Other Laboratory Findings With Hepatic Disease

Dogs with congenital PSSs often have erythrocyte microcytosis which may or may not be accompanied by anemia, hypochromic RBCs, or both. The reason for this finding is not known, but may relate to impaired transferrin synthesis and iron utilization rather than true iron deficiency.

The abnormal lipid metabolism that can accompany liver disease may result in cholesterol loading of erythrocyte membranes and increased presence of leptocytes and codocytes on peripheral blood smears. Cats with hepatic disease often have abnormal erythrocyte morphology, particularly echinoelliptocytes. Acanthocytes are infrequently associated with liver disease in domestic animals.

Animals with diffuse inflammatory hepatic disease, such as cholangiohepatitis, may have inflammatory leukograms. Also, increased endogenous cortisol concentrations associated with illness may result in a stress leukogram with neutrophilia and lymphopenia.

Ammonium urate crystals can be seen on urine sediment examination in those animals with impaired urea synthesis, most often associated with PSSs. Occasionally these result in urolithiasis.

Impaired urea synthesis, leading to low serum urea concentration, can interfere with the corticomedullary gradient in the kidneys and, consequently, result in an inability to concentrate urine. Such animals may be polyuric and polydipsic and have USGs in the isosthenuric to hyposthenuric range, in the absence of renal disease.