogs in our research colony are hypersensitive to multiple food allergens. Currently we are recommending that affected dogs be fed either hydrolysate or novel protein source diets. The exact role that these diets will have in the management of affected SCWT remains to be determined. There is no role for these diets in unaffected SCWT. Dogs with severe PLE may benefit from corticosteroid administration.

These treatment recommendations are made in general terms only. Some drugs or dietary changes may not be appropriate for some dogs. The treatment plan for an affected SCWT should be derived through consultation with the attending veterinarian.

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5. Prognosis of affected SCWT

The prognosis of affected SCWT is quite variable. We have seen severely affected dogs recover and live for an additional 2 to 3 years and we have seen apparently mildly affected dogs die within a couple of months of making the diagnosis. Dogs with PLN that are in renal failure at the time of diagnosis have a poorer prognosis.

Environmental factors appear to affect the severity of clinical signs. Stress should be limited whenever possible. Affected females should not be bred, not only because the disease is hereditary but also because whelping will exacerbate the disease. Frequent dietary changes should be avoided in affected dogs.

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