Clinicopathologic manifestations of progressive renal disease in Lhasa Apso and Shih Tzu dogs

Abstract

SUMMARY Chronic generalized renal disease was detected in 21 Lhasa Apso and 14 Shih Tzu dogs. Most were growing pups or young adults at the time of diagnosis. The most commonly reported clinical abnormalities were vomiting, polydipsia, weight loss, and diarrhea. Less frequently reported signs included polyuria, anorexia, dehydration, and depression. Common abnormal laboratory findings included non-regenerative anemia, impaired ability to concentrate urine, and azotemia. Less common abnormal laboratory findings included hyperphosphatemia, hypocalcemia, metabolic acidosis, hypoproteinemia, hyperamylasemia, and mild hyperkalemia. Two dogs were mildly hypercalcemic. Gross morphologic renal changes included bilateral reduction in size and irregular capsular surfaces. Microscopic lesions of varying severity affected various components of nephrons in the cortex and medulla. Cortical lesions were often segmental in distribution; medullary lesions were consistently diffuse and generally more severe than those in the cortex. Lesions in both areas commonly resulted in destruction of nephrons, with subsequent replacement by collagenous connective tissue. Infiltrates of interstitial mononuclear cells were conspicuously absent. The cause of the renal disorder in Lhasa Apso and Shih Tzu dogs could not be determined on the basis of observations in this study. Current managment is limited to appropriate supportive and symptomatic therapy designed to minimize fluid, electrolyte, acid-base, endocrine, and nutrient imbalances caused by renal dysfunction.